Income Taxes - Summary of Provision for Income Taxes and U.S. Federal Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Computed "expected" tax expense, amount	$ 141,249	$ 108,777	$ 73,807
Foreign income tax differential, amount	(16,021)	(11,695)	(8,333)
State taxes net of federal benefits, amount	4,744	3,858	1,923
Foreign-sourced nontaxable income, amount	(11,967)	(8,840)	(4,423)
Other, amount	1,063	2,491	568
Provision for income taxes, amount	$ 119,068	$ 94,591	$ 63,542
Computed "expected" tax expense, rate	35.00%	35.00%	35.00%
Foreign income tax differential, rate	(3.97%)	(3.76%)	(3.95%)
State taxes net of federal benefits, rate	1.18%	1.24%	0.91%
Foreign-sourced nontaxable income, rate	(2.97%)	(2.84%)	(2.10%)
Other, rate	0.26%	0.76%	0.27%
Provision for income taxes, rate	29.50%	30.40%	30.13%