Income Taxes - Summary of Provision for Income Taxes and U.S. Federal Tax Rate (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Computed "expected" tax expense, amount	$ 54,919	$ 48,877
Foreign income tax differential, amount	(4,769)	(4,495)
State taxes net of federal benefits, amount	1,832	1,994
Foreign-sourced nontaxable income, amount	(2,178)	(2,882)
Other, amount	(2,864)	2,001
Provision for income taxes, amount	$ 46,940	$ 45,495
Computed "expected" tax expense, rate	35.00%	35.00%
Foreign income tax differential, rate	(3.00%)	(3.20%)
State taxes net of federal benefits, rate	1.10%	1.40%
Foreign-sourced nontaxable income, rate	(1.40%)	(2.00%)
Other, rate	(1.80%)	1.40%
Provision for income taxes, rate	29.90%	32.60%