| Cover | Jul. 29, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jul. 29, 2022 |
| Entity File Number | 000-24049 |
| Entity Registrant Name | CRA INTERNATIONAL, INC. |
| Entity Central Index Key | 0001053706 |
| Entity Tax Identification Number | 04-2372210 |
| Entity Incorporation, State or Country Code | MA |
| Entity Address, Address Line One | 200 Clarendon Street |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02116 |
| City Area Code | 617 |
| Local Phone Number | 425-3000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, no par value |
| Trading Symbol | CRAI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
