Fair Value of Assets and Liabilities - Schedule of Unobservable Inputs Utilized in Determining the Fair Value of Level 3 Recurring and Non-Recurring Measurements (Details) $ in Millions	Mar. 31, 2026 USD ($) month	Dec. 31, 2025 USD ($) month
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale at fair value	$ 8,146	$ 8,165
Loans held for sale (elected fair value)	167	151
Derivative liabilities, fair value	395	376
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value	18	25
Loans and leases, fair value	363	370
OREO	$ 2	$ 3
Level 3 | Minimum | Visa covered litigation resolution amount | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	3,600	3,700
Level 3 | Minimum | Probability of resolution scenarios | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.20	0.10
Level 3 | Minimum | Time until resolution | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input | month	12	18
Level 3 | Minimum | Marketability adjustments for specific properties | Appraisals from comparable properties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases, measurement input	0	0
Level 3 | Minimum | Borrowing base certificates liquidation adjustment | Other collateral valuations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases, measurement input	0.25	0.25
Level 3 | Minimum | Financial statements liquidation adjustment | Other collateral valuations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases, measurement input	0.50	0.50
Level 3 | Minimum | Auction appraisals marketability adjustment | Other collateral valuations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases, measurement input	0	0
Level 3 | Minimum | Adjustment for value changes since appraisal | Appraisals from comparable properties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
OREO measurement input	0	0
Level 3 | Maximum | Visa covered litigation resolution amount | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	4,200	4,500
Level 3 | Maximum | Probability of resolution scenarios | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.30	0.25
Level 3 | Maximum | Time until resolution | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input | month	42	48
Level 3 | Maximum | Marketability adjustments for specific properties | Appraisals from comparable properties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases, measurement input	0.25	0.25
Level 3 | Maximum | Borrowing base certificates liquidation adjustment | Other collateral valuations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases, measurement input	0.50	0.50
Level 3 | Maximum | Financial statements liquidation adjustment | Other collateral valuations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases, measurement input	1	1
Level 3 | Maximum | Auction appraisals marketability adjustment | Other collateral valuations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases, measurement input	0.10	0.10
Level 3 | Maximum | Adjustment for value changes since appraisal | Appraisals from comparable properties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
OREO measurement input	0.10	0.10
Level 3 | Weighted Average | Visa covered litigation resolution amount | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	4,000	4,200
Level 3 | Weighted Average | Probability of resolution scenarios | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.25	0.20
Level 3 | Weighted Average | Time until resolution | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input | month	32	35
Level 3 | SBA interest-only strips
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale at fair value	$ 35	$ 45
Level 3 | SBA interest-only strips | Minimum | Constant prepayment rate | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.16	0.16
Level 3 | SBA interest-only strips | Minimum | Bond equivalent yield | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.03	0.04
Level 3 | SBA interest-only strips | Maximum | Constant prepayment rate | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.24	0.30
Level 3 | SBA interest-only strips | Maximum | Bond equivalent yield | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.12	0.14
Level 3 | SBA interest-only strips | Weighted Average | Constant prepayment rate | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.16	0.17
Level 3 | SBA interest-only strips | Weighted Average | Bond equivalent yield | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.12	0.14
Level 3 | Loans Held For Sale, Residential Real Estate | Residential Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale (elected fair value)	$ 14	$ 14
Level 3 | Loans Held For Sale, Residential Real Estate | Minimum | Prepayment speeds - First mortgage | Discounted cash flow | Loans held for sale—first mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, measurement input	0.02	0.02
Level 3 | Loans Held For Sale, Residential Real Estate | Minimum | Foreclosure losses | Discounted cash flow | Residential Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, measurement input	0.62	0.64
Level 3 | Loans Held For Sale, Residential Real Estate | Minimum | Loss severity trends - First mortgage | Discounted cash flow | Loans held for sale—first mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, measurement input	0.000	0
Level 3 | Loans Held For Sale, Residential Real Estate | Maximum | Prepayment speeds - First mortgage | Discounted cash flow | Loans held for sale—first mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, measurement input	0.07	0.07
Level 3 | Loans Held For Sale, Residential Real Estate | Maximum | Foreclosure losses | Discounted cash flow | Residential Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, measurement input	0.65	0.65
Level 3 | Loans Held For Sale, Residential Real Estate | Maximum | Loss severity trends - First mortgage | Discounted cash flow | Loans held for sale—first mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, measurement input	0.015	0.013
Level 3 | Loans Held For Sale, Residential Real Estate | Weighted Average | Prepayment speeds - First mortgage | Discounted cash flow | Loans held for sale—first mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, measurement input	0.03	0.03
Level 3 | Loans Held For Sale, Residential Real Estate | Weighted Average | Foreclosure losses | Discounted cash flow | Residential Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, measurement input	0.64	0.64
Level 3 | Loans Held For Sale, Residential Real Estate | Weighted Average | Loss severity trends - First mortgage | Discounted cash flow | Loans held for sale—first mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, measurement input	0.005	0.005