Investment Securities - Fair Value and Gross Unrealized Losses on Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Fair Value
Less than 12 months	$ 1,836	$ 2,253
12 months or more	30,706	32,243
Total	32,542	34,496
Unrealized Losses
Less than 12 months	(21)	(34)
12 months or more	(3,452)	(4,303)
Total	(3,473)	(4,337)
U.S. Treasury and federal agencies securities
Fair Value
Less than 12 months	0	569
12 months or more	0	0
Total	0	569
Unrealized Losses
Less than 12 months	0	0
12 months or more	0	0
Total	0	0
Agency mortgage-backed securities \| Residential mortgage backed securities
Fair Value
Less than 12 months	1,431	1,061
12 months or more	4,477	4,566
Total	5,908	5,627
Unrealized Losses
Less than 12 months	(15)	(14)
12 months or more	(617)	(765)
Total	(632)	(779)
Agency mortgage-backed securities \| Commercial mortgage-backed securities
Fair Value
Less than 12 months	166	157
12 months or more	20,580	20,536
Total	20,746	20,693
Unrealized Losses
Less than 12 months	(4)	(6)
12 months or more	(2,439)	(3,016)
Total	(2,443)	(3,022)
Non-agency commercial mortgage-backed securities \| Commercial mortgage-backed securities
Fair Value
Less than 12 months	76	183
12 months or more	3,136	3,984
Total	3,212	4,167
Unrealized Losses
Less than 12 months	(1)	(3)
12 months or more	(253)	(335)
Total	(254)	(338)
Asset-backed securities and other debt securities
Fair Value
Less than 12 months	163	283
12 months or more	2,513	3,157
Total	2,676	3,440
Unrealized Losses
Less than 12 months	(1)	(11)
12 months or more	(143)	(187)
Total	$ (144)	$ (198)

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