Fair Values of Assets and Liabilities - Changes in Fair Value for Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning of Period Balance		$ (107)	$ (2,303)	$ (1,800)	$ (1,885)
Net Gains (Losses) Included in Net Income		(403)	651	(584)	(2,036)
Purchases		193	264	914	912
Sales		(2)	(9)	(4)	(14)
Issuances		0	0	1	0
Settlements		389	585	1,543	2,211
End of Period Balance		70	(812)	70	(812)
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		152	1,438	1,351	666
Available-for-sale securities	[1]	89,065		89,065		$ 85,992
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning of Period Balance		3,305	3,326	3,369	3,377
Net Gains (Losses) Included in Net Income		(88)	(212)	(276)	(194)
Purchases		0	0	0	1
Sales		1	1	2	(188)
Issuances		71	72	194	191
Settlements		0	0	0	0
End of Period Balance		3,289	3,187	3,289	3,187
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		(88)	(212)	(276)	(194)
Mortgage Banking Revenue
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Gains (Losses) Included in Net Income		69	89	173	185
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		20	20	20	20
Commercial Products Revenue
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Gains (Losses) Included in Net Income		(464)	563	(666)	(2,200)
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		139	1,400	1,400	716
Other Noninterest Income
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Gains (Losses) Included in Net Income		(8)	(1)	(91)	(70)
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		$ (7)	$ (1)	$ (91)	$ (70)

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