FAIR VALUE DISCLOSURES - Financial assets and financial liabilities measured at fair value on a recurring basis (Details) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Financial Liabilities
Transfers from level 1 and level 2	$ 0	$ 0
Transfers from level 2 and level 1	0	0
Transfers from level 1 and level 2	0	0
Transfers from level 2 and level 1	0	0
Transfers into level 3	0	0
Transfers from level 3	0	0
Recurring basis
Financial Liabilities
Total financial liabilities	5,902,000	8,618,000
Level 1 Inputs \| Recurring basis
Financial Assets
Equity securities	1,176,000	1,193,000
Level 1 Inputs \| Recurring basis \| U.S. Treasury securities
Financial Assets
Debt securities available for sale	11,821,000
Level 2 Inputs \| Recurring basis \| Interest rate swaps
Financial Assets
Interest rate swaps assets	5,902,000	8,618,000
Financial Liabilities
Interest rate swaps liabilities	5,902,000	8,618,000
Level 2 Inputs \| Recurring basis \| State and municipal securities
Financial Assets
Debt securities available for sale	106,185,000	93,037,000
Level 2 Inputs \| Recurring basis \| Callable debentures
Financial Assets
Debt securities available for sale	2,951,000
Level 2 Inputs \| Recurring basis \| Collateralized mortgage obligations
Financial Assets
Debt securities available for sale	33,994,000	35,402,000
Level 2 Inputs \| Recurring basis \| Mortgage-backed securities
Financial Assets
Debt securities available for sale	132,964,000	107,649,000
Level 3 Inputs \| Recurring basis
Financial Assets
Credit risk participation agreement	11,000	40,000
Total financial assets	$ 295,004,000	$ 245,939,000

Fair value portion of assets related to investment contracts .

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

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Amount 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, 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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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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Amount of transfers of liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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