Derivative Financial Instruments And Hedging Activities (Schedule Of Gains (Losses) Recognized Related To Derivatives Not Designated As Hedging Instruments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	$ 117	$ 35	$ 31
Capital Markets Income [Member]
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	45	55	39
Capital Markets Income [Member] \| Interest Rate Swaps [Member]
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	13	19	11
Capital Markets Income [Member] \| Interest Rate Options [Member]
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	23	28	28
Capital Markets Income [Member] \| Interest Rate Futures And Forward Commitments [Member]
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	10	3	10
Capital Markets Income [Member] \| Other Contracts [Member]
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	(1)	5	(10)
Mortgage Income [Member]
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	72	(20)	(8)
Mortgage Income [Member] \| Interest Rate Swaps [Member]
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	68	(12)	2
Mortgage Income [Member] \| Interest Rate Options [Member]
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	(1)	0	(7)
Mortgage Income [Member] \| Interest Rate Futures And Forward Commitments [Member]
Derivative [Line Items]
Gain or (Loss) of Derivatives Not Designated as Hedging Instruments	$ 5	$ (8)	$ (3)