Description of Business (Details)	9 Months Ended
Oct. 01, 2016 item
Description of Business
Number of broad areas of services	2

Represents the area of services broadly offered by the entity.

No definition available.

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