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, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Tax Disclosure [Abstract]
Income tax expense at federal statutory rate, amount	$ 36,863	$ 27,544
Foreign income tax differential, amount	(4,082)	(2,155)
State taxes, net of federal benefit, amount	1,337	653
Foreign-sourced nontaxable income, amount	(2,785)	(2,729)
Other, amount	892	982
Provision for income taxes, amount	$ 32,225	$ 24,295	$ 58,076	$ 42,540
Income tax expense at federal statutory rate, rate	35.00%	35.00%	35.00%	35.00%
Foreign income tax differential, rate	(3.90%)	(2.70%)
State taxes, net of federal benefit, rate	1.30%	0.80%
Foreign-sourced nontaxable income, rate	(2.60%)	(3.50%)
Other, rate	0.80%	1.30%
Provision for income taxes, rate	30.60%	30.90%