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Document and Entity Information - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2016
Mar. 10, 2017
Jul. 02, 2016
Document and Entity Information      
Entity Registrant Name CRA INTERNATIONAL, INC.    
Entity Central Index Key 0001053706    
Document Type 10-K    
Document Period End Date Dec. 31, 2016    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Public Float     $ 201.7
Entity Common Stock, Shares Outstanding   8,543,170  
Document Fiscal Year Focus 2016    
Document Fiscal Period Focus FY