Supplementary Information Foreign Currency Exchange Gain (Loss) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Foreign Currency Exchange Gain (Loss) [Line Items]
Exchange gains (losses) - net	[1]	$ (11)	$ (74)	$ (70)	$ (190)	[2]
Foreign Currency Transaction Gain (Loss) Tax (Expense) Benefit		(12)	0	0	26
Foreign Currency Transaction Gain (Loss) After Tax		(23)	(74)	(70)	(164)
Subsidiary Monetary Position
Foreign Currency Exchange Gain (Loss) [Line Items]
Exchange gains (losses) - net	[3]	(66)	(105)	(59)	(217)
Foreign Currency Transaction Gain (Loss) Tax (Expense) Benefit		1	7	(2)	32
Foreign Currency Transaction Gain (Loss) After Tax		(65)	(98)	(61)	(185)
Hedging Program [Member]
Foreign Currency Exchange Gain (Loss) [Line Items]
Exchange gains (losses) - net		55	31	(11)	27	[4]
Foreign Currency Transaction Gain (Loss) Tax (Expense) Benefit		(13)	(7)	2	(6)
Foreign Currency Transaction Gain (Loss) After Tax		42	24	(9)	21
Argentine peso devaluation [Member] | Hedging Program [Member]
Foreign Currency Exchange Gain (Loss) [Line Items]
Exchange gains (losses) - net		$ (42)	$ (40)	$ (33)	(73)
Tax Reform Foreign Currency Exchange Impact [Member] | Hedging Program [Member]
Foreign Currency Exchange Gain (Loss) [Line Items]
Exchange gains (losses) - net					$ (50)

[1] Includes net pre-tax exchange losses of $(33) million and $(42) million for the three and nine months ended September 30, 2019, respectively and $(40) million and $(73) million for the three and nine months ended September 30, 2018, respectively, associated with the devaluation of the Argentine peso.

[2] Includes a $(50) million foreign exchange loss for the nine months ended September 30, 2018 related to adjustments to foreign currency exchange contracts as a result of U.S. tax reform, which is included within significant items.

[3] Includes net pre-tax exchange losses of $(33) million and $(42) million for the three and nine months ended September 30, 2019, respectively and $(40) million and $(73) million for the three and nine months ended September 30, 2018, respectively, associated with the devaluation of the Argentine peso.

[4] Includes a $(50) million foreign exchange loss for the nine months ended September 30, 2018 related to adjustments to foreign currency exchange contracts as a result of U.S. tax reform.