v3.25.2
Cover Page - shares
 6 Months Ended
Jun. 30, 2025
Aug. 04, 2025
Document and Entity Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2025  
Document Transition Report false  
Entity File Number 001-38098  
Entity Registrant Name APPIAN CORPORATION  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 54-1956084  
Entity Address, Address Line One 7950 Jones Branch Drive  
Entity Address, City or Town McLean  
Entity Address, State or Province VA  
Entity Address, Postal Zip Code 22102  
City Area Code (703)  
Local Phone Number 442-8844  
Title of 12(b) Security Class A Common Stock  
Trading Symbol APPN  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Central Index Key 0001441683  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Amendment Flag false  
Class A Common Stock    
Document and Entity Information [Line Items]    
Entity Common Stock, Shares Outstanding   42,943,872
Class B Common Stock    
Document and Entity Information [Line Items]    
Entity Common Stock, Shares Outstanding   31,088,085