Special Charges By Segment (Detail) - USD ($)	3 Months Ended			12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Special Charges [Line Items]
Special charges	$ 1,628,000	$ 5,347,000	$ 9,364,000	$ 0	$ 16,339,000	$ 38,414,000
Operating Segments
Special Charges [Line Items]
Special charges					426,000	12,478,000
Operating Segments | Corporate Finance & Restructuring
Special Charges [Line Items]
Special charges					84,000	10,274,000
Operating Segments | Forensic and Litigation Consulting
Special Charges [Line Items]
Special charges					308,000	2,111,000
Operating Segments | Economic Consulting
Special Charges [Line Items]
Special charges					12,000	11,000
Operating Segments | Technology
Special Charges [Line Items]
Special charges					19,000	16,000
Operating Segments | Strategic Communications
Special Charges [Line Items]
Special charges					3,000	66,000
Unallocated Corporate
Special Charges [Line Items]
Special charges					$ 15,913,000	$ 25,936,000