Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions - Fair Value of Derivatives (Details)	12 Months Ended
Dec. 31, 2024 USD ($) item	Dec. 31, 2024 USD ($) item	Dec. 31, 2023 USD ($) item
Two financial institutions
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Cash collateral pledged with financial institutions, dollars	$ 2,300,000	$ 2,300,000	$ 7,300,000
Number of financial institutions in which cash collateral pledged \| item		1	2
Interest Rate Swap
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Investment securities pledged with financial institutions, dollars	$ 0	$ 0	$ 0
Number of financial institutions in which cash collateral pledged	5,200,000	2	1
Interest Rate Swap \| Two financial institutions
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Cash collateral pledged with financial institutions, dollars			$ 4,100,000
Designated as Hedging Instrument
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Derivative assets designated as hedging instruments, fair value	$ 3,823,000	$ 3,823,000	2,576,000
Derivative liabilities designated as hedging instruments, fair value	$ 1,512,000	$ 1,512,000	$ 5,598,000
Designated as Hedging Instrument \| Interest Rate Products \| OSBC Affiliates
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Derivative, number of transactions \| item	5	5	5
Notional amount	$ 325,774,000	$ 325,774,000	$ 325,774,000
Derivative assets designated as hedging instruments, fair value	3,823,000	3,823,000	2,576,000
Derivative liabilities designated as hedging instruments, fair value	1,512,000	1,512,000	5,598,000
Designated as Hedging Instrument \| Interest Rate Swap \| Cash flow hedges of certain variable rate commercial and commercial real estate loan pools
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Notional amount	300,000,000.0	300,000,000.0	300,000,000.0
Designated as Hedging Instrument \| Interest Rate Swap \| Cash flow hedge of junior subordinated debentures and was executed to pay fixed and receive variable rate cash flows
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Notional amount	25,800,000	25,800,000	25,800,000
Not Designated as Hedging Instrument
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Derivative assets designated as hedging instruments, fair value	1,758,000	1,758,000	2,805,000
Derivative liabilities designated as hedging instruments, fair value	$ 1,680,000	$ 1,680,000	$ 2,726,000
Not Designated as Hedging Instrument \| Interest Rate Products \| Commercial Loan Customers
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Derivative, number of transactions \| item	13	13	17
Notional amount	$ 154,137,000	$ 154,137,000	$ 104,777,000
Derivative assets designated as hedging instruments, fair value	1,675,000	1,675,000	2,726,000
Derivative liabilities designated as hedging instruments, fair value	1,675,000	1,675,000	2,726,000
Not Designated as Hedging Instrument \| Interest Rate Swap
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Notional amount	121,200,000	121,200,000	104,800,000
Not Designated as Hedging Instrument \| Commitments.
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Notional amount	$ 8,700,000	$ 8,700,000	$ 8,400,000
Not Designated as Hedging Instrument \| Interest Rate Lock Commitments and Forward Contracts.
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Derivative, number of transactions \| item	30	30	24
Notional amount	$ 8,667,000	$ 8,667,000	$ 8,375,000
Derivative assets designated as hedging instruments, fair value	$ 55,000	$ 55,000	$ 10,000
Not Designated as Hedging Instrument \| Other Contracts
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Derivative, number of transactions \| item	5	5	4
Notional amount	$ 58,259,000	$ 58,259,000	$ 44,790,000
Derivative assets designated as hedging instruments, fair value	28,000	28,000	89,000
Derivative liabilities designated as hedging instruments, fair value	5,000	5,000
Not Designated as Hedging Instrument \| Forward Contracts
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Notional amount	5,500,000	5,500,000	$ 6,000,000
Interest Income
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Amount to be reclassified as an decrease to interest expense during the next twelve months	404,000	404,000
Interest Expense
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Amount to be reclassified as an decrease to interest expense during the next twelve months	$ 1,500,000	$ 1,500,000

Represents the number of financial institutions in which cash collateral pledged.

No definition available.

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- Definition

Carrying amount as of the balance sheet date of cash collateral held for borrowed securities, for which the cash is restricted as to withdrawal or usage.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 210
-Name Accounting Standards Codification
-Section S99
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- Definition

Fair value of all asset derivatives designated as cash flow hedging instruments.

+ References

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- Definition

Fair value of all liability derivatives designated as cash flow hedging instruments.

+ References

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- Definition

Amount, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity), and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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