Income Taxes - Summary of Provision for Income Taxes and U.S. Federal Tax Rate (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Disclosure [Abstract]
Computed "expected" tax expense, amount	$ 50,852	$ 44,784
Foreign income tax differential, amount	(5,747)	(5,761)
State taxes net of federal benefits, amount	2,022	1,466
Foreign-sourced nontaxable income, amount	(4,061)	(3,484)
Other, amount	3,547	2,401
Provision for income taxes, amount	$ 46,613	$ 39,406	$ 92,108	$ 72,428
Computed "expected" tax expense, rate	35.00%	35.00%
Foreign income tax differential, rate	(4.00%)	(4.50%)
State taxes net of federal benefits, rate	1.40%	1.20%
Foreign-sourced nontaxable income, rate	(2.80%)	(2.70%)
Other, rate	2.50%	1.80%
Provision for income taxes, rate	32.10%	30.80%