Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 29, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements include the accounts of CRA International, Inc. and its wholly-owned subsidiaries (collectively the, "CRA" or "Company") which require consolidation after the elimination of intercompany accounts and transactions. These financial statements have been prepared in accordance with the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) for Quarterly Reports on Form 10-Q. Accordingly, these financial statements do not include all the information and note disclosures required by accounting principles generally accepted in the United States of America (“U.S. GAAP”) for annual financial statements. Certain prior period amounts have been reclassified to conform to the current period presentation. These reclassifications had no effect on previously reported results of operations, financial position, or cash flows. In the opinion of management, these financial statements reflect all adjustments of a normal, recurring nature necessary for the fair presentation of CRA’s results of operations, financial position, cash flows, and shareholders’ equity for the interim periods presented in conformity with U.S. GAAP. Results of operations for the interim periods presented herein are not necessarily indicative of results of operations for a full year. These financial statements should be read in conjunction with the consolidated financial statements and notes thereto for the fiscal year ended December 30, 2023 included in CRA’s Annual Report on Form 10-K filed with the SEC on February 29, 2024 (the “2023 Form 10-K”).
Recent Accounting Standards Not Yet Adopted	Recent Accounting Standards Not Yet Adopted Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures In November 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (ASU 2023-07). The ASU improves reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. ASU 2023-07 also requires that a public entity that has a single reportable segment provide all disclosures required by these amendments and all existing segment disclosures in Topic 280. ASU 2023-07 is effective for CRA for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. CRA plans to adopt the amendment during the fourth fiscal quarter of 2024. CRA expects the adoption of this ASU will impact its disclosures, but will not have a material effect on its consolidated financial statements. Income Taxes (Topic 740): Improvements to Income Tax Disclosures In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (ASU 2023-09). The ASU requires disclosure of specific categories in the rate reconciliation, provides additional information for reconciling items that meet a quantitative threshold, and discloses the amount of income taxes paid disaggregated by federal, state, foreign taxes, and individual jurisdiction. ASU 2023-09 also requires income (or loss) from continuing operations before income tax expense (or benefit) disaggregated between domestic and foreign, and income tax expense (or benefit) from continuing operations disaggregated by federal (national), state, and foreign. ASU 2023-09 is effective for CRA for annual periods beginning after December 15, 2024. CRA plans to adopt the amendment during the annual reporting for fiscal year 2025. CRA has