Special Charges By Segment (Detail) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Special Charges [Line Items]
Special charges	$ 3,634	$ 1,750	$ 5,061	$ 10,445	$ 0	$ 16,339
Operating Segments
Special Charges [Line Items]
Special charges				9,833		426
Operating Segments | Corporate Finance & Restructuring
Special Charges [Line Items]
Special charges						84
Operating Segments | Forensic and Litigation Consulting
Special Charges [Line Items]
Special charges				2,304		308
Operating Segments | Economic Consulting
Special Charges [Line Items]
Special charges						12
Operating Segments | Technology
Special Charges [Line Items]
Special charges				7,529		19
Operating Segments | Strategic Communications
Special Charges [Line Items]
Special charges						3
Unallocated Corporate
Special Charges [Line Items]
Special charges				$ 612		$ 15,913