Supplemental Condensed Consolidating Guarantor and Non-Guarantor Financial Information Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 138,511	$ 216,158	$ 182,665	$ 149,760
Accounts receivable, net	553,215	474,897
Other current assets	86,063	92,116
Total current assets	777,789	783,171
Property and equipment, net	60,280	61,856
Goodwill	1,187,664	1,180,001
Other intangible assets, net	48,213	52,120
Other assets	150,847	148,220
Total assets	2,224,793	2,225,368
Liabilities
Other current liabilities	314,738	378,455
Total current liabilities	314,738	378,455
Long-term debt, net	480,906	365,528
Other liabilities	289,971	274,027
Total liabilities	1,085,615	1,018,010
Stockholders' equity	1,139,178	1,207,358
Total liabilities and stockholders' equity	2,224,793	2,225,368
FTI Consulting
Assets
Cash and cash equivalents	15,113	47,420	73,009	35,211
Accounts receivable, net	153,823	137,523
Other current assets	35,918	44,708
Total current assets	204,854	229,651
Property and equipment, net	24,897	25,466
Goodwill	558,978	558,978
Other intangible assets, net	20,174	21,959
Investments in subsidiaries	2,119,854	2,065,819
Other assets	40,435	47,308
Total assets	2,969,192	2,949,181
Liabilities
Intercompany payables	1,045,139	1,027,050
Other current liabilities	82,260	137,710
Total current liabilities	1,127,399	1,164,760
Long-term debt, net	480,906	365,528
Other liabilities	221,709	211,535
Total liabilities	1,830,014	1,741,823
Stockholders' equity	1,139,178	1,207,358
Total liabilities and stockholders' equity	2,969,192	2,949,181
Guarantor Subsidiaries
Assets
Cash and cash equivalents	158	156	163	165
Accounts receivable, net	193,611	163,820
Intercompany receivables	1,026,529	1,029,800
Other current assets	21,818	24,944
Total current assets	1,242,116	1,218,720
Property and equipment, net	12,647	14,118
Goodwill	416,053	416,053
Other intangible assets, net	12,312	13,393
Investments in subsidiaries	516,041	490,634
Other assets	66,946	65,398
Total assets	2,266,115	2,218,316
Liabilities
Other current liabilities	127,094	129,810
Total current liabilities	127,094	129,810
Other liabilities	16,940	16,411
Total liabilities	144,034	146,221
Stockholders' equity	2,122,081	2,072,095
Total liabilities and stockholders' equity	2,266,115	2,218,316
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	123,240	168,582	$ 109,493	$ 114,384
Accounts receivable, net	205,781	173,554
Intercompany receivables	18,610
Other current assets	28,327	22,464
Total current assets	375,958	364,600
Property and equipment, net	22,736	22,272
Goodwill	212,633	204,970
Other intangible assets, net	32,222	34,725
Other assets	43,466	35,514
Total assets	687,015	662,081
Liabilities
Intercompany payables		2,750
Other current liabilities	105,384	110,935
Total current liabilities	105,384	113,685
Other liabilities	51,322	46,081
Total liabilities	156,706	159,766
Stockholders' equity	530,309	502,315
Total liabilities and stockholders' equity	687,015	662,081
Eliminations
Assets
Intercompany receivables	(1,045,139)	(1,029,800)
Total current assets	(1,045,139)	(1,029,800)
Other intangible assets, net	(16,495)	(17,957)
Investments in subsidiaries	(2,635,895)	(2,556,453)
Total assets	(3,697,529)	(3,604,210)
Liabilities
Intercompany payables	(1,045,139)	(1,029,800)
Total current liabilities	(1,045,139)	(1,029,800)
Total liabilities	(1,045,139)	(1,029,800)
Stockholders' equity	(2,652,390)	(2,574,410)
Total liabilities and stockholders' equity	$ (3,697,529)	$ (3,604,210)