Stock-Based Compensation - Impact of Stock Options and Restricted Stock Awards on Net Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total stock-based compensation	$ 5,762		$ 5,379		$ 9,837		$ 10,515
Tax impact	(1,844)	[1]	(1,635)	[1]	(2,853)	[1]	(3,427)	[1]
Reduction in net income, net of tax	$ 3,918		$ 3,744		$ 6,984		$ 7,088

[1] Tax impact is determined at the Company's combined effective tax rate, which includes the income statement line item "Increase/decrease in income tax benefit payable to former stockholder" (see Note 11).