Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2017
Document And Entity Information [Abstract]
Document Type	S-1
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Trading Symbol	APPN
Entity Registrant Name	APPIAN CORP
Entity Central Index Key	0001441683
Entity Filer Category	Non-accelerated Filer

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 72,289	$ 31,143	$ 31,393
Accounts receivable, net of allowance of $400	41,399	46,814	34,228
Deferred commissions, current	7,719	7,146	5,316
Prepaid expenses and other current assets	6,318	3,281	2,030
Total current assets	127,725	88,384	72,967
Property and equipment, net	2,737	3,101	2,892
Deferred commissions, net of current portion	11,343	10,860	7,354
Deferred tax assets	107	12	22
Other assets	414	381	165
Total assets	142,326	102,738	83,400
Current liabilities
Accounts payable	2,712	5,057	2,633
Accrued expenses	5,977	2,860	4,350
Accrued compensation and related benefits	9,742	9,554	5,737
Deferred revenue, current	57,181	52,000	40,220
Current portion of long-term debt	0	6,111	0
Other current liabilities	574	437	564
Total current liabilities	76,186	76,019	53,504
Long-term debt, net of current portion	0	13,889	10,000
Deferred tax liabilities	35	32	916
Deferred revenue, net of current portion	14,577	18,108	12,890
Preferred stock warrant liability	0	850	650
Other long-term liabilities	1,624	1,917	1,415
Total liabilities	92,422	110,815	79,375
Stockholders' equity (deficit)
Common stock	0	3	3
Additional paid-in capital	138,767	0	0
Accumulated other comprehensive income	451	1,330	971
Accumulated deficit	(89,320)	(64,825)	(51,507)
Total stockholders' equity (deficit)	49,904	(63,492)	(50,533)
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	142,326	102,738	83,400
Series A Convertible Preferred Stock
Convertible preferred stock
Preferred stock	0	17,915	17,058
Series B Convertible Preferred Stock
Convertible preferred stock
Preferred stock	0	37,500	$ 37,500
Class A Common Stock
Stockholders' equity (deficit)
Common stock	1	0
Class B Common Stock
Stockholders' equity (deficit)
Common stock	$ 5	$ 0

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts	$ 400	$ 400	$ 400
Preferred stock, shares authorized		18,247,518
Common stock, par value	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares authorized	0	61,462,320	61,462,320
Common stock, shares issued	0	34,274,718	34,274,718
Common stock, shares outstanding	0	34,274,718	34,274,718
Series A Convertible Preferred Stock
Preferred stock, par value	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	0	12,127,468	12,127,468
Preferred stock, shares issued	0	12,043,108	12,043,108
Preferred stock, shares outstanding	0	12,043,108	12,043,108
Liquidation preference		$ 17,915
Series B Convertible Preferred Stock
Preferred stock, par value	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	0	6,120,050	6,120,050
Preferred stock, shares issued	0	6,120,050	6,120,050
Preferred stock, shares outstanding	0	6,120,050	6,120,050
Liquidation preference		$ 37,500
Class A Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	500,000,000	0
Common stock, shares issued	7,203,271	0
Common stock, shares outstanding	7,203,271	0
Class B Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	0
Common stock, shares issued	53,073,459	0
Common stock, shares outstanding	53,073,459	0

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Subscriptions, software and support	$ 22,660	$ 17,668	$ 66,116	$ 50,607	$ 69,972	$ 53,207	$ 37,076
Professional services	21,988	13,077	60,059	48,569	62,951	57,997	51,920
Total revenue	44,648	30,745	126,175	99,176	132,923	111,204	88,996
Cost of revenue:
Subscriptions, software and support	2,341	1,890	6,891	5,508	7,437	6,079	4,273
Professional services	14,272	9,315	39,049	34,016	42,686	42,402	32,524
Total cost of revenue	16,613	11,205	45,940	39,524	50,123	48,481	36,797
Gross profit	28,035	19,540	80,235	59,652	82,800	62,723	52,199
Operating expenses:
Sales and marketing	19,725	14,480	59,503	39,477	54,137	38,300	29,088
Research and development	8,596	6,702	25,867	16,925	22,994	16,750	13,488
General and administrative	6,237	4,531	19,721	12,779	17,039	12,515	23,373
Total operating expenses	34,558	25,713	105,091	69,181	94,170	67,565	65,949
Operating loss	(6,523)	(6,173)	(24,856)	(9,529)	(11,370)	(4,842)	(13,750)
Other (income) expense:
Other (income) expense, net	(425)	(67)	(1,658)	129	1,792	1,579	2,086
Interest (income) expense	(2)	243	451	726	982	188	19
Total other (income) expense	(427)	176	(1,207)	855	2,774	1,767	2,105
Net loss before income taxes	(6,096)	(6,349)	(23,649)	(10,384)	(14,144)	(6,609)	(15,855)
Income tax expense (benefit)	188	(1,610)	489	(2,106)	(1,683)	378	1,204
Net loss	(6,284)	(4,739)	(24,138)	(8,278)	(12,461)	(6,987)	(17,059)
Accretion of dividends on convertible preferred stock	0	214	357	642	857	861	856
Net loss attributable to common stockholders	$ (6,284)	$ (4,953)	$ (24,495)	$ (8,920)	$ (13,318)	$ (7,848)	$ (17,915)
Net loss per share attributable to common stockholders:
Basic and diluted (in dollar per share)	$ (0.10)	$ (0.14)	$ (0.53)	$ (0.26)	$ (0.39)	$ (0.23)	$ (0.50)
Weighted average common shares outstanding:
Basic and diluted (in shares)	60,204,596	34,274,718	45,855,044	34,274,718	34,274,718	34,274,718	35,717,803

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (6,284)	$ (4,739)	$ (24,138)	$ (8,278)	$ (12,461)	$ (6,987)	$ (17,059)
Comprehensive loss, net of income taxes:
Foreign currency translation adjustment	517	(177)	(879)	(537)	359	159	812
Total other comprehensive loss, net of income taxes	$ (5,767)	$ (4,916)	$ (25,017)	$ (8,815)	$ (12,102)	$ (6,828)	$ (16,247)

Condensed Consolidated Statement of Changes in Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Restricted Stock Units	Restricted Stock Units Common Stock
Beginning Balance (in shares) at Dec. 31, 2013		40,000,000
Beginning Balance at Dec. 31, 2013	$ (4,608)	$ 4			$ (4,612)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(17,059)				(17,059)
Repurchase and retirement of common stock (in shares)		(5,725,282)
Repurchase and retirement of common stock	(21,013)	$ (1)			(21,012)
Accretion of dividends on convertible preferred stock	(856)				(856)
Accretion of issuance costs on convertible preferred stock	(120)				(120)
Other comprehensive income (loss)	812			$ 812
Ending Balance, (in shares) at Dec. 31, 2014		34,274,718
Ending Balance at Dec. 31, 2014	(42,844)	$ 3		812	(43,659)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(6,987)				(6,987)
Accretion of dividends on convertible preferred stock	(861)				(861)
Accretion of issuance costs on convertible preferred stock	0
Other comprehensive income (loss)	159			159
Ending Balance, (in shares) at Dec. 31, 2015		34,274,718
Ending Balance at Dec. 31, 2015	(50,533)	$ 3		971	(51,507)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ (12,461)				(12,461)
Repurchase and retirement of common stock (in shares)	460,266
Accretion of dividends on convertible preferred stock	$ (857)				(857)
Accretion of issuance costs on convertible preferred stock	$ 0
Exercise of stock options (in shares)	0
Other comprehensive income (loss)	$ 359			359
Ending Balance, (in shares) at Dec. 31, 2016		34,274,718
Ending Balance at Dec. 31, 2016	(63,492)	$ 3		1,330	(64,825)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(24,138)				(24,138)
Accretion of dividends on convertible preferred stock	(357)				(357)
Conversion of convertible preferred stock to common stock (in shares)		18,163,158
Conversion of convertible preferred stock to common stock	48,207	$ 2	$ 48,205
Conversion of convertible preferred stock warrant to common stock warrant	1,191		1,191
Issuance of common stock from initial public offering, net of issuance costs (in shares)		7,187,500
Issuance of common stock from initial public offering, net of issuance costs	$ 77,789	$ 1	77,788
Exercise of common stock warrant (in shares)		79,363
Issuance of common stock to directors (in shares)		10,841
Vesting of restricted stock units (in shares)						4,930	4,930
Exercise of stock options (in shares)	556,220	556,220
Exercise of stock options	$ 664		664
Stock-based compensation expense	10,919		10,919
Other comprehensive income (loss)	(879)			(879)
Ending Balance, (in shares) at Sep. 30, 2017		60,276,730
Ending Balance at Sep. 30, 2017	$ 49,904	$ 6	$ 138,767	$ 451	$ (89,320)

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net loss	$ (24,138)	$ (8,278)	$ (12,461)	$ (6,987)	$ (17,059)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	673	567	764	763	610
Bad debt expense	0	4	7	(22)	30
Deferred income taxes	(91)	(883)	(1,122)	(291)	399
Stock-based compensation	10,919	0
Fair value adjustment for warrant liability	341	200	200	299	351
Loss on extinguishment of debt	384	0
Changes in assets and liabilities:
Accounts receivable	4,329	6,208	(11,154)	(6,639)	(1,450)
Prepaid expenses and other assets	(3,184)	(2,360)	(1,665)	(988)	130
Deferred commissions	(1,056)	(1,389)	(5,335)	(3,965)	(4,486)
Accounts payable and accrued expenses	1,202	(2,931)	1,287	1,058	1,932
Accrued compensation and related benefits	(339)	1,617	3,717	(968)	1,929
Other current liabilities	(75)	(1,377)	19	(251)	1,395
Deferred revenue	1,043	374	17,410	15,490	16,744
Other long-term liabilities	(143)	433	577	356	1,009
Net cash used in operating activities	(10,135)	(7,815)	(7,756)	(2,145)	1,534
Cash flows from investing activities:
Purchases of property and equipment	(295)	(935)	(984)	(524)	(2,633)
Net cash used in investing activities	(295)	(935)	(984)	(524)	(2,633)
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriting discounts	80,213	0
Proceeds from issuance of long-term debt			20,000	10,000	0
Payment of deferred initial public offering costs	(2,424)	0
Payment of dividend to Series A preferred stockholders	(7,565)	0
Proceeds from exercise of common stock options	664	0
Proceeds from issuance of long-term debt, net of debt issuance costs	19,616	20,000
Repayment of long-term debt	(40,000)	(10,000)	(10,000)	0	0
Proceeds from issuance of Series B convertible preferred stock, net of offering costs			0	0	37,380
Repurchase of common stock			0	0	(21,013)
Net cash provided by financing activities	50,504	10,000	10,000	10,000	16,367
Effect of foreign exchange rate changes on cash and cash equivalents	1,072	(907)	(1,510)	(930)	(912)
Net increase in cash and cash equivalents	41,146	343	(250)	6,401	14,356
Cash and cash equivalents, beginning of period	31,143	31,393	31,393	24,992	10,636
Cash and cash equivalents, end of period	72,289	31,736	31,143	31,393	24,992
Supplemental disclosure of cash flow information:
Cash paid for interest	0	643	895	193	0
Cash paid for income taxes	484	580	610	1,055	70
Supplemental disclosure of non-cash financing activities:
Accretion of dividends on convertible preferred stock	357	642	857	861	856
Accretion of issuance costs on convertible preferred stock			$ 0	$ 0	$ 120
Conversion of Convertible Preferred Stock to Common Stock
Supplemental disclosure of non-cash financing activities:
Conversion of convertible stock	48,207	0
Conversion of Convertible Preferred Stock Warrant to Common Stock Warrant
Supplemental disclosure of non-cash financing activities:
Conversion of convertible stock	$ 1,191	$ 0

Organization and Description of Business

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Accounting Policies [Abstract]

Organization and Description of Business

1.	Organization and Description of Business

Appian Corporation (together with its subsidiaries, “Appian,” the “Company,” “we” or “our”) provides a leading low-code software development platform that enables organizations to rapidly develop powerful and unique applications. The applications created on our platform help companies drive digital transformation and competitive differentiation. We were incorporated in the state of Delaware in August 1999. We are headquartered in Reston, Virginia and have offices in Canada, Switzerland, the United Kingdom, France, Germany, the Netherlands, Italy, and Australia.

1. Organization and Description of Business

Significant Accounting Policies

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Accounting Policies [Abstract]

Significant Accounting Policies

2.	Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements and footnotes have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) as contained in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (the “Codification” or “ASC”) for interim financial information. In the opinion of management, the interim financial information includes all adjustments of a normal recurring nature necessary for a fair presentation of the results of operations, financial position, changes in stockholders’ equity (deficit) and cash flows. The results of operations for the current period are not necessarily indicative of the results for the full year or the results for any future periods. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related footnotes included in our final prospectus for our initial public offering (“IPO”) dated as of May 24, 2017 and filed with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended.

Use of Estimates

The preparation of our condensed consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and judgments that affect the amounts reported in these condensed consolidated financial statements and accompanying notes. Although we believe that the estimates we use are reasonable, due to the inherent uncertainty involved in making these estimates, actual results reported in future periods could differ from those estimates.

Significant estimates embedded in the condensed consolidated financial statements include revenue recognition, income taxes and the related valuation allowance, stock-based compensation and fair value measurements for our common stock and preferred stock warrant.

Principles of Consolidation

The accompanying condensed consolidated financial statements include the accounts of Appian and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Initial Public Offering

In May 2017, we completed an IPO in which we sold 7,187,500 shares of our newly-authorized Class A common stock at an initial price to the public of $12.00 per share. We received net proceeds of $77.8 million, after deducting underwriting discounts and commissions and offering expenses paid and payable by us, from sales of our shares in the IPO. Immediately prior to the completion of the IPO, (1) all shares of common stock then outstanding were converted into Class B common stock on a one-for-one basis, (2) a warrant to purchase shares of convertible preferred stock was converted into a warrant to purchase shares of Class B common stock and (3) all shares of convertible preferred stock then outstanding were converted into shares of our common stock on a one-for-one basis, and then reclassified as shares of Class B common stock. See Note 7 for further discussion of the convertible preferred stock and Note 8 for further discussion of the warrant.

Deferred offering costs of $2.4 million, consisting of legal, accounting and other fees and costs related to our IPO, were recorded to additional paid-in capital as a reduction of the proceeds upon the closing of our IPO.

Revenue Recognition

We generate revenue primarily through sales of subscriptions to our platform, as well as professional services. We recognize revenue when all of the following conditions are met: (1) there is persuasive evidence of an arrangement; (2) the service or product has been provided to the customer; (3) the amount of fees to be paid by the customer is fixed or determinable; and (4) the collection of related fees is reasonably assured. If collection is not reasonably assured, we defer revenue recognition until collectability becomes reasonably assured. Our arrangements do not contain general rights of return. Revenue is recognized net of any taxes collected from customers and subsequently remitted to governmental authorities.

Subscriptions, Software and Support Revenue

Subscriptions, software and support revenue is primarily related to (1) software as a service (“SaaS”) subscriptions bundled with maintenance and support and hosting services and (2) term license subscriptions bundled with maintenance and support. To a lesser extent, we also generate revenue from the sale of perpetual software licenses and associated maintenance and support.

Historically, we licensed our software primarily under perpetual licenses, but over time we transitioned from perpetual licenses to subscriptions. As a result, revenue from our perpetual software licenses was less than 1.0% of our total revenue for the three and nine months ended September 30, 2016 and September 30, 2017.

We generally charge subscription fees on a per-user basis. We bill customers and collect payment for subscriptions to our platform in advance on a monthly, quarterly or annual basis. In certain instances, we have had customers pay their entire contract up front.

SaaS Subscriptions

Our SaaS subscription revenue is derived from customers accessing our cloud offering pursuant to contracts that are generally one to five years in length. We perform all required maintenance and support for our cloud offering and we do not separately charge customers for hosting costs. In these arrangements, our customers do not have the right to take the software on-premises and, as a result, such arrangements are not accounted for within the scope of the software revenue guidance. Revenue from SaaS subscriptions is recognized ratably over the term of the subscription, beginning with the date our service is made available to our customer.

Term License Subscriptions

Our term license subscription revenue is derived from customers with on-premises installations of our platform pursuant to contracts that are generally one to five years in length. Customers with term license subscriptions have the right to use our software and receive maintenance and support. Since we do not sell maintenance and support separately from the subscription, revenue for the term license subscription and maintenance and support is recognized ratably over the term of the subscription, upon delivery of the platform to the customer when sold on a standalone basis.

Perpetual Licenses

Our perpetual license revenue is derived from customers with perpetual licenses to our platform and associated maintenance and support contracts. We recognize revenue from perpetual licenses on the date of delivery to our customer. We sell maintenance and support to perpetual license customers separately from the perpetual licenses pursuant to agreements that generally renew annually. Maintenance and support revenue is deferred and recognized ratably over the term of the support period.

Professional Services

Our professional services revenue is comprised of fees for consulting services, including application development and deployment assistance and training related to our platform. Our professional services are not essential to the functionality of our platform because the platform is ready for the customer’s use immediately upon delivery and is not modified or customized in any manner.

Consulting services are billed under both time-and-material and fixed-fee arrangements. For standalone time-and-material contracts, we recognize revenue at contractually agreed upon billing rates applied to hours performed, plus the cost of any materials delivered. For standalone fixed-fee contracts, we also recognize revenue as the work is performed using the proportional performance method of accounting. Training revenue is recognized when the associated training services are delivered. Training is also sold in the form of a subscription arrangement where a customer agrees to pay an annual fixed fee for a fixed number of users to have access to all of our training offerings during the year. Revenue from training subscription agreements is recognized ratably over the subscription period.

We defer recognition of revenue from work performed on pending contract modifications until the period in which the modifications are accepted and funding is approved by the customer. Costs of work performed on pending contract modifications are expensed as incurred.

Multiple Element Arrangements

Our multiple element arrangements are from SaaS subscriptions, term license subscriptions, and perpetual licenses that are generally sold in combination with maintenance and support service and frequently with professional services.

SaaS Subscriptions

For multiple element arrangements involving SaaS subscriptions that include professional services in addition to the subscription to our platform, we evaluate each element to determine whether it represents a separate unit of accounting. Because there are third-party vendors who routinely sell and provide the same professional services to our customers, our professional services are deemed to have standalone value apart from the SaaS subscription. Additionally, we offer both SaaS subscriptions and professional services on a standalone basis. Professional services revenue is therefore accounted for separately from subscription fees and recognized as the professional services are performed. We allocate revenue to the elements based on the selling price hierarchy using vendor-specific objective evidence (“VSOE”) of selling price, third-party evidence (“TPE”) of selling price, or if neither exists, best estimated selling price (“BESP”). In cases where we do not have VSOE or TPE of the elements of our arrangements, we use BESP to allocate revenue. We determine BESP for a service by considering multiple factors including, but not limited to, evaluating the weighted average of actual sales prices and other factors such as gross margin objectives, pricing practices and growth strategy. Pricing practices taken into consideration include historic contractually stated prices, volume discounts where applicable and our price lists. While we believe we can make reliable estimates regarding these matters, these estimates are inherently subjective. Once the revenue is allocated to these elements, revenue is recognized as such services are provided.

Term License Subscriptions

For multiple element arrangements involving term license subscriptions, maintenance and support and professional services, we do not have VSOE of fair value for the maintenance and support. Our term license subscriptions are generally not sold on a standalone basis, and therefore, we have not established VSOE of fair value for the subscriptions. Consequently, for our bundled arrangements that include certain professional services, there are two undelivered elements for which VSOE of fair value has not been established and, therefore, we utilize the combined services approach and defer all revenue until the software has been delivered and the provision of all services has commenced. We then recognize the entire fee from the arrangement ratably over the remaining period of the arrangement, assuming all other software revenue recognition criteria have been met.

Perpetual Licenses

For multiple element arrangements involving our perpetual software licenses, we allocate revenue to the software license arrangement by determining if VSOE of fair value exists for the undelivered elements, which are usually maintenance and support and professional services. In situations where VSOE of fair value exists for the undelivered elements, we apply the residual method whereby the fees allocated to license revenue are recognized upon delivery, the fees allocated to maintenance and support revenue are recognized over the service period and the fees allocated to professional services and training are recognized as performed. In instances where we lack VSOE of fair value for the undelivered elements, revenue is either deferred until the final element is delivered or recognized ratably over the service period when the only undelivered elements are either professional services or maintenance and support. We have VSOE for maintenance and support elements and professional services elements performed on a time and materials basis. VSOE of fair value is based upon the price charged when the same element is sold separately. In determining VSOE of fair value, we require that a substantial majority of the selling prices fall within a reasonably narrow pricing range. We reassess VSOE annually or more frequently if required.

Deferred Revenue

Deferred revenue primarily consists of amounts billed or billable in advance of revenue recognition from our subscriptions, software, and support and professional services described above. Deferred revenue is recognized as the revenue recognition criteria are met.

Cost of Revenue

Cost of Subscriptions, Software and Support Revenue

Cost of subscriptions, software and support revenue consists primarily of fees paid to our third-party managed hosting providers and other third-party service providers, personnel costs, including payroll and benefits for our technology operations and customer support teams, and allocated facility costs and overhead.

Cost of Professional Services Revenue

Cost of professional services revenue includes all direct and indirect costs to deliver our professional services and training, including employee compensation for our global professional services and training personnel, travel costs, third-party contractor costs and allocated facility costs and overhead.

Concentration of Credit Risk

Our financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents and trade accounts receivable. Cash deposits may be in excess of insured limits. We believe that the financial institutions that hold our cash deposits are financially sound and, accordingly, minimal credit risk exists with respect to these balances.

With regard to our customers, credit evaluation and account monitoring procedures are used to minimize the risk of loss. We believe that no additional credit risk beyond amounts provided for collection loss are inherent in accounts receivable. Revenue generated from government agencies represented 19.4% and 28.5% of our revenue for the three and nine months ended September 30, 2016, respectively, of which the top three federal government agencies generated 13.1% and 19.5% of our revenue for the three and nine months ended September 30, 2016, respectively. Additionally, 23.1% and 18.6% of our revenue during the three and nine months ended September 30, 2016, respectively, was generated from foreign customers. Revenue generated from government agencies represented 14.2% and 15.4% of our revenue for the three and nine months ended September 30, 2017, respectively, of which the top three federal government agencies generated 7.7% and 9.1% of our revenue for the three and nine months ended September 30, 2017, respectively. Additionally, 28.6% and 25.6% of our revenue during the three and nine months ended September 30, 2017, respectively, was generated from foreign customers. Federal government agencies accounted for 17.2% and 9.1% of accounts receivable at December 31, 2016 and September 30, 2017, respectively.

Accounts Receivable and Allowance for Doubtful Accounts

Accounts receivable are stated at realizable value, net of an allowance for doubtful accounts. The allowance for doubtful accounts is based on our assessment of the collectability of accounts. We regularly review the composition of the accounts receivable aging, historical bad debts, changes in payment patterns, customer creditworthiness and current economic trends. If the financial condition of our customers were to deteriorate, resulting in their inability to make required payments, additional provisions for doubtful accounts would be required and would increase bad debt expense. To date, our allowance and related bad debt write-offs have been nominal. There was no change in the allowance for doubtful accounts from December 31, 2016 to September 30, 2017.

Deferred Commissions

Deferred commissions are the incremental costs that are directly associated with subscription agreements with customers and consist of sales commissions paid to our direct sales force. Commissions are considered direct and incremental and as such are deferred and amortized over the terms of the related customer contracts consistent with the related revenue. Amortization of deferred commissions is included in sales and marketing expense in the accompanying condensed consolidated statements of operations. Commission expense was $1.8 million and $5.4 million for the three and nine months ended September 30, 2016, respectively. Commission expense was $3.2 million and $8.5 million for the three and nine months ended September 30, 2017, respectively.

Fair Value of Financial Instruments

The carrying amounts of our cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate fair value as of December 31, 2016 and September 30, 2017 because of the relatively short duration of these instruments. The carrying value of our long-term debt as of December 31, 2016 approximated fair value given interest rates for similar debt instruments available to the Company.

We use a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires us to use observable inputs when available, and to minimize the use of unobservable inputs when determining fair value. The three tiers are defined as follows:

•

Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities;

•

Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and

•

Level 3. Unobservable inputs for which there is little or no market data, which require us to develop our own assumptions.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

We evaluate our financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level in which to classify them for each reporting period. This determination requires significant judgments to be made. After the reclassification of the convertible preferred stock warrant in May 2017, we did not have any assets or liabilities subject to fair value measurements as of September 30, 2017. See Note 8 for further discussion of the warrant reclassification. The following table summarizes the conclusions reached as of December 31, 2016 (in thousands):


	December 31, 2016		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	850	$	—	$	—	$	850

	$	850	$	—	$	—	$	850

(1)

In order to determine the fair value of the convertible preferred stock warrant, we used the Black-Scholes option pricing model (“OPM”). Significant inputs for the OPM included an estimate of the fair value of the Series A convertible preferred stock, the remaining contractual life of the warrant, an estimate of the timing of a liquidity event, a risk-free rate of interest and an estimate of our stock volatility using the volatilities of guideline peer companies.

Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs

There were no changes in our Level 3 instruments measured at fair value on a recurring basis during the three months ended September 30, 2016 and 2017.

The following table presents the changes in our Level 3 instruments measured at fair value on a recurring basis during the nine months ended September 30, 2016 and 2017 (in thousands):


	Nine Months Ended September 30,
	2016		2017
Balance as of January 1	$	650	$	850
Change in fair value of warrant liability		200		341
Reclassification of warrant liability to equity		—		(1,191	)

Balance as of September 30	$	850	$	—

Stock-Based Compensation

We account for stock-based compensation expense related to stock-based awards based on the estimated fair value of the award on the grant date. We calculate the fair value of stock options using the Black-Scholes OPM. For service-based awards, stock-based compensation expense is recognized on a straight-line basis over the requisite service period. For performance-based awards, stock-based compensation expense is recognized using the accelerated attribution method, based on the probability of satisfying the performance condition. For awards that contain market conditions, compensation expense is measured using a Monte Carlo simulation model and recognized using the accelerated attribution method over the derived service period based on the expected market performance as of the grant date. For restricted stock units, stock-based compensation expense is recognized on a straight-line basis over the requisite service period.

As discussed in “—Recent Accounting Pronouncements,” we have elected to early adopt Accounting Standards Update (“ASU”) No. 2016-9, which, among other things, permits an entity to make an entity-wide policy election to either (1) estimate the number of awards that are expected to vest or (2) account for forfeitures when they occur. We have elected to account for forfeitures as they occur, rather than estimate expected forfeitures.

Emerging Growth Company Status

We are an “emerging growth company” as defined in the Jumpstart Our Business Startups Act (“JOBS Act”). The JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. Thus, an emerging growth company can delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this extended transition period and, as a result, we will not adopt new or revised accounting standards on the relevant dates on which adoption of such standards is required for other public companies.

Recent Accounting Pronouncements

Adopted

In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”), which amends ASC Subtopic 205-40 to provide guidance about management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related disclosures. Specifically, the amendments (1) provide a definition of the term “substantial doubt,” (2) require an evaluation of every reporting period, (3) provide principles for considering the mitigating effect of management’s plans, (4) require certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans, (5) require an express statement and other disclosures when substantial doubt is not alleviated and (6) require an assessment for a period of one year after the date that financial statements are issued. ASU 2014-15 was effective for our year ended December 31, 2016, and its adoption did not have a material impact on our financial condition, results of operations or cash flows.

In April 2015, the FASB issued ASU No. 2015-3, Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-3”), which simplifies the presentation of debt issuance costs by requiring that such costs be presented in the condensed consolidated balance sheets as a direct deduction from the carrying value of the associated debt instrument, consistent with debt discounts. Subsequent to the issuance of ASU 2015-3, the SEC staff announced that the presentation of debt issuance costs associated with line-of-credit arrangements may be presented as an asset. This announcement was codified by the FASB in ASU No. 2015-15, Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements (“ASU 2015-15”). ASU 2015-3 and ASU 2015-15 were both effective for our year ended December 31, 2016, and their adoption did not have a material impact on our financial condition, results of operations or cash flows.

In April 2015, the FASB issued ASU No. 2015-5, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement (“ASU 2015-5”), which provides clarification on whether a cloud computing arrangement includes a software license. If a software license is included, the customer should account for the license consistent with its accounting for other software licenses. If a software license is not included, the arrangement should be accounted for as a service contract. ASU 2015-5 was effective for our year ended December 31, 2016, and its adoption did not have a material impact on our financial condition, results of operations or cash flows.

In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes (Topic 740) (“ASU 2015-17”), which requires that all deferred tax assets and liabilities, including any related valuation allowance, be classified as noncurrent on the balance sheet. We elected to early adopt ASU 2015-17 beginning with our year ended December 31, 2015. The adoption of ASU 2015-17 did not have a material impact on our financial condition, results of operations or cash flows.

In March 2016, the FASB issued ASU No. 2016-9, Improvements to Employee Share-Based Payment Accounting (Topic 718) (“ASU 2016-9”), which is intended to simplify several aspects of the accounting for share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. We elected to early adopt ASU 2016-9 beginning with our year ended December 31, 2016, and have applied the guidance retrospectively. The adoption of ASU 2016-9 did not have a material impact on our financial condition, results of operations or cash flows.

Not Yet Adopted

In May 2014, the FASB issued ASU No. 2014-9, Revenue from Contracts with Customers (Topic 606)(“ASU 2014-9”), which provides new guidance for revenue recognition. ASU 2014-9 provides that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-9 also requires improved disclosures to help users of financial statements better understand the nature, amount, timing, and uncertainty of revenue that is recognized. Entities have the option of using either a full retrospective or modified retrospective approach for the adoption of the standard. In March 2016, the FASB issued ASU No. 2016-8, Principal Versus Agent Considerations (Reporting Revenue Gross Versus Net) (“ASU 2016-8”), which clarifies implementation guidance on principal versus agent considerations in ASU 2014-9. In April 2016, the FASB issued ASU No. 2016-10, Identifying Performance Obligations and Licensing (“ASU 2016-10”), which clarifies the identification of performance obligations and the licensing implementation guidance in ASU 2014-9. In addition, in May 2016, the FASB issued ASU No. 2016-12, Narrow-Scope Improvements and Practical Expedients (“ASU 2016-12”), which clarifies the guidance on assessing collectibility, presentation of sales taxes, noncash consideration and completed contracts and contract modifications at transition. For public entities, the new standard is effective for annual periods and interim periods within those annual periods, beginning after December 15, 2017. For all other entities, the new standard is effective for annual periods beginning after December 15, 2018, and interim periods within those annual periods beginning after December 15, 2019. We intend to avail ourselves of the JOBS Act extended transition period that permits us to defer adoption until January 1, 2019. We are currently evaluating the impact the adoption of these standards will have on our consolidated financial statements.

We currently plan to adopt the new standard using the full retrospective approach; however, the decision regarding the adoption method has not been finalized. Our final determination will depend on a number of factors such as the significance of the impact of the new standard on our financial results, system readiness, including that of software procured from third-party providers, and our ability to accumulate and analyze the information necessary to assess the impact on prior period financial statements, as necessary.

We are in the initial stages of our evaluation of the impact of the new standard on our accounting policies, processes, and system requirements. We have assigned internal resources in addition to the engagement of third-party service providers to assist in the evaluation. Furthermore, we have made and will continue to make investments in systems to enable timely and accurate reporting under the new standard. While we continue to assess all potential impacts under the new standard there is the potential for significant impacts to the timing of recognition of revenue, particularly term license subscriptions and professional services revenue. We also expect an impact to our accounting for contract acquisition costs, both with respect to the amounts that will be capitalized as well as the period of amortization.

Under current industry-specific software revenue recognition guidance, we have historically concluded that we did not have VSOE of fair value of the undelivered services related to term license subscriptions, and accordingly, have recognized term license subscriptions and related services ratably over the subscription term. Professional services included in an arrangement with subscription revenue has also been recognized ratably over the subscription term. The new standard, which does not retain the concept of VSOE, requires an evaluation of whether term license subscriptions and related services, including professional services, are distinct performance obligations and therefore should be separately recognized at a point in time or over time. Depending on the outcome of our evaluation, the timing of when revenue is recognized could change significantly for term license subscriptions and professional services under the new standard.

In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842) (“ASU 2016-2”), which requires that lessees recognize assets and liabilities for leases with lease terms greater than 12 months in the statement of financial position. ASU 2016-2 also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. The update is effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. Early adoption is permitted. We are currently evaluating the impact the adoption of ASU 2016-2 will have on our consolidated financial statements.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”), which aims to reduce the existing diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. ASU 2016-15 will require adoption on a retrospective basis unless it is impracticable to apply, in which case we would be required to apply the amendments prospectively as of the earliest date practicable. ASU 2016-15 is effective for fiscal years beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted. We are currently in the process of evaluating the impact of adoption of this standard on our consolidated financial statements.

2. Significant Accounting Policies

Basis of Presentation

The consolidated financial statements and accompanying notes were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Use of Estimates

The preparation of our consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and judgments that affect the amounts reported in these financial statements and accompanying notes. Although we believe that the estimates we use are reasonable, due to the inherent uncertainty involved in making these estimates, actual results reported in future periods could differ from those estimates.

Significant estimates embedded in the consolidated financial statements include revenue recognition, income taxes and the related valuation allowance, stock-based compensation and fair value measurements for our common stock and outstanding warrant.

Principles of Consolidation

The accompanying consolidated financial statements include the accounts of Appian and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Revenue Recognition

Subscriptions, Software and Support Revenue

Historically, we licensed our software primarily under perpetual licenses, but over time we transitioned from perpetual licenses to subscriptions. As a result, revenue from our perpetual software licenses was 5.0%, 1.9%, and 0.9% of our total revenue for 2014, 2015 and 2016, respectively.

SaaS Subscriptions

Term License Subscriptions

Perpetual Licenses

Professional Services

Multiple Element Arrangements

SaaS Subscriptions

For multiple element arrangements involving SaaS subscriptions that include professional services in addition to the subscription to our platform, we evaluate each element to determine whether it represents a separate unit of accounting. Because there are third-party vendors who routinely sell and provide the same professional services to our customers, our professional services are deemed to have standalone value apart from the SaaS subscription. Additionally, we offer both SaaS subscriptions and professional services on a standalone basis. Professional services revenue is therefore accounted for separately from subscription fees and recognized as the professional services are performed. We allocate revenue to the elements based on the selling price hierarchy using vendor-specific objective evidence, or VSOE, of selling price, third-party evidence, or TPE, of selling price, or if neither exists, best estimated selling price, or BESP. In cases where we do not have VSOE or TPE of the elements of our arrangements, we use BESP to allocate revenue. We determine BESP for a service by considering multiple factors including, but not limited to, evaluating the weighted average of actual sales prices and other factors such as gross margin objectives, pricing practices and growth strategy. Pricing practices taken into consideration include historic contractually stated prices, volume discounts where applicable and our price lists. While we believe we can make reliable estimates regarding these matters, these estimates are inherently subjective. Once the revenue is allocated to these elements, revenue is recognized as such services are provided.

Term License Subscriptions

Perpetual Licenses

Deferred Revenue

Deferred revenue primarily consists of amounts billed in advance of revenue recognition from our subscriptions, software, and support and professional services described above. Deferred revenue is recognized as the revenue recognition criteria are met.

Cost of Revenue

Cost of Subscriptions, Software and Support Revenue

Cost of Professional Services Revenue

Concentration of Credit Risk

Our financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents and trade account receivables. Cash deposits may be in excess of insured limits. We believe that the financial institutions that hold our cash deposits are financially sound and, accordingly, minimal credit risk exists with respect to these balances.

No individual customer represented more than 10% of accounts receivable at December 31, 2015. One customer accounted for 17.2% of accounts receivable at December 31, 2016.

Cash and Cash Equivalents

We consider all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase, as well as overnight repurchase investments, to be cash equivalents.

Accounts Receivable and Allowance for Doubtful Accounts

Deferred Commissions

Deferred commissions are the incremental costs that are directly associated with subscription agreements with customers and consist of sales commissions paid to our direct sales force. Commissions are considered direct and incremental and as such are deferred and amortized over the terms of the related customer contracts consistent with the related revenue. Amortization of deferred commissions is included in sales and marketing expense in the accompanying consolidated statements of operations. Commission expense was $3.8 million, $4.6 million, and $6.5 million for the years ended December 31, 2014, 2015 and 2016, respectively.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets. Significant additions or improvements extending the useful life of an asset are capitalized, while repairs and maintenance costs which do not significantly improve the related assets or extend their useful lives are charged to expense as incurred.


Asset Category		Useful Life (in years)
Computer software		3
Computer hardware		3
Equipment		5
Office furniture and fixtures		10
Leasehold improvements		Shorter of useful life of assets or lease term

Impairment of Long-Lived Assets

Long-lived assets and certain intangible assets are reviewed for impairment whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable through undiscounted cash flows from the use of the assets. If such assets are considered to be impaired, the assets are written down to their estimated fair value. No indicators of impairment were identified for the years ended December 31, 2014, 2015 and 2016.

Fair Value of Financial Instruments

The carrying amounts of our cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate fair value as of December 31, 2015 and 2016 because of the relatively short duration of these instruments. The carrying value of our long-term debt approximates fair value given interest rates for similar debt instruments available to the Company.

•

Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities;

•

Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and

•

Level 3. Unobservable inputs for which there is little or no market data, which require us to develop our own assumptions.

Assets and Liabilities Measured at Fair Value on a Recurring Basis


	2015		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	650		—		—	$	650

	$	650	$	—	$	—	$	650


	2016		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	850		—		—	$	850

	$	850	$	—	$	—	$	850

(1)

In order to determine the fair value of the convertible preferred stock warrant, we used an option pricing model (“OPM”). Significant inputs for the OPM included an estimate of the fair value of the Series A convertible preferred stock, the remaining contractual life of the warrant, an estimate of the timing of a liquidity event, a risk-free rate of interest and an estimate of our stock volatility using the volatilities of guideline peer companies.

Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs

The following table presents the changes in our Level 3 instruments measured at fair value on a recurring basis during the years ended December 31 (in thousands):


	Series A Convertible Preferred Stock Warrant
	2014		2015		2016
Balance as of January 1	$	—	$	351	$	650
Change in fair value of warrant liability		351		299		200

Balance as of December 31	$	351	$	650	$	850

The fair value of the warrant as of December 31, 2013 was de minimis and therefore not recorded as of January 1, 2014.

Stock-Based Compensation

All of our currently outstanding awards require the satisfaction of both a service condition and a liquidity event condition. The liquidity condition is satisfied upon the occurrence of a qualifying event, defined as a change of control transaction or the effective date of our IPO. No compensation expense will be recognized until the performance condition is achieved, at which time the cumulative compensation expense using the accelerated attribution method from the service start date will be recognized.

As discussed in “—Recent Accounting Pronouncements,” we have elected to early adopt Accounting Standards Update No. 2016-09, which, among other things, permits an entity to make an entity-wide policy election to either (1) estimate the number of awards that are expected to vest or (2) account for forfeitures when they occur. We have elected to account for forfeitures as they occur, rather than estimate expected forfeitures.

Basic and Diluted Loss per Common Share

We use the two-class method to compute net loss per common share because we have issued securities, other than common stock, that contractually entitle the holders to participate in dividends and earnings. These participating securities include our convertible preferred stock which have non-forfeitable rights to participate in any dividends declared on our common stock. The two-class method requires earnings for the period to be allocated between common stock and participating securities based upon their respective rights to receive distributed and undistributed earnings.

Under the two-class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that the participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed. No such adjustment to earnings is made during periods with a net loss, as the holders of the participating securities have no obligation to fund losses.

Diluted net income per common share is computed under the two-class method by using the weighted average number of shares of common stock outstanding, plus, for periods with net income attributable to common stockholders, the potential dilutive effects of stock options and warrants. In addition, we analyze the potential dilutive effect of the outstanding participating securities under the “if-converted” method when calculating diluted earnings per share, in which it is assumed that the outstanding participating securities convert into common stock at the beginning of the period or date of issuance, if later. We report the more dilutive of the approaches (two-class or “if-converted”) as our diluted net income per share during the period.

Due to net losses for the years ended December 31, 2014, 2015 and 2016, basic and diluted loss per share were the same, as the effect of potentially dilutive securities would have been anti-dilutive.

Income Taxes

We use the asset and liability method of accounting for income taxes in which deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the consolidated financial statement carrying amounts of existing assets and liabilities and their respective tax bases. We measure deferred tax assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be reversed. We recognize the effect on deferred tax assets and liabilities of a change in tax rates as income and expense in the period that includes the enactment date. A valuation allowance is established if it is more likely than not that all or a portion of the deferred tax asset will not be realized.

Our tax positions are subject to income tax audits by multiple tax jurisdictions throughout the world. We recognize the tax benefit of an uncertain tax position only if it is more likely than not the position is sustainable upon examination by the taxing authority. We measure the tax benefit recognized as the largest amount of benefit which is more likely than not to be realized upon settlement with the taxing authority. We recognize penalties and interest related to unrecognized tax benefits as income tax expense.

We calculate the current and deferred income tax provision based on estimates and assumptions that could differ from the actual results reflected in income tax returns filed in subsequent years and record adjustments based on filed income tax returns when identified. The amount of income taxes paid is subject to examination by U.S. federal, state and foreign tax authorities. The estimate of the potential outcome of any uncertain tax issue is subject to our assessment of relevant risks, facts and circumstances existing at that time. To the extent the assessment of such tax position changes, we record the change in estimate in the period in which we make that determination.

Due to changing economic and political environments in the United States and abroad, we may be impacted by possible tax reform or similar changes in tax law. Specifically, certain proposed changes in the United States may impact the U.S. taxation of our foreign earnings and adversely impact our effective tax rate. However, it is not possible to estimate the impact of such changes at this time and we continue to monitor these changes.

Segment Reporting

Operating segments are defined as components of an enterprise for which discrete financial information is available that is evaluated regularly by the chief operating decision maker (“CODM”) for purposes of allocating resources and evaluating financial performance. Our CODM is our chief executive officer, who reviews financial information presented on a companywide basis for purposes of allocating resources and evaluating financial performance. As such, our operations constitute a single operating segment and one reportable segment.

Foreign Currency

Our operations located outside of the United States where the local currency is the functional currency are translated into U.S. dollars using the current rate method. Results of operations are translated at the average rate of exchange for the period. Assets and liabilities are translated at the closing rates on the balance sheet date. Gains and losses on translation of these accounts are accumulated and reported as a separate component of stockholders’ deficit and other comprehensive income (loss).

Gains and losses on foreign currency transactions are recognized in the accompanying consolidated statements of operations as a component of other expense, net. Transaction gains and losses from transactions denominated in foreign currencies resulted in net transaction losses of $1.7 million, $1.3 million and $1.5 million for the years ended December 31, 2014, 2015 and 2016, respectively.

Research and Development

Research and development expenses include payroll, employee benefits, and other headcount-related costs associated with product development. Our product utilizes a common codebase, whether accessed by customers via the cloud or via an on-premises installation. Since our software is sold and licensed externally, we consider our software as external-use software for purposes of applying the capitalized software development guidance. Product development costs are expensed as incurred until technological feasibility has been established, which we define as the completion of all planning, designing, coding and testing activities that are necessary to establish products that meet design specifications including functions, features and technical performance requirements. We have determined that technological feasibility for our software products is reached shortly before they are released for sale. Costs incurred after technological feasibility is established are not significant, and accordingly we expense all research and development costs when incurred.

Advertising

We expense advertising costs as they are incurred. Advertising expenses totaled $0.5 million for each of the years ended December 31, 2014 and 2015 and $1.4 million for the year ended December 31, 2016.

Recent Accounting Pronouncements

Adopted

In August 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”), which amends ASC Subtopic 205-40 to provide guidance about management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related disclosures. Specifically, the amendments (1) provide a definition of the term “substantial doubt,” (2) require an evaluation of every reporting period, (3) provide principles for considering the mitigating effect of management’s plans, (4) require certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans, (5) require an express statement and other disclosures when substantial doubt is not alleviated and (6) require an assessment for a period of one year after the date that financial statements are issued. ASU 2014-15 was effective for our year ended December 31, 2016, and its adoption did not have a material impact on our financial condition, results of operations or cash flows.

In April 2015, the FASB issued ASU No. 2015-03, Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”), which simplifies the presentation of debt issuance costs by requiring that such costs be presented in the consolidated balance sheets as a direct deduction from the carrying value of the associated debt instrument, consistent with debt discounts. Subsequent to the issuance of ASU 2015-03, the SEC staff announced that the presentation of debt issuance costs associated with line-of-credit arrangements may be presented as an asset. This announcement was codified by the FASB in ASU No. 2015-15. These ASUs were effective for our year ended December 31, 2016, and their adoption did not have a material impact on our financial condition, results of operations or cash flows.

In April 2015, the FASB issued ASU No. 2015-05, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement (“ASU 2015-05”), which provides clarification on whether a cloud computing arrangement includes a software license. If a software license is included, the customer should account for the license consistent with its accounting for other software licenses. If a software license is not included, the arrangement should be accounted for as a service contract. ASU 2015-05 was effective for our year ended December 31, 2016, and its adoption did not have a material impact on our financial condition, results of operations or cash flows.

In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718) (“ASU 2016-09”), which is intended to simplify several aspects of the accounting for share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. We elected to early adopt ASU 2016-09 beginning with our year ended December 31, 2016, and have applied the guidance retrospectively. The adoption of ASU 2016-09 did not have a material impact on our financial condition, results of operations or cash flows.

Not Yet Adopted

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”), which provides new guidance for revenue recognition. ASU 2014-09 provides that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 also requires improved disclosures to help users of financial statements better understand the nature, amount, timing, and uncertainty of revenue that is recognized. Entities have the option of using either a full retrospective or modified retrospective approach for the adoption of the standard. In March 2016, the FASB issued ASU No. 2016-08, Principal Versus Agent Considerations (Reporting Revenue Gross Versus Net) (“ASU 2016-08”), which clarifies implementation guidance on principal versus agent considerations in ASU 2014-09. In April 2016, the FASB issued ASU No. 2016-10, Identifying Performance Obligations and Licensing (“ASU 2016-10”), which clarifies the identification of performance obligations and the licensing implementation guidance in ASU 2014-09. In addition, in May 2016, the FASB issued ASU No. 2016-12, Narrow-Scope Improvements and Practical Expedients (“ASU 2016-12”), which clarifies the guidance on assessing collectibility, presentation of sales taxes, noncash consideration and completed contracts and contract modifications at transition. For public entities, the new standard is effective for annual periods and interim periods within those annual periods, beginning after December 15, 2017. For all other entities, the new standard is effective for annual periods beginning after December 15, 2018, and interim periods within those annual periods beginning after December 15, 2019. We intend to avail ourselves of the JOBS Act extended transition period that permits us to defer adoption until January 1, 2019. We are currently evaluating the impact the adoption of these standards will have on our consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), which requires that lessees recognize assets and liabilities for leases with lease terms greater than 12 months in the statement of financial position. ASU 2016-02 also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. The update is effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. Early adoption is permitted. We are currently evaluating the impact the adoption of ASU 2016-02 will have on our consolidated financial statements.

Property and Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property and Equipment

3. Property and Equipment

Property and equipment consisted of the following as of December 31 (in thousands):


	2015			2016
Computer software	$	1,562		$	1,701
Computer hardware		1,201			1,408
Leasehold improvements		3,555			4,098
Office furniture and fixtures		386			464
Equipment		96			116

		6,800			7,787
Less: accumulated depreciation		(3,908	)		(4,686	)

Property and equipment, net	$	2,892		$	3,101

Depreciation and amortization expense totaled $0.6 million for the year ended December 31, 2014 and $0.8 million for each of the years ended December 31, 2015 and 2016.

Debt

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Debt Disclosure [Abstract]

Debt

Debt

2015 Line of Credit

2015 Term Loan

2017 Financing Facility

In April 2017, we entered into a new financing facility consisting of a $5.0 million senior revolving credit facility, a $20.0 million senior term loan, and a $10.0 million subordinated term loan. In connection with the execution of this financing facility, the prior line of credit was terminated, and we borrowed the full $20.0 million available under the senior term loan and repaid the outstanding balance under our prior term loan. Additionally, in connection with the execution of our new financing facility, the lender waived the prepayment fee associated with our prior line of credit. In June 2017, we used proceeds from our IPO to pay all remaining outstanding principal and interest under the senior term loan and subsequently terminated the senior term loan and subordinated term loan. In connection with the repayment of the senior term loan, we recognized a loss on extinguishment of debt of $0.4 million related to unamortized debt issuance costs, which is included within other (income) expense, net in the accompanying condensed consolidated statements of operations. As of September 30, 2017, we had no outstanding borrowings. This financing facility was terminated in November 2017 in connection with our entry into a new $20.0 million revolving line of credit. See Note 11 for additional information regarding our new revolving line of credit.

4. Debt

Line of Credit

At December 31, 2015, we had a $10.0 million revolving line of credit with a lender, expiring in June 2016, which was subsequently amended in June 2016 to extend the maturity date through June 2017. The amount of borrowing available under the credit facility at any time may not exceed 80% of eligible accounts receivable at such time and any amounts borrowed are collateralized by substantially all of our assets. Amounts drawn on the revolving line of credit bear interest at a floating rate of prime plus 0.75%. The agreement contains certain affirmative covenants related to the timely delivery of financial information to the bank and maintaining a liquidity ratio of at least 1.25 to 1, as well as certain customary negative covenants. We were in compliance with all covenants as of December 31, 2016, and would be able to draw up to a maximum of $3.5 million on the revolving line of credit while maintaining compliance with the liquidity ratio. As of December 31, 2015 and 2016, there were no advances against the line of credit.

Term Loan

In March 2015, we entered into a collateralized $10.0 million term loan facility with a lender, maturing in March 2019, and borrowed the full amount under the term loan facility in June 2015. In January 2016, we paid off the outstanding balance of the term loan and simultaneously entered into a collateralized $20.0 million term loan facility, maturing in January 2020. We borrowed the full amount under the term loan facility in January 2016. Amounts drawn on the term loan bear interest at a floating rate of prime plus 1.25%, or 5.00% as of December 31, 2016. We are required to repay the term loan over 48 months. The first 12 months will be interest-only payments followed by 36 months of monthly amortization payments. We may pay off the entire term loan at any time by paying all outstanding principal, accrued interest, and a prepayment fee of 1% of the amount advanced through month 12, 0.5% during months 13 through 24 and no prepayment fee thereafter. The term loan includes a financial covenant related to our short-term liquidity. We were in compliance with this covenant as of December 31, 2016.

Income Taxes

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

5.	Income Taxes

The provision for income taxes is based upon the estimated annual effective tax rates for the year applied to the current period income (loss) before tax plus the tax effect of any significant unusual items, discrete events or changes in tax law. Our operating subsidiaries are exposed to statutory effective tax rates ranging from zero to approximately 40%. Fluctuations in the distribution of pre-tax income (loss) among our operating subsidiaries can lead to fluctuations of the effective tax rate in the consolidated financial statements. For the three and nine months ended September 30, 2016, the actual effective tax rates were 25.4% and 20.3%, respectively. For the three and nine months ended September 30, 2017, the actual effective tax rates were (3.1)% and (2.1)%, respectively.

We assess uncertain tax positions in accordance with ASC 740-10, Accounting for Uncertainties in Tax. As of September 30, 2017, our net unrecognized tax benefits totaled $0.5 million of which the entire portion would impact our effective tax rate if recognized. We anticipate that the amount of reasonably possible unrecognized tax benefits that could decrease over the next 12 months due to the expiration of certain statutes of limitations and settlement of tax audits is not material to our consolidated financial statements.

We file income tax returns in the United States federal jurisdiction and in many state and foreign jurisdictions. The tax years 2013 through 2016 remain open to examination by the major taxing jurisdictions to which we are subject. No material examinations are currently open.

5. Income Taxes

For the years ended December 31, 2014, 2015 and 2016, our net (loss) income before income taxes was comprised of the following (in thousands):


	2014			2015			2016
Domestic	$	(11,026	)	$	1,079		$	(4,524	)
Foreign		(4,829	)		(7,688	)		(9,620	)

Total	$	(15,855	)	$	(6,609	)	$	(14,144	)

For the years ended December 31, 2014, 2015, and 2016, our income tax expense (benefit) was comprised of the following (in thousands):


	2014		2015			2016
Current:
Federal	$	430	$	390		$	(627	)
State		128		62			(200	)
Foreign		247		217			266

Total current expense (benefit)		805		669			(561	)

Deferred:
Federal		325		(334	)		(922	)
State		51		43			(230	)
Foreign		23		—			30

Total deferred expense (benefit)		399		(291	)		(1,122	)

Total income tax expense (benefit)	$	1,204	$	378		$	(1,683	)

For the years ended December 31, 2014, 2015, and 2016, the provision for income taxes differs from the amount computed by applying the federal statutory income tax rates to our loss before the provision for income taxes, as follows:


	2014			2015			2016
U.S. federal statutory tax rate		34.0	%		34.0	%		34.0	%
State tax expense		(0.8	)		(0.9	)		1.4
Expense on purchase of common stock		(30.2	)		—			—
Foreign rate differential		(7.9	)		(29.4	)		(17.8	)
Nondeductible expenses		(1.5	)		(4.1	)		(2.3	)
Tax credits		3.2			10.0			6.5
Unrecognized tax benefits		(0.5	)		(1.8	)		(0.2	)
Other		(0.5	)		(1.9	)		(0.2	)
Change in valuation allowance		(3.4	)		(11.5	)		(9.6	)

Total		(7.6	)%		(5.6	)%		11.8	%

Deferred tax assets and liabilities reflect the net tax effects of temporary differences between the carrying amount of the assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.

As of December 31, 2015 and 2016, significant components of our deferred tax assets and liabilities are as follows (in thousands):


	2015			2016
Deferred tax assets:
Accrued vacation	$	482		$	529
Bad debt		157			159
Deferred revenue		3,173			2,176
Deferred rent		603			834
Tax credits		1,381			2,401
Net operating losses		1,289			2,939
Other		209			929

Gross deferred tax assets		7,294			9,967
Less: Valuation allowance		(1,283	)		(2,642	)

Total deferred tax assets		6,011			7,325

Deferred tax liabilities:
Depreciation		(491	)		(349	)
Unbilled receivables		(1,835	)		(491	)
Prepaid expenses		(4,579	)		(6,505	)

Total deferred tax liabilities		(6,905	)		(7,345	)

Net deferred tax liability	$	(894	)	$	(20	)

As of December 31, 2015 and 2016, we had $0 and $1.8 million of gross net operating loss (“NOL”) carryforwards for U.S. federal tax purposes, respectively. Federal NOL carryforwards will expire, if unused, in 2036. As of December 31, 2015 and 2016, we had U.S. gross state NOL carryforwards of $0.1 million and $1.7 million, respectively. We had tax effected state NOL carryforwards of $0.1 million as of December 31, 2016. Tax effected state NOL carryforwards as of December 31, 2015 were nominal. U.S. state NOL carryforwards will substantially expire, if unused, in 2036.

Section 382 of the Internal Revenue Code limits the utilization of the NOLs when ownership changes occur, as defined by that section. A number of states have similar state laws that limit utilization of the state NOLs when ownership changes occur. We have performed an analysis of our Section 382 ownership changes and have determined that all federal and U.S state NOLs are available for use as of December 31, 2016.

As of December 31, 2015 and 2016, we had $1.8 million and $2.8 million, respectively, of federal tax credit carryforwards which will expire, if unused, in 2036.

As of December 31, 2015 and 2016, we had $13.3 million and $23.7 million, respectively, of gross NOL carryforwards for Swiss tax purposes. The NOL carryforwards will expire, if unused, between 2021 and 2023.

The net change during the year in the total valuation allowance was $1.4 million, driven by the valuation allowance recorded against the U.S. deferred tax assets and the change in the Switzerland deferred tax assets.

Based on our cumulative operating results as of December 31, 2016, three-year cumulative loss, and assessment of our expected future results of operations, we determined that it was not more-likely-than not that we would be able to realize the U.S. deferred tax assets. We recorded a valuation allowance in the fourth quarter of 2016 on the U.S. deferred tax assets. We have evaluated all evidence, both positive and negative, in assessing the likelihood of realizability and the negative evidence outweighed the positive evidence.

We continue to maintain a full valuation allowance on the deferred tax assets of our subsidiary in Switzerland as we determined that it was not more likely than not that we would be able to realize a benefit from the NOL at that subsidiary. Based on our cumulative operating results as of December 31, 2016, and assessment of our expected future results of operations, we determined that it was not more-likely-than not that we would be able to realize the deferred tax assets prior to expiration.

We are subject to income taxes in the United States, Australia, Canada, France, Germany, Italy, Netherlands, Switzerland, and United Kingdom.

Any undistributed earnings of our foreign subsidiaries are considered to be indefinitely reinvested; accordingly, no U.S. income taxes have been provided thereon. Upon repatriation of those earnings, if any, we would be subject to U.S. income taxes, net of any applicable foreign tax credits, and foreign withholding taxes. We did not have any undistributed earnings at our foreign subsidiaries as of December 31, 2015 and 2016.

As of December 31, 2015 and 2016, we had unrecognized tax benefits of $0.4 million, of which the entire portion would affect our effective tax rate if recognized. The following table summarizes the activity related to our unrecognized tax benefit from January 1, 2014 to December 31, 2016 (in thousands):


Balance as of January 1, 2014	$	218
Additions for tax positions in current years		68
Additions for tax positions in prior years		—
Reductions due to lapse in statutes of limitations		—
Settlements		—

Balance as of December 31, 2014		286
Additions for tax positions in current years		98
Additions for tax positions in prior years		—
Reductions due to lapse in statutes of limitations		—
Settlements		—

Balance as of December 31, 2015		384
Additions for tax positions in current years		171
Additions for tax positions in prior years		—
Reductions due to lapse in statutes of limitations		(136	)
Settlements		—

Balance as of December 31, 2016	$	419

We recognize interest and penalties related to uncertain tax positions in income tax expense. During the years ended December 31, 2014, 2015, and 2016, we recognized potential interest and penalties of $15,000, $19,000, and $2,000, respectively, and the cumulative balance of interest and penalties as of December 31, 2015 and 2016 was $39,000 and $35,000, respectively.

We anticipate that total unrecognized tax benefits will decrease by approximately $0.1 million over the next 12 months due to the expiration of certain statutes of limitations.

We file income tax returns in the United States federal jurisdiction and in many state and foreign jurisdictions. The tax years 2011 through 2015 remain open to examination by the major taxing jurisdictions to which we are subject to. We are currently under examination by the Internal Revenue Service for tax year 2014.

Stock-Based Compensation

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

6.	Stock-Based Compensation

In May 2017, our board of directors adopted, and our stockholders approved, the 2017 Equity Incentive Plan (the “2017 Plan”), which became effective as of the date of the final prospectus for our IPO. The 2017 Plan provides for the grant of incentive stock options to employees, and for the grant of nonstatutory stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance-based stock awards and other forms of equity compensation to employees, including officers, and to non-employee directors and consultants. We initially reserved 6,421,442 shares of Class A common stock for issuance under the 2017 Plan, which included 421,442 shares that remained available for issuance under our 2007 Stock Option Plan (the “2007 Plan”) at the time that the 2017 Plan became effective. The number of shares reserved under the 2017 Plan increases for any shares subject to outstanding awards originally granted under the 2007 Plan that expire or are forfeited prior to exercise. As a result of the adoption of the 2017 Plan, no further grants may be made under the 2007 Plan. As of September 30, 2017, there were 6,481,622 shares of Class A common stock reserved for issuance under the 2017 Plan, of which 6,425,767 were available to be issued.

The 2007 Plan provided for the grant of stock options to employees, directors, and officers. Options under the 2007 Plan are exercisable into shares of Class B common stock and generally expire ten years from the date of grant. Under the 2007 Plan, the exercise price of each award was established by the board of directors, but could not be less than the fair market value of a share of our common stock on the grant date. Options generally vest upon the satisfaction of both a service condition and a performance condition. The service condition is satisfied at various rates as determined by us, typically on an annual basis over five years. The performance condition required the occurrence of a qualifying event, defined as a change of control transaction or upon the completion of an IPO. The performance condition was satisfied upon the effectiveness of our IPO in May 2017, on which date we recognized $6.2 million of cumulative stock-based compensation expense using the accelerated attribution method from the service start date.

We estimate the fair value of stock options using the Black-Scholes OPM, which requires the use of subjective assumptions, including the expected term of the option, the current price of the underlying stock, the expected stock price volatility, expected dividend yield and the risk-free interest rate for the expected term of the option. The expected term represents the period of time the stock options are expected to be outstanding. Due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to otherwise estimate the expected term of the stock options, we use the simplified method to estimate the expected term for our stock options. Under the simplified method, the expected term of an option is presumed to be the mid-point between the vesting date and the end of the contractual term. Expected volatility is based on historical volatilities for publicly traded stock of comparable companies over the estimated expected term of the stock options. We assume no dividend yield because dividends are not expected to be paid in the near future, which is consistent with our history of not paying dividends.

The following table summarizes the assumptions used to estimate the fair value of stock options granted during the three and nine months ended September 30, 2016 and 2017:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2016	2017	2016	2017
Risk-free interest rate	1.3%	1.9% - 2.1%	1.3% - 1.5%	1.9% - 2.2%
Expected term (in years)	6.5	6.5	6.5	6.5
Expected volatility	41.6%	38.6%	41.2% - 42.0%	38.6% - 40.6%
Expected dividend yield	— %	— %	— %	— %

Stock Options

The following table summarizes the stock option activity for the nine months ended September 30, 2017:


	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2017		6,784,448		$	4.65		6.5	$	44,259
Granted		1,252,200			11.89
Exercised		(556,220	)		1.19				8,386
Canceled		(96,500	)		6.30

Outstanding at September 30, 2017		7,383,928			6.16		6.7		164,688

Exercisable at September 30, 2017		2,992,648			1.85		3.8		79,636

The weighted average grant-date fair value of options granted during the nine months ended September 30, 2016 and 2017 was $4.38 and $5.04 per share, respectively. The total fair value of stock options that vested during the nine months ended September 30, 2017 was $5.3 million. No stock options vested during the nine months ended September 30, 2016 because a qualifying event had not yet occurred. As of September 30, 2017, the total compensation cost related to unvested stock options not yet recognized was $12.6 million, which will be recognized over a weighted average period of 3.0 years.

On April 25, 2017, our board of directors modified certain outstanding stock options nearing their expiration date to remove the performance condition. Stock options to purchase an aggregate of 216,160 shares of common stock were modified, and we recognized stock-based compensation expense of $2.4 million related to this modification.

Restricted Stock Units

The following table summarizes the restricted stock unit activity for the nine months ended September 30, 2017:


	Number of Shares			Weighted Average Grant Date Fair Value
Non-vested outstanding at December 31, 2016		—		$	—
Granted		47,855			20.38
Vested		(4,930	)		20.24
Canceled		—			—

Non-vested outstanding at September 30, 2017		42,925			20.40

As of September 30, 2017, total unrecognized compensation cost related to unvested restricted stock units was approximately $0.8 million and the weighted average remaining vesting period was 2.7 years.

The following table summarizes the components of our stock-based compensation expense for the three and nine months ended September 30, 2017 (in thousands):


	Nine Months Ended September 30, 2017		Three Months Ended September 30, 2017
Stock-based compensation expense related to stock option modifications	$	2,394	$	—
Cumulative stock-based compensation expense related to stock options recorded upon effectiveness of our IPO		6,236		—
Post-IPO stock-based compensation expense related to stock options		2,025		1,440
Stock-based compensation expense related to the issuance of common stock to directors		130		—
Stock-based compensation expense related to restricted stock units		134		134

Total stock-based compensation expense	$	10,919	$	1,574

Stock-based compensation expense for restricted stock units, stock options and issuances of common stock is included in the following line items in the accompanying condensed consolidated statements of operations for the three and nine months ended September 30, 2017 (in thousands):


	Nine Months Ended September 30, 2017		Three Months Ended September 30, 2017
Cost of revenue
Subscriptions, software and support	$	484	$	80
Professional services		1,126		142
Operating expenses
Sales and marketing		2,782		359
Research and development		2,458		256
General and administrative		4,069		737

Total stock-based compensation expense	$	10,919	$	1,574

For the three and nine months ended September 30, 2016, no stock-based compensation expense was recognized for our stock option awards because a qualifying event had not yet occurred.

6. Stock-Based Compensation

Under the Appian Corporation 2007 Stock Option Plan (the “Plan”), we have reserved shares of common stock for the issuance of stock options to employees, directors, and officers. In July 2016, the Plan was revised to increase the maximum number of shares issuable under the Plan from 4,757,610 to 8,413,770. Of this amount, 1,629,322 shares were available to be issued under the Plan as of December 31, 2016. These shares consist of authorized but unissued or reacquired shares. Options under the Plan may be granted for periods of up to ten years.

Under the Plan, the exercise price of each award is established by the board of directors, but may not be less than the fair market value of a share of our common stock on the grant date. Options generally vest upon the satisfaction of both a service condition and a performance condition. The service condition is satisfied at various rates as determined by us, typically on an annual basis over five years. The performance condition is satisfied upon the occurrence of a qualifying event, defined as a change of control transaction or upon the completion of an IPO.

We estimate the fair value of stock options using the Black-Scholes OPM, which requires the use of subjective assumptions, including the expected term of the option, the current price of the underlying stock, the expected stock price volatility, expected dividend yield and the risk-free interest rate for the expected term of the option. The expected term represents the period of time the stock options are expected to be outstanding. Due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to otherwise estimate the expected term of the stock options, we use the simplified method to estimate the expected term for stock options granted to employees and directors. Under the simplified method, the expected term of an option is presumed to be the mid-point between the vesting date and the end of the contractual term. Expected volatility is based on historical volatilities for publicly traded stock of comparable companies over the estimated expected term of the stock options. We assume no dividend yield because dividends are not expected to be paid in the near future on our common stock, which is consistent with our history of not paying dividends on our common stock.

The following table summarizes the assumptions used to estimate the fair value of stock options granted during the years ended December 31:


	2014	2015	2016
Risk-free interest rate	1.8% - 2.1%	1.7% - 1.9%	1.3% - 1.5%
Expected term (in years)	6.5	6.5	6.5
Expected volatility	44.7% - 46.0%	39.7% - 44.4%	40.9% - 42.0%
Expected dividend yield	0%	0%	0%

The following table summarizes the stock option activity for the year ended December 31, 2016:


	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2016		4,589,988		$	2.22		6.0	$	24,239
Granted		2,375,080			9.30
Cancelled		(180,620	)		4.22

Outstanding at December 31, 2016		6,784,448			4.65		6.5		44,259

Exercisable at December 31, 2016		—		$	—		—	$	—

The weighted average grant-date fair value of options granted was $1.81, $2.61, and $4.35 per share during the years ended December 31, 2014, 2015, and 2016, respectively.

For the years ended December 31, 2014, 2015 and 2016, no stock-based compensation expense was recognized for our stock option awards because a qualifying event had not occurred.

Convertible Preferred Stock and Stockholders' Deficit

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Equity [Abstract]

Convertible Preferred Stock and Stockholders' Deficit

7.	Convertible Preferred Stock and Stockholders’ Equity (Deficit)

Convertible Preferred Stock

Immediately prior to the completion of the IPO, all shares of convertible preferred stock then outstanding were automatically converted into 18,163,158 shares of common stock on a one-for-one basis, and then reclassified as shares of Class B common stock.

Summary of Activity

The following tables present a summary of activity for our convertible preferred stock issued and outstanding for the nine months ended September 30, 2017 (dollar amounts in thousands):


	Series A Convertible Preferred Stock						Series B Convertible Preferred Stock
	Amount			Shares			Amount			Shares
Balance as of January 1, 2017	$	17,915			12,043,108		$	37,500			6,120,050
Accretion of dividends on convertible preferred stock		357			—			—			—
Payment of accrued dividend to Series A convertible preferred stockholders		(7,565	)		—			—			—
Conversion of convertible preferred stock to common stock		(10,707	)		(12,043,108	)		(37,500	)		(6,120,050	)

Balance as of September 30, 2017	$	—			—		$	—			—

Common Stock

Immediately prior to the completion of the IPO, all shares of common stock then outstanding were converted into Class B common stock on a one-for-one basis. We offered and sold newly authorized shares of Class A common stock in the IPO.

The rights of the holders of Class A common stock and Class B common stock are identical, except with respect to voting and conversion rights. The holders of Class A common stock are entitled to one vote per share, and the holders of Class B common stock are entitled to ten votes per share, on all matters that are subject to stockholder vote. The holders of Class B common stock also have approval rights for certain corporate actions. Each share of Class B common stock may be converted into one share of Class A common stock at the option of its holder and will be automatically converted into one share of Class A common stock upon transfer thereof, subject to certain exceptions. In addition, upon the date on which the outstanding shares of Class B common stock represent less than 10% of the aggregate voting power of our capital stock, all outstanding shares of Class B common stock shall convert automatically into Class A common stock.

7. Convertible Preferred Stock and Stockholders’ Deficit

We are authorized to issue two classes of capital stock, common stock and preferred stock. We are authorized to issue 79,709,838 total shares, consisting of 61,462,320 shares of common stock and 18,247,518 shares of Series A and Series B convertible preferred stock.

Common Stock Repurchase

In February 2014, we purchased, and subsequently retired, 5,725,282 shares of common stock held by common stockholders at a price of $6.1274 per share. The fair value of our common stock in February 2014 was determined to be $3.67 per share. The amount representing the fair value of the repurchased shares, $21.0 million, is included in the accompanying consolidated statement of changes in stockholders’ deficit. The difference between the amount paid and the fair value of the common stock, $14.1 million, was recognized as compensation expense.

Additionally, the board of directors authorized an exercisable event that allowed for the exercise of certain stock options via a cashless exercise. We repurchased, and subsequently retired, 460,266 shares of common stock underlying these stock options from the option holders, resulting in compensation expense of $2.4 million.

The compensation expense related to this transaction is included in the accompanying statement of operations for the year ended December 31, 2014 as follows (in thousands):


Cost of revenue:
Subscriptions, software and support	$	119
Professional services		737
Operating expenses:
Sales and marketing		1,802
Research and development		515
General and administrative		13,315

	$	16,488

Stock Split

In May 2015, our common stock and convertible preferred stock was split on a two-for-one basis. The number of shares and per-share prices have been retrospectively adjusted to reflect the stock split.

Common Stock

At December 31, 2016, we had reserved shares of common stock for future issuance as follows:


For conversion of Series A and Series B convertible preferred stock			18,163,158
Outstanding stock options			6,784,448
Outstanding preferred stock warrant			84,360
Possible future issuance under equity incentive plan			1,629,322

Total shares of common stock reserved for future issuance			26,661,288

Liquidation Rights

In the event of any liquidation or dissolution of the Company, the holders of common stock are entitled to the remaining assets of the Company legally available for distribution after the payment of the full liquidation preference for all series of outstanding convertible preferred stock.

Dividend and Voting Rights

The holders of common stock are entitled to receive dividends if and when declared by the Company, but not until holders of convertible preferred stock have been paid a dividend on each outstanding share equal to at least 8% of the original issue price. Holders of common stock have the right to one vote per share.

Convertible Preferred Stock

The following table summarizes the issuances of convertible preferred stock:


Name	Original Issue Price per Share		Number of Shares		Conversion Price per Share
Series A convertible preferred stock	$	0.88903		12,043,108	$	0.88903
Series B convertible preferred stock	$	6.1274		6,120,050	$	6.1274

Any costs incurred in connection with the issuance of the Series A convertible preferred stock and Series B convertible preferred stock (the “Preferred Stock”) have been recorded as a reduction of the carrying amount of the Preferred Stock. Since the Preferred Stock has deemed liquidation provisions which require the shares to be redeemed upon a change in control or other deemed liquidation event, these shares are classified outside of permanent equity and carried at redemption value, which includes cumulative dividends in the case of the Series A convertible preferred stock.

Dividend Rights

The holders of our Preferred Stock shall be entitled to receive dividends in preference to any dividend on our common stock at the rate of 8% of the original purchase price per annum for each such series. Such dividends with respect to the Series A convertible preferred stock shall be cumulative and shall accrue from day to day until paid, whether or not the dividends are authorized or declared, whether or not funds are legally available for payment and whether or not the corporation has earnings. Such dividends with respect to the Series B convertible preferred stock shall be non-cumulative and shall not accrue unless declared; provided, however, that in each such case, dividends with respect to the Series A convertible preferred stock and Series B convertible preferred stock shall be payable, on a pari passu basis, only when, as and if declared by the board of directors. In the event dividends are paid on any share of common stock, whether in cash or property, we shall pay an additional dividend on all outstanding shares of Preferred Stock in a per share amount (on an as-if converted to common stock basis) equal to the amount paid or set aside for each share of common stock. We had cumulative dividends of $6.4 million and $7.2 million, or $0.53 and $0.60 per share, on the Series A convertible preferred stock as of December 31, 2015 and 2016, respectively.

Liquidation Rights

Upon any liquidation (as defined in our certificate of incorporation), before any payment to holders of common stock, the holders of Preferred Stock are entitled to receive an amount per share, on a pari passu basis, equal to the greater of (1) the original purchase price per share for each such series (as adjusted for stock splits, stock dividends, recapitalizations, etc.), plus any accrued but unpaid dividends on such shares, or (2) the amount per share of Preferred Stock the holders would be entitled to receive if all shares of Preferred Stock were converted into shares of common stock. We have the option to pay the portion of the liquidation preference attributable to accrued and unpaid dividends in cash or common stock.

Voting Rights

Each share of Preferred Stock has voting rights equal to an equivalent number of shares of common stock into which it is convertible and votes together as one class with the common stockholders.

Conversion Rights

The holders of the Preferred Stock have the right to convert their shares to common stock at any time. In addition, each share of outstanding Preferred Stock shall automatically be converted into common stock immediately upon the closing of a firm commitment underwritten public offering of common stock by the Company, at a price per share of at least 1.5 times the original issue price of the Series B convertible preferred stock, or $9.18, pursuant to an effective registration statement under the Securities Act of 1933, as amended, and resulting in at least $50,000,000 in gross proceeds to the Company, or upon the vote of the requisite holders of Preferred Stock. The number of shares of common stock to which a preferred stockholder shall be entitled to upon conversion shall be the number obtained by dividing the original issue price by the applicable conversion price. No fractional shares will be issued upon conversion of Preferred Stock.

Summary of Activity

The following table presents a summary of activity for our Preferred Stock issued and outstanding for the years ended December 31, 2014, 2015 and 2016 (dollar amounts in thousands):


	Series A Convertible Preferred Stock				Series B Convertible Preferred Stock
	Amount		Shares		Amount		Shares
Balance as of January 1, 2014	$	15,341		12,043,108	$	—		—
Issuance of Series B convertible preferred stock, net of offering costs of $120		—		—		37,380		6,120,050
Accretion of dividends on convertible preferred stock		856		—		—		—
Accretion of issuance costs on convertible preferred stock		—		—		120		—

Balance as of December 31, 2014		16,197		12,043,108		37,500		6,120,050
Accretion of dividends on convertible preferred stock		861		—		—		—

Balance as of December 31, 2015		17,058		12,043,108		37,500		6,120,050
Accretion of dividends on convertible preferred stock		857		—		—		—

Balance as of December 31, 2016	$	17,915		12,043,108	$	37,500		6,120,050

Warrants

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Warrants and Rights Note Disclosure [Abstract]

Warrants

8.	Warrants

We previously issued a warrant to purchase 84,360 shares of Series A convertible preferred stock in conjunction with a credit facility with a lender at an exercise price of $0.88905 per share. Immediately prior to the completion of the IPO, this warrant was converted into a warrant to purchase 84,360 shares of Class B common stock. The fair value at the time of the conversion was $1.2 million and was recorded as additional paid-in capital and a reduction of the preferred stock warrant liability. In May 2017, the warrant holder exercised the warrant and we issued 79,363 shares of Class B common stock through a cashless exercise of the warrant, in accordance with its terms.

8. Warrants

In November 2008, we issued a warrant to purchase 84,360 shares of our Series A convertible preferred stock in connection with a credit facility with a lender. The warrant has a 10-year term and an exercise price of $0.88905 per share. This warrant is subject to remeasurement at each reporting period. The fair value of the warrant as of December 31, 2015 and 2016 was $0.7 million and $0.9 million, respectively. Subsequent changes in fair value are recorded within other expense, net in the accompanying consolidated statements of operations. The inputs and valuation techniques used to measure the fair value of this warrant are discussed in Note 2.

Basic and Diluted Loss per Common Share

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Earnings Per Share [Abstract]

Basic and Diluted Loss per Common Share

9.	Basic and Diluted Loss per Common Share

Under the two-class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current period earnings that the participating securities would have been entitled to receive pursuant to their dividend rights had all of the period’s earnings been distributed. No such adjustment to earnings is made during periods with a net loss, as the holders of the participating securities have no obligation to fund losses.

Diluted net income (loss) per common share is computed under the two-class method by using the weighted average number of shares of common stock outstanding, plus, for periods with net income attributable to common stockholders, the potential dilutive effects of stock options and warrants. In addition, we analyze the potential dilutive effect of the outstanding participating securities under the “if-converted” method when calculating diluted earnings per share, in which it is assumed that the outstanding participating securities convert into common stock at the beginning of the period or date of issuance, if later. We report the more dilutive of the approaches (two-class or “if-converted”) as our diluted net income per share during the period.

The following securities have been excluded from the calculation of weighted average common shares outstanding because the effect is anti-dilutive or performance or market conditions had not been met at the end of the period:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2017		2016		2017
Convertible preferred stock:
Series A convertible preferred stock		12,043,108		—		12,043,108		—
Series B convertible preferred stock		6,120,050		—		6,120,050		—
Warrant to purchase Series A convertible preferred stock		84,360		—		84,360		—
Stock options		6,699,048		7,383,928		6,699,048		7,383,928
Restricted stock units		—		42,925		—		42,925

9. Net Loss Per Share

Diluted loss per share is the same as basic loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive given our net loss. The following securities have been excluded from the calculation of weighted average common shares outstanding because the effect is anti-dilutive for the years ended December 31:


	2014		2015		2016
Convertible preferred stock:
Series A convertible preferred stock		12,043,108		12,043,108		12,043,108
Series B convertible preferred stock		6,120,050		6,120,050		6,120,050
Warrant to purchase Series A convertible preferred stock		84,360		84,360		84,360
Stock options		3,886,408		4,589,988		6,784,448

Commitments and Contingencies

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

10. Commitments and Contingencies

Operating Leases

We lease office space and equipment in our headquarters location in Reston, Virginia, as well as in the United Kingdom, France, Germany, Canada, and Australia, under non-cancellable operating lease agreements which have various expiration dates through 2026 for our office space and various expiration dates through 2019 for our equipment.

A summary of our future minimum gross and net lease commitments by year as of December 31, 2016 is as follows (in thousands):


	Office Leases			Equipment Leases
2017	$	6,868		$	277
2018		6,538			131
2019		6,720			6
2020		4,780			—
2021		2,466			—
Thereafter		1,304			—

		28,676			414
Less: minimum payments to be received from subleases		(527	)		—

Total	$	28,149		$	414

We record rent expense using the total minimum rent commitment, amortized on the straight-line method over the term of the lease. The difference between monthly rental payments and recorded rent expense is charged to deferred rent. As of December 31, 2015 and 2016, deferred rent totaled $1.5 million and $2.4 million, respectively, and is included within other current liabilities and other long-term liabilities on the accompanying consolidated balance sheets.

In September 2014, we entered into an agreement to sublease a certain rented facility to a subtenant. The sublease agreement commenced on November 1, 2014 and will expire when the original lease agreement expires in October 2017. We received $0.1 million for the year ended December 31, 2014 and $0.6 million for each of the years ended December 31, 2015 and 2016 in rental income from the subtenant.

Total rent and lease expense was $3.8 million, $4.6 million and $6.6 million for the years ended December 31, 2014, 2015 and 2016, respectively.

Other Commitments

We also have entered into a non-cancellable agreement for the use of technology that is integral in the development of our software and pay annual royalty fees of $0.3 million.

Letters of Credit

As of December 31, 2015 and 2016, we had outstanding letters of credit totaling $0.8 million and $1.3 million, respectively, in connection with securing our leased office space. All letters of credit are secured by our borrowing arrangement as described in Note 4.

Legal

From time to time, we are subject to legal, regulatory and other proceedings and claims that arise in the ordinary course of business. There are no issues or resolution of any matters that are expected to have a material adverse impact on our consolidated financial statements.

Segment and Geographic Information

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Segment Reporting [Abstract]

Segment and Geographic Information

10.

Segment and Geographic Information

The following table summarizes revenue by geography for the three and nine months ended September 30, 2016 and 2017 (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2017		2016		2017
Domestic	$	23,650	$	31,878	$	80,715	$	93,860
International		7,095		12,770		18,461		32,315

Total	$	30,745	$	44,648	$	99,176	$	126,175

With respect to geographic information, revenue is attributed to respective geographies based on the contracting address of the customer. There were no individual foreign countries from which more than 10% of our total revenue was attributable for the three and nine months ended September 30, 2016 and 2017. Substantially all of our long-lived assets were held in the United States as of December 31, 2016 and September 30, 2017.

11.

Segment and Geographic Information

The following table summarizes revenue by geography for the years ended December 31 (in thousands):


	2014		2015		2016
Revenue:
Domestic	$	66,285	$	89,043	$	107,069
International		22,711		22,161		25,854

Total	$	88,996	$	111,204	$	132,923

With respect to geographic information, revenues are attributed to respective geographies based on the contracting address of the customer. Revenues from external customers attributed to the United Kingdom were 10.8% of total revenue for the year ended December 31, 2014. There were no individual foreign countries from which more than 10% of our total revenues were attributable for the years ended December 31, 2015 and 2016. Substantially all of our long-lived assets were held in the United States as of December 31, 2015 and 2016.

Retirement Plans

12 Months Ended

Dec. 31, 2016

Postemployment Benefits [Abstract]

Retirement Plans

12.

Retirement Plans

We have a defined contribution 401(k) retirement and savings plan (the “401(k) Plan”) to provide retirement benefits for all eligible employees. All employees who have completed forty-five days of service and are at least twenty-one years of age are eligible to participate in the 401(k) Plan. The 401(k) Plan allows eligible employees to make salary-deferred contributions up to 75% of their annual compensation, as defined, and subject to certain Internal Revenue Service limitations. Employer contributions vest at 25% per year, over four years. For the years ending December 31, 2014, 2015 and 2016, we incurred $1.3 million, $1.9 million and $2.6 million, respectively, in contribution expense related to the employer matching contributions.

We are obligated to make plan contributions for the employees of certain of our wholly-owned foreign subsidiaries. For the years ending December 31, 2014, 2015 and 2016, we incurred $0.3 million, $0.5 million and $0.7 million, respectively, in contribution expense related to our foreign subsidiaries.

Subsequent Events

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Subsequent Events [Abstract]

Subsequent Events

11.

Subsequent Events

In preparing our condensed consolidated financial statements, we evaluated subsequent events through November 13, 2017, which is the date that the condensed consolidated financial statements were available to be issued.

In November 2017, we entered into a $20.0 million revolving line of credit with a lender. The facility matures in November 2022. We may elect whether amounts drawn on the revolving line of credit bear interest at a floating rate per annum equal to either the LIBOR or the prime rate plus an additional interest rate margin that is determined by the availability of borrowings under the revolving line of credit. The additional interest rate margin will range from 2.00% to 2.50% in the case of LIBOR advances and from 1.00% to 1.50% in the case of prime rate advances. The revolving line of credit contains an unused facility fee in an amount between 0.15% and 0.25% of the average unused portion of the revolving line of credit, which is payable quarterly. The agreement contains certain customary affirmative and negative covenants and requires us to maintain (i) an adjusted quick ratio of at least 1.35 to 1.0 and (ii) minimum adjusted EBITDA, in the amounts and for the periods set forth in the agreement. Any amounts borrowed under the credit facility are collateralized by substantially all of our assets.

On October 25, 2017, our board of directors approved the grant of 689,200 restricted stock units under the 2017 Plan at a fair value of $22.27 per share to members of management and other employees. The value of these awards at the grant date was $15.3 million and will be amortized over the vesting periods. In addition, our board of directors also approved stock option grants under the 2017 Plan to purchase an aggregate of 4,000 shares of common stock at an exercise price of $22.27 per share. The restricted stock units and options vest over five years through October 25, 2022.

13.

Subsequent Events

We have evaluated subsequent events through February 17, 2017, which is the date that the consolidated financial statements were available to be issued.

On January 31, 2017, our board of directors approved stock option grants under the Plan to purchase an aggregate of 249,700 shares of common stock at an exercise price of $11.17 per share.

Accrued Expenses

9 Months Ended

Sep. 30, 2017

Payables and Accruals [Abstract]

Accrued Expenses

3.	Accrued Expenses

Accrued expenses consist of the following:


	December 31, 2016		September 30, 2017
Accrued contract labor costs	$	743	$	3,122
Accrued audit and tax expenses		358		364
Accrued reimbursable employee expenses		134		285
Accrued marketing and tradeshow expenses		111		251
Other accrued expenses		1,514		1,955

Total	$	2,860	$	5,977

Significant Accounting Policies (Policies)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation

The consolidated financial statements and accompanying notes were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Use of Estimates

Use of Estimates

Principles of Consolidation

Principles of Consolidation

The accompanying consolidated financial statements include the accounts of Appian and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Revenue Recognition

Revenue Recognition

Subscriptions, Software and Support Revenue

SaaS Subscriptions

Term License Subscriptions

Perpetual Licenses

Professional Services

Multiple Element Arrangements

SaaS Subscriptions

Term License Subscriptions

Perpetual Licenses

Revenue Recognition

Subscriptions, Software and Support Revenue

Historically, we licensed our software primarily under perpetual licenses, but over time we transitioned from perpetual licenses to subscriptions. As a result, revenue from our perpetual software licenses was 5.0%, 1.9%, and 0.9% of our total revenue for 2014, 2015 and 2016, respectively.

SaaS Subscriptions

Term License Subscriptions

Perpetual Licenses

Professional Services

Multiple Element Arrangements

SaaS Subscriptions

For multiple element arrangements involving SaaS subscriptions that include professional services in addition to the subscription to our platform, we evaluate each element to determine whether it represents a separate unit of accounting. Because there are third-party vendors who routinely sell and provide the same professional services to our customers, our professional services are deemed to have standalone value apart from the SaaS subscription. Additionally, we offer both SaaS subscriptions and professional services on a standalone basis. Professional services revenue is therefore accounted for separately from subscription fees and recognized as the professional services are performed. We allocate revenue to the elements based on the selling price hierarchy using vendor-specific objective evidence, or VSOE, of selling price, third-party evidence, or TPE, of selling price, or if neither exists, best estimated selling price, or BESP. In cases where we do not have VSOE or TPE of the elements of our arrangements, we use BESP to allocate revenue. We determine BESP for a service by considering multiple factors including, but not limited to, evaluating the weighted average of actual sales prices and other factors such as gross margin objectives, pricing practices and growth strategy. Pricing practices taken into consideration include historic contractually stated prices, volume discounts where applicable and our price lists. While we believe we can make reliable estimates regarding these matters, these estimates are inherently subjective. Once the revenue is allocated to these elements, revenue is recognized as such services are provided.

Term License Subscriptions

Perpetual Licenses

Deferred Revenue

Deferred Revenue

Cost of Revenue

Cost of Revenue

Cost of Subscriptions, Software and Support Revenue

Cost of Professional Services Revenue

Cost of Revenue

Cost of Subscriptions, Software and Support Revenue

Cost of Professional Services Revenue

Concentration of Credit Risk

Concentration of Credit Risk

No individual customer represented more than 10% of accounts receivable at December 31, 2015. One customer accounted for 17.2% of accounts receivable at December 31, 2016.

Cash and Cash Equivalents

Cash and Cash Equivalents

We consider all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase, as well as overnight repurchase investments, to be cash equivalents.

Accounts Receivable and Allowance for Doubtful Accounts

Accounts Receivable and Allowance for Doubtful Accounts

Deferred Commissions

Deferred Commissions

Deferred commissions are the incremental costs that are directly associated with subscription agreements with customers and consist of sales commissions paid to our direct sales force. Commissions are considered direct and incremental and as such are deferred and amortized over the terms of the related customer contracts consistent with the related revenue. Amortization of deferred commissions is included in sales and marketing expense in the accompanying consolidated statements of operations. Commission expense was $3.8 million, $4.6 million, and $6.5 million for the years ended December 31, 2014, 2015 and 2016, respectively.

Property and Equipment

Property and Equipment


Asset Category		Useful Life (in years)
Computer software		3
Computer hardware		3
Equipment		5
Office furniture and fixtures		10
Leasehold improvements		Shorter of useful life of assets or lease term

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets

Fair Value of Financial Instruments

Fair Value of Financial Instruments

•

Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities;

•

Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and

•

Level 3. Unobservable inputs for which there is little or no market data, which require us to develop our own assumptions.

Assets and Liabilities Measured at Fair Value on a Recurring Basis


	December 31, 2016		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	850	$	—	$	—	$	850

	$	850	$	—	$	—	$	850

(1)

Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs

There were no changes in our Level 3 instruments measured at fair value on a recurring basis during the three months ended September 30, 2016 and 2017.

The following table presents the changes in our Level 3 instruments measured at fair value on a recurring basis during the nine months ended September 30, 2016 and 2017 (in thousands):


	Nine Months Ended September 30,
	2016		2017
Balance as of January 1	$	650	$	850
Change in fair value of warrant liability		200		341
Reclassification of warrant liability to equity		—		(1,191	)

Balance as of September 30	$	850	$	—

Fair Value of Financial Instruments

•

Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities;

•

Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and

•

Level 3. Unobservable inputs for which there is little or no market data, which require us to develop our own assumptions.

Assets and Liabilities Measured at Fair Value on a Recurring Basis


	2015		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	650		—		—	$	650

	$	650	$	—	$	—	$	650


	2016		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	850		—		—	$	850

	$	850	$	—	$	—	$	850

(1)

Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs

The following table presents the changes in our Level 3 instruments measured at fair value on a recurring basis during the years ended December 31 (in thousands):


	Series A Convertible Preferred Stock Warrant
	2014		2015		2016
Balance as of January 1	$	—	$	351	$	650
Change in fair value of warrant liability		351		299		200

Balance as of December 31	$	351	$	650	$	850

The fair value of the warrant as of December 31, 2013 was de minimis and therefore not recorded as of January 1, 2014.

Stock-Based Compensation

Stock-Based Compensation

Emerging Growth Company Status

Stock-Based Compensation

Basic and Diluted Loss per Common Share

Basic and Diluted Loss per Common Share

Due to net losses for the years ended December 31, 2014, 2015 and 2016, basic and diluted loss per share were the same, as the effect of potentially dilutive securities would have been anti-dilutive.

Income Taxes

Income Taxes

Segment Reporting

Segment Reporting

Foreign Currency

Foreign Currency

Research and Development

Research and Development

Advertising

Advertising

Recent Accounting Pronouncements

Recent Accounting Pronouncements

Adopted

Not Yet Adopted

Recent Accounting Pronouncements

Adopted

Not Yet Adopted

Initial Public Offering

Initial Public Offering

Significant Accounting Policies (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Accounting Policies [Abstract]

Schedule of Additions or Improvements Extending Useful Life

Significant additions or improvements extending the useful life of an asset are capitalized, while repairs and maintenance costs which do not significantly improve the related assets or extend their useful lives are charged to expense as incurred.


Asset Category		Useful Life (in years)
Computer software		3
Computer hardware		3
Equipment		5
Office furniture and fixtures		10
Leasehold improvements		Shorter of useful life of assets or lease term

Summary of Liabilities Fair Value Measurements

The following table summarizes the conclusions reached as of December 31 (in thousands):


	2015		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	650		—		—	$	650

	$	650	$	—	$	—	$	650


	2016		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	850		—		—	$	850

	$	850	$	—	$	—	$	850

(1)

FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock

The following table presents the changes in our Level 3 instruments measured at fair value on a recurring basis during the nine months ended September 30, 2016 and 2017 (in thousands):


	Nine Months Ended September 30,
	2016		2017
Balance as of January 1	$	650	$	850
Change in fair value of warrant liability		200		341
Reclassification of warrant liability to equity		—		(1,191	)

Balance as of September 30	$	850	$	—

The following table presents the changes in our Level 3 instruments measured at fair value on a recurring basis during the years ended December 31 (in thousands):


	Series A Convertible Preferred Stock Warrant
	2014		2015		2016
Balance as of January 1	$	—	$	351	$	650
Change in fair value of warrant liability		351		299		200

Balance as of December 31	$	351	$	650	$	850

Summary of Liabilities Fair Value Measurements

The following table summarizes the conclusions reached as of December 31, 2016 (in thousands):


	December 31, 2016		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	850	$	—	$	—	$	850

	$	850	$	—	$	—	$	850

(1)

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment

Property and equipment consisted of the following as of December 31 (in thousands):


	2015			2016
Computer software	$	1,562		$	1,701
Computer hardware		1,201			1,408
Leasehold improvements		3,555			4,098
Office furniture and fixtures		386			464
Equipment		96			116

		6,800			7,787
Less: accumulated depreciation		(3,908	)		(4,686	)

Property and equipment, net	$	2,892		$	3,101

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Components of net (loss) income before income taxes

For the years ended December 31, 2014, 2015 and 2016, our net (loss) income before income taxes was comprised of the following (in thousands):


	2014			2015			2016
Domestic	$	(11,026	)	$	1,079		$	(4,524	)
Foreign		(4,829	)		(7,688	)		(9,620	)

Total	$	(15,855	)	$	(6,609	)	$	(14,144	)

Schedule of Income Tax Expense (Benefit)

For the years ended December 31, 2014, 2015, and 2016, our income tax expense (benefit) was comprised of the following (in thousands):


	2014		2015			2016
Current:
Federal	$	430	$	390		$	(627	)
State		128		62			(200	)
Foreign		247		217			266

Total current expense (benefit)		805		669			(561	)

Deferred:
Federal		325		(334	)		(922	)
State		51		43			(230	)
Foreign		23		—			30

Total deferred expense (benefit)		399		(291	)		(1,122	)

Total income tax expense (benefit)	$	1,204	$	378		$	(1,683	)

Scedule of Provision for Income Taxes Differs from Computed Applying Federal Statutory Income Tax Rate


	2014			2015			2016
U.S. federal statutory tax rate		34.0	%		34.0	%		34.0	%
State tax expense		(0.8	)		(0.9	)		1.4
Expense on purchase of common stock		(30.2	)		—			—
Foreign rate differential		(7.9	)		(29.4	)		(17.8	)
Nondeductible expenses		(1.5	)		(4.1	)		(2.3	)
Tax credits		3.2			10.0			6.5
Unrecognized tax benefits		(0.5	)		(1.8	)		(0.2	)
Other		(0.5	)		(1.9	)		(0.2	)
Change in valuation allowance		(3.4	)		(11.5	)		(9.6	)

Total		(7.6	)%		(5.6	)%		11.8	%

Schedule of Significant Components of Deferred Tax Assets and Liabilities

As of December 31, 2015 and 2016, significant components of our deferred tax assets and liabilities are as follows (in thousands):


	2015			2016
Deferred tax assets:
Accrued vacation	$	482		$	529
Bad debt		157			159
Deferred revenue		3,173			2,176
Deferred rent		603			834
Tax credits		1,381			2,401
Net operating losses		1,289			2,939
Other		209			929

Gross deferred tax assets		7,294			9,967
Less: Valuation allowance		(1,283	)		(2,642	)

Total deferred tax assets		6,011			7,325

Deferred tax liabilities:
Depreciation		(491	)		(349	)
Unbilled receivables		(1,835	)		(491	)
Prepaid expenses		(4,579	)		(6,505	)

Total deferred tax liabilities		(6,905	)		(7,345	)

Net deferred tax liability	$	(894	)	$	(20	)

Schedule of Activity Related to Unrecognized Tax Benefit

recognized. The following table summarizes the activity related to our unrecognized tax benefit from January 1, 2014 to December 31, 2016 (in thousands):


Balance as of January 1, 2014	$	218
Additions for tax positions in current years		68
Additions for tax positions in prior years		—
Reductions due to lapse in statutes of limitations		—
Settlements		—

Balance as of December 31, 2014		286
Additions for tax positions in current years		98
Additions for tax positions in prior years		—
Reductions due to lapse in statutes of limitations		—
Settlements		—

Balance as of December 31, 2015		384
Additions for tax positions in current years		171
Additions for tax positions in prior years		—
Reductions due to lapse in statutes of limitations		(136	)
Settlements		—

Balance as of December 31, 2016	$	419

Stock-Based Compensation (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Estimate the Fair Value of Stock Options Granted

The following table summarizes the assumptions used to estimate the fair value of stock options granted during the three and nine months ended September 30, 2016 and 2017:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2016	2017	2016	2017
Risk-free interest rate	1.3%	1.9% - 2.1%	1.3% - 1.5%	1.9% - 2.2%
Expected term (in years)	6.5	6.5	6.5	6.5
Expected volatility	41.6%	38.6%	41.2% - 42.0%	38.6% - 40.6%
Expected dividend yield	— %	— %	— %	— %

The following table summarizes the assumptions used to estimate the fair value of stock options granted during the years ended December 31:


	2014	2015	2016
Risk-free interest rate	1.8% - 2.1%	1.7% - 1.9%	1.3% - 1.5%
Expected term (in years)	6.5	6.5	6.5
Expected volatility	44.7% - 46.0%	39.7% - 44.4%	40.9% - 42.0%
Expected dividend yield	0%	0%	0%

Summary of the Stock Option Activity

The following table summarizes the stock option activity for the nine months ended September 30, 2017:


	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2017		6,784,448		$	4.65		6.5	$	44,259
Granted		1,252,200			11.89
Exercised		(556,220	)		1.19				8,386
Canceled		(96,500	)		6.30

Outstanding at September 30, 2017		7,383,928			6.16		6.7		164,688

Exercisable at September 30, 2017		2,992,648			1.85		3.8		79,636

The following table summarizes the stock option activity for the year ended December 31, 2016:


	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2016		4,589,988		$	2.22		6.0	$	24,239
Granted		2,375,080			9.30
Cancelled		(180,620	)		4.22

Outstanding at December 31, 2016		6,784,448			4.65		6.5		44,259

Exercisable at December 31, 2016		—		$	—		—	$	—

Schedule of Stock-based Compensation Expense Included in Condensed Consolidated Statements of Operations


	Nine Months Ended September 30, 2017		Three Months Ended September 30, 2017
Cost of revenue
Subscriptions, software and support	$	484	$	80
Professional services		1,126		142
Operating expenses
Sales and marketing		2,782		359
Research and development		2,458		256
General and administrative		4,069		737

Total stock-based compensation expense	$	10,919	$	1,574

The compensation expense related to this transaction is included in the accompanying statement of operations for the year ended December 31, 2014 as follows (in thousands):


Cost of revenue:
Subscriptions, software and support	$	119
Professional services		737
Operating expenses:
Sales and marketing		1,802
Research and development		515
General and administrative		13,315

	$	16,488

Schedule of Restricted Stock Unit Activity

The following table summarizes the restricted stock unit activity for the nine months ended September 30, 2017:


	Number of Shares			Weighted Average Grant Date Fair Value
Non-vested outstanding at December 31, 2016		—		$	—
Granted		47,855			20.38
Vested		(4,930	)		20.24
Canceled		—			—

Non-vested outstanding at September 30, 2017		42,925			20.40

Schedule of Components of Stock-based Compensation Expense

The following table summarizes the components of our stock-based compensation expense for the three and nine months ended September 30, 2017 (in thousands):


	Nine Months Ended September 30, 2017		Three Months Ended September 30, 2017
Stock-based compensation expense related to stock option modifications	$	2,394	$	—
Cumulative stock-based compensation expense related to stock options recorded upon effectiveness of our IPO		6,236		—
Post-IPO stock-based compensation expense related to stock options		2,025		1,440
Stock-based compensation expense related to the issuance of common stock to directors		130		—
Stock-based compensation expense related to restricted stock units		134		134

Total stock-based compensation expense	$	10,919	$	1,574

Convertible Preferred Stock and Stockholders' Deficit (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Equity [Abstract]

Schedule of Reserved Shares of Common Stock for Future Issuance

At December 31, 2016, we had reserved shares of common stock for future issuance as follows:


For conversion of Series A and Series B convertible preferred stock			18,163,158
Outstanding stock options			6,784,448
Outstanding preferred stock warrant			84,360
Possible future issuance under equity incentive plan			1,629,322

Total shares of common stock reserved for future issuance			26,661,288

Summary of Activity for Convertible Preferred Stock Issued and Outstanding

The following tables present a summary of activity for our convertible preferred stock issued and outstanding for the nine months ended September 30, 2017 (dollar amounts in thousands):


	Series A Convertible Preferred Stock						Series B Convertible Preferred Stock
	Amount			Shares			Amount			Shares
Balance as of January 1, 2017	$	17,915			12,043,108		$	37,500			6,120,050
Accretion of dividends on convertible preferred stock		357			—			—			—
Payment of accrued dividend to Series A convertible preferred stockholders		(7,565	)		—			—			—
Conversion of convertible preferred stock to common stock		(10,707	)		(12,043,108	)		(37,500	)		(6,120,050	)

Balance as of September 30, 2017	$	—			—		$	—			—

The following table presents a summary of activity for our Preferred Stock issued and outstanding for the years ended December 31, 2014, 2015 and 2016 (dollar amounts in thousands):


	Series A Convertible Preferred Stock				Series B Convertible Preferred Stock
	Amount		Shares		Amount		Shares
Balance as of January 1, 2014	$	15,341		12,043,108	$	—		—
Issuance of Series B convertible preferred stock, net of offering costs of $120		—		—		37,380		6,120,050
Accretion of dividends on convertible preferred stock		856		—		—		—
Accretion of issuance costs on convertible preferred stock		—		—		120		—

Balance as of December 31, 2014		16,197		12,043,108		37,500		6,120,050
Accretion of dividends on convertible preferred stock		861		—		—		—

Balance as of December 31, 2015		17,058		12,043,108		37,500		6,120,050
Accretion of dividends on convertible preferred stock		857		—		—		—

Balance as of December 31, 2016	$	17,915		12,043,108	$	37,500		6,120,050

The following table summarizes the issuances of convertible preferred stock:


Name	Original Issue Price per Share		Number of Shares		Conversion Price per Share
Series A convertible preferred stock	$	0.88903		12,043,108	$	0.88903
Series B convertible preferred stock	$	6.1274		6,120,050	$	6.1274

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=65877616&loc=d3e177068-122764

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21553-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65888546&loc=d3e21300-112643

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(27))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21484-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21488-112644

+ Details

Basic and Diluted Loss per Common Share (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Earnings Per Share [Abstract]

Summary of Securities Excluded From Calculation of Weighted Average Common Shares Outstanding


	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2017		2016		2017
Convertible preferred stock:
Series A convertible preferred stock		12,043,108		—		12,043,108		—
Series B convertible preferred stock		6,120,050		—		6,120,050		—
Warrant to purchase Series A convertible preferred stock		84,360		—		84,360		—
Stock options		6,699,048		7,383,928		6,699,048		7,383,928
Restricted stock units		—		42,925		—		42,925

The following securities have been excluded from the calculation of weighted average common shares outstanding because the effect is anti-dilutive for the years ended December 31:


	2014		2015		2016
Convertible preferred stock:
Series A convertible preferred stock		12,043,108		12,043,108		12,043,108
Series B convertible preferred stock		6,120,050		6,120,050		6,120,050
Warrant to purchase Series A convertible preferred stock		84,360		84,360		84,360
Stock options		3,886,408		4,589,988		6,784,448

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Summary Future Minimum Gross and Net Lease commitments

A summary of our future minimum gross and net lease commitments by year as of December 31, 2016 is as follows (in thousands):


	Office Leases			Equipment Leases
2017	$	6,868		$	277
2018		6,538			131
2019		6,720			6
2020		4,780			—
2021		2,466			—
Thereafter		1,304			—

		28,676			414
Less: minimum payments to be received from subleases		(527	)		—

Total	$	28,149		$	414

Segment and Geographic Information (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Segment Reporting [Abstract]

Summary of Revenue By Geography

The following table summarizes revenue by geography for the three and nine months ended September 30, 2016 and 2017 (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2017		2016		2017
Domestic	$	23,650	$	31,878	$	80,715	$	93,860
International		7,095		12,770		18,461		32,315

Total	$	30,745	$	44,648	$	99,176	$	126,175

The following table summarizes revenue by geography for the years ended December 31 (in thousands):


	2014		2015		2016
Revenue:
Domestic	$	66,285	$	89,043	$	107,069
International		22,711		22,161		25,854

Total	$	88,996	$	111,204	$	132,923

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2017

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consist of the following:


	December 31, 2016		September 30, 2017
Accrued contract labor costs	$	743	$	3,122
Accrued audit and tax expenses		358		364
Accrued reimbursable employee expenses		134		285
Accrued marketing and tradeshow expenses		111		251
Other accrued expenses		1,514		1,955

Total	$	2,860	$	5,977

Significant Accounting Policies - Additional Information (Detail)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	May 31, 2017 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) Agency	Sep. 30, 2016 USD ($) Agency	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($) Agency	Dec. 31, 2016 USD ($) Agency Customer Segment	Dec. 31, 2015 USD ($) Agency Customer	Dec. 31, 2014 USD ($) Agency
Summary Of Significant Accounting Policies [Line Items]
Percentage of license revenue		1.00%	1.00%	1.00%	1.00%	0.90%	1.90%	5.00%
Change in allowance for doubtful accounts				$ 0		$ 0	$ 0
Commission expense		$ 3,200,000	$ 1,800,000	8,500,000	$ 5,400,000	$ 6,500,000	4,600,000	$ 3,800,000
Number of Reportable Segments \| Segment						1
Number of Operating Segments \| Segment						1
Transaction gains and losses						$ (1,500,000)	(1,300,000)	(1,700,000)
Advertising expenses						$ 1,400,000	$ 500,000	$ 500,000
Net proceeds from initial public offering				80,213,000	$ 0
Deferred offering costs		$ 2,400,000		$ 2,400,000
Customer Concentration Risk \| Sales Revenue, Net \| Foreign Customers
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		28.60%	23.10%	25.60%	18.60%	19.50%	19.90%	25.50%
Customer Concentration Risk \| Sales Revenue, Net \| Government Agencies
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		14.20%	19.40%	15.40%	28.50%	26.20%	32.70%	34.40%
Customer Concentration Risk \| Sales Revenue, Net \| Federal Government Agencies
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		7.70%	13.10%	9.10%	19.50%	17.70%	20.80%	22.90%
Number of federal government agencies \| Agency		3	3		3	3	3	3
Customer Concentration Risk \| Accounts Receivable \| Federal Government Agencies
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage				9.10%	17.20%	17.20%	10.00%
Number of customers \| Customer						1	0
Minimum
Summary Of Significant Accounting Policies [Line Items]
SaaS Subscriptions contracts term				1 year		1 year
Term license subscription contracts term				1 year		1 year
Maximum
Summary Of Significant Accounting Policies [Line Items]
SaaS Subscriptions contracts term				5 years		5 years
Term license subscription contracts term				5 years		5 years
Class A Common Stock
Summary Of Significant Accounting Policies [Line Items]
Net proceeds from initial public offering	$ 77,800,000
Class B Common Stock
Summary Of Significant Accounting Policies [Line Items]
Preferred stock conversion basis				1
IPO \| Class A Common Stock
Summary Of Significant Accounting Policies [Line Items]
Issuance of common stock from initial public offering, net of issuance costs, Shares \| shares	7,187,500
Shares issued price per share \| $ / shares	$ 12.00

Significant Accounting Policies - Property and Equipment Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2016
Computer Software
Property, Plant and Equipment [Line Items]
Useful life	3 years
Computer Hardware
Property, Plant and Equipment [Line Items]
Useful life	3 years
Equipment
Property, Plant and Equipment [Line Items]
Useful life	5 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Useful life	10 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Useful life	Shorter of useful life of assets or lease term

Significant Accounting Policies - Summary of Liabilities Fair Value Measurements (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Liabilities		$ 850		$ 650
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Liabilities	$ 0	850	$ 850	650	$ 351	$ 0
Series A Convertible Preferred Stock Warrant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Liabilities		850		650
Series A Convertible Preferred Stock Warrant \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Liabilities		$ 850		$ 650

Significant Accounting Policies - Summary of Changes in Level 3 Instruments Measured at Fair Value On Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 850	$ 650	$ 650
Ending Balance			850	$ 650
Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	850	650	650	351	$ 0
Change in fair value of warrant liability	341	200	200	299	351
Reclassification of warrant liability to equity	(1,191)	0
Ending Balance	$ 0	$ 850	$ 850	$ 650	$ 351

Property and Equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 7,787	$ 6,800
Less: accumulated depreciation		(4,686)	(3,908)
Property and equipment, net	$ 2,737	3,101	2,892
Computer Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross		1,701	1,562
Computer Hardware
Property, Plant and Equipment [Line Items]
Property and equipment, gross		1,408	1,201
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross		4,098	3,555
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross		464	386
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 116	$ 96

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 673	$ 567	$ 764	$ 763	$ 610

Debt - Additional Information (Detail) - USD ($)		1 Months Ended		9 Months Ended		12 Months Ended
Debt - Additional Information (Detail) - USD ($)	Dec. 31, 2015	Jan. 31, 2016	Mar. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Apr. 30, 2017
Line of Credit Facility [Line Items]
Loss on extinguishment of debt				$ 384,000	$ 0
Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility	$ 10,000,000						$ 5,000,000
Credit facility expiration date	Jun. 30, 2016
Maximum revolving line of credit	$ 3,500,000
Advances against line of credit	$ 0					$ 0
Term Loan
Line of Credit Facility [Line Items]
Credit facility		$ 20,000,000	$ 10,000,000				20,000,000
Credit facility expiration date		Jan. 31, 2020	Mar. 31, 2019
Interest rate						5.00%
Prepayment fee advanced through month 12						1.00%
Prepayment fee during months 13 through 24						0.50%
Prepayment fee thereafter						0.00%
Line of credit, outstanding borrowings				0
Term Loan \| Other (Income) Expense
Line of Credit Facility [Line Items]
Loss on extinguishment of debt				$ 400,000
Subordinated Term Loan
Line of Credit Facility [Line Items]
Credit facility							$ 10,000,000
Prime Rate \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate	0.75%
Prime Rate \| Term Loan
Line of Credit Facility [Line Items]
Interest rate						1.25%

Income Taxes - Components of net (loss) income before income taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Domestic					$ (4,524)	$ 1,079	$ (11,026)
Foreign					(9,620)	(7,688)	(4,829)
Net loss before income taxes	$ (6,096)	$ (6,349)	$ (23,649)	$ (10,384)	$ (14,144)	$ (6,609)	$ (15,855)

Income Taxes - Income Taxes Expense (Benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal					$ (627)	$ 390	$ 430
State					(200)	62	128
Foreign					266	217	247
Total current expense (benefit)					(561)	669	805
Deferred:
Federal					(922)	(334)	325
State					(230)	43	51
Foreign					30		23
Total deferred expense (benefit)					(1,122)	(291)	399
Total income tax expense (benefit)	$ 188	$ (1,610)	$ 489	$ (2,106)	$ (1,683)	$ 378	$ 1,204

Income Taxes - Provision of Income Tax (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
Income Taxes - Provision of Income Tax (Detail)	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
U.S. federal statutory tax rate					34.00%	34.00%	34.00%
State tax expense					1.40%	(0.90%)	(0.80%)
Expense on purchase of common stock							(30.20%)
Foreign rate differential					(17.80%)	(29.40%)	(7.90%)
Nondeductible expenses					(2.30%)	(4.10%)	(1.50%)
Tax credits					6.50%	10.00%	3.20%
Unrecognized tax benefits					(0.20%)	(1.80%)	(0.50%)
Other					(0.20%)	(1.90%)	(0.50%)
Change in valuation allowance					(9.60%)	(11.50%)	(3.40%)
Total	(3.10%)	25.40%	(2.10%)	20.30%	11.80%	(5.60%)	(7.60%)

Income Taxes - Deferred tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Accrued vacation	$ 529	$ 482
Bad debt	159	157
Deferred revenue	2,176	3,173
Deferred rent	834	603
Tax credits	2,401	1,381
Net operating losses	2,939	1,289
Other	929	209
Gross deferred tax assets	9,967	7,294
Less: Valuation allowance	(2,642)	(1,283)
Total deferred tax assets	7,325	6,011
Deferred tax liabilities:
Depreciation	(349)	(491)
Unbilled receivables	(491)	(1,835)
Prepaid expenses	(6,505)	(4,579)
Total deferred tax liabilities	(7,345)	(6,905)
Net deferred tax liability	$ (20)	$ (894)

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Tax effected state NOL carryforwards					$ 100
Net change during the year in total valuation allowance					1,400
Unrecognized Tax Benefits					419	$ 384	$ 286	$ 218
Potential interest and penalties recognized					2	19	$ 15
Cumulative balance of interest and penalties					35	$ 39
Amount by which total unrecognized tax benefits is anticipated to decrease over the next 12 months					$ (100)
Effective tax rate	(3.10%)	25.40%	(2.10%)	20.30%	11.80%	(5.60%)	(7.60%)
Net unrecognized tax benefits which would impact effective tax rate if recognized	$ 500		$ 500
Earliest Tax Year
Income Taxes [Line Items]
Open tax year			2013
Latest Tax Year
Income Taxes [Line Items]
Open tax year			2016
Minimum \| Subsidiaries
Income Taxes [Line Items]
Effective tax rate			0.00%
Maximum \| Subsidiaries
Income Taxes [Line Items]
Effective tax rate			40.00%
Federal
Income Taxes [Line Items]
Gross net operating loss carryforwards					$ 1,800	$ 0
NOL carryforwards, Expiration					Federal NOL carryforwards will expire, if unused, in 2036.
Federal tax credit carryforwards					$ 2,800	1,800
State
Income Taxes [Line Items]
Gross net operating loss carryforwards					$ 1,700	100
NOL carryforwards, Expiration					U.S. state NOL carryforwards will substantially expire, if unused, in 2036.
Foreign Tax Authority [Member] \| Swiss Federal Tax Administration (FTA)
Income Taxes [Line Items]
Gross net operating loss carryforwards					$ 23,700	$ 13,300
NOL carryforwards, Expiration					The NOL carryforwards will expire, if unused, between 2021 and 2023.

Income Taxes - Unrecognized Tax Benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Beginning Balance	$ 384	$ 286	$ 218
Additions for tax positions in current years	171	98	68
Additions for tax positions in prior years	0	0	0
Reductions due to lapse in statutes of limitations	(136)
Settlements	0	0	0
Ending Balance	$ 419	$ 384	$ 286

Stock-Based Compensation - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended
	Apr. 25, 2017	May 31, 2017	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 31, 2017	Jul. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance									249,700
Number of shares available to be issued						26,661,288
Service period for option exercise				5 years		5 years
Granted				$ 5.04	$ 4.38	$ 4.35	$ 2.61	$ 1.81
Stock-based compensation expense			$ 1,574,000	$ 10,919,000				$ 16,488,000
Vested				5,300,000	$ 0
Compensation cost related to nonvested stock options not yet recognized			12,600,000	$ 12,600,000
Unrecognized compensation cost related to nonvested stock option recognized over weighted average period, in years				3 years
Aggregate purchase of stock options	216,160
Performance-based Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant-date fair value of performance-based stock option awards						$ 14,900,000
Stock-based compensation expense						$ 0	$ 0	$ 0
Cumulative Stock-based Compensation Expense Related to Stock Options Recorded upon Effectiveness of Our IPO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			0	$ 6,236,000
Cumulative Stock-based Compensation Expense Related to Stock Options Recorded upon Effectiveness of Our IPO \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 6,200,000
Stock Option Modifications
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,400,000		$ 0	$ 2,394,000
2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available to be issued			6,425,767	6,425,767
2017 Equity Incentive Plan \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available to be issued		6,421,442	6,481,622	6,481,622
2007 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance						8,413,770				4,757,610
Number of shares available to be issued		421,442				1,629,322
Period for which options can be granted				10 years		10 years
Number of shares available for grants		0

Stock-Based Compensation - Summary of Estimate the Fair Value of Stock Options Granted (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Goods and Nonemployee Services Transaction [Line Items]
Risk-free interest rate		1.30%
Expected term (in years)	6 years 6 months	6 years 6 months	6 years 6 months	6 years 6 months	6 years 6 months	6 years 6 months	6 years 6 months
Expected volatility	38.60%	41.60%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Minimum
Share-based Goods and Nonemployee Services Transaction [Line Items]
Risk-free interest rate	1.90%		1.90%	1.30%	1.30%	1.70%	1.80%
Expected volatility			38.60%	41.20%	40.90%	39.70%	44.70%
Maximum
Share-based Goods and Nonemployee Services Transaction [Line Items]
Risk-free interest rate	2.10%		2.20%	1.50%	1.50%	1.90%	2.10%
Expected volatility			40.60%	42.00%	42.00%	44.40%	46.00%

Stock-Based Compensation - Summary of the Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Number of Shares, Outstanding, Beginning balance	6,784,448	4,589,988
Granted	1,252,200	2,375,080
Exercised	(556,220)	0
Canceled	(96,500)	(180,620)
Number of Shares, Outstanding, Ending balance	7,383,928	6,784,448	4,589,988
Number of Shares, Exercisable	2,992,648
Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 4.65	$ 2.22
Granted	11.89	9.30
Exercised	1.19
Canceled	6.30	4.22
Weighted Average Exercise Price, Outstanding, Ending balance	6.16	$ 4.65	$ 2.22
Weighted Average Exercise Price, Exercisable	$ 1.85
Weighted Average Remaining Contractual Term (Years)
Weighted Average Remaining Contractual Term (Years), Outstanding	6 years 8 months 12 days	6 years 6 months	6 years
Weighted Average Remaining Contractual Term, Exercisable	3 years 9 months 18 days
Aggregate Intrinsic Value (in thousands)
Aggregate Intrinsic Value, Exercised	$ 8,386
Aggregate Intrinsic Value, Outstanding	164,688	$ 44,259	$ 24,239
Aggregate Intrinsic Value, Exercisable	$ 79,636

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Additional Information (Detail)		1 Months Ended		9 Months Ended		12 Months Ended
	May 24, 2017 shares	May 31, 2015	Feb. 28, 2014 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) Vote shares	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2014 USD ($)	Jan. 31, 2017 $ / shares	Dec. 31, 2015 USD ($) $ / shares shares
Temporary Equity [Line Items]
Capital stock shares authorized						79,709,838
Common stock shares authorized				0		61,462,320			61,462,320
Convertible preferred stock authorized						18,247,518
Stock Repurchased and Retired During Period, Shares			5,725,282			460,266
Accelerated Share Repurchases, Final Price Paid Per Share \| $ / shares			$ 6.1274
Share price \| $ / shares			$ 3.67					$ 11.17
Stock Repurchased and Retired During Period, value \| $			$ 21,013,000				$ 21,013,000
Compensation expense \| $			$ 14,100,000	$ 10,919,000	$ 0
Compensation expense for stock options \| $						$ 2,400,000
Stockholders' Equity Note, Stock Split		two-for-one basis
Stockholders' Equity Note, conversion ratio		2
Common stock holders voting right						one vote per share
Preferred stock conversion term						Each share of outstanding Preferred Stock shall automatically be converted into common stock immediately upon the closing of a firm commitment underwritten public offering of common stock by the Company, at a price per share of at least 1.5 times the original issue price of the Series B convertible preferred stock, or $9.18, pursuant to an effective registration statement under the Securities Act of 1933, as amended, and resulting in at least $50,000,000 in gross proceeds to the Company
Preferred stock conversion threshold \| $						$ 50,000,000
Convertible preferred stock outstanding shares converted into common stock				1
Minimum
Temporary Equity [Line Items]
Preferred Stock, Dividend Rate, Percentage						8.00%
Series A Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock authorized				0		12,127,468			12,127,468
Cumulative Dividends \| $						$ 7,200,000			$ 6,400,000
Preferred Stock, Dividends, Per Share, Cash Paid \| $ / shares						$ 0.60			$ 0.53
Class B Common Stock
Temporary Equity [Line Items]
Common stock shares authorized				100,000,000		0
Conversion of convertible preferred stock to common stock (in shares)	18,163,158
Convertible preferred stock outstanding shares converted into common stock				1
Preferred stock conversion basis				1
Number of votes entitled to stockholders per share \| Vote				10
Class A Common Stock
Temporary Equity [Line Items]
Common stock shares authorized				500,000,000		0
Number of votes entitled to stockholders per share \| Vote				1
Conversion of stock (in shares)				1
Maximum percentage of aggregate voting power of capital stock which triggers conversion of stock				10.00%

Stock-Based Compensation - Schedule of Stock-based Compensation Expense Included in Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,574	$ 10,919	$ 16,488
Subscriptions, software and support
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	80	484	119
Professional services
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	142	1,126	737
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	359	2,782	1,802
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	256	2,458	515
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 737	$ 4,069	$ 13,315

Convertible Preferred Stock and Stockholders' Deficit - Share of Common Stock for Future Issuance (Detail)	Dec. 31, 2016 shares
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	26,661,288
Convertible Preferred Stock
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	18,163,158
Preferred Stock Warrant
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	84,360
Employee Stock Option
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	6,784,448
Equity incentive plan.
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	1,629,322

Convertible Preferred Stock and Stockholders' Deficit - Summary of Issuances of Convertible Preferred Stock (Detail) - $ / shares	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Series A Convertible Preferred Stock
Temporary Equity [Line Items]
Original Issue Price per Share		$ 0.88903
Number of Shares	0	12,043,108	12,043,108	12,043,108	12,043,108
Conversion Price per Share		$ 0.88903
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Original Issue Price per Share		$ 6.12740
Number of Shares	0	6,120,050	6,120,050	6,120,050
Conversion Price per Share		$ 6.12740

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of Activity for Convertible Preferred Stock Issued and Outstanding (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Increase (Decrease) in Temporary Equity [Roll Forward]
Payment of accrued dividend to Series A convertible preferred stockholders	$ (7,565)	$ 0
Series A Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	$ 17,915	$ 17,058	$ 17,058	$ 16,197	$ 15,341
Beginning balance, shares issued	12,043,108	12,043,108	12,043,108	12,043,108	12,043,108
Accretion of dividends on convertible preferred stock	$ 357		$ 857	$ 861	$ 856
Payment of accrued dividend to Series A convertible preferred stockholders	(7,565)
Conversion of convertible preferred stock to common stock	$ (10,707)
Conversion of convertible preferred stock to common stock (in shares)	(12,043,108)
Ending balance	$ 0		$ 17,915	$ 17,058	$ 16,197
Ending balance, shares issued	0		12,043,108	12,043,108	12,043,108
Series B Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	$ 37,500	$ 37,500	$ 37,500	$ 37,500
Beginning balance, shares issued	6,120,050	6,120,050	6,120,050	6,120,050
Issuance convertible preferred stock					$ 37,380
Issuance of convertible preferred stock, shares					6,120,050
Accretion of dividends on convertible preferred stock	$ 0
Accretion of issuance costs on convertible preferred stock					$ 120
Payment of accrued dividend to Series A convertible preferred stockholders	0
Conversion of convertible preferred stock to common stock	$ (37,500)
Conversion of convertible preferred stock to common stock (in shares)	(6,120,050)
Ending balance	$ 0		$ 37,500	$ 37,500	$ 37,500
Ending balance, shares issued	0		6,120,050	6,120,050	6,120,050

Warrants - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Nov. 30, 2008	Sep. 30, 2017	May 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Warrant or Right [Line Items]
Warrant term	10 years
Warrant exercise price (in dollars per share)	$ 0.88905	$ 0.88905
Warrant
Class of Warrant or Right [Line Items]
Fair value of warrant		$ 1.2		$ 0.9	$ 0.7
Series A Convertible Preferred Stock
Class of Warrant or Right [Line Items]
Warrant to purchase shares of preferred stock (in shares)	84,360	84,360
Class B Common Stock
Class of Warrant or Right [Line Items]
Shares issued on cashless exercise of warrants (in shares)			79,363
Class B Common Stock \| Prior to IPO
Class of Warrant or Right [Line Items]
Warrant to purchase shares of preferred stock (in shares)		84,360

Basic and Diluted Income (Loss) per Common Share - Summary of Securities Excluded From Calculation of Weighted Average Common Shares Outstanding (Detail) - shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	0	12,043,108	0	12,043,108	12,043,108	12,043,108	12,043,108
Series B Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	0	6,120,050	0	6,120,050	6,120,050	6,120,050	6,120,050
Warrant To Purchase Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	0	84,360	0	84,360	84,360	84,360	84,360
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	7,383,928	6,699,048	7,383,928	6,699,048	6,784,448	4,589,988	3,886,408
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	42,925	0	42,925	0

Commitments and Contingencies - Summary of Future Minimum Gross and Net Lease commitments (Detail) $ in Thousands	Dec. 31, 2016 USD ($)
Office Leases
Operating Leased Assets [Line Items]
2017	$ 6,868
2018	6,538
2019	6,720
2020	4,780
2021	2,466
Thereafter	1,304
Operating Leases, Future Minimum Payments Due, Total	28,676
Less: minimum payments to be received from subleases	(527)
Total	28,149
Equipment Leases
Operating Leased Assets [Line Items]
2017	277
2018	131
2019	6
Operating Leases, Future Minimum Payments Due, Total	414
Total	$ 414

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Deferred rent	$ 2.4	$ 1.5
Original lease agreement expires date	Oct. 31, 2017
Rental income received from subtenant	$ 0.6	0.6	$ 0.1
Total rent and lease expense	6.6	4.6	$ 3.8
Annual royalty fees	0.3
Outstanding letters of credit	$ 1.3	$ 0.8

Segment and Geographic Information - Summary of Revenues By Geography (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 44,648	$ 30,745	$ 126,175	$ 99,176	$ 132,923	$ 111,204	$ 88,996
Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	31,878	23,650	93,860	80,715	107,069	89,043	66,285
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 12,770	$ 7,095	$ 32,315	$ 18,461	$ 25,854	$ 22,161	$ 22,711

Segment and Geographic Information - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Sales Revenue, Net \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk, percentage	10.00%	10.00%	10.00%	10.00%	10.00%	10.00%	10.80%

Retirement Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employer matching contribution, annual vesting percentage	25.00%
Defined benefit vesting period	4 years
Contribution expense	$ 2.6	$ 1.9	$ 1.3
Foreign Subsidiaries
Contribution expense	$ 0.7	$ 0.5	$ 0.3
Maximum
Employer matching contribution, percent of employees' gross pay	75.00%

Subsequent Events (Detail) - USD ($)				9 Months Ended	12 Months Ended
Subsequent Events (Detail) - USD ($)	Nov. 02, 2017	Oct. 25, 2017	Dec. 31, 2015	Sep. 30, 2017	Dec. 31, 2016	Jan. 31, 2017	Feb. 28, 2014
Subsequent Event [Line Items]
Number of Shares, authorized						249,700
Exercise price per share						$ 11.17	$ 3.67
Granted				1,252,200	2,375,080
Granted				$ 11.89	$ 9.30
Revolving Credit Facility \| Subsequent Event
Subsequent Event [Line Items]
Credit facility	$ 20,000,000
Quick ratio	135.00%
Restricted Stock Units
Subsequent Event [Line Items]
Granted				$ 20.38
Minimum \| Revolving Credit Facility \| Subsequent Event
Subsequent Event [Line Items]
Unused credit facility fee	0.15%
Maximum \| Revolving Credit Facility \| Subsequent Event
Subsequent Event [Line Items]
Unused credit facility fee	0.25%
2017 Equity Incentive Plan \| Subsequent Event
Subsequent Event [Line Items]
Vesting period		5 years
2017 Equity Incentive Plan \| Restricted Stock Units \| Subsequent Event
Subsequent Event [Line Items]
Restricted stock units, granted		689,200
Granted		$ 22.27
Value of awards, at grant date		$ 15,300,000
2017 Equity Incentive Plan \| Common Stock \| Subsequent Event
Subsequent Event [Line Items]
Granted		4,000
Granted		$ 22.27
London Interbank Offered Rate (LIBOR) \| Minimum \| Revolving Credit Facility \| Subsequent Event
Subsequent Event [Line Items]
Interest rate margin	2.00%
London Interbank Offered Rate (LIBOR) \| Maximum \| Revolving Credit Facility \| Subsequent Event
Subsequent Event [Line Items]
Interest rate margin	2.50%
Prime Rate \| Revolving Credit Facility
Subsequent Event [Line Items]
Interest rate margin			0.75%
Prime Rate \| Minimum \| Revolving Credit Facility \| Subsequent Event
Subsequent Event [Line Items]
Interest rate margin	1.00%
Prime Rate \| Maximum \| Revolving Credit Facility \| Subsequent Event
Subsequent Event [Line Items]
Interest rate margin	1.50%

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Accrued contract labor costs	$ 3,122	$ 743
Accrued audit and tax expenses	364	358
Accrued reimbursable employee expenses	285	134
Accrued marketing and tradeshow expenses	251	111
Other accrued expenses	1,955	1,514
Total	$ 5,977	$ 2,860	$ 4,350

Stock-Based Compensation - Schedule of Restricted Stock Unit Activity (Detail) - Restricted Stock Units $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Number of Shares
Non-vested outstanding at December 31, 2016 \| shares	0
Granted \| shares	47,855
Vested \| shares	(4,930)
Canceled \| shares	0
Non-vested outstanding at September 30, 2017 \| shares	42,925
Weighted Average Grant Date Fair Value
Non-vested outstanding at December 31, 2016 \| $ / shares	$ 0.00
Granted \| $ / shares	20.38
Vested \| $ / shares	20.24
Canceled \| $ / shares	0.00
Non-vested outstanding at September 30, 2017 \| $ / shares	$ 20.40
Total unrecognized compensation cost related to unvested restricted stock units \| $	$ 0.8
Weighted average remaining vesting period	2 years 8 months 12 days

Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 25, 2017	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		$ 1,574	$ 10,919	$ 16,488
Stock Option Modifications
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 2,400	0	2,394
Cumulative Stock-based Compensation Expense Related to Stock Options Recorded upon Effectiveness of Our IPO
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		0	6,236
Post-IPO Stock-based Compensation Expense Related to Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		1,440	2,025
Stock-based Compensation Expense Related to the Issuance of Common Stock to Directors
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		0	130
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		$ 134	$ 134