Forgivable Loans (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jul. 03, 2021	Jan. 02, 2021
Forgivable loan activity
Beginning balance	$ 61,613	$ 55,141
Advances	4,530	42,418
Reclassifications from accrued expenses or to other assets	0	(9,713)
Amortization	(12,656)	(26,628)
Effects of foreign currency translation	107	395
Ending balance	53,594	61,613
Current portion of forgivable loans	8,654	14,749
Non-current portion of forgivable loans	$ 44,940	$ 46,864

Forgivable Loan Activity

No definition available.

Name:	crai_ForgivableLoanActivityRollForward
Namespace Prefix:	crai_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Represents information pertaining to forgivable loans provided as on the balance sheet date.

No definition available.

Amounts of increase as a result of advances on loans forgivable.

No definition available.

Name:	crai_ForgivableLoansAdvances
Namespace Prefix:	crai_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents information pertaining to amortizations on forgivable loans during the period.

No definition available.

Name:	crai_ForgivableLoansAmortization
Namespace Prefix:	crai_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The current portion of forgivable loans to employees and non employee experts on the balance sheet date.

No definition available.

Name:	crai_ForgivableLoansCurrent
Namespace Prefix:	crai_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amounts due on long-term loans forgivable on the balance sheet date.

No definition available.

Name:	crai_ForgivableLoansNoncurrent
Namespace Prefix:	crai_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amounts of decrease as a result of reclassification from accrued expenses and reclassification to other assets.

No definition available.

Name:	crai_ForgivableLoansReclassificationFromAccruedExpensesToOtherAssets
Namespace Prefix:	crai_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amounts of increase (decrease) as a result of foreign currency translation on loans forgivable.

No definition available.

Name:	crai_ForgivableLoansTranslationAdjustments
Namespace Prefix:	crai_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration