Unaudited Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Crude oil and natural gas sales	$ 626,548	$ 525,711	$ 1,260,398	$ 929,302
Gain (loss) on crude oil and natural gas derivatives, net	28,022	(82,257)	74,880	(40,145)
Crude oil and natural gas service operations	6,916	7,757	11,636	15,227
Total revenues	661,486	451,211	1,346,914	904,384
Operating costs and expenses:
Production expenses	82,474	74,083	155,328	152,724
Production taxes	41,965	39,141	83,198	69,634
Exploration expenses	3,204	1,674	8,202	4,739
Crude oil and natural gas service operations	4,478	3,576	7,315	6,618
Depreciation, depletion, amortization and accretion	395,770	441,761	777,926	905,752
Property impairments	123,316	66,112	174,689	145,039
General and administrative expenses	39,186	36,246	86,407	68,654
Net (gain) loss on sale of assets and other	134	(100,835)	5,669	(99,127)
Total operating costs and expenses	690,527	561,758	1,298,734	1,254,033
Income (loss) from operations	(29,041)	(110,547)	48,180	(349,649)
Other income (expense):
Interest expense	(72,744)	(81,922)	(143,916)	(162,875)
Other	373	435	815	819
Total other income (expense)	(72,371)	(81,487)	(143,101)	(162,056)
Loss before income taxes	(101,412)	(192,034)	(94,921)	(511,705)
Benefit for income taxes	37,855	72,632	31,833	193,978
Net loss	(63,557)	(119,402)	(63,088)	(317,727)
Foreign currency translation adjustments	189	25	327	451
Total other comprehensive income, net of tax	189	25	327	451
Comprehensive loss	$ (63,368)	$ (119,377)	$ (62,761)	$ (317,276)
Basic net income (loss) per share (in dollars per share)	$ (0.17)	$ (0.32)	$ (0.17)	$ (0.86)
Diluted net income (loss) per share (in dollars per share)	$ (0.17)	$ (0.32)	$ (0.17)	$ (0.86)