Equity-Based Compensation - Impact of Stock Options and Restricted Stock Awards on Net Income (Details) (USD $) In Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]
Total equity-based compensation	$ 6,588		$ 7,193		$ 22,134		$ 22,403
Tax impact	(1,746)	[1]	(2,072)	[1]	(5,644)	[1]	(6,923)	[1]
Reduction in net income, net of tax	$ 4,842		$ 5,121		$ 16,490		$ 15,480

[1] Tax impact is determined at the Company's combined effective tax rate, which includes the income statement line item “Increase in income tax benefit payable to former stockholder” (see Note 8).