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Debt Securities (Schedule Of Amortized Cost, Gross Unrealized Gains And Losses, And Estimated Fair Value Of Securities Available For Sale And Securities Held To Maturity) (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 31,612	$ 30,864
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	27	62
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(3,102)	(2,822)
Available-for-sale debt securities, net carrying value	28,537	28,104
Debt securities available for sale	28,537	28,104
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities held to maturity, amortized cost	741	763
Held To Maturity Debt Securities Gross Unrealized Gains	0	0
Held To Maturity Debt Securities Gross Unrealized Losses	(8)	(9)
Debt Securities held to maturity	733	754
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss	(43)	(38)
Debt Securities held to maturity, estimated fair value	690	716
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	1,486	1,322
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(97)	(99)
Available-for-sale debt securities, net carrying value	1,390	1,223
Debt securities available for sale	1,390	1,223
Federal agency securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	530	1,085
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2	4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(20)	(46)
Available-for-sale debt securities, net carrying value	512	1,043
Debt securities available for sale	512	1,043
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	2	2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale debt securities, net carrying value	2	2
Debt securities available for sale	2	2
Residential agency
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	22,263	19,450
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	21	52
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(2,452)	(2,130)
Available-for-sale debt securities, net carrying value	19,832	17,372
Debt securities available for sale	19,832	17,372
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities held to maturity, amortized cost	228	247
Held To Maturity Debt Securities Gross Unrealized Gains	0	0
Held To Maturity Debt Securities Gross Unrealized Losses	(8)	(8)
Debt Securities held to maturity	220	239
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss	(20)	(16)
Debt Securities held to maturity, estimated fair value	200	223
Commercial agency
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	6,289	7,807
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1	2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(490)	(502)
Available-for-sale debt securities, net carrying value	5,800	7,307
Debt securities available for sale	5,800	7,307
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities held to maturity, amortized cost	513	516
Held To Maturity Debt Securities Gross Unrealized Gains	0	0
Held To Maturity Debt Securities Gross Unrealized Losses	0	(1)
Debt Securities held to maturity	513	515
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss	(23)	(22)
Debt Securities held to maturity, estimated fair value	490	493
Commercial non-agency
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	92	93
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(11)	(10)
Available-for-sale debt securities, net carrying value	81	83
Debt securities available for sale	81	83
Corporate and other debt securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	950	1,105
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2	4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(32)	(35)
Available-for-sale debt securities, net carrying value	920	1,074
Debt securities available for sale	$ 920	$ 1,074

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