Derivative Instruments and Hedging Activities (Policies)	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives, Policy [Policy Text Block]	Derivative Instruments. The Corporation uses derivative instruments to protect against the risk of adverse price or interest rate movements on the value of certain assets, liabilities, future cash flows, and economic hedges for written client derivative contracts. Derivative instruments represent contracts between parties that usually require little or no initial net investment and result in one party delivering cash to the other party based on a notional amount and an underlying variable, as specified in the contract, and may be subject to master netting agreements. Market risk is the risk of loss arising from an adverse change in interest rates, exchange rates, or equity prices. The Corporation’s primary market risk is interest rate risk. Instruments designed to manage interest rate risk include interest rate swaps, interest rate options, and interest rate caps and floors with indices that relate to the pricing of specific assets and liabilities. The nature and volume of the derivative instruments used to manage interest rate risk depend on the level and type of assets and liabilities on the balance sheet and the risk management strategies for the current and anticipated rate environments. Counterparty risk with respect to derivative instruments occurs when a counterparty to a derivative contract with an unrealized gain fails to perform according to the terms of the agreement. Counterparty risk is managed by limiting the counterparties to highly rated dealers, requiring collateral postings when values are in deficit positions, applying uniform credit standards to all activities with credit risk, and monitoring the size and the maturity structure of the derivative portfolio. All derivative instruments are to be carried at fair value on the Consolidated Balance Sheets. The accounting for the gain or loss due to changes in the fair value of a derivative instrument depends on whether the derivative instrument qualifies as a hedge. If the derivative instrument does not qualify as a hedge, the gains or losses are reported in earnings when they occur. However, if the derivative instrument qualifies as a hedge, the accounting varies based on the type of risk being hedged. The Corporation utilizes interest rate swaps offered directly to qualified commercial borrowers, which do not qualify for hedge accounting, and therefore, all changes in fair value and gains and losses on these instruments are reported in earnings as they occur. The effects of netting arrangements are disclosed within the Notes of the Consolidated Financial Statements. The Corporation offers interest rate swap products directly to qualified commercial borrowers. The Corporation economically hedges client derivative transactions by entering into offsetting interest rate swap contracts executed with a third party. Derivative transactions executed as part of this program are not considered hedging instruments and are marked-to-market through earnings each period. The derivative contracts have mirror-image terms, which results in the positions’ changes in fair value offsetting through earnings each period. The credit risk and risk of non-performance embedded in the fair value calculations is different between the dealer counterparties and the commercial borrowers which may result in a difference in the changes in the fair value of the mirror-image swaps. The Corporation incorporates credit valuation adjustments to appropriately reflect both its own non-performance risk and the counterparty’s risk in the fair value measurements. When evaluating the fair value of its derivative contracts for the effects of non-performance and credit risk, the Corporation considers the impact of netting and any applicable credit enhancements such as collateral postings, thresholds and guarantees. The Corporation also enters into interest rate swaps to manage interest rate risk and reduce the cost of match-funding certain long-term fixed rate loans. These derivative contracts are designated as a cash flow hedge as the receipt of floating interest from the counterparty is used to manage interest rate risk associated with forecasted issuances of short-term FHLB advances. The change in fair value of the hedging instrument is recorded in accumulated other comprehensive income.