FAIR VALUES OF FINANCIAL INSTRUMENTS - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financial assets
Cash and cash equivalents	$ 185,840	$ 220,819
Securities available-for-sale, at fair value	1,303,368	1,231,431
Federal Home Loan Bank and other bank stock	44,604	44,506
Loans held-for-sale, carried at fair value	3,422	1,413
Loans receivable, net of allowance for credit losses	6,235,625	5,936,708
Accrued interest receivable	30,546	29,445
Derivative assets	4,668	7,632
Financial liabilities
Deposits	6,543,653	6,087,714
Advances from Federal Home Loan Bank	437,111	585,416
Other borrowings	100,000
Long-term debt	274,493	273,230
Derivative liabilities	4,898	8,102
Accrued interest payable	6,645	3,714
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets
Cash and cash equivalents	185,840	220,819
Securities available-for-sale, at fair value	0	0
Federal Home Loan Bank and other bank stock	0	0
Loans held-for-sale, carried at fair value	0	0
Loans receivable, net of allowance for credit losses	0	0
Accrued interest receivable	30,546	29,445
Derivative assets	0	0
Financial liabilities
Deposits	0	0
Advances from Federal Home Loan Bank	0	0
Other borrowings	0
Long-term debt	0	0
Derivative liabilities	0	0
Accrued interest payable	6,645	3,714
Significant Other Observable Inputs (Level 2)
Financial assets
Cash and cash equivalents	0	0
Securities available-for-sale, at fair value	1,303,368	1,231,431
Federal Home Loan Bank and other bank stock	44,604	44,506
Loans held-for-sale, carried at fair value	2,427	468
Loans receivable, net of allowance for credit losses	0	0
Accrued interest receivable	0	0
Derivative assets	4,668	7,632
Financial liabilities
Deposits	0	0
Advances from Federal Home Loan Bank	437,111	585,416
Other borrowings	100,000
Long-term debt	274,493	273,230
Derivative liabilities	4,898	8,102
Accrued interest payable	0	0
Significant Unobservable Inputs (Level 3)
Financial assets
Cash and cash equivalents	0	0
Securities available-for-sale, at fair value	0	0
Federal Home Loan Bank and other bank stock	0	0
Loans held-for-sale, carried at fair value	995	945
Loans receivable, net of allowance for credit losses	6,235,625	5,936,708
Accrued interest receivable	0	0
Derivative assets	0	0
Financial liabilities
Deposits	6,543,653	6,087,714
Advances from Federal Home Loan Bank	0	0
Other borrowings	0
Long-term debt	0	0
Derivative liabilities	0	0
Accrued interest payable	0	0
Carrying Value
Financial assets
Cash and cash equivalents	185,840	220,819
Securities available-for-sale, at fair value	1,303,368	1,231,431
Federal Home Loan Bank and other bank stock	44,604	44,506
Loans held-for-sale, carried at fair value	3,422	1,413
Loans receivable, net of allowance for credit losses	6,155,051	5,817,375
Accrued interest receivable	30,546	29,445
Derivative assets	4,668	7,632
Financial liabilities
Deposits	6,543,225	6,085,800
Advances from Federal Home Loan Bank	405,738	539,795
Other borrowings	100,000
Long-term debt	256,706	256,315
Derivative liabilities	4,898	8,102
Accrued interest payable	$ 6,645	$ 3,714

Investment in Federal Home Loan and Other Banks Stock, Fair Value Disclosure

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Fair value portion of amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties.

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Fair value portion of accrued expenses.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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No definition available.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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- Definition

Fair value portion of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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