Long-Term Debt - Senior Secured Revolving Credit Facility (Details) (USD $) In Thousands, unless otherwise specified				6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Eurodollar Rate	Jun. 30, 2013 Line of Credit	Jun. 30, 2013 Line of Credit Election One	Jun. 30, 2013 Line of Credit Election Two	Jun. 30, 2013 Line of Credit Election Three	Jun. 30, 2013 Line of Credit Minimum	Jun. 30, 2013 Line of Credit Maximum	Jun. 30, 2013 Line of Credit Eurodollar Rate	Jun. 30, 2013 Line of Credit Prime Rate	Jun. 30, 2013 Line of Credit Federal Funds Effective Rate	Jun. 30, 2013 Line of Credit Adjusted LIBO Rate
Line of Credit Facility [Line Items]
Debt instrument, maturity date				Nov. 01, 2017
Borrowing base amount				$ 500,000
Senior secured revolving credit facility	$ 93,000	$ 25,000	$ 93,000
One month interest period										1 month
Two month interest period										2 months
Three month interest period										3 months
Six month interest period										6 months
Basis spread on variable rate										1.50%		0.50%	1.00%
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%				0.375%	0.50%
Current Ratio covenant				1
Ratio Of Consolidated Net Debt To Consolidated EBITDAX covenant				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