Note 7 - Share Repurchase Program (Details Textual)	Jun. 30, 2017
Line of Credit Facility, Conditions for the Elimination of Limits on Shares Repurchases, Leverage Ratio	3.25

The maximum leverage ratio requirement that represents a condition for the elimination of limits on share repurchases, with regard to credit facility covenants.

No definition available.

Name:	icfi_LineOfCreditFacilityConditionsForTheEliminationOfLimitsOnSharesRepurchasesLeverageRatio
Namespace Prefix:	icfi_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant