Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Deferred tax assets, Allowance for doubtful accounts	$ 17,953	$ 14,088
Deferred tax assets, Accrued vacation and bonus	37,481	22,021
Deferred tax assets, Deferred rent	13,415	15,036
Deferred tax assets, Share-based compensation	30,037	18,617
Deferred tax assets, Notes receivable from employees	20,353	23,158
Deferred tax assets, State net operating loss carryforward & credits	3,883	3,558
Deferred tax assets, Foreign net operating loss carryforward	6,614	8,040
Deferred tax assets, Foreign tax credits		2,929
Deferred tax assets, Future foreign tax credit asset	3,753	5,259
Deferred compensation	2,279	4,669
Deferred tax assets, Other-net	3,754	9,583
Total deferred tax assets	139,522	126,958
Deferred tax liabilities, Revenue recognition	(12,452)	(9,402)
Deferred tax liabilities, Property, equipment and capitalized software	(5,739)	(4,142)
Deferred tax liabilities, Goodwill and other intangible asset amortization	(247,951)	(233,572)
Total deferred tax liabilities	(266,142)	(247,116)
Valuation allowance	(13,167)	(14,442)
Net deferred tax assets (liabilities)	$ (139,787)	$ (134,600)