Investment Securities - Investment Securities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Available-for-sale debt and other securities:
Total	$ 39,617	$ 43,878
Unrealized Gains	18	6
Unrealized Losses	(3,174)	(4,337)
Fair Value	36,461	39,547
Held-to-maturity securities:
Amortized Cost	11,498	11,278
Unrealized Gains	69	0
Unrealized Losses	(61)	(313)
Fair Value	11,506	10,965
Trading debt securities	1,266	1,185
Equity securities	287	341
Available-for-sale debt securities transferred to held-to-maturity securities
Held-to-maturity securities:
AOCI offset, unamortized portion of unrealized losses on securities	774	865
U.S. Treasury and federal agencies securities
Available-for-sale debt and other securities:
Total	2,105	4,358
Unrealized Gains	0	2
Unrealized Losses	0	0
Fair Value	2,105	4,360
Held-to-maturity securities:
Amortized Cost	2,421	2,370
Unrealized Gains	15	0
Unrealized Losses	0	(26)
Fair Value	2,436	2,344
Agency mortgage-backed securities \| Residential mortgage backed securities
Available-for-sale debt and other securities:
Total	8,102	6,460
Unrealized Gains	12	0
Unrealized Losses	(579)	(779)
Fair Value	7,535	5,681
Held-to-maturity securities:
Amortized Cost	5,133	4,898
Unrealized Gains	13	0
Unrealized Losses	(56)	(197)
Fair Value	5,090	4,701
Agency mortgage-backed securities \| Commercial mortgage-backed securities
Available-for-sale debt and other securities:
Total	22,812	23,853
Unrealized Gains	4	1
Unrealized Losses	(2,252)	(3,022)
Fair Value	20,564	20,832
Held-to-maturity securities:
Amortized Cost	3,942	4,008
Unrealized Gains	41	0
Unrealized Losses	(5)	(90)
Fair Value	3,978	3,918
Non-agency mortgage-backed securities \| Commercial mortgage-backed securities
Available-for-sale debt and other securities:
Total	3,163	4,505
Unrealized Gains	1	0
Unrealized Losses	(217)	(338)
Fair Value	2,947	4,167
Asset-backed securities and other debt securities
Available-for-sale debt and other securities:
Total	2,567	3,924
Unrealized Gains	1	3
Unrealized Losses	(126)	(198)
Fair Value	2,442	3,729
Held-to-maturity securities:
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:
Total	868	778
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	868	778
Held-to-maturity securities:
FHLB, restricted stock holdings	362	276
FRB, restricted stock holdings	504	500
DTCC, restricted stock holdings	$ 2	$ 2

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

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