Financial Instruments (Effects of Derivatives Recognized) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	$ 59	$ 13
Interest rate swaps | Derivatives designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	35	(18)
Interest rate swaps | Derivatives not designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	(1)	0
Euro-Denominated Notes | Derivatives designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	33	11
Foreign exchange contracts | Derivatives not designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	(8)	27
Foreign exchange contracts | Derivatives not designated as hedging instruments | Interest Expense
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	(7)	28
Foreign exchange contracts | Derivatives not designated as hedging instruments | Operating Expense
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	(1)	(1)
Commodity Contracts | Derivatives not designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	$ 0	$ (7)