Name:	crai_ShareBasedCompensationArrangementByShareBasedPaymentAwardFungibilityRatio
Namespace Prefix:	crai_
Data Type:	num:percentItemType
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Period Type:	duration

Represents the number of shares initially reserved for issuance under the share-based compensation plan.

No definition available.

Name:	crai_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedInitially
Namespace Prefix:	crai_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

Name:	crai_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesUsingFungibilityRatioAbstract
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Data Type:	xbrli:sharesItemType
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Period Type:	instant

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Name:	us-gaap_AwardDateAxis=crai_ShareBasedCompensationArrangementsSharesApprovedIn2008Member
Namespace Prefix:
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Name:	us-gaap_AwardDateAxis=crai_ShareBasedCompensationArrangementsSharesApprovedIn2010Member
Namespace Prefix:
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Name:	us-gaap_AwardDateAxis=crai_ShareBasedCompensationArrangementsSharesApprovedIn2012Member
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