Supplemental Condensed Consolidating Guarantor and Non-Guarantor Financial Information Condensed Consolidating Statement Of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net cash (used in) provided by operating activities	$ 233,488	$ 139,920	$ 135,401
Investing activities
Payments for acquisition of businesses, net of cash received	(1,251)	(575)	(23,467)
Purchases of property and equipment	(28,935)	(31,399)	(39,256)
Other	54	237	5,128
Net cash used in investing activities	(30,132)	(31,737)	(57,595)
Financing activities
Borrowings under revolving line of credit, net	(130,000)	200,000
Payments of long-term debt		(425,671)	(6,014)
Payments of debt issue costs		(3,843)
Deposits	4,006	3,227	13,071
Purchase and retirement of common stock	(21,489)	(26,532)	(4,367)
Net issuance of common stock under equity compensation plans	21,708	16,666	4,772
Other	465	191	(1,132)
Net cash (used in) provided by financing activities	(125,310)	(235,962)	6,330
Effect of exchange rate changes on cash and cash equivalents	(11,648)	(6,141)	(6,289)
Net increase (decrease) in cash and cash equivalents	66,398	(133,920)	77,847
Cash and cash equivalents, beginning of period	149,760	283,680	205,833
Cash and cash equivalents, end of period	216,158	149,760	283,680
FTI Consulting
Operating activities
Net cash (used in) provided by operating activities	46,908	14,815	(36,921)
Investing activities
Payments for acquisition of businesses, net of cash received			(14,729)
Purchases of property and equipment	(3,576)	(9,192)	(12,738)
Other	54	79	139
Net cash used in investing activities	(3,522)	(9,113)	(27,328)
Financing activities
Borrowings under revolving line of credit, net	(130,000)	200,000
Payments of long-term debt		(425,671)
Payments of debt issue costs		(3,843)
Purchase and retirement of common stock	(21,489)	(26,532)	(4,367)
Net issuance of common stock under equity compensation plans	21,708	16,666	4,772
Other	1,121	485	366
Intercompany transfers	97,483	97,314	122,625
Net cash (used in) provided by financing activities	(31,177)	(141,581)	123,396
Net increase (decrease) in cash and cash equivalents	12,209	(135,879)	59,147
Cash and cash equivalents, beginning of period	35,211	171,090	111,943
Cash and cash equivalents, end of period	47,420	35,211	171,090
Guarantor Subsidiaries
Operating activities
Net cash (used in) provided by operating activities	123,101	83,516	142,540
Investing activities
Payments for acquisition of businesses, net of cash received			(7,783)
Purchases of property and equipment	(20,185)	(16,487)	(13,080)
Net cash used in investing activities	(20,185)	(16,487)	(20,863)
Financing activities
Payments of long-term debt			(6,000)
Other	(656)	(294)	(555)
Intercompany transfers	(102,269)	(66,729)	(115,457)
Net cash (used in) provided by financing activities	(102,925)	(67,023)	(122,012)
Net increase (decrease) in cash and cash equivalents	(9)	6	(335)
Cash and cash equivalents, beginning of period	165	159	494
Cash and cash equivalents, end of period	156	165	159
Non-Guarantor Subsidiaries
Operating activities
Net cash (used in) provided by operating activities	63,479	41,589	29,782
Investing activities
Payments for acquisition of businesses, net of cash received	(1,251)	(575)	(955)
Purchases of property and equipment	(5,174)	(5,720)	(13,438)
Other		158	4,989
Net cash used in investing activities	(6,425)	(6,137)	(9,404)
Financing activities
Payments of long-term debt			(14)
Deposits	4,006	3,227	13,071
Other			(943)
Intercompany transfers	4,786	(30,585)	(7,168)
Net cash (used in) provided by financing activities	8,792	(27,358)	4,946
Effect of exchange rate changes on cash and cash equivalents	(11,648)	(6,141)	(6,289)
Net increase (decrease) in cash and cash equivalents	54,198	1,953	19,035
Cash and cash equivalents, beginning of period	114,384	112,431	93,396
Cash and cash equivalents, end of period	$ 168,582	$ 114,384	$ 112,431