Long-Term Debt (Schedule Of Long-Term Debt) (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jul. 30, 2012	Jun. 30, 2013 9.25% Senior Notes due 2020 [Member]		Dec. 31, 2012 9.25% Senior Notes due 2020 [Member]		Jun. 30, 2013 Letters Of Credit [Member]		Dec. 31, 2012 Letters Of Credit [Member]		Dec. 31, 2012 2006 Gulf Coast Acquisition [Member]	Dec. 31, 2006 2006 Gulf Coast Acquisition [Member]
Debt Instrument [Line Items]
Credit Agreement, amount outstanding	$ 480,000,000	$ 470,000,000						$ 23,488,000	[1]	$ 23,488,000	[1]
Long-term debt				296,334,000	[2]	296,076,000	[2]
Total long-term debt	776,334,000	766,076,000
Stated interest rate			9.25%
Long-term debt unamortized discount	3,700,000	3,900,000
Issued letter of credit in addition to escrow		$ 100,000										$ 23,400,000	$ 3,000,000

[1] These letters of credit relate to a reclamation deposit requirement of $23.4 million and others totaling $0.1 million. Refer to Note 9 - Commitment and Contingencies for details

[2] The amount is net of unamortized discount of $3.7 million and $3.9 million as of June 30, 2013 and December 31, 2012, respectively