CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues and Other
Oil sales	$ 2,265	$ 1,422	$ 4,392	$ 3,085
Natural-gas sales	203	319	450	821
Natural-gas liquids sales	318	214	610	503
Gathering, processing, and marketing sales	382	464	742	908
Gains (losses) on divestitures and other, net	123	297	142	1,166
Total	3,291	2,716	6,336	6,483
Costs and Expenses
Oil and gas operating	275	229	551	485
Oil and gas transportation	209	229	405	478
Exploration	94	532	262	1,616
Gathering, processing, and marketing	252	355	489	705
General and administrative	288	244	566	507
Depreciation, depletion, and amortization	1,003	1,037	1,993	2,152
Production, property, and other taxes	201	135	391	290
Impairments	128	10	147	383
Other operating expense	22	12	162	34
Total	2,472	2,783	4,966	6,650
Operating Income (Loss)	819	(67)	1,370	(167)
Other (Income) Expense
Interest expense	237	229	465	452
(Gains) losses on derivatives, net	437	32	473	(115)
Other (income) expense, net	4	44	(8)	46
Total	677	305	928	383
Income (Loss) Before Income Taxes	142	(372)	442	(550)
Income tax expense (benefit)	125	(38)	251	59
Net Income (Loss)	17	(334)	191	(609)
Net income (loss) attributable to noncontrolling interests	(12)	81	41	124
Net Income (Loss) Attributable to Common Stockholders	$ 29	$ (415)	$ 150	$ (733)
Per Common Share
Net income (loss) attributable to common stockholders—basic (in usd per share)	$ 0.05	$ (0.76)	$ 0.28	$ (1.34)
Net income (loss) attributable to common stockholders—diluted (in usd per share)	$ 0.05	$ (0.76)	$ 0.28	$ (1.34)
Average Number of Common Shares Outstanding—Basic	504	552	511	552
Average Number of Common Shares Outstanding—Diluted	505	552	512	552
Dividends (in usd per share)	$ 0.25	$ 0.05	$ 0.5	$ 0.10
Commodity Contract and Interest Rate Swap [Member]
Other (Income) Expense
(Gains) losses on derivatives, net	$ 436	$ 32	$ 471	$ (115)