Supplemental Condensed Consolidating Guarantor and Non-Guarantor Financial Information Condensed Consolidating Statement Of Cash Flow (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities
Net cash provided by operating activities		$ 139,920	$ 135,401	$ 193,271
Investing activities
Payments for acquisition of businesses, net of cash received		(575)	(23,467)	(55,498)
Purchases of property and equipment		(31,399)	(39,256)	(42,544)
Other		237	5,128	(5,049)
Net cash used in investing activities		(31,737)	(57,595)	(103,091)
Financing activities
Borrowings under revolving line of credit, net		200,000
Payments of long-term debt		(425,671)	(6,014)	(6,021)
Payments of debt issue costs		(3,843)
Payments of long-term debt and capital lease obligations			(6,014)	(6,021)
Deposits		3,227	13,071
Purchase and retirement of common stock	$ (4,400)	(26,532)	(4,367)	(66,763)
Net issuance of common stock under equity compensation plans		16,666	4,772	29,392
Other		191	(1,132)	263
Net cash (used in) provided by financing activities		(235,962)	6,330	(43,129)
Effect of exchange rate changes on cash and cash equivalents		(6,141)	(6,289)	1,997
Net increase (decrease) in cash and cash equivalents		(133,920)	77,847	49,048
Cash and cash equivalents, beginning of period	205,833	283,680	205,833	156,785
Cash and cash equivalents, end of period		149,760	283,680	205,833
FTI Consulting, Inc.
Operating activities
Net cash provided by operating activities		14,815	(36,921)	(37,166)
Investing activities
Payments for acquisition of businesses, net of cash received			(14,729)	(12,555)
Purchases of property and equipment		(9,192)	(12,738)	(4,296)
Other		79	139	45
Net cash used in investing activities		(9,113)	(27,328)	(16,806)
Financing activities
Borrowings under revolving line of credit, net		200,000
Payments of long-term debt		(425,671)
Payments of debt issue costs		(3,843)
Purchase and retirement of common stock		(26,532)	(4,367)	(66,763)
Net issuance of common stock under equity compensation plans		16,666	4,772	29,392
Other		485	366	1,515
Intercompany transfers		97,314	122,625	135,108
Net cash (used in) provided by financing activities		(141,581)	123,396	99,252
Net increase (decrease) in cash and cash equivalents		(135,879)	59,147	45,280
Cash and cash equivalents, beginning of period	111,943	171,090	111,943	66,663
Cash and cash equivalents, end of period		35,211	171,090	111,943
Guarantor Subsidiaries
Operating activities
Net cash provided by operating activities		83,516	142,540	178,234
Investing activities
Payments for acquisition of businesses, net of cash received			(7,783)	(7,157)
Purchases of property and equipment		(16,487)	(13,080)	(17,507)
Net cash used in investing activities		(16,487)	(20,863)	(24,664)
Financing activities
Payments of long-term debt and capital lease obligations			(6,000)	(6,000)
Other		(294)	(555)
Intercompany transfers		(66,729)	(115,457)	(147,686)
Net cash (used in) provided by financing activities		(67,023)	(122,012)	(153,686)
Net increase (decrease) in cash and cash equivalents		6	(335)	(116)
Cash and cash equivalents, beginning of period	494	159	494	610
Cash and cash equivalents, end of period		165	159	494
Non-Guarantor Subsidiaries
Operating activities
Net cash provided by operating activities		41,589	29,782	52,203
Investing activities
Payments for acquisition of businesses, net of cash received		(575)	(955)	(35,786)
Purchases of property and equipment		(5,720)	(13,438)	(20,741)
Other		158	4,989	(5,094)
Net cash used in investing activities		(6,137)	(9,404)	(61,621)
Financing activities
Payments of long-term debt and capital lease obligations			(14)	(21)
Deposits		3,227	13,071
Other			(943)	(1,252)
Intercompany transfers		(30,585)	(7,168)	12,578
Net cash (used in) provided by financing activities		(27,358)	4,946	11,305
Effect of exchange rate changes on cash and cash equivalents		(6,141)	(6,289)	1,997
Net increase (decrease) in cash and cash equivalents		1,953	19,035	3,884
Cash and cash equivalents, beginning of period	$ 93,396	112,431	93,396	89,512
Cash and cash equivalents, end of period		$ 114,384	$ 112,431	$ 93,396