INVESTMENT SECURITIES - Amortized cost and fair value of securities available-for-sale (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Mar. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 35,750	$ 30,075
Gross Unrealized Gains	980	833
Gross Unrealized Losses	(64)	(65)
Fair Value	36,666	30,843
U.S. Treasury debt
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	250	250
Gross Unrealized Gains	4	3
Fair Value	254	253
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	6,000	6,000
Gross Unrealized Gains	55	126
Gross Unrealized Losses	(11)	(38)
Fair Value	6,044	6,088
Government National Mortgage Association ("GNMA") mortgage-backed securities - residential
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	23,806	19,402
Gross Unrealized Gains	798	581
Gross Unrealized Losses		(3)
Fair Value	24,604	19,980
Federal National Mortgage Association ("FNMA") mortgage-backed securities - residential
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,616	1,602
Gross Unrealized Gains	61	68
Fair Value	1,677	1,670
Corporate collateralized mortgage obligations ("CMO") and MBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,078	2,821
Gross Unrealized Gains	62	55
Gross Unrealized Losses	(53)	(24)
Fair Value	4,087	2,852
Small Business Investment Company ("SBIC")
Debt Securities, Available-for-sale [Line Items]
Payments to Acquire Investments	500
Contractual Obligation		900
Other Assets [Member] \| Small Business Investment Company ("SBIC")
Debt Securities, Available-for-sale [Line Items]
Balance with SBIC included in other assets	$ 2,100	$ 2,100

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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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Amortized cost 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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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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Sum of the carrying amounts as of the balance sheet date of all investments.

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The cash outflow associated with the purchase of all investments (debt, security, other) during the period.

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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.

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