Balance Sheet Effect of Derivative Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional	$ 135,279	$ 133,452
Derivative Asset, Current	766	802
Derivative Asset, Noncurrent	506	746
Derivative Asset	1,272	1,548
Derivative Liability, Current	460	568
Derivative Liability, Noncurrent	619	344
Derivative Liability	1,079	912
Held collateral	9	15
Posted collateral	56	38
Designated as Hedging Instrument [Member] \| Foreign Exchange Contract [Member] \| Cash Flow Hedging [Member]
Derivative [Line Items]
Notional	17,640	19,595
Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member] \| Fair Value Hedging [Member]
Derivative [Line Items]
Notional	26,033	28,008
Not Designated as Hedging Instrument [Member] \| Foreign Exchange Contract [Member]
Derivative [Line Items]
Notional	19,644	20,679
Not Designated as Hedging Instrument [Member] \| Cross-currency interest rate swap contracts [Member]
Derivative [Line Items]
Notional	5,852	4,006
Not Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member]
Derivative [Line Items]
Notional	65,447	60,504
Not Designated as Hedging Instrument [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Notional	663	660
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Derivative [Line Items]
Fair Value of Assets	1,272	1,548
Fair Value of Liabilities	1,079	912
Counterparty Netting, Not Offset	401	618
Counterparty Netting, Not Offset	401	618
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Designated as Hedging Instrument [Member] \| Foreign Exchange Contract [Member] \| Cash Flow Hedging [Member]
Derivative [Line Items]
Fair Value of Assets	309	407
Fair Value of Liabilities	111	306
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member] \| Fair Value Hedging [Member]
Derivative [Line Items]
Fair Value of Assets	137	248
Fair Value of Liabilities	441	135
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Not Designated as Hedging Instrument [Member] \| Foreign Exchange Contract [Member]
Derivative [Line Items]
Fair Value of Assets	297	172
Fair Value of Liabilities	103	302
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Not Designated as Hedging Instrument [Member] \| Cross-currency interest rate swap contracts [Member]
Derivative [Line Items]
Fair Value of Assets	270	408
Fair Value of Liabilities	143	28
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Not Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member]
Derivative [Line Items]
Fair Value of Assets	247	276
Fair Value of Liabilities	255	137
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Not Designated as Hedging Instrument [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Fair Value of Assets	12	37
Fair Value of Liabilities	$ 26	$ 4

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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