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
		Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning of Period Balance		$ (1,800)	$ (1,885)
Net Gains (Losses) Included in Net Income		(191)	(1,683)
Purchases		669	378
Sales		(2)	(2)
Issuances		1	0
Settlements		596	831
End of Period Balance		(727)	(2,361)
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		996	(181)
Available-for-sale securities	[1]	86,774		$ 85,992
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning of Period Balance		3,369	3,377
Net Gains (Losses) Included in Net Income		(117)	30
Purchases		0	0
Sales		1	0
Issuances		59	55
Settlements		0	0
End of Period Balance		3,312	3,462
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		(117)	30
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		51	44
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		16	19
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		(241)	(1,700)
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		981	(125)
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		(1)	(75)
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		$ (1)	$ (75)

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