| **Financial Instruments - Cumulative Basis Adjustments for Fair Value Hedges (Details) - USD ($) $ in Millions**                         | Mar. 29, 2020 | Dec. 31, 2019 |
|------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| Long-term investments [Member]                                                                                                           |               |          |   |
| **Derivative [Line Items]**                                                                                                              |               |          |   |
| Carrying Amount of Actively Hedged Assets                                                                                                | [1]           | $ 45          | $ 45 |
| Cumulative Amount of Fair Value Hedging Adjustment Increase/(Decrease) to Carrying Amount, Active Hedging Relationships, Asset           |               | 0             | 0 |
| Cumulative Amount of Fair Value Hedging Adjustment Increase/(Decrease) to Carrying Amount, Discontinued Hedging Relationships, Asset     |               | 0             | 0 |
| Long-term debt [Member]                                                                                                                  |               |          |   |
| **Derivative [Line Items]**                                                                                                              |               |          |   |
| Carrying Amount of Actively Hedged Liabilities                                                                                           | [1]           | 2,027         | 7,092 |
| Cumulative Amount of Fair Value Hedging Adjustment Increase/(Decrease) to Carrying Amount, Active Hedging Relationships, Liability       |               | 134           | 266 |
| Cumulative Amount of Fair Value Hedging Adjustment Increase/(Decrease) to Carrying Amount, Discontinued Hedging Relationships, Liability |               | $ 1,196       | $ 690 |
|                                                                                                                                          |
| [1]Carrying amounts exclude the cumulative amount of fair value hedging adjustments.                                                     |

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| - Definition
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+ References
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| - Definition
Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk, remaining after discontinued hedge.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of asset hedged in fair value hedging relationship.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
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| - Definition
Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk.
+ References
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| - Definition
Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk, remaining after discontinued hedge.
+ References
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| - Definition
Amount of liability hedged in fair value hedging relationship.
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| - Definition
Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk.
+ References
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