Income Before Provision for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Income Before Income Tax [Line Items]
Domestic										$ 286,537	$ 202,210	$ 88,065
Foreign										57,708	48,006	27,103
Income before income taxes	$ 97,242	$ 94,467	$ 72,272	[1]	$ 80,264	$ 72,161	$ 72,195	$ 61,284	$ 44,576	$ 344,245	$ 250,216	$ 115,168

[1] The decrease in second quarter 2012 income before income taxes, net income, and net income per share was primarily due to a charge related to a litigation settlement disclosed in the Company's July 5, 2012, Form 8-K. The settlement resulted in a non-recurring $19.0 million pre-tax charge to selling, general and administrative expenses and reduced second quarter net income and net income per share by $11.4 million and $0.08 per share, respectively.