Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenues	$ 3,792	$ 4,868
Cost of sales:
Production and delivery	2,919	2,808
Depreciation, depletion and amortization	347	451
Metals inventory adjustments	57	0
Total cost of sales	3,323	3,259
Selling, general and administrative expenses	112	131
Mining exploration and research expenses	27	21
Environmental obligations and shutdown costs	42	9
Net gain on sales of assets	(33)	(11)
Total costs and expenses	3,471	3,409
Operating income	321	1,459
Interest expense, net	(146)	(151)
Net loss on early extinguishment of debt	(6)	(1)
Other income, net	14	29
Income from continuing operations before income taxes and equity in affiliated companies’ net losses	183	1,336
Provision for income taxes	(105)	(506)
Equity in affiliated companies’ net losses	(3)	(2)
Net income from continuing operations	75	828
Net gain (loss) from discontinued operations	1	(11)
Net income	76	817
Net (income) loss attributable to noncontrolling interests:
Continuing operations	(45)	(125)
Net income attributable to common stockholders	$ 31	$ 692
Earnings Per Share, Basic and Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Basic and Diluted Share	$ 0.02	$ 0.48
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic and Diluted Share	0	(0.01)
Earnings Per Share, Basic and Diluted	$ 0.02	$ 0.47
Basic weighted-average shares of common stock outstanding	1,451	1,449
Diluted weighted-average shares of common shares outstanding	1,457	1,458
Dividends declared per share of common stock (in dollars per share)	$ 0.05	$ 0.05