Income Taxes - Summary of Provision for Income Taxes and U.S. Federal Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]
Computed "expected" tax expense, amount	$ 38,056	$ 31,680
Foreign income tax differential, amount	(4,408)	(3,633)
State taxes net of federal benefits, amount	1,219	985
Foreign-sourced nontaxable income, amount	(3,138)	(4,318)
Other, amount	1,293	1,137
Provision for income taxes, amount	$ 33,022	$ 25,851
Computed "expected" tax expense, rate	35.00%	35.00%
Foreign income tax differential, rate	(4.00%)	(4.00%)
State taxes, net of federal benefits, rate	1.10%	1.10%
Foreign-sourced nontaxable income, rate	(2.90%)	(4.80%)
Other, rate	1.30%	1.30%
Provision for income taxes, rate	30.50%	28.60%