Fair Value Measurements - Fair Values of Assets and Liabilities (Significant Unobservable Level 3 Inputs Nonrecurring Basis) (Details) - Nonrecurring - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	$ 344	$ 409
OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	3	7
Bank premises and equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	19	11
Operating lease equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	1	13
Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	10	15
Commercial | Commercial loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	40	2
Commercial | Commercial loans and leases
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	162	236
Consumer | Consumer and residential mortgage loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	109	125
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	335	408
Level 3     | OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	3	7
Level 3     | Bank premises and equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	19	11
Level 3     | Operating lease equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	1	13
Level 3     | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	1	14
Level 3     | Commercial | Commercial loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	40	2
Level 3     | Commercial | Commercial loans and leases
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	162	236
Level 3     | Consumer | Consumer and residential mortgage loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	109	125
Level 3     | Comparable company analysis | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	1	14
Level 3     | Comparable company analysis | Commercial | Commercial loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	40	2
Level 3     | Appraised value | OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	3	7
Level 3     | Appraised value | Bank premises and equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	19	11
Level 3     | Appraised value | Operating lease equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	1	13
Level 3     | Appraised value | Commercial | Commercial loans and leases
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	162	236
Level 3     | Appraised value | Consumer | Consumer and residential mortgage loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	$ 109	$ 125