Equity-Based Compensation - Impact of Stock Options and Restricted Stock Awards on Net Income (Details) (USD $) In Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]
Share-based Compensation	$ 8,525		$ 8,536		$ 15,546		$ 15,210
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	(2,626)	[1]	(2,399)	[1]	(3,887)	[1]	(4,974)	[1]
Share Based Compensation Expense Net Of Tax	$ 5,899		$ 6,137		$ 11,659		$ 10,236

[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).