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
		Mar. 31, 2020	Mar. 31, 2019
Total interest on medium- and long-term debt	[1]	$ 40	$ 51
Swaps - fair value - receive fixed/pay floating | Risk management purposes | Interest rate swap
Interest rate contract: Hedge items interest expense		30	26
Interest rate contracts: Derivatives designated as hedging instruments net interest income		$ (6)	$ 1

[1] Includes the effects of hedging.