Revenue Recognition - General (Details)	Dec. 28, 2019 item
Revenue Recognition
Number of broad lines of consulting services	2

Number of broad areas in consulting services offered by the reporting entity.

No definition available.

Name:	crai_NumberOfBroadAreasOfConsultingServices
Namespace Prefix:	crai_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant