Supplementary Information Foreign Currency Exchange (Loss) Gain (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Foreign Currency Exchange (Loss) Gain [Line Items]
Foreign Currency Transaction (Loss) Gain, before Tax	$ (32)	$ (132)
Foreign Currency Transaction (Loss) Gain Tax Benefit	2	74
Foreign Currency Transaction (Loss) Gain After Tax	(30)	(58)
Subsidiary Monetary Position
Foreign Currency Exchange (Loss) Gain [Line Items]
Foreign Currency Transaction (Loss) Gain, before Tax	(23)	49
Foreign Currency Transaction (Loss) Gain Tax Benefit	0	32
Foreign Currency Transaction (Loss) Gain After Tax	(23)	81
Hedging Program [Member]
Foreign Currency Exchange (Loss) Gain [Line Items]
Foreign Currency Transaction (Loss) Gain, before Tax	(9)	(181)	[1]
Foreign Currency Transaction (Loss) Gain Tax Benefit	2	42
Foreign Currency Transaction (Loss) Gain After Tax	$ (7)	(139)
Tax Reform Foreign Currency Exchange Impact [Member] | Hedging Program [Member]
Foreign Currency Exchange (Loss) Gain [Line Items]
Foreign Currency Transaction (Loss) Gain, before Tax		$ 50

[1] Includes a $50 million foreign exchange loss for the three months ended March 31, 2018 related to adjustments to foreign currency exchange contracts as a result of U.S. tax reform.