Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities
Net loss	$ (565,861)	$ (1,256,245)
Adjustments to reconcile net loss to cash flows from operating activities
Depletion, depreciation, and amortization	143,907	297,898
Write-down of oil and natural gas properties	735,400	1,852,000
Deferred income taxes	(318,055)	(700,508)
Stock-based compensation	4,122	14,967
Commodity derivatives expense (income)	121,035	(34,150)
Receipt on settlements of commodity derivatives	124,253	272,616
Gain on debt extinguishment	(107,269)	0
Debt issuance costs and discounts	14,072	4,501
Other, net	(1,743)	(4,019)
Changes in assets and liabilities, net of effects from acquisitions
Accrued production receivable	(20,060)	17,683
Trade and other receivables	17,568	57,865
Other current and long-term assets	(7,974)	(7,770)
Accounts payable and accrued liabilities	(71,830)	(71,892)
Oil and natural gas production payable	(3,624)	(13,217)
Other liabilities	(997)	(3,008)
Net cash provided by operating activities	62,944	426,721
Cash flows from investing activities
Oil and natural gas capital expenditures	(126,302)	(276,783)
CO2 capital expenditures	(451)	(15,608)
Pipelines and plants capital expenditures	(1,965)	(20,349)
Other	1,198	(23,772)
Net cash used in investing activities	(127,520)	(336,512)
Cash flows from financing activities
Bank repayments	(994,000)	(1,007,000)
Bank borrowings	1,139,000	962,000
Repurchases of senior subordinated notes	(55,521)	0
Pipeline financing and capital lease debt repayments	(14,336)	(17,122)
Cash dividends paid	(413)	(43,528)
Other	(10,421)	(3,299)
Net cash provided by (used in) financing activities	64,309	(108,949)
Net decrease in cash and cash equivalents	(267)	(18,740)
Cash and cash equivalents at beginning of period	2,812	23,153
Cash and cash equivalents at end of period	$ 2,545	$ 4,413