Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Accounts receivable, principally due to the allowance for doubtful accounts	$ 7,148	$ 6,277
Accrued expenses not currently deductible for tax	2,647	5,797
Stock based compensation	41,415	35,066
Income tax credits	376	3,830
Net operating loss carry forwards	45,969	39,970
Equity investment	53,379	38,760
Accrued escheat	7,290	13,497
Fixed assets, intangibles and other	15,622	14,191
Deferred tax assets before valuation allowance	173,846	157,388
Valuation allowance	(76,395)	(62,605)
Deferred tax assets, net	97,451	94,783
Deferred tax liabilities:
Intangibles—including goodwill	(687,443)	(732,017)
Basis difference in investment in foreign subsidiaries	(48,354)	(47,737)
Prepaid expenses	(3,644)	0
Property and equipment, principally due to differences between book and tax depreciation, and other	(24,157)	(19,544)
Deferred tax liabilities	(763,598)	(799,298)
Net deferred tax liabilities	$ (666,147)	$ (704,515)