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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Tax Disclosure [Abstract]
Computed "expected" tax expense, amount	$ 56,822	$ 50,852
Foreign income tax differential, amount	(4,424)	(5,747)
State taxes net of federal benefits, amount	1,909	2,022
Foreign-sourced nontaxable income, amount	(2,020)	(4,061)
Other, amount	(4,124)	3,547
Provision for income taxes, amount	$ 48,163	$ 46,613	$ 95,103	$ 92,108
Computed "expected" tax expense, rate	35.00%	35.00%
Foreign income tax differential, rate	(2.70%)	(4.00%)
State taxes net of federal benefits, rate	1.20%	1.40%
Foreign-sourced nontaxable income, rate	(1.20%)	(2.80%)
Other, rate	(2.60%)	2.50%
Provision for income taxes, rate	29.70%	32.10%