Financial Instruments (Unrealized gains losses) (Details) oz in Thousands, lb in Millions, $ in Millions		3 Months Ended		9 Months Ended
	Sep. 30, 2019 lb oz $ / lb $ / oz $ / lb	Sep. 30, 2019 USD ($) $ / lb $ / oz $ / lb	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) $ / lb $ / oz $ / lb	Sep. 30, 2018 USD ($)
Not Designated as Hedging Instrument [Member] | Amounts recorded in Sales [Member]
Realized gains (losses):
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net | $		$ (51)	$ (118)	$ (40)	$ (279)
Commodity Contract [Member]
Unrealized gains (losses):
Derivative financial instruments | $		(2)	7	3	(12)
Hedged item – firm sales commitments | $		2	(7)	(3)	12
Realized gains (losses):
Matured derivative financial instruments | $		$ (8)	(19)	$ (9)	(17)
Commodity Contract [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	72
Derivative, Average Forward Price	2.66	2.66		2.66
Copper Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	1
Derivative, Average Forward Price	2.65	2.65		2.65
Copper Forward Contracts [Member] | Not Designated as Hedging Instrument [Member] | Amounts recorded in Cost of Sales
Realized gains (losses):
Matured derivative financial instruments | $		$ 0	9	$ (3)	17
Copper | Not Designated as Hedging Instrument [Member] | Amounts recorded in Sales [Member]
Realized gains (losses):
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net | $		$ (57)	(93)	$ (57)	(242)
Copper | Short [Member] | Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	424
Derivative, Average Forward Price	2.63	2.63		2.63
Realized gains (losses):
Derivative Average Market Price	2.59	2.59		2.59
Copper | Long [Member] | Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	97
Derivative, Average Forward Price	2.63	2.63		2.63
Realized gains (losses):
Derivative Average Market Price	2.59	2.59		2.59
Gold | Short [Member] | Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | oz	150
Derivative, Average Forward Price | $ / oz	1,510	1,510		1,510
Realized gains (losses):
Derivative Average Market Price | $ / oz	1,491	1,491		1,491
gold and other [Member] | Not Designated as Hedging Instrument [Member] | Amounts recorded in Sales [Member]
Realized gains (losses):
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net | $		$ 6	$ (25)	$ 17	$ (37)
Cobalt | Long [Member] | Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	6
Derivative, Average Forward Price	9.81	9.81		9.81
Realized gains (losses):
Derivative Average Market Price	12.18	12.18		12.18