Financial Instruments (Unrealized gains losses) (Details) oz in Thousands, lb in Millions, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2020 lb $ / lb	Sep. 30, 2020 USD ($) $ / oz $ / lb $ / lb	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) lb oz $ / oz $ / lb $ / lb	Sep. 30, 2019 USD ($)
Not Designated as Hedging Instrument [Member] | Amounts recorded in Sales [Member]
Realized gains (losses):
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net		$ 109	$ (51)	$ 57	$ (40)
Commodity Contract [Member]
Unrealized gains (losses):
Derivative financial instruments		1	(2)	8	3
Hedged item – firm sales commitments		(1)	2	(8)	(3)
Realized gains (losses):
Matured derivative financial instruments		$ 15	(8)	$ (1)	(9)
Commodity Contract [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb				50
Derivative, Average Forward Price | $ / lb		2.76		2.76
Copper Forward Contracts [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	150
Derivative, Average Forward Price | $ / lb	2.34
Realized gains (losses):
Matured derivative financial instruments				$ 24
Copper Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb				26
Derivative, Average Forward Price | $ / lb		3.05		3.05
Copper Forward Contracts [Member] | Not Designated as Hedging Instrument [Member] | Amounts recorded in Cost of Sales
Realized gains (losses):
Matured derivative financial instruments		$ (7)	0	$ 12	(3)
Copper | Not Designated as Hedging Instrument [Member] | Amounts recorded in Sales [Member]
Realized gains (losses):
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net		$ 94	(57)	$ 18	(57)
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				381
Derivative, Average Forward Price | $ / lb		2.91		2.91
Realized gains (losses):
Derivative Average Market Price | $ / lb		3.03		3.03
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				113
Derivative, Average Forward Price | $ / lb		2.95		2.95
Realized gains (losses):
Derivative Average Market Price | $ / lb		3.03		3.03
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				116
Derivative, Average Forward Price | $ / oz		1,941		1,941
Realized gains (losses):
Derivative Average Market Price | $ / oz		1,891		1,891
gold and other | Not Designated as Hedging Instrument [Member] | Amounts recorded in Sales [Member]
Realized gains (losses):
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net		$ 15	$ 6	$ 39	$ 17