Summary of Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Deferred tax assets, Allowance for doubtful accounts	$ 17,220	$ 17,953
Deferred tax assets, Accrued vacation and bonus	38,596	37,481
Deferred tax assets, Deferred rent	12,034	13,415
Deferred tax assets, Share-based compensation	24,783	30,037
Deferred tax assets, Notes receivable from employees	21,010	20,353
Deferred tax assets, State net operating loss carryforward and credits	4,169	3,883
Deferred tax assets, Foreign net operating loss carryforward	12,437	6,614
Deferred tax assets, Future foreign tax credit asset	2,545	3,753
Deferred compensation	3,084	2,279
Deferred tax assets, Other-net	5,284	3,754
Total deferred tax assets	141,162	139,522
Deferred tax liabilities, Revenue recognition	(11,590)	(12,452)
Deferred tax liabilities, Property, equipment and capitalized software	(6,527)	(5,739)
Deferred tax liabilities, Goodwill and other intangible asset amortization	(273,990)	(247,951)
Total deferred tax liabilities	(292,107)	(266,142)
Valuation allowance	(18,900)	(13,167)
Net deferred tax liabilities	$ (169,845)	$ (139,787)