v3.7.0.1
Document and Entity Information - shares
6 Months Ended
Jun. 30, 2017
Jul. 31, 2017
Document and Entity Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2017  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q2  
Trading Symbol APPN  
Entity Registrant Name APPIAN CORP  
Entity Central Index Key 0001441683  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Class A Common Stock [Member]    
Document and Entity Information [Line Items]    
Entity Common Stock, Shares Outstanding   7,198,341
Class B Common Stock [Member]    
Document and Entity Information [Line Items]    
Entity Common Stock, Shares Outstanding   52,919,419