Long-Term Debt - Senior Secured Revolving Credit Facility (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended								3 Months Ended	9 Months Ended									9 Months Ended
	Sep. 30, 2012	Nov. 01, 2012	Dec. 31, 2011	Sep. 30, 2012 Eurodollar Rate Minimum	Sep. 30, 2012 Eurodollar Rate Maximum	Sep. 30, 2012 Alternate Base Rate Minimum	Sep. 30, 2012 Alternate Base Rate Maximum	Nov. 13, 2012 Subsequent Event	Sep. 30, 2012 Line of Credit	Sep. 30, 2012 Line of Credit	Sep. 30, 2012 Line of Credit Election One	Sep. 30, 2012 Line of Credit Election Two	Sep. 30, 2012 Line of Credit Election Three	Sep. 30, 2012 Line of Credit Eurodollar Rate	Sep. 30, 2012 Line of Credit Eurodollar Rate Minimum	Sep. 30, 2012 Line of Credit Eurodollar Rate Maximum	Sep. 30, 2012 Line of Credit Alternate Base Rate Minimum	Sep. 30, 2012 Line of Credit Alternate Base Rate Maximum	Sep. 30, 2012 Line of Credit Prime Rate	Sep. 30, 2012 Line of Credit Federal Funds Effective Rate	Sep. 30, 2012 Line of Credit Adjusted LIBO Rate	Sep. 30, 2012 Line of Credit Adjusted LIBO Rate Minimum
Line of Credit Facility [Line Items]
Borrowing base amount	$ 375,000	$ 500,000
Maximum borrowing capacity	450,000	750,000
Maximum borrowing capiticty given exercise of accordion option		850,000
interest rate margin				1.50%	2.50%	0.50%	1.50%
Minimal borrowing base utilized before reduction in commitment fees	50.00%
Reduction of borrowing base	25.00%
Senior secured revolving credit facility	118,000		0					145,000						118,000
Basis spread on variable rate															1.75%	2.75%	0.75%	1.75%		0.50%		1.00%
Commitment fee									$ 378	$ 1,236
Description of variable rate basis																			the Prime Rate	the Federal Funds Effective Rate	the Adjusted LIBO Rate
Commitment fee on unused portion of the borrowing base	0.375%									0.50%
Current Ratio Covenant									1	1
Ratio Of Consolidated Net Debt To Consolidated EBITDAX Covenant									4.5	4.5
Days to elect method to eliminate borrowings in excess of borrowing base										10 days
Days to eliminate borrowings in excess of borrowing base											30 days	30 days	30 days
Months over which borrowings in excess of borrowing base may be repaid in equal monthly installments											6 months