Financial Instruments - Fair Value of Derivative Financial Instruments and Related Notional Amounts (Details) - USD ($) $ in Millions |
Dec. 31, 2018 |
Dec. 31, 2017 |
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|---|---|---|---|---|---|
| Derivative [Line Items] | |||||
| Derivative asset | $ 1,140 | $ 822 | |||
| Derivative liability | 1,024 | 691 | |||
| Designated as Hedging Instrument [Member] | |||||
| Derivative [Line Items] | |||||
| Derivative asset | 1,085 | 760 | |||
| Derivative liability | 968 | 637 | |||
| Foreign exchange contracts [Member] | Designated as Hedging Instrument [Member] | |||||
| Derivative [Line Items] | |||||
| Derivative, notional amount | [1] | 22,984 | 18,723 | ||
| Derivative asset | [1] | 654 | 179 | ||
| Derivative liability | [1] | 586 | 459 | ||
| Foreign exchange contracts [Member] | Not Designated as Hedging Instrument [Member] | |||||
| Derivative [Line Items] | |||||
| Derivative, notional amount | 15,154 | 14,300 | |||
| Derivative asset | 55 | 62 | |||
| Derivative liability | 55 | 54 | |||
| Interest rate contracts [Member] | Designated as Hedging Instrument [Member] | |||||
| Derivative [Line Items] | |||||
| Derivative, notional amount | 11,145 | 12,430 | |||
| Derivative asset | 432 | 581 | |||
| Derivative liability | 383 | $ 178 | |||
| Sales [Member] | Foreign exchange contracts [Member] | Designated as Hedging Instrument [Member] | |||||
| Derivative [Line Items] | |||||
| Derivative, notional amount | $ 5,800 | ||||
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