Document and Entity Information - shares
3 Months Ended
Mar. 31, 2016
May. 03, 2016
Document And Entity Information    
Entity Registrant Name PCM, INC.  
Entity Central Index Key 0000937941  
Document Type 10-Q  
Document Period End Date Mar. 31, 2016  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   11,589,442
Trading Symbol PCMI  
Document Fiscal Period Focus Q1  
Document Fiscal Year Focus 2016