Stock-Based Compensation - Impact of Stock Options and Restricted Stock Awards on Net Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total stock-based compensation	$ 4,075		$ 5,136
Tax impact	(628)	[1]	(1,823)	[1]
Reduction in net income, net of tax	$ 3,447		$ 3,313

[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 10).