Securities - Amortized Cost and Fair Value of Asset Backed Securities (Detail) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Securities available-for-sale:
Amortized Cost	$ 34,536	$ 31,651
Unrealized Gains	44	56
Unrealized Losses	(1,763)	(1,677)
Fair Value	32,817	30,030
Securities held-to-maturity:
Amortized Cost	20,489	18,293
Unrealized Gains	69	140
Unrealized Losses	(437)	(296)
Fair Value	20,121	18,137
U.S. Treasury
Securities available-for-sale:
Amortized Cost	15,519	13,895
Unrealized Gains	13	32
Unrealized Losses	(145)	(107)
Fair Value	15,387	13,820
Securities held-to-maturity:
Amortized Cost	5,980	2,846
Unrealized Gains	4	7
Unrealized Losses	(71)	(4)
Fair Value	5,913	2,849
U.S. Government sponsored enterprises
Securities available-for-sale:
Amortized Cost	4,430	4,603
Unrealized Gains	2	2
Unrealized Losses	(805)	(808)
Fair Value	3,627	3,797
Securities held-to-maturity:
Amortized Cost	1,014	1,062
Unrealized Gains	2	3
Unrealized Losses	(54)	(47)
Fair Value	962	1,018
U.S. Government agency issued or guaranteed
Securities available-for-sale:
Amortized Cost	9,920	8,750
Unrealized Gains	18	11
Unrealized Losses	(804)	(752)
Fair Value	9,134	8,009
Securities held-to-maturity:
Amortized Cost	13,493	14,383
Unrealized Gains	63	130
Unrealized Losses	(312)	(245)
Fair Value	13,244	14,268
Home equity mortgages
Securities available-for-sale:
Amortized Cost	8	8
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	8	8
Corporate loans
Securities available-for-sale:
Amortized Cost	208	179
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	208	179
Other
Securities available-for-sale:
Amortized Cost	79	85
Unrealized Gains	0	0
Unrealized Losses	(8)	(9)
Fair Value	71	76
Foreign debt securities
Securities available-for-sale:
Amortized Cost	4,372	4,131
Unrealized Gains	11	11
Unrealized Losses	(1)	(1)
Fair Value	4,382	4,141
Obligations of U.S. states and political subdivisions
Securities held-to-maturity:
Amortized Cost	2	2
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 2	$ 2

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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