Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Crude oil and natural gas sales	$ 2,982,966	$ 2,026,958	$ 2,551,131
Crude oil and natural gas sales to affiliates	0	0	1,400
Gain (loss) on crude oil and natural gas derivatives, net	91,647	(71,859)	91,085
Crude oil and natural gas service operations	46,215	25,174	36,551
Total revenues	3,120,828	1,980,273	2,680,167
Operating costs and expenses:
Production expenses	324,214	289,289	347,243
Production expenses to affiliates	0	0	1,654
Production taxes	208,278	142,388	200,637
Exploration expenses	12,393	16,972	19,413
Crude oil and natural gas service operations	16,880	11,386	17,337
Depreciation, depletion, amortization and accretion	1,674,901	1,708,744	1,749,056
Property impairments	237,370	237,292	402,131
General and administrative expenses	191,706	169,580	189,846
Litigation settlement	59,600	0	0
Net gain on sale of assets and other	(53,915)	(307,844)	(23,149)
Total operating costs and expenses	2,671,427	2,267,807	2,904,168
Income (loss) from operations	449,401	(287,534)	(224,001)
Other income (expense):
Interest expense	(294,495)	(320,562)	(313,079)
Loss on extinguishment of debt	(554)	(26,055)	0
Other	1,715	1,697	1,995
Total other income (expense)	(293,334)	(344,920)	(311,084)
Income (loss) before income taxes	156,067	(632,454)	(535,085)
Benefit for income taxes	633,380	232,775	181,417
Net income (loss)	$ 789,447	$ (399,679)	$ (353,668)
Basic net income (loss) per share (in dollars per share)	$ 2.13	$ (1.08)	$ (0.96)
Diluted net income (loss) per share (in dollars per share)	$ 2.11	$ (1.08)	$ (0.96)
Foreign currency translation adjustments	$ 567	$ 3,094	$ (2,969)
Other Comprehensive Income (Loss), Net of Tax	567	3,094	(2,969)
Comprehensive Income (Loss)	$ 790,014	$ (396,585)	$ (356,637)