Supplemental Condensed Consolidating Guarantor and Non-Guarantor Financial Information Condensed Consolidating Balance Sheet Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Assets
Cash and cash equivalents	$ 104,974	$ 283,680	$ 178,778	$ 205,833
Accounts receivable, net	554,400	485,101
Other current assets	129,105	115,392
Total current assets	788,479	884,173
Property and equipment, net	77,716	82,163
Goodwill	1,199,490	1,211,689
Other intangible assets, net	67,252	77,034
Other assets	161,075	175,468
Total assets	2,294,012	2,430,527
Liabilities
Other current liabilities	334,510	367,092
Total current liabilities	334,510	367,092
Long-term debt, net	520,000	700,000
Other liabilities	277,099	260,689
Total liabilities	1,131,609	1,327,781
Stockholders' equity	1,162,403	1,102,746
Total liabilities and stockholders' equity	2,294,012	2,430,527
FTI Consulting, Inc.
Assets
Cash and cash equivalents	17,366	171,090	96,462	111,943
Accounts receivable, net	179,097	153,495
Other current assets	84,501	74,455
Total current assets	280,964	399,040
Property and equipment, net	34,786	33,864
Goodwill	558,978	559,318
Other intangible assets, net	26,849	29,807
Investments in subsidiaries	1,971,516	1,915,869
Other assets	45,907	61,025
Total assets	2,919,000	2,998,923
Liabilities
Intercompany payables	872,934	832,253
Other current liabilities	139,131	148,299
Total current liabilities	1,012,065	980,552
Long-term debt, net	520,000	700,000
Other liabilities	224,532	215,625
Total liabilities	1,756,597	1,896,177
Stockholders' equity	1,162,403	1,102,746
Total liabilities and stockholders' equity	2,919,000	2,998,923
Guarantor Subsidiaries
Assets
Cash and cash equivalents	156	159	163	494
Accounts receivable, net	189,277	162,032
Intercompany receivables	893,594	875,000
Other current assets	25,454	22,994
Total current assets	1,108,481	1,060,185
Property and equipment, net	14,843	17,050
Goodwill	416,053	416,053
Other intangible assets, net	16,286	18,432
Investments in subsidiaries	481,967	484,162
Other assets	76,636	78,388
Total assets	2,114,266	2,074,270
Liabilities
Intercompany payables	19,765	14,197
Other current liabilities	96,965	113,450
Total current liabilities	116,730	127,647
Other liabilities	12,117	14,955
Total liabilities	128,847	142,602
Stockholders' equity	1,985,419	1,931,668
Total liabilities and stockholders' equity	2,114,266	2,074,270
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	87,452	112,431	$ 82,153	$ 93,396
Accounts receivable, net	186,026	169,574
Intercompany receivables	36,038	12,195
Other current assets	19,150	17,943
Total current assets	328,666	312,143
Property and equipment, net	28,087	31,249
Goodwill	224,459	236,318
Other intangible assets, net	46,026	53,357
Other assets	38,532	36,055
Total assets	665,770	669,122
Liabilities
Intercompany payables	36,933	40,745
Other current liabilities	98,414	105,343
Total current liabilities	135,347	146,088
Other liabilities	40,450	30,109
Total liabilities	175,797	176,197
Stockholders' equity	489,973	492,925
Total liabilities and stockholders' equity	665,770	669,122
Eliminations
Assets
Intercompany receivables	(929,632)	(887,195)
Total current assets	(929,632)	(887,195)
Other intangible assets, net	(21,909)	(24,562)
Investments in subsidiaries	(2,453,483)	(2,400,031)
Total assets	(3,405,024)	(3,311,788)
Liabilities
Intercompany payables	(929,632)	(887,195)
Total current liabilities	(929,632)	(887,195)
Total liabilities	(929,632)	(887,195)
Stockholders' equity	(2,475,392)	(2,424,593)
Total liabilities and stockholders' equity	$ (3,405,024)	$ (3,311,788)