Debt and Other Long-Term Liabilities (Schedule Of Debt And Other Long-Term Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Debt
Principal	$ 874,375		$ 956,250
Discount	(8,349)		(8,783)
Total	866,026		947,467
Less: current portion	(10,313)		(9,390)
Total long-term portion	855,713		938,077
Other Liabilities
Capital Lease Obligations	12,652		15,391
Capital Lease Obligations, Current	(9,231)		(11,026)
Capital Lease Obligations, Noncurrent	3,421		4,365
Asset retirement obligations	12,663		13,576
Asset Retirement Obligation, Current	0		0
Asset Retirement Obligations, Noncurrent	12,663		13,576
Other long-term liabilities	15,292		17,651
Other Long-term Liabilities, Current	0		0
Other Long-term Liabilities, Noncurrent	15,292		17,651
Long Term Debt And Other Long Term Liabilities	906,633		994,085
Current portion of long-term debt and other long-term liabilities	(19,544)		(20,416)
Long Term Debt And Other Liabilities Noncurrent	887,089		973,669
Unamortized deferred financing fees	4,729	[1]	4,986	[1]
Senior Notes | Senior Unsecured Notes due 2019
Debt
Principal	350,000		350,000
Discount	(4,041)		(4,296)
Total	345,959		345,704
Less: current portion	0		0
Total long-term portion	345,959		345,704
Other Liabilities
Unamortized deferred financing fees	611	[1]	649	[1]
Senior Notes | Senior Unsecured Notes due 2021
Debt
Principal	300,000		300,000
Discount	(3,991)		(4,152)
Total	296,009		295,848
Less: current portion	0		0
Total long-term portion	296,009		295,848
Other Liabilities
Unamortized deferred financing fees	1,319	[1]	1,372	[1]
Term Loans | Credit Facility
Debt
Principal	144,375		146,250
Discount	(317)		(335)
Total	144,058		145,915
Less: current portion	(10,313)		(9,390)
Total long-term portion	133,745		136,525
Other Liabilities
Unamortized deferred financing fees	0	[1]	0	[1]
Revolving Line of Credit | Credit Facility
Debt
Principal	80,000		160,000
Discount	0		0
Total	80,000		160,000
Less: current portion	0		0
Total long-term portion	80,000		160,000
Other Liabilities
Unamortized deferred financing fees	$ 2,799	[1]	$ 2,965	[1]

[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.