Fair Value (Schedule of Assets and Liabilities Measured at Fair Value by Class on a Recurring Basis Using Level 3 Inputs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt And Equity Securities, Unrealized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Securities gains (losses), net	Securities gains (losses), net
Other Noninterest Expense
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Unrealized securities gains (losses), net and Other noninterest income (expense)	$ (1)	$ (2)	$ 31
Level 3 | Private equity investments 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of year	81	66	80
Purchases	14	16	17
Cost of investments sold	(1)	(3)	(24)
Redemptions and paydowns	0	0	0
Transfers out	0	(1)	(78)
Balance at end of year	92	81	66
Level 3 | Private equity investments 1 | Debt And Equity Securities, Unrealized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Unrealized securities gains (losses), net and Other noninterest income (expense)	(2)	3	71
Level 3 | Private equity investments 1 | Other Noninterest Expense
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Unrealized securities gains (losses), net and Other noninterest income (expense)	0	0	0
Level 3 | Ag loan servicing
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of year	14	12	16
Purchases	0	0	0
Cost of investments sold	0	0	0
Redemptions and paydowns	0	0	(1)
Transfers out	0	0	0
Balance at end of year	19	14	12
Level 3 | Ag loan servicing | Debt And Equity Securities, Unrealized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Unrealized securities gains (losses), net and Other noninterest income (expense)	0	0	0
Level 3 | Ag loan servicing | Other Noninterest Expense
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Unrealized securities gains (losses), net and Other noninterest income (expense)	$ 5	$ 2	$ (3)