Investment Securities - Available-For-Sale Securities (Details) - USD ($) $ in Millions		Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		$ 93,067	$ 92,793
Unrealized Gains		88	58
Unrealized Losses		(6,381)	(6,859)
Fair Value	[1]	86,774	85,992
Portfolio level basis adjustments, Amortized Cost		204	13
Portfolio level basis adjustments, Unrealized Losses		(204)	(13)
U.S. Treasury and agencies
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		30,387	30,467
Unrealized Gains		11	1
Unrealized Losses		(1,782)	(2,081)
Fair Value		28,616	28,387
Residential mortgage-backed securities | Agency
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		35,535	35,558
Unrealized Gains		51	13
Unrealized Losses		(1,912)	(2,290)
Fair Value		33,674	33,281
Commercial mortgage-backed securities | Agency
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		8,647	8,673
Unrealized Gains		0	0
Unrealized Losses		(1,144)	(1,322)
Fair Value		7,503	7,351
Commercial mortgage-backed securities | Non-agency
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		7	7
Unrealized Gains		0	0
Unrealized Losses		0	(1)
Fair Value		7	6
Asset-backed securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		7,323	7,136
Unrealized Gains		15	30
Unrealized Losses		(6)	(1)
Fair Value		7,332	7,165
Obligations of state and political subdivisions
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		10,650	10,690
Unrealized Gains		9	13
Unrealized Losses		(1,333)	(1,151)
Fair Value		9,326	9,552
Other
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		314	249
Unrealized Gains		2	1
Unrealized Losses		0	0
Fair Value		316	250
Excluding portfolio level basis adjustments
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		92,863	92,780
Unrealized Gains		88	58
Unrealized Losses		(6,177)	(6,846)
Fair Value		$ 86,774	$ 85,992

[1] Includes only collateral pledged by the Company where counterparties have the right to sell or pledge the collateral.