Long-Term Debt And Other Long-Term Liabilities (Long-Term Debt) (Details) (USD $)	0 Months Ended			6 Months Ended
	Nov. 13, 2012	Jul. 24, 2012	May 18, 2011	Jun. 30, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Credit agreement with an average interest rate of 1.9% and 2.9% at June 30, 2013 and December 31, 2012, respectively				$ 70,000,000	$ 71,100,000
6.625% senior subordinated notes due 2021, net of unamortized discount of $4.5 million at June 30, 2013 and $4.7 million at December 31, 2012				645,474,000	645,259,000
Total long-term debt				715,474,000	716,359,000
Revolving credit facility interest rate				1.90%	2.90%
Interest percentage of senior subordinated notes	6.625%	6.625%	6.625%	6.625%
Debt instrument maturity date	May 15, 2021	May 15, 2021	May 15, 2021	May 15, 2021
Debt instrument, unamortized discount				$ 4,500,000	$ 4,700,000