Fair Value (Quantitative Information) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2015 USD ($)
Fair Value Inputs Quantitative Information [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ 133	$ 118	$ 93	$ 56	$ 53	$ 81
Interest Rate Contract [Member]
Fair Value Inputs Quantitative Information [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(96)	(111)	(151)	(192)	(195)	(179)
Foreign Exchange Contract [Member]
Fair Value Inputs Quantitative Information [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	221	219	240	242	239	255
Commodity Contract [Member]
Fair Value Inputs Quantitative Information [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	8	$ 10	$ 4	$ 6	$ 9	$ 5
Argentina, Pesos | Foreign Exchange Contract [Member]
Fair Value Inputs Quantitative Information [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ 221
Argentina, Pesos | Foreign Exchange Contract [Member] | Minimum [Member]
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Argentine Peso to U.S. Dollar currency exchange rate after 1 year	42.1
Argentina, Pesos | Foreign Exchange Contract [Member] | Maximum [Member]
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Argentine Peso to U.S. Dollar currency exchange rate after 1 year	166.5
Argentina, Pesos | Foreign Exchange Contract [Member] | Weighted Average [Member]
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Argentine Peso to U.S. Dollar currency exchange rate after 1 year	99.2
Measurement Input, Entity Credit Risk [Member] | Interest Rate Contract [Member] | Minimum [Member]
Fair Value Inputs Quantitative Information [Line Items]
Fair Value Measurement Inputs, Nonrecurring	1.78%
Measurement Input, Entity Credit Risk [Member] | Interest Rate Contract [Member] | Maximum [Member]
Fair Value Inputs Quantitative Information [Line Items]
Fair Value Measurement Inputs, Nonrecurring	4.38%
Measurement Input, Entity Credit Risk [Member] | Interest Rate Contract [Member] | Weighted Average [Member]
Fair Value Inputs Quantitative Information [Line Items]
Fair Value Measurement Inputs, Nonrecurring	3.63%