Fair Value (Schedule of Assets and Liabilities Measured at Fair Value by Class on a Recurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
ASSETS
Investment securities, available-for-sale	$ 9,931	$ 10,300
Trading securities	59	48
Total assets	11,276	11,602
LIABILITIES
Securities sold, not yet purchased	76	65
Total liabilities	464	398
U.S. Treasury, agencies, and corporations
ASSETS
Investment securities, available-for-sale	8,648	8,959
Municipal securities
ASSETS
Investment securities, available-for-sale	1,259	1,318
Other debt securities
ASSETS
Investment securities, available-for-sale	24	23
Bank-owned life insurance
ASSETS
Other noninterest-bearing investments	555	553
Private equity investments
ASSETS
Other noninterest-bearing investments	101	95
Agriculture loan servicing
ASSETS
Other assets	19	19
Loans held for sale
ASSETS
Other assets		43
Derivatives
ASSETS
Other assets	481	420
LIABILITIES
Other liabilities	388	333
Level 1
ASSETS
Investment securities, available-for-sale	481	492
Trading securities
Total assets	614	619
LIABILITIES
Securities sold, not yet purchased	76	65
Total liabilities	76	65
Level 1 | U.S. Treasury, agencies, and corporations
ASSETS
Investment securities, available-for-sale	481	492
Level 1 | Municipal securities
ASSETS
Investment securities, available-for-sale
Level 1 | Other debt securities
ASSETS
Investment securities, available-for-sale
Level 1 | Bank-owned life insurance
ASSETS
Other noninterest-bearing investments
Level 1 | Private equity investments
ASSETS
Other noninterest-bearing investments	3	3
Level 1 | Agriculture loan servicing
ASSETS
Other assets
Level 1 | Loans held for sale
ASSETS
Other assets
Level 1 | Derivatives
ASSETS
Other assets
LIABILITIES
Other liabilities
Level 2
ASSETS
Investment securities, available-for-sale	9,450	9,808
Trading securities	59	48
Total assets	10,545	10,872
LIABILITIES
Securities sold, not yet purchased	0	0
Total liabilities	388	333
Level 2 | U.S. Treasury, agencies, and corporations
ASSETS
Investment securities, available-for-sale	8,167	8,467
Level 2 | Municipal securities
ASSETS
Investment securities, available-for-sale	1,259	1,318
Level 2 | Other debt securities
ASSETS
Investment securities, available-for-sale	24	23
Level 2 | Bank-owned life insurance
ASSETS
Other noninterest-bearing investments	555	553
Level 2 | Private equity investments
ASSETS
Other noninterest-bearing investments
Level 2 | Agriculture loan servicing
ASSETS
Other assets
Level 2 | Loans held for sale
ASSETS
Other assets		43
Level 2 | Derivatives
ASSETS
Other assets	481	420
LIABILITIES
Other liabilities	388	333
Level 3
ASSETS
Investment securities, available-for-sale	0	0
Trading securities
Total assets	117	111
LIABILITIES
Securities sold, not yet purchased	0	0
Total liabilities	0	0
Level 3 | U.S. Treasury, agencies, and corporations
ASSETS
Investment securities, available-for-sale	0	0
Level 3 | Municipal securities
ASSETS
Investment securities, available-for-sale
Level 3 | Other debt securities
ASSETS
Investment securities, available-for-sale
Level 3 | Bank-owned life insurance
ASSETS
Other noninterest-bearing investments
Level 3 | Private equity investments
ASSETS
Other noninterest-bearing investments	98	92
Level 3 | Agriculture loan servicing
ASSETS
Other assets	19	19
Level 3 | Loans held for sale
ASSETS
Other assets
Level 3 | Derivatives
ASSETS
Other assets
LIABILITIES
Other liabilities
Deferred compensation plan assets | Deferred compensation plan assets
ASSETS
Other assets	130	124
Deferred compensation plan assets | Level 1 | Deferred compensation plan assets
ASSETS
Other assets	130	124
Deferred compensation plan assets | Level 2 | Deferred compensation plan assets
ASSETS
Other assets
Deferred compensation plan assets | Level 3 | Deferred compensation plan assets
ASSETS
Other assets