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Description of Business (Details) | 9 Months Ended
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Sep. 30, 2017 segment item
Description of Business |
Number of broad areas of consulting services | item | 2
Number of business segment | segment | 1

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- References No definition available. + Details
Name: | crai_DescriptionOfBusinessDisclosureAbstract
Namespace Prefix: | crai_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Number of broad areas in consulting services. + References No definition available. + Details
Name: | crai_NumberOfBroadAreasOfConsultingServices
Namespace Prefix: | crai_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. + References No definition available. + Details
Name: | us-gaap_NumberOfOperatingSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration