SECURITIES - Summary of amortized cost of securities available for sale and their estimated fair value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 272,385	$ 238,870
Gross Unrealized Gains	4,147	5,928
Gross Unrealized Losses	(2,070)	(211)
Estimated Fair Value	274,462	244,587
U.S. Treasury Note
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	6,896	9,989
Gross Unrealized Gains	0	11
Gross Unrealized Losses	(288)	0
Estimated Fair Value	6,608	10,000
Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	65,288	57,478
Gross Unrealized Gains	1,614	1,863
Gross Unrealized Losses	(454)	0
Estimated Fair Value	66,448	59,341
U.S. Government agency obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	23,020	19,787
Gross Unrealized Gains	81	89
Gross Unrealized Losses	(242)	(201)
Estimated Fair Value	22,859	19,675
Obligations issued by U.S. states and their political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	21,222	23,280
Gross Unrealized Gains	1,235	1,515
Gross Unrealized Losses	(1)	0
Estimated Fair Value	22,456	24,795
Residential one-to-four family
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	109,233	71,773
Gross Unrealized Gains	440	951
Gross Unrealized Losses	(1,044)	(8)
Estimated Fair Value	108,629	72,716
Multifamily
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	46,726	56,563
Gross Unrealized Gains	777	1,499
Gross Unrealized Losses	(41)	(2)
Estimated Fair Value	$ 47,462	$ 58,060