Financial Instruments (Effects of Derivatives Recognized) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	$ 30	$ (51)	$ 67	$ (61)
Interest rate swaps | Derivatives designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	6	(7)	27	(33)
Euro-denominated notes | Derivatives designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	19	(32)	42	(34)
Foreign exchange contracts | Derivatives not designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	6	(12)	1	14
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	(10)	2	18
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)	(2)	(1)	(4)
Interest rate caps | Derivatives not designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	(1)	(1)	(3)	(2)
Commodity contracts | Derivatives not designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative gain (loss) recognized in OCI	$ 0	$ 1	$ 0	$ (6)