Basis of Presentation (Policies)	9 Months Ended
Sep. 30, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements are of ICF International, Inc. (“ICFI”) and its principal subsidiary, ICF Consulting Group, Inc. (“Consulting,” and together with ICFI, the “Company”), and have been prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“U.S. GAAP”). Consulting is a wholly owned subsidiary of ICFI. ICFI is a holding company with no operations or assets other than its investment in the common stock of Consulting. All other subsidiaries of the Company are wholly owned by Consulting. Intercompany transactions and balances have been eliminated. The terms “federal” or “federal government” refer to the U.S. federal government, and “state and local” or “state and local government” refer to U.S. state (including territories) and local governments, unless otherwise indicated.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities, and the reported amounts of revenue and expenses. Key estimates include estimates related to variable consideration on contracts with customers, costs to complete fixed-price contracts, bonus and other incentive compensation, reserves for tax benefits and valuation allowances on deferred tax assets, collectability of receivables, valuation and useful lives of acquired tangible and intangible assets, impairment of goodwill and long-lived assets, and contingencies. Actual results experienced by the Company may differ from management’s estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recent Accounting Pronouncements Not Yet Adopted Segment Reporting In November 2023, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2023-07: Improvements to Reportable Segment Disclosures to update reportable segment disclosure requirements for public entities under the Accounting Standards Codification (“ASC”). ASU 2023-07 enhances the current segment reporting disclosures of Topic 280 by requiring disclosure of significant segment expenses that are regularly reviewed by the Chief Operating Decision Maker (the “CODM”), the amount and description of other segment items, and interim disclosures of each reportable segment’s profit or loss and assets. ASU 2023-07 also requires public entities that have a single reportable segment to provide all of the disclosures required in Topic 280, as amended. ASU 2023-07 is effective for the Company for the fiscal year ending December 31, 2024 and interim periods within the 2025 fiscal year on a retrospective basis, with early adoption permitted. The Company expects to adopt the amendments of ASU 2023-07 for the fiscal year ending December 31, 2024, but does not expect the adoption to have a material impact, if any, on the consolidated financial statements. Income Taxes In December 2023, the FASB issued ASU 2023-09, Income Taxes: Improvements to Income Tax Disclosures, which requires greater disaggregation of income tax rates and amounts paid by entities. ASU 2023-09 specifically requires all entities to disclose, on an annual basis, disaggregated domestic and foreign pre-tax income or loss from continuing operations and the disaggregated income tax expense or benefit by federal, state, and foreign components, and a tabular rate reconciliation, using both percentages and reporting currency amounts, of eight specific categories as well as any individual reconciling items that are equal to or greater than 5% of a threshold computed by multiplying pretax income or loss from continuing operations by the applicable federal rate. Additionally, the amendments also require disclosure of income taxes paid disaggregated by federal, state, and foreign jurisdictions as well as any individual jurisdictions over 5% of the total income taxes paid. ASU 2023-09 is effective for the Company for the fiscal year ending December 31, 2025, with early adoption permitted. The amendments may be adopted on a prospective or retrospective basis. The Company is currently evaluating the impact of the adoption of ASU 2023-09 but does not expect the adoption to have a material impact, if any, on the consolidated financial statements.

Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2024

The accompanying consolidated financial statements are of ICF International, Inc. (“ICFI”) and its principal subsidiary, ICF Consulting Group, Inc. (“Consulting,” and together with ICFI, the “Company”), and have been prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“U.S. GAAP”). Consulting is a wholly owned subsidiary of ICFI. ICFI is a holding company with no operations or assets other than its investment in the common stock of Consulting. All other subsidiaries of the Company are wholly owned by Consulting. Intercompany transactions and balances have been eliminated. The terms “federal” or “federal government” refer to the U.S. federal government, and “state and local” or “state and local government” refer to U.S. state (including territories) and local governments, unless otherwise indicated.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities, and the reported amounts of revenue and expenses. Key estimates include estimates related to variable consideration on contracts with customers, costs to complete fixed-price contracts, bonus and other incentive compensation, reserves for tax benefits and valuation allowances on deferred tax assets, collectability of receivables, valuation and useful lives of acquired tangible and intangible assets, impairment of goodwill and long-lived assets, and contingencies. Actual results experienced by the Company may differ from management’s estimates.

Recent Accounting Pronouncements

Recent Accounting Pronouncements Not Yet Adopted

Segment Reporting

In November 2023, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2023-07: Improvements to Reportable Segment Disclosures to update reportable segment disclosure requirements for public entities under the Accounting Standards Codification (“ASC”). ASU 2023-07 enhances the current segment reporting disclosures of Topic 280 by requiring disclosure of significant segment expenses that are regularly reviewed by the Chief Operating Decision Maker (the “CODM”), the amount and description of other segment items, and interim disclosures of each reportable segment’s profit or loss and assets. ASU 2023-07 also requires public entities that have a single reportable segment to provide all of the disclosures required in Topic 280, as amended. ASU 2023-07 is effective for the Company for the fiscal year ending December 31, 2024 and interim periods within the 2025 fiscal year on a retrospective basis, with early adoption permitted. The Company expects to adopt the amendments of ASU 2023-07 for the fiscal year ending December 31, 2024, but does not expect the adoption to have a material impact, if any, on the consolidated financial statements.

Income Taxes

In December 2023, the FASB issued ASU 2023-09, Income Taxes: Improvements to Income Tax Disclosures, which requires greater disaggregation of income tax rates and amounts paid by entities. ASU 2023-09 specifically requires all entities to disclose, on an annual basis, disaggregated domestic and foreign pre-tax income or loss from continuing operations and the disaggregated income tax expense or benefit by federal, state, and foreign components, and a tabular rate reconciliation, using both percentages and reporting currency amounts, of eight specific categories as well as any individual reconciling items that are equal to or greater than 5% of a threshold computed by multiplying pretax income or loss from continuing operations by the applicable federal rate. Additionally, the amendments also require disclosure of income taxes paid disaggregated by federal, state, and foreign jurisdictions as well as any individual jurisdictions over 5% of the total income taxes paid. ASU 2023-09 is effective for the Company for the fiscal year ending December 31, 2025, with early adoption permitted. The amendments may be adopted on a prospective or retrospective basis. The Company is currently evaluating the impact of the adoption of ASU 2023-09 but does not expect the adoption to have a material impact, if any, on the consolidated financial statements.