Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenues	$ 3,153	$ 4,908	$ 10,491	$ 14,944
Cost of sales:
Production and delivery	2,665	3,069	8,584	8,790
Depreciation, depletion and amortization	322	458	1,021	1,351
Metals inventory adjustments	41	0	100	2
Total cost of sales	3,028	3,527	9,705	10,143
Selling, general and administrative expenses	106	101	315	341
Mining exploration and research expenses	25	27	83	72
Environmental obligations and shutdown costs	20	8	85	76
Net loss (gain) on sales of assets	12	(70)	(13)	(126)
Total costs and expenses	3,191	3,593	10,175	10,506
Operating (loss) income	(38)	1,315	316	4,438
Interest expense, net	(123)	(143)	(401)	(436)
Net (loss) gain on early extinguishment of debt	(21)	0	(27)	8
Other income, net	33	14	52	63
(Loss) income from continuing operations before income taxes and equity in affiliated companies’ net earnings	(149)	1,186	(60)	4,073
Provision for income taxes	(91)	(522)	(181)	(1,543)
Equity in affiliated companies’ net earnings	5	4	7	5
Net (loss) income from continuing operations	(235)	668	(234)	2,535
Net income (loss) from discontinued operations	1	(4)	2	(19)
Net income	(234)	664	(232)	2,516
Net (income) loss attributable to noncontrolling interests:
Continuing operations	27	(108)	(16)	(399)
Net (loss) income attributable to common stockholders	$ (207)	$ 556	$ (248)	$ 2,117
Earnings Per Share, Basic and Diluted [Abstract]
Continuing operations (in dollars per share)	$ (0.15)	$ 0.38	$ (0.17)	$ 1.47
Discontinued operations (in dollars per share)	0	0	0	(0.01)
Earnings per share, basic (in dollars per share)	(0.15)	0.38	(0.17)	1.46
Continuing operations (in dollars per share)	(0.15)	0.38	(0.17)	1.46
Discontinued operations (in dollars per share)	0	0	0	(0.01)
Earnings per share, diluted (in dollars per share)	$ (0.15)	$ 0.38	$ (0.17)	$ 1.45
Basic weighted-average shares of common stock outstanding	1,452	1,450	1,451	1,449
Diluted weighted-average shares of common shares outstanding	1,452	1,458	1,451	1,458
Dividends declared per share of common stock (in dollars per share)	$ 0.05	$ 0.05	$ 0.15	$ 0.15