Fair Value (Quantitative Information) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	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	$ 118	$ 99	$ 93	$ 53	$ 50	$ 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	(111)	(129)	(151)	(195)	(183)	(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	219	225	240	239	231	255
Commodity Contract [Member]
Fair Value Inputs Quantitative Information [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	10	$ 3	$ 4	$ 9	$ 2	$ 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	$ 219
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	36.9
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	87.4
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	62.0
Measurement Input, Entity Credit Risk [Member] | Interest Rate Contract [Member] | Minimum [Member]
Fair Value Inputs Quantitative Information [Line Items]
Fair Value Measurement Inputs, Nonrecurring	2.38%
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	3.61%