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, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Line Items]
Computed "expected" tax expense, amount	$ 108,777	$ 73,807	$ 52,948
Foreign income tax differential, amount	(11,695)	(8,333)	(7,074)
State taxes net of federal benefits, amount	3,858	1,923	1,279
Foreign-sourced non-taxable income, amount	(8,840)	(4,423)	(3,873)
Other, amount	2,491	568	104
Total provision	$ 94,591	$ 63,542	$ 43,384
Computed "expected" tax expense, rate	35.00%	35.00%	35.00%
Foreign income tax differential, rate	(3.76%)	(3.95%)	(4.68%)
State taxes net of federal benefits, rate	1.24%	0.91%	0.85%
Foreign-sourced nontaxable income, rate	(2.84%)	(2.10%)	(2.56%)
Other, rate	0.76%	0.27%	0.07%
Provision for income taxes, rate	30.40%	30.13%	28.68%