Summary of Significant Accounting Policies - Goodwill and Intangible Assets (Details)	12 Months Ended
Jan. 01, 2022 reporting_unit quarter
Accounting Policies [Abstract]
Number of reporting units \| reporting_unit	1
Number of trailing quarters used to determine the control premium \| quarter	4

Number of trailing quarters used to determine the control premium utilizing data from publicly available premium studies.

No definition available.

Name:	crai_NumberOfTrailingQuartersToDetermineControlPremium
Namespace Prefix:	crai_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration