Long-Term Debt And Other Long-Term Liabilities (Long-Term Debt) (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Long-term debt and other long-term liabilites [Abstract]
Credit agreement with and average interest rates of 2.9% and 2.7% at December 31, 2012 and 2011, respectively	$ 71,100,000	$ 50,000,000
6.625% senior subordinated notes due 2021, net of unamortized discount of $4.7 million at December 31, 2012	645,259,000	250,000,000
Total long-term debt	716,359,000	300,000,000
Line of Credit Facility, Interest Rate at Period End	2.90%	2.70%
Debt Instrument, Unamortized Discount	$ 4,700,000