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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	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 30,090	$ 30,864
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	234	62
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(1,626)	(2,822)
Available-for-sale debt securities, net carrying value	28,698	28,104
Debt securities available for sale	28,698	28,104
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities held to maturity, amortized cost	3,230	763
Held To Maturity Debt Securities Gross Unrealized Gains	0	0
Held To Maturity Debt Securities Gross Unrealized Losses	(443)	(9)
Debt Securities held to maturity	2,787	754
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss	(28)	(38)
Debt Securities held to maturity, estimated fair value	2,759	716
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	2,102	1,322
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	13	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(69)	(99)
Available-for-sale debt securities, net carrying value	2,046	1,223
Debt securities available for sale	2,046	1,223
Federal agency securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	461	1,085
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	6	4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(10)	(46)
Available-for-sale debt securities, net carrying value	457	1,043
Debt securities available for sale	457	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	21,564	19,450
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	199	52
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(1,304)	(2,130)
Available-for-sale debt securities, net carrying value	20,459	17,372
Debt securities available for sale	20,459	17,372
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities held to maturity, amortized cost	2,718	247
Held To Maturity Debt Securities Gross Unrealized Gains	0	0
Held To Maturity Debt Securities Gross Unrealized Losses	(442)	(8)
Debt Securities held to maturity	2,276	239
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss	(16)	(16)
Debt Securities held to maturity, estimated fair value	2,260	223
Commercial agency
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	5,135	7,807
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	10	2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(223)	(502)
Available-for-sale debt securities, net carrying value	4,922	7,307
Debt securities available for sale	4,922	7,307
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities held to maturity, amortized cost	512	516
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	511	515
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss	(12)	(22)
Debt Securities held to maturity, estimated fair value	499	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	(7)	(10)
Available-for-sale debt securities, net carrying value	85	83
Debt securities available for sale	85	83
Corporate and other debt securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	734	1,105
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	6	4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(13)	(35)
Available-for-sale debt securities, net carrying value	727	1,074
Debt securities available for sale	$ 727	$ 1,074

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