Fair Value Measurements, Derivative Assets & Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Cumulative Amount of Fair Value Hedging Adjustment - Increase (Decrease) Included in Carrying Amount of Liability	$ (13)	$ (93)
Long-term Obligations [Member]
Derivatives, Fair Value [Line Items]
Hedged Liability, Fair Value Hedge	980	3,291
Cumulative Amount of Fair Value Hedging Adjustment - Increase (Decrease) Included in Carrying Amount of Liability	(13)	(93)
Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)		30
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount Of Derivatives	1,000	3,100
Interest Rate Swaps [Member] \| Derivatives Designated as Hedging Instrument [Member] \| Other Long-term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	13	129
Cross Currency Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Notional Amount Of Derivatives	900	1,500
Cross Currency Interest Rate Contract [Member] \| Derivatives Designated as Hedging Instrument [Member] \| Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	33	28
Currency Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional Amount Of Derivatives	2,846	3,424
Currency Exchange Contracts [Member] \| Derivatives Not Designated as Hedging Instrument [Member] \| Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	4	3
Currency Exchange Contracts [Member] \| Derivatives Not Designated as Hedging Instrument [Member] \| Other Accrued Expenses [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	11	16
Fair Value, Recurring [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	37	31
Derivative Liabilities	$ 24	$ 145

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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