Debt and Other Long-Term Liabilities (Schedule Of Debt And Other Long-Term Liabilities) (Details) - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014
Debt
Principal		$ 882,500	$ 956,250
Discount		(7,914)	(8,783)
Total		874,586	947,467
Less: current portion		(11,250)	(9,390)
Total long-term portion		863,336	938,077
Other Liabilities
Capital Lease Obligations		9,876	15,391
Capital Lease Obligations, Current		(7,240)	(11,026)
Capital Lease Obligations, Noncurrent		2,636	4,365
Asset retirement obligations		9,577	13,576
Asset Retirement Obligation, Current		0	0
Asset Retirement Obligations, Noncurrent		9,577	13,576
Other long-term liabilities		16,526	17,651
Other Long-term Liabilities, Current		0	0
Other Long-term Liabilities, Noncurrent		16,526	17,651
Long Term Debt And Other Long Term Liabilities		910,565	994,085
Current portion of long-term debt and other long-term liabilities		(18,490)	(20,416)
Long-term debt and other long-term liabilities		892,075	973,669
Unamortized deferred financing fees	[1]	4,470	4,986
Senior Notes | Senior Unsecured Notes due 2019
Debt
Principal		350,000	350,000
Discount		(3,786)	(4,296)
Total		346,214	345,704
Less: current portion		0	0
Total long-term portion		346,214	345,704
Other Liabilities
Unamortized deferred financing fees	[1]	572	649
Senior Notes | Senior Unsecured Notes due 2021
Debt
Principal		300,000	300,000
Discount		(3,830)	(4,152)
Total		296,170	295,848
Less: current portion		0	0
Total long-term portion		296,170	295,848
Other Liabilities
Unamortized deferred financing fees	[1]	1,266	1,372
Term Loans | Credit Facility
Debt
Principal		142,500	146,250
Discount		(298)	(335)
Total		142,202	145,915
Less: current portion		(11,250)	(9,390)
Total long-term portion		130,952	136,525
Other Liabilities
Unamortized deferred financing fees	[1]	0	0
Revolving Line of Credit | Credit Facility
Debt
Principal		90,000	160,000
Discount		0	0
Total		90,000	160,000
Less: current portion		0	0
Total long-term portion		90,000	160,000
Other Liabilities
Unamortized deferred financing fees	[1]	$ 2,632	$ 2,965

[1] Deferred financing fees are recorded in other long-term assets in our Consolidated Balance Sheets and are amortized on a straight line basis over the life of the related loan.