Income Taxes - Summary of Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets, Gross [Abstract]
Allowance for doubtful accounts	$ 13,041	$ 11,792
Accrued vacation and bonus	27,438	23,545
Deferred rent	0	9,016
Share-based compensation	12,647	11,837
Notes receivable from employees	12,187	12,993
State net operating loss carryforward	2,066	3,510
Foreign net operating loss carryforward	9,388	9,857
Federal tax credit and capital loss carryforward	7,336	9,470
Deferred compensation	2,117	1,801
Operating lease assets	43,397
Employee benefits obligations	1,191	943
Other, net	1,898	186
Total deferred tax assets	132,706	94,950
Deferred tax liabilities
Revenue recognition	(6,732)	(5,087)
Operating lease liabilities	(29,671)
Property and equipment, net	(3,797)	(6,652)
Equity debt discount	(8,890)	(11,014)
Goodwill and other intangible assets	(209,250)	(199,964)
Total deferred tax liabilities	(258,340)	(222,717)
Foreign withholding tax	(1,195)	(413)
Valuation allowance	(19,865)	(21,929)
Net deferred tax liabilities	$ (146,694)	$ (150,109)