Objectives and Strategies for Using Derivatives (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), before Reclassification and Tax		$ 75
Foreign Exchange Contract \| Not Designated as Hedging Instrument
Aggregate notional value	$ 1,900	1,900
Gains (Losses) on undesignated foreign exchange hedging instruments	(39)		$ 17	$ 52
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2
Derivative Assets	44	44	34
Derivative Liability	92	92	$ 44
Net Investment Hedging \| Foreign Exchange Contract
Aggregate notional value	1,500	1,500
Fair Value Hedging \| Interest Rate Contract
Aggregate notional value	300	300
Long-term Debt, Fair Value	322	322
Cash Flow Hedging \| Foreign Exchange Contract
Aggregate notional value	$ 721	$ 721

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