Investment Securities - Investment Securities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Available-for-sale debt and other securities:
Amortized Cost	$ 43,878	$ 55,789
Unrealized Gains	6	9
Unrealized Losses	(4,337)	(5,379)
Fair Value	39,547	50,419
Held-to-maturity securities:(b)
Amortized Cost	11,278	2
Unrealized Gains	0	0
Unrealized Losses	(313)	0
Fair Value	10,965	2
Trading debt securities	1,185	899
Equity securities	341	613
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale Transferred to Held-to-Maturity, Parent
Available-for-sale debt and other securities:
AOCI offset, unamortized portion of unrealized losses on securities	865
U.S. Treasury and federal agencies securities
Available-for-sale debt and other securities:
Amortized Cost	4,358	4,477
Unrealized Gains	2	1
Unrealized Losses	0	(142)
Fair Value	4,360	4,336
Held-to-maturity securities:(b)
Amortized Cost	2,370
Unrealized Gains	0
Unrealized Losses	(26)
Fair Value	2,344
Obligations of states and political subdivisions securities
Available-for-sale debt and other securities:
Amortized Cost	0	2
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	0	2
Agency mortgage-backed securities \| Residential mortgage backed securities
Available-for-sale debt and other securities:
Amortized Cost	6,460	11,564
Unrealized Gains	0	0
Unrealized Losses	(779)	(1,282)
Fair Value	5,681	10,282
Held-to-maturity securities:(b)
Amortized Cost	4,898
Unrealized Gains	0
Unrealized Losses	(197)
Fair Value	4,701
Agency mortgage-backed securities \| Commercial mortgage-backed securities
Available-for-sale debt and other securities:
Amortized Cost	23,853	28,945
Unrealized Gains	1	5
Unrealized Losses	(3,022)	(3,230)
Fair Value	20,832	25,720
Held-to-maturity securities:(b)
Amortized Cost	4,008
Unrealized Gains	0
Unrealized Losses	(90)
Fair Value	3,918
Non-agency mortgage-backed securities \| Commercial mortgage-backed securities
Available-for-sale debt and other securities:
Amortized Cost	4,505	4,872
Unrealized Gains	0	0
Unrealized Losses	(338)	(427)
Fair Value	4,167	4,445
Asset-backed securities and other debt securities
Available-for-sale debt and other securities:
Amortized Cost	3,924	5,207
Unrealized Gains	3	3
Unrealized Losses	(198)	(298)
Fair Value	3,729	4,912
Held-to-maturity securities:(b)
Amortized Cost	2	2
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	2	2
Other securities
Available-for-sale debt and other securities:
Amortized Cost	778	722
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	778	722
FHLB, restricted stock holdings	276	224
FRB, restricted stock holdings	500	496
DTCC, restricted stock holdings	$ 2	$ 2

AOCI, Debt Securities, Available-for-Sale, Transferred To Held To Maturity, Before Tax

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