Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenues	$ 3,054	$ 3,546	$ 5,852	$ 7,338
Cost of sales:
Production and delivery	2,394	3,005	4,939	5,929
Depreciation, depletion and amortization	358	352	699	699
Metals inventory adjustments	(139)	2	83	59
Total cost of sales	2,613	3,359	5,721	6,687
Selling, general and administrative expenses	91	92	201	199
Mining exploration and research expenses	18	31	34	58
Environmental obligations and shutdown costs	11	23	37	65
Net loss (gain) on sales of assets	0	8	11	(25)
Total costs and expenses	2,733	3,513	6,004	6,984
Operating income (loss)	321	33	(152)	354
Interest expense, net	(115)	(132)	(242)	(278)
Net loss on early extinguishment of debt	(9)	0	(41)	(6)
Other income, net	20	5	40	19
Income (loss) from continuing operations before income taxes and equity in affiliated companies’ net earnings	217	(94)	(395)	89
(Provision for) benefit from income taxes	(96)	15	(36)	(90)
Equity in affiliated companies’ net earnings	3	5	6	2
Net income (loss) from continuing operations	124	(74)	(425)	1
Net gain from discontinued operations	0	0	0	1
Net income	124	(74)	(425)	2
Net (income) loss attributable to noncontrolling interests:
Continuing operations	(71)	2	(13)	(43)
Net income (loss) attributable to common stockholders	$ 53	$ (72)	$ (438)	$ (41)
Earnings Per Share, Basic and Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Basic and Diluted Share	$ 0.03	$ (0.05)	$ (0.30)	$ (0.03)
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic and Diluted Share	0	0	0	0
Earnings Per Share, Basic and Diluted	$ 0.03	$ (0.05)	$ (0.30)	$ (0.03)
Basic weighted-average shares of common stock outstanding	1,453	1,451	1,453	1,451
Diluted weighted-average shares of common shares outstanding	1,458	1,451	1,453	1,451
Dividends declared per share of common stock (in dollars per share)	$ 0	$ 0.05	$ 0	$ 0.10