Document and Entity Information
6 Months Ended
Jun. 30, 2014
Jul. 24, 2014
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2014  
Document Fiscal Year Focus 2014  
Document Fiscal Period Focus Q2  
Trading Symbol SPSC  
Entity Registrant Name SPS COMMERCE INC  
Entity Central Index Key 0001092699  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Entity Common Stock, Shares Outstanding   16,234,758