Summary of Significant Accounting Policies (Policies)	3 Months Ended
Apr. 04, 2026
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements include the accounts of CRA and its wholly-owned subsidiaries (collectively, the "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. In the opinion of management, these financial statements reflect all adjustments of a normal, recurring nature necessary for the fair presentation of the Company’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 January 3, 2026 included in CRA’s Annual Report on Form 10-K filed with the SEC on February 26, 2026.
Recent Accounting Standards Not Yet Adopted	Recent Accounting Standards Not Yet Adopted Interim Reporting (Topic 270): Narrow‑Scope Improvements In December 2025, the Financial Accounting Standards Board ("FASB") issued ASU 2025‑11, Interim Reporting (Topic 270): Narrow‑Scope Improvements (“ASU 2025‑11”). ASU 2025-11 is intended to improve the navigability of interim reporting guidance by clarifying when Topic 270 applies, enhancing the organization of required interim disclosures, and providing additional direction on the form and content of interim financial statements. The amendments introduce a disclosure principle requiring entities to disclose events occurring after the end of the most recent annual reporting period that have a material impact on the entity. ASU 2025-11 also compiles a comprehensive list of interim disclosures currently required under U.S. GAAP, without expanding or reducing existing requirements. ASU 2025‑11 is effective for interim periods within annual reporting periods beginning after December 15, 2027, for public business entities, with early adoption permitted. CRA is evaluating the impact of the amendments and does not expect them to materially affect its interim reporting, as the changes primarily clarify existing disclosure requirements. 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"). ASU 2024-03 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.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Apr. 04, 2026

The unaudited condensed consolidated financial statements include the accounts of CRA and its wholly-owned subsidiaries (collectively, the "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. In the opinion of management, these financial statements reflect all adjustments of a normal, recurring nature necessary for the fair presentation of the Company’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 January 3, 2026 included in CRA’s Annual Report on Form 10-K filed with the SEC on February 26, 2026.

Recent Accounting Standards Not Yet Adopted

Interim Reporting (Topic 270): Narrow‑Scope Improvements

In December 2025, the Financial Accounting Standards Board ("FASB") issued ASU 2025‑11, Interim Reporting (Topic 270): Narrow‑Scope Improvements (“ASU 2025‑11”). ASU 2025-11 is intended to improve the navigability of interim reporting guidance by clarifying when Topic 270 applies, enhancing the organization of required interim disclosures, and providing additional direction on the form and content of interim financial statements. The amendments introduce a disclosure principle requiring entities to disclose events occurring after the end of the most recent annual reporting period that have a material impact on the entity. ASU 2025-11 also compiles a comprehensive list of interim disclosures currently required under U.S. GAAP, without expanding or reducing existing requirements.

ASU 2025‑11 is effective for interim periods within annual reporting periods beginning after December 15, 2027, for public business entities, with early adoption permitted. CRA is evaluating the impact of the amendments and does not expect them to materially affect its interim reporting, as the changes primarily clarify existing disclosure requirements.

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"). ASU 2024-03 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.