Derivative Instruments and Hedging Activities (Assets and LIabilities - Designated vs. Not Designated Hedging Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Total asset derivatives	$ 262	$ 348
Total liability derivatives	257	315
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	35	57
Total liability derivatives	238	138
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	227	291
Total liability derivatives	19	177
Interest Rate Contract
Derivatives, Fair Value [Line Items]
Total asset derivatives	29	15
Total liability derivatives	208	262
Interest Rate Contract | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	29	15
Total liability derivatives	205	125
Interest Rate Contract | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	0	0
Total liability derivatives	3	137
Cross Currency Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Total asset derivatives	6	29
Total liability derivatives	5	3
Cross Currency Interest Rate Contract [Member] | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	6	29
Total liability derivatives	5	3
Cross Currency Interest Rate Contract [Member] | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	0	0
Total liability derivatives	0	0
Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Total asset derivatives	217	269
Total liability derivatives	41	30
Foreign Exchange Contract [Member] | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	0	8
Total liability derivatives	28	1
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	217	261
Total liability derivatives	13	29
Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Total asset derivatives	10	35
Total liability derivatives	3	20
Commodity Contract [Member] | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	0	5
Total liability derivatives	0	9
Commodity Contract [Member] | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Total asset derivatives	10	30
Total liability derivatives	$ 3	$ 11