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		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning of Period Balance	$ (2,361)	$ (2,265)	$ (1,885)	$ (3,199)
Net Gains (Losses) Included in Net Income	(1,004)	(1,927)	(2,687)	(2,243)
Purchases	270	(18)	648	405
Sales	(3)	(7)	(5)	(19)
Principal Payments	0	0	0	0
Issuances	0	0	0	0
Settlements	795	798	1,626	1,637
End of Period Balance	(2,303)	(3,419)	(2,303)	(3,419)
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period	4	(1,631)	(676)	(1,242)
Available-for-sale investment securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning of Period Balance		1		1
Purchases		0		0
Sales		0		0
Principal Payments		(1)		(1)
Issuances		0		0
Settlements		0		0
End of Period Balance		0		0
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		0		0
Obligations of state and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning of Period Balance		1		1
Purchases		0		0
Sales		0		0
Principal Payments		(1)		(1)
Issuances		0		0
Settlements		0		0
End of Period Balance		0		0
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period		0		0
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning of Period Balance	3,462	3,724	3,377	3,755
Net Gains (Losses) Included in Net Income	(12)	(42)	18	(171)
Purchases	1	1	1	2
Sales	(189)	(149)	(189)	(148)
Principal Payments	0	0	0	0
Issuances	64	99	119	195
Settlements	0	0	0	0
End of Period Balance	3,326	3,633	3,326	3,633
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period	(12)	(42)	18	(171)
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	52	46	96	98
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period	17	18	17	18
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	(1,000)	(2,000)	(2,700)	(2,300)
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period	(19)	(1,700)	(624)	(1,300)
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	6	1	(69)	(1)
Net Change in Unrealized Gains (Losses) Relating to Assets and Liabilities Held at End of Period	$ 6	$ 1	$ (69)	$ (1)