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Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Narrative) (Details) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 USD ($) segments | Dec. 31, 2023 USD ($)
Federal Home Loan Bank Stock |  | $ 171,000,000 | $ 316,550,000
Federal Reserve Bank Stock |  | 85,271,550 | 85,271,550
Net Deferred Income on Originated Loans |  | $ (92,000,000) | (94,000,000)
Delinquency Status, Period of Unpaid Scheduled Monthly Payment |  | 30 days |
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, after Accumulated Amortization |  | $ 65,000,000 | 61,000,000
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization |  | 30,000,000 | 14,000,000
Hosting Arrangement, Service Contract, Implementation Cost, Depreciation Expense |  | $ 15,000,000 | 9,000,000
Number of Reporting Units | segments |  | 3 |
Derivative, Notional Amount | [1] | $ 69,729,000,000 | $ 70,737,000,000
Defined Benefit Plan Investment Gain Loss Amortization Adjustment, Allowable Percentage |  | 1000.00% |
Defined Benefit Plan Actuarial Gain Loss Amortization Adjustment, Allowable Percentage |  | 1000.00% |
Defined Benefit Plan Market-related Value Plan Assets, Amortization Period |  | 5 years |
Cumulative effect of change in accounting principle |  | $ (4,000,000) |
Premises the Corporation owns | Minimum |  |  |
Premises and Equipment, Useful Life |  | 3 years |
Premises the Corporation owns | Maximum |  |  |
Premises and Equipment, Useful Life |  | 33 years |
Furniture and equipment | Minimum |  |  |
Premises and Equipment, Useful Life |  | 3 years |
Furniture and equipment | Maximum |  |  |
Premises and Equipment, Useful Life |  | 8 years |
Leasehold improvements | Maximum |  |  |
Premises and Equipment, Useful Life |  | 10 years |
Software |  |  |
Premises and Equipment, Useful Life |  | 5 years |
Retail loans | Commercial mortgage |  |  |
Past Due Period Residential Mortgage And Home Equity Loans Placed On Nonaccrual Status |  | 90 days |
Past Due Threshold For Charge-Off |  | 180 days |
Commercial borrower | Business loans |  |  |
Past Due Period Business Loans Placed On Nonaccrual Status |  | 90 days |
Consumer borrower | Retail loans | Home equity |  |  |
Maximum Past Due Status Junior Lien Home Equity Placed On Nonaccrual Status |  | 90 days |
Consumer borrower | Retail loans | Other consumer |  |  |
Threshold, Days Past Due, Other Consumer Placed On Nonaccrual Status |  | 90 days |
Past Due Threshold For Charge-Off |  | 120 days |
Retained Earnings |  |  |
Cumulative effect of change in accounting principle |  | $ (4,000,000) |
Fair Value Hedging | Short-Cut Method | Not Designated as Hedging Instrument [Member] | Interest rate swap |  |  |
Derivative, Notional Amount |  | $ 6,800,000,000 |
[1] | Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected on the Consolidated Balance Sheets. (b)December 31, 2023 included $2 billion of forward starting swaps that became effective on their contractual start dates in 2024. There were no forward starting swaps at December 31, 2024.

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