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	Sep. 30, 2025 USD ($) month	Dec. 31, 2024 USD ($) month
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale at fair value	$ 8,102	$ 7,896
Loans held-for-sale	139	85
Derivative Liabilities, fair value	401	655
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, fair value	22	15
Loans and leases, fair value	412	344
OREO, fair value	7	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 liabilities, measurement input, value	$ 3,400	$ 3,100
Level 3 | Minimum | Probability of resolution scenarios | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, measurement input	0.10	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 liabilities, measurement input | month	12	6
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 liabilities, measurement input, value	$ 4,400	$ 4,100
Level 3 | Maximum | Probability of resolution scenarios | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, measurement input	0.25	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 liabilities, measurement input | month	36	36
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 liabilities, measurement input, value	$ 4,000	$ 3,800
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 liabilities, measurement input	0.16	0.18
Level 3 | Weighted Average | Time until resolution | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, measurement input | month	26	23
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	$ 13	$ 16
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	0.64	0.63
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	0.06
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	0.71
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	0.017	0.002
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	0.006	0.001
SBA interest-only strips | Level 3 | Trading Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale at fair value	$ 26	$ 23
SBA interest-only strips | Level 3 | Trading Securities | 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	0.18	0.16
SBA interest-only strips | Level 3 | Trading Securities | 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	0.04	0.03
SBA interest-only strips | Level 3 | Trading Securities | 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	0.30	0.30
SBA interest-only strips | Level 3 | Trading Securities | 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	0.16	0.18
SBA interest-only strips | Level 3 | Trading Securities | 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	0.19	0.17
SBA interest-only strips | Level 3 | Trading Securities | 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	0.15	0.17