Activity Related to Liability for Special Charges (Parenthetical) (Detail) $ in Millions	6 Months Ended
Jun. 30, 2016 USD ($)
Other Income And Expenses [Abstract]
Net non-cash expense reversals	$ 0.2

Special charges reserve net non-cash expense reversals.

No definition available.

Name:	fcn_SpecialChargesReserveNetNonCashExpenseReversals
Namespace Prefix:	fcn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration