Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Property and Equipment
Proved oil and gas properties		$ 5,910,250	$ 5,826,995
Unproved oil and gas properties		69,697	64,903
Furniture, fixtures, and other equipment		43,687	42,257
Less - Accumulated depreciation, depletion, and amortization		(5,061,058)	(3,839,118)
Property and Equipment, Net		962,576	2,095,037
Accounts Payable and Accrued Liabilities
Trade accounts payable	[1]	17,600	31,153
Accrued operating expenses		8,134	10,784
Accrued payroll costs		7,064	8,715
Asset retirement obligation - current portion		7,124	10,709
Accrued taxes		5,652	2,957
Other payables		3,542	3,926
Total accounts payable and accrued liabilities		$ 49,116	$ 68,244

[1] Included in “trade accounts payable” are liabilities of approximately $2.2 million and $13.7 million at September 30, 2015 and December 31, 2014, respectively, for outstanding checks.