Derivative And Credit-Related Financial Instruments Derivative and Credit-Related Financial Instruments (Schedule of the Effects of Fair Value Hedging on the Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Total interest on medium- and long-term debt	[1]	$ 9	$ 19	$ 18	$ 59
Swaps - fair value - receive fixed/pay floating | Risk management purposes | Interest rate swap
Interest rate contract: Hedge items interest expense		26	28	51	58
Interest rate contracts: Derivatives designated as hedging instruments net interest income		$ (17)	$ (12)	$ (34)	$ (18)

[1] Includes the effects of hedging.