Basis of Presentation and Nature of Operations	12 Months Ended
Dec. 31, 2023
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. Nature of Operations The Company provides professional services and technology-based solutions, including management, technology, and policy consulting and implementation services, in the areas of energy, environment, infrastructure, and disaster recovery; health and social programs; security and other civilian & commercial. The Company offers a full range of services to clients throughout the entire life cycle of a policy, program, project, or initiative, from research and analysis, assessment and advice, to design and implementation of programs and technology-based solutions, and the provision of engagement services and programs. The Company’s major customers are U.S. federal government departments and agencies. The Company also serves U.S. state (including territories) and local government departments and agencies, international governments, and commercial clients worldwide. Commercial clients primarily include airlines, airports, electric and gas utilities, health care companies, banks and other financial services companies. 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 55 offices in the U.S. and U.S. territories and 15 offices in key markets outside the U.S., including offices in the United Kingdom (“U.K.”), Belgium, India, and Canada.

Basis of Presentation and Nature of Operations

12 Months Ended

Dec. 31, 2023

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.

Nature of Operations

The Company provides professional services and technology-based solutions, including management, technology, and policy consulting and implementation services, in the areas of energy, environment, infrastructure, and disaster recovery; health and social programs; security and other civilian & commercial. The Company offers a full range of services to clients throughout the entire life cycle of a policy, program, project, or initiative, from research and analysis, assessment and advice, to design and implementation of programs and technology-based solutions, and the provision of engagement services and programs.

The Company’s major customers are U.S. federal government departments and agencies. The Company also serves U.S. state (including territories) and local government departments and agencies, international governments, and commercial clients worldwide. Commercial clients primarily include airlines, airports, electric and gas utilities, health care companies, banks and other financial services companies. 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 55 offices in the U.S. and U.S. territories and 15 offices in key markets outside the U.S., including offices in the United Kingdom (“U.K.”), Belgium, India, and Canada.