Investment Securities - Investment Securities (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Available-for-sale debt and other securities:
Total	$ 49,238	$ 39,107
Unrealized Gains	18	25
Unrealized Losses	(3,095)	(2,973)
Fair Value	46,161	36,159
Held-to-maturity securities:
Amortized Cost	16,389	11,368
Unrealized Gains	50	85
Unrealized Losses	(98)	(49)
Fair Value	16,341	11,404
Trading debt securities	1,669	1,057
Equity securities	544	453
Available-for-sale debt securities transferred to held-to-maturity securities
Held-to-maturity securities:
AOCI offset, unamortized portion of unrealized losses on securities	715	742
U.S. Treasury and federal agencies securities
Available-for-sale debt and other securities:
Total	3,454	1,575
Unrealized Gains	2	0
Unrealized Losses	(2)	0
Fair Value	3,454	1,575
Held-to-maturity securities:
Amortized Cost	2,154	2,438
Unrealized Gains	3	19
Unrealized Losses	0	0
Fair Value	2,157	2,457
Agency mortgage-backed securities \| Residential mortgage backed securities
Available-for-sale debt and other securities:
Total	15,183	9,138
Unrealized Gains	10	18
Unrealized Losses	(599)	(533)
Fair Value	14,594	8,623
Held-to-maturity securities:
Amortized Cost	5,612	5,023
Unrealized Gains	11	23
Unrealized Losses	(71)	(44)
Fair Value	5,552	5,002
Agency mortgage-backed securities \| Commercial mortgage-backed securities
Available-for-sale debt and other securities:
Total	24,403	22,307
Unrealized Gains	3	4
Unrealized Losses	(2,168)	(2,124)
Fair Value	22,238	20,187
Held-to-maturity securities:
Amortized Cost	8,621	3,905
Unrealized Gains	36	43
Unrealized Losses	(27)	(5)
Fair Value	8,630	3,943
Non-agency mortgage-backed securities \| Commercial mortgage-backed securities
Available-for-sale debt and other securities:
Total	2,962	3,032
Unrealized Gains	1	1
Unrealized Losses	(212)	(200)
Fair Value	2,751	2,833
Asset-backed securities and other debt securities
Available-for-sale debt and other securities:
Total	2,438	2,381
Unrealized Gains	2	2
Unrealized Losses	(114)	(116)
Fair Value	2,326	2,267
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	798	674
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	798	674
Held-to-maturity securities:
FHLB, restricted stock holdings	204	167
FRB, restricted stock holdings	591	505
DTCC, restricted stock holdings	$ 3	$ 2

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

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