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, 2019	Mar. 31, 2018
Total interest on medium- and long-term debt	[1]	$ 51	$ 25
Swaps - fair value - receive fixed/pay floating | Risk management purposes | Interest rate swap
Interest rate contract: Hedge items interest expense		26	15
Interest rate contracts: Derivatives designated as hedging instruments net interest income		$ 1	$ (3)

[1] Includes the effects of hedging.