Financial Instruments (Unrealized gains losses) (Details) oz in Thousands, lb in Millions, $ in Millions			3 Months Ended		6 Months Ended
	Jun. 30, 2019 lb oz $ / lb $ / oz	Mar. 31, 2019 lb $ / lb $ / lb	Jun. 30, 2019 USD ($) $ / lb $ / oz	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) $ / lb $ / oz	Jun. 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 | $			$ (109)	$ (44)	$ 11	$ (161)
Commodity Contract [Member]
Unrealized gains (losses):
Derivative financial instruments | $			(13)	(4)	5	(19)
Hedged item – firm sales commitments | $			13	4	(5)	19
Realized gains (losses):
Matured derivative financial instruments | $			(3)	0	(1)	2
Commodity Contract [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb		74
Derivative, Average Forward Price		2.76
Copper Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb		2
Derivative, Average Forward Price		2.66
Copper Forward Contracts [Member] | Not Designated as Hedging Instrument [Member] | Amounts recorded in Cost of Sales
Realized gains (losses):
Matured derivative financial instruments | $			(4)	6	(3)	8
Copper | Not Designated as Hedging Instrument [Member] | Amounts recorded in Sales [Member]
Realized gains (losses):
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net | $			$ (122)	(14)	$ 0	(149)
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	505
Derivative, Average Forward Price	2.79		2.79		2.79
Realized gains (losses):
Derivative Average Market Price	2.72		2.72		2.72
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	86
Derivative, Average Forward Price	2.83		2.83		2.83
Realized gains (losses):
Derivative Average Market Price	2.72		2.72		2.72
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	74
Derivative, Average Forward Price | $ / oz	1,328		1,328		1,328
Realized gains (losses):
Derivative Average Market Price | $ / oz	1,416		1,416		1,416
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 | $			$ 13	$ (30)	$ 11	$ (12)
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	10.56		10.56		10.56
Realized gains (losses):
Derivative Average Market Price	8.88		8.88		8.88