CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions		3 Months Ended								12 Months Ended
	Dec. 18, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues		$ 3,911	$ 3,153	$ 3,546	$ 3,792	$ 3,684	$ 4,908	$ 5,168	$ 4,868	$ 14,402	$ 18,628	$ 16,403
Cost of sales:
Production and delivery										11,514	11,687	10,258
Cost, Depreciation, Amortization and Depletion										1,412	1,754	1,714
Total cost of sales										13,105	13,445	11,980
Selling, general and administrative expenses										414	443	477
Exploration Expense										104	105	93
Environmental obligations and shutdown costs										105	89	244
Net gain on sales of assets						(82)	(70)	(45)	(11)	(417)	(208)	(81)
Total costs and expenses										13,311	13,874	12,713
Operating income		775	(38)	33	321	316	1,315	1,664	1,459	1,091	4,754	3,690
Interest expense, net										(620)	(945)	(801)
Net (loss) gain on early extinguishment of debt										(27)	7	21
Other (expense) income, net										(138)	76	(8)
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings										306	3,892	2,902
Provision for (benefit from) income taxes										(510)	(991)	(883)
Equity in affiliated companies’ net earnings										12	8	10
Net (loss) income from continuing operations		42	(235)	(74)	75	374	668	1,039	828	(192)	2,909	2,029
Net income (loss) from discontinued operations		1	1	0	1	4	(4)	(4)	(11)	3	(15)	66
Net (loss) income		43	(234)	(74)	76	378	664	1,035	817	(189)	2,894	2,095
Net income from continuing operations attributable to noncontrolling interests										(50)	(292)	(274)
Net income attributable to noncontrolling interests: Discontinued Operations										0	0	(4)
Net (loss) income attributable to common stockholders		$ 9	$ (207)	$ (72)	$ 31	$ 485	$ 556	$ 869	$ 692	$ (239)	$ 2,602	$ 1,817
Basic net income (loss) per share attributable to common stockholders:
Income (Loss) from Continuing Operations, Per Basic Share						$ 0.33	$ 0.38	$ 0.60	$ 0.48	$ (0.17)	$ 1.80	$ 1.21
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share										0	(0.01)	0.04
Earnings per share, basic (in dollars per share)		$ 0	$ (0.15)	$ (0.05)	$ 0.02	0.33	0.38	0.60	0.47	(0.17)	1.79	1.25
Diluted net income (loss) per share attributable to common stockholders:
Income (Loss) from Continuing Operations, Per Diluted Share						0.33	0.38	0.59	0.48	(0.17)	1.79	1.21
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share						0	0	0	(0.01)	0	(0.01)	0.04
Earnings Per Share, Diluted		$ 0	$ (0.15)	$ (0.05)	$ 0.02	$ 0.33	$ 0.38	$ 0.59	$ 0.47	$ (0.17)	$ 1.78	$ 1.25
Weighted Average Number of Shares Outstanding, Basic		1,452,000,000	1,452,000,000	1,451,000,000	1,451,000,000	1,450,000,000	1,450,000,000	1,449,000,000	1,449,000,000	1,451,000,000	1,449,000,000	1,447,000,000
Weighted Average Number of Shares Outstanding, Diluted		1,457,000,000	1,452,000,000	1,451,000,000	1,457,000,000	1,457,000,000	1,458,000,000	1,458,000,000	1,458,000,000	1,451,000,000	1,458,000,000	1,454,000,000
Dividends declared per share of common stock (in dollars per share)	$ 0.05									$ 0.20	$ 0.20	$ 0