Document And Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 29, 2015
Entity Registrant Name	ICF International, Inc.
Entity Central Index Key	0001362004
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Common Stock, Shares Outstanding (in shares)		19,525,185
Document Type	10-Q
Document Period End Date	Mar. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Amendment Flag	false