FAIR VALUE MEASUREMENTS - Unobservable Inputs Non-recurring (Details) - Non-recurring - Level 3 - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items}
Individually evaluated loans	$ 9,247	$ 8,746
Capitalized servicing rights	4,867	3,605
Premises held for sale	822	962
Total	14,936	13,313
Premises held for sale, carrying value	822,000
Fair value of collateral -appraised value
Fair Value Measurement Inputs and Valuation Techniques [Line Items}
Individually evaluated loans	6,226	6,128
Discount cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items}
Individually evaluated loans	$ 3,021	$ 2,618
Impaired loans \| Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items}
Loss severity	10.00%	0.00%
Appraised value	$ 71	$ 0
Cash flows	$ 6	$ 19
Discount rate	2.88%	3.50%
Impaired loans \| Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items}
Loss severity	70.00%	70.00%
Appraised value	$ 1,792	$ 1,730
Cash flows	$ 939	$ 953
Discount rate	9.50%	9.50%
Capitalized servicing rights
Fair Value Measurement Inputs and Valuation Techniques [Line Items}
Constant prepayment rate (CPR)	13.66%	18.53%
Discount rate	9.53%	10.05%
Assets held for sale
Fair Value Measurement Inputs and Valuation Techniques [Line Items}
Premises held for sale	$ 822	$ 962
Selling Costs	6.00%	6.00%
Assets held for sale \| Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items}
Appraised value	$ 220	$ 220
Assets held for sale \| Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items}
Appraised value	$ 386	$ 386

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- Definition

Fair Value Inputs, Cash Flow

+ References

No definition available.

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- Definition

Fair Value Inputs, Selling Costs

+ References

No definition available.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

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-Publisher FASB
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- Definition

Fair value portion of assets classified as held for sale.

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- Definition

Amount of assets held-for-sale that are not part of a disposal group.

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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

No definition available.

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- Definition

The balance of financing receivables that were individually evaluated for impairment.

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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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- Definition

Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

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- Definition

Percentage of contractually collectible principal associated with a financial asset expected not to be collected due to default by the borrower.

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- Definition

Estimated rate of prepayments of principal on servicing assets and servicing liabilities.

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