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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	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 30,864	$ 31,367
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	62	1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(2,822)	(3,435)
Available-for-sale debt securities, net carrying value	28,104	27,933
Debt securities available for sale	28,104	27,933
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities held to maturity, amortized cost	763	812
Held To Maturity Debt Securities Gross Unrealized Gains	0	0
Held To Maturity Debt Securities Gross Unrealized Losses	(9)	(11)
Debt Securities held to maturity	754	801
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss	(38)	(50)
Debt Securities held to maturity, estimated fair value	716	751
US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	1,322	1,310
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(99)	(123)
Available-for-sale debt securities, net carrying value	1,223	1,187
Debt securities available for sale	1,223	1,187
Federal agency securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	1,085	898
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	4	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(46)	(62)
Available-for-sale debt securities, net carrying value	1,043	836
Debt securities available for sale	1,043	836
US States and Political Subdivisions Debt Securities
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 [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	19,450	19,477
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	52	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(2,130)	(2,523)
Available-for-sale debt securities, net carrying value	17,372	16,954
Debt securities available for sale	17,372	16,954
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities held to maturity, amortized cost	247	289
Held To Maturity Debt Securities Gross Unrealized Gains	0	0
Held To Maturity Debt Securities Gross Unrealized Losses	(8)	(10)
Debt Securities held to maturity	239	279
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss	(16)	(21)
Debt Securities held to maturity, estimated fair value	223	258
Residential Non-Agency [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax		0
Available-for-sale debt securities, net carrying value		1
Debt securities available for sale		1
Commercial Agency [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	7,807	8,262
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(502)	(649)
Available-for-sale debt securities, net carrying value	7,307	7,613
Debt securities available for sale	7,307	7,613
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities held to maturity, amortized cost	516	523
Held To Maturity Debt Securities Gross Unrealized Gains	0	0
Held To Maturity Debt Securities Gross Unrealized Losses	(1)	(1)
Debt Securities held to maturity	515	522
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss	(22)	(29)
Debt Securities held to maturity, estimated fair value	493	493
Commercial Non Agency [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	93	198
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(10)	(12)
Available-for-sale debt securities, net carrying value	83	186
Debt securities available for sale	83	186
Corporate and other debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	1,105	1,219
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	4	1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(35)	(66)
Available-for-sale debt securities, net carrying value	1,074	1,154
Debt securities available for sale	$ 1,074	$ 1,154

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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-5B

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-5

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