Financial Instruments (Unrealized gains losses) (Details) oz in Thousands, lb in Millions, $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2020 lb $ / lb	Jun. 30, 2020 USD ($) lb $ / lb $ / lb $ / oz	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) lb oz $ / lb $ / lb $ / oz	Jun. 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		$ 179	$ (109)	$ (52)	$ 11
Commodity Contract [Member]
Unrealized gains (losses):
Derivative financial instruments		40	(13)	7	5
Hedged item – firm sales commitments		(40)	13	(7)	(5)
Realized gains (losses):
Matured derivative financial instruments		$ (8)	(3)	$ (17)	(1)
Commodity Contract [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb		54		54
Derivative, Average Forward Price | $ / lb		2.50		2.50
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		$ 24
Copper Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb				16
Derivative, Average Forward Price | $ / lb		2.62		2.62
Copper Forward Contracts [Member] | Not Designated as Hedging Instrument [Member] | Amounts recorded in Cost of Sales
Realized gains (losses):
Matured derivative financial instruments		$ (4)	(4)	$ 19	(3)
Copper | Not Designated as Hedging Instrument [Member] | Amounts recorded in Sales [Member]
Realized gains (losses):
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net		$ 162	(122)	$ (76)	0
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				314
Derivative, Average Forward Price | $ / lb		2.50		2.50
Realized gains (losses):
Derivative Average Market Price | $ / lb		2.73		2.73
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				116
Derivative, Average Forward Price | $ / lb		2.48		2.48
Realized gains (losses):
Derivative Average Market Price | $ / lb		2.73		2.73
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				87
Derivative, Average Forward Price | $ / oz		1,725		1,725
Realized gains (losses):
Derivative Average Market Price | $ / oz		1,779		1,779
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		$ 17	$ 13	$ 24	$ 11