Supplemental Condensed Consolidating Guarantor and Non-Guarantor Financial Information (Condensed Consolidating Statement Of Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues	$ 444,715	$ 460,147	$ 891,059	$ 930,432
Operating expenses
Direct cost of revenues	304,071	303,194	613,143	608,830
Selling, general and administrative expenses	107,342	108,245	214,637	211,854
Special charges	30,074	1,750	30,074	6,811
Acquisition-related contingent consideration	777	206	1,172	1,340
Amortization of other intangible assets	2,422	2,590	4,915	5,196
Costs and Expenses, Total	444,686	415,985	863,941	834,031
Operating income	29	44,162	27,118	96,401
Other income (expense)	(4,658)	(2,178)	(9,854)	(5,850)
Income (loss) before income tax provision	(4,629)	41,984	17,264	90,551
Income tax (benefit) provision	527	15,437	8,404	33,823
Net income (loss)	(5,156)	26,547	8,860	56,728
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of tax expense of $0	10,174	(18,809)	17,544	(19,167)
Total other comprehensive income (loss), net of tax	10,174	(18,809)	17,544	(19,167)
Comprehensive income	5,018	7,738	26,404	37,561
FTI Consulting
Revenues	163,649	175,278	315,456	358,272
Operating expenses
Direct cost of revenues	108,445	115,254	219,703	229,683
Selling, general and administrative expenses	45,908	45,983	91,706	90,650
Special charges	13,592	1,750	13,592	1,750
Acquisition-related contingent consideration				6
Amortization of other intangible assets	883	986	1,785	1,972
Costs and Expenses, Total	168,828	163,973	326,786	324,061
Operating income	(5,179)	11,305	(11,330)	34,211
Other income (expense)	(5,361)	(6,892)	(10,613)	(11,969)
Income (loss) before income tax provision	(10,540)	4,413	(21,943)	22,242
Income tax (benefit) provision	(7,034)	3,034	(12,617)	11,183
Equity in net earnings of subsidiaries	(1,650)	25,168	18,186	45,669
Net income (loss)	(5,156)	26,547	8,860	56,728
Other comprehensive income (loss), net of tax:
Comprehensive income	(5,156)	26,547	8,860	56,728
Guarantor Subsidiaries
Revenues	151,716	146,603	322,742	309,166
Operating expenses
Direct cost of revenues	108,388	99,622	226,174	208,812
Selling, general and administrative expenses	30,953	31,065	61,937	61,786
Special charges	7,306		7,306	4,563
Acquisition-related contingent consideration	777	206	1,172	1,334
Amortization of other intangible assets	540	540	1,080	1,098
Costs and Expenses, Total	147,964	131,433	297,669	277,593
Operating income	3,752	15,170	25,073	31,573
Other income (expense)	(71)	(1,559)	(498)	(2,269)
Income (loss) before income tax provision	3,681	13,611	24,575	29,304
Income tax (benefit) provision	4,219	6,865	15,137	13,724
Equity in net earnings of subsidiaries	(3,862)	17,107	4,711	26,989
Net income (loss)	(4,400)	23,853	14,149	42,569
Other comprehensive income (loss), net of tax:
Comprehensive income	(4,400)	23,853	14,149	42,569
Non-Guarantor Subsidiaries
Revenues	131,480	140,557	257,583	267,623
Operating expenses
Direct cost of revenues	89,307	90,556	171,868	174,871
Selling, general and administrative expenses	30,542	31,250	61,114	59,511
Special charges	9,176		9,176	498
Amortization of other intangible assets	1,741	1,882	3,511	3,761
Costs and Expenses, Total	130,766	123,688	245,669	238,641
Operating income	714	16,869	11,914	28,982
Other income (expense)	774	6,273	1,257	8,388
Income (loss) before income tax provision	1,488	23,142	13,171	37,370
Income tax (benefit) provision	3,342	5,538	5,884	8,916
Net income (loss)	(1,854)	17,604	7,287	28,454
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of tax expense of $0	10,174	(18,809)	17,544	(19,167)
Total other comprehensive income (loss), net of tax	10,174	(18,809)	17,544	(19,167)
Comprehensive income	8,320	(1,205)	24,831	9,287
Eliminations
Revenues	(2,130)	(2,291)	(4,722)	(4,629)
Operating expenses
Direct cost of revenues	(2,069)	(2,238)	(4,602)	(4,536)
Selling, general and administrative expenses	(61)	(53)	(120)	(93)
Amortization of other intangible assets	(742)	(818)	(1,461)	(1,635)
Costs and Expenses, Total	(2,872)	(3,109)	(6,183)	(6,264)
Operating income	742	818	1,461	1,635
Income (loss) before income tax provision	742	818	1,461	1,635
Equity in net earnings of subsidiaries	5,512	(42,275)	(22,897)	(72,658)
Net income (loss)	6,254	(41,457)	(21,436)	(71,023)
Other comprehensive income (loss), net of tax:
Comprehensive income	$ 6,254	$ (41,457)	$ (21,436)	$ (71,023)