Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Operating revenues:
Oil sales	$ 461	$ 339	$ 963	$ 581
Natural gas sales	106	57	216	99
Total operating revenues	567	396	1,179	680
Operating costs and expenses:
Oil and natural gas production	100	77	187	169
Production and ad valorem taxes	44	33	92	56
Exploration and abandonments	20	21	35	44
Depreciation, depletion and amortization	281	281	564	591
Accretion of discount on asset retirement obligations	2	1	4	3
Impairments of long-lived assets	0	0	0	1,525
General and administrative (including non-cash stock-based compensation of $14 and $12 for the three months ended June 30, 2017 and 2016, respectively, and $26 and $28 for the six months ended June 30, 2017 and 2016, respectively)	60	53	116	107
(Gain) loss on derivatives	(209)	298	(495)	217
(Gain) loss on disposition of assets, net	0	1	(654)	(110)
Total operating costs and expenses	298	765	(151)	2,602
Income (loss) from operations	269	(369)	1,330	(1,922)
Other income (expense):
Interest expense	(39)	(55)	(79)	(109)
Loss on extinguishment of debt	(1)	0	(1)	0
Other, net	16	0	16	(7)
Total other expense	(24)	(55)	(64)	(116)
Income (loss) before income taxes	245	(424)	1,266	(2,038)
Income tax (expense) benefit	(93)	158	(464)	752
Net income (loss)	$ 152	$ (266)	$ 802	$ (1,286)
Earnings per share:
Basic net income (loss)	$ 1.02	$ (2.04)	$ 5.41	$ (9.94)
Diluted net income (loss)	$ 1.02	$ (2.04)	$ 5.39	$ (9.94)