Income Taxes - Summary of Provision for Income Taxes and U.S. Federal Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Abstract]
Computed "expected" tax expense, amount	$ 44,784	$ 36,863
Foreign income tax differential, amount	(5,761)	(4,082)
State taxes net of federal benefits, amount	1,466	1,337
Foreign-sourced nontaxable income, amount	(3,484)	(2,785)
Other, amount	2,401	892
Provision for income taxes, amount	$ 39,406	$ 32,225	$ 72,428	$ 58,076
Computed "expected" tax expense, rate	35.00%	35.00%
Foreign income tax differential, rate	(4.50%)	(3.90%)
State taxes net of federal benefits, rate	1.20%	1.30%
Foreign-sourced nontaxable income, rate	(2.70%)	(2.60%)
Other, rate	1.80%	0.80%
Provision for income taxes, rate	30.80%	30.60%