Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 27, 2025
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Description of Business CRA International, Inc. and its wholly-owned subsidiaries (collectively, "CRA, "the "Company," “we,” “our” or “us”) is a worldwide leading consulting services firm that applies advanced analytic techniques and in-depth industry knowledge to complex engagements for a broad range of clients. CRA offers services in two broad areas: litigation, regulatory, and financial consulting and management consulting. CRA operates in one business segment. CRA operates its business under its registered trade name, Charles River Associates. Basis of Presentation The unaudited condensed consolidated financial statements include the accounts of CRA 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. 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 28, 2024 included in CRA’s Annual Report on Form 10-K filed with the SEC on February 20, 2025. Note 1 to the Consolidated Financial Statements included in Part II, Item 8, on Form 10-K for the fiscal year ended December 28, 2024 describes the significant accounting policies and methods used in preparation of the Condensed Consolidated Financial Statements in this Quarterly Report on Form 10-Q. Recent Accounting Standards Not Yet Adopted Income Taxes (Topic 740): Improvements to Income Tax Disclosures In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update ("ASU") No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures ("ASU 2023-09"). The ASU expands annual disclosures in an entity’s income tax rate reconciliation table and requires annual disclosures regarding cash taxes paid both in the U.S. (federal, state and local) and foreign jurisdictions. 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 assessed the impact of the amendment and has modeled out the changes to its income tax disclosures. As the amendment relates solely to disclosures, the adoption is not expected to have an impact on CRA's financial position or its results of operations. Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses ("ASU 2024-03"). The ASU requires disclosure, in the notes to the financial statements, specified information about certain costs and expenses including employee compensation, depreciation, and intangible asset amortization. ASU 2024-03, further clarified in ASU 2025-01, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date is effective for CRA for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. CRA expects the adoption of this ASU will have no impact on its financial position or its results of operations, but will result in additional disclosures.