v3.7.0.1
Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2016
Mar. 01, 2017
Jun. 30, 2016
Document And Entity Information [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2016    
Document Fiscal Year Focus 2016    
Document Fiscal Period Focus FY    
Trading Symbol BBSI    
Entity Registrant Name BARRETT BUSINESS SERVICES INC    
Entity Central Index Key 0000902791    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Accelerated Filer    
Entity Common Stock, Shares Outstanding   7,251,024  
Entity Public Float     $ 289,288,504