Fair Value of Assets and Liabilities - Nonrecurring Fair Value Measurements (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale	$ 84	$ 68
Loans and leases	61,753	61,292
Non Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases	244	245
OREO	4	4
Other assets		90
Non Recurring | Loans held for sale—SBAs and USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale	284	406
Non Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases	0	0
OREO	0	0
Other assets		0
Non Recurring | Level 1 | Loans held for sale—SBAs and USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale	0	0
Non Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases	0	0
OREO	0	0
Other assets		0
Non Recurring | Level 2 | Loans held for sale—SBAs and USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale	284	406
Non Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases	244	245
OREO	4	4
Other assets		90
Non Recurring | Level 3 | Loans held for sale—SBAs and USDA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale	$ 0	$ 0