Investment Securities - Fair Value and Gross Unrealized Losses on Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Fair Value
Less than 12 months	$ 11,738	$ 2,964
12 months or more	28,195	29,029
Total	39,933	31,993
Unrealized Losses
Less than 12 months	(72)	(9)
12 months or more	(3,023)	(2,964)
Total	(3,095)	(2,973)
U.S. Treasury and federal agencies securities
Fair Value
Less than 12 months	1,496	1,225
12 months or more	0	0
Total	1,496	1,225
Unrealized Losses
Less than 12 months	(2)	0
12 months or more	0	0
Total	(2)	0
Agency mortgage-backed securities \| Residential mortgage backed securities
Fair Value
Less than 12 months	7,900	1,454
12 months or more	4,469	4,615
Total	12,369	6,069
Unrealized Losses
Less than 12 months	(50)	(7)
12 months or more	(549)	(526)
Total	(599)	(533)
Agency mortgage-backed securities \| Commercial mortgage-backed securities
Fair Value
Less than 12 months	1,973	149
12 months or more	19,366	19,826
Total	21,339	19,975
Unrealized Losses
Less than 12 months	(15)	(1)
12 months or more	(2,153)	(2,123)
Total	(2,168)	(2,124)
Non-agency commercial mortgage-backed securities \| Commercial mortgage-backed securities
Fair Value
Less than 12 months	64	1
12 months or more	2,598	2,695
Total	2,662	2,696
Unrealized Losses
Less than 12 months	(1)	0
12 months or more	(211)	(200)
Total	(212)	(200)
Asset-backed securities and other debt securities
Fair Value
Less than 12 months	305	135
12 months or more	1,762	1,893
Total	2,067	2,028
Unrealized Losses
Less than 12 months	(4)	(1)
12 months or more	(110)	(115)
Total	$ (114)	$ (116)

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