Basis of Presentation and Nature of Operations	12 Months Ended
Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Nature of Operations	NOTE 1 - BASIS OF PRESENTATION AND NATURE OF OPERATIONS Basis of Presentation The accompanying consolidated financial statements include the accounts 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. Software assets, which were previously included within “Property and equipment, net” and “Other assets” on the Company’s consolidated balance sheets, have been reclassified and consolidated under “Other intangible assets, net”. To conform to the current year’s presentation, $1.6 million and $21.8 million, as of December 31, 2024, have been reclassified from “Property and equipment, net” and “Other assets”, respectively, to “Other intangible assets, net”. Previously separate financial statement line items “Depreciation and amortization” and “Amortization of intangible assets” on the Company’s consolidated statements of comprehensive income have been combined under “Depreciation and amortization”. Nature of Operations The Company primarily provides consulting and technology services across several key domains: strategy and public policy, energy and environmental sustainability, and climate resilience; digital transformation including information technology (“IT”) modernization, cloud, cybersecurity, and data analytics; health and social programs such as public health and education; international development and capacity building; disaster management and recovery planning; transportation, aviation, and infrastructure; and marketing and strategic communications. These areas combine expertise in policy, technology, and program implementation to help organizations and governments address complex challenges and drive impactful outcomes. The Company’s customers are primarily U.S. federal government departments and agencies, U.S. state (including territories) and local government departments and agencies, international governments, and commercial clients worldwide. 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. The Company, incorporated in Delaware, is headquartered in Reston, Virginia. It maintains additional offices throughout the world, including 49 offices in the U.S. and U.S. territories and 14 offices in key markets outside the U.S., including offices in the United Kingdom (“U.K.”), Belgium, Spain, India, and Canada.

Basis of Presentation and Nature of Operations

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation and Nature of Operations

NOTE 1 - BASIS OF PRESENTATION AND NATURE OF OPERATIONS

Basis of Presentation

The accompanying consolidated financial statements include the accounts 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.

Software assets, which were previously included within “Property and equipment, net” and “Other assets” on the Company’s consolidated balance sheets, have been reclassified and consolidated under “Other intangible assets, net”. To conform to the current year’s presentation, $1.6 million and $21.8 million, as of December 31, 2024, have been reclassified from “Property and equipment, net” and “Other assets”, respectively, to “Other intangible assets, net”.

Previously separate financial statement line items “Depreciation and amortization” and “Amortization of intangible assets” on the Company’s consolidated statements of comprehensive income have been combined under “Depreciation and amortization”.

Nature of Operations

The Company primarily provides consulting and technology services across several key domains: strategy and public policy, energy and environmental sustainability, and climate resilience; digital transformation including information technology (“IT”) modernization, cloud, cybersecurity, and data analytics; health and social programs such as public health and education; international development and capacity building; disaster management and recovery planning; transportation, aviation, and infrastructure; and marketing and strategic communications. These areas combine expertise in policy, technology, and program implementation to help organizations and governments address complex challenges and drive impactful outcomes.

The Company’s customers are primarily U.S. federal government departments and agencies, U.S. state (including territories) and local government departments and agencies, international governments, and commercial clients worldwide. 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.

The Company, incorporated in Delaware, is headquartered in Reston, Virginia. It maintains additional offices throughout the world, including 49 offices in the U.S. and U.S. territories and 14 offices in key markets outside the U.S., including offices in the United Kingdom (“U.K.”), Belgium, Spain, India, and Canada.