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SECURITIES - Summary of amortized cost of securities available for sale and their estimated fair value (Details) - USD ($) $ in Thousands | Dec. 31, 2021 | Dec. 31, 2020
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Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | $ 323,801 | $ 238,870
Gross Unrealized Gains | 3,734 | 5,928
Gross Unrealized Losses | (2,643) | (211)
Estimated Fair Value | 324,892 | 244,587
U.S. Treasury Notes |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 36,933 | 9,989
Gross Unrealized Gains | 4 | 11
Gross Unrealized Losses | (105) | 0
Estimated Fair Value | 36,832 | 10,000
Corporate Bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 86,118 | 57,478
Gross Unrealized Gains | 1,791 | 1,863
Gross Unrealized Losses | (290) | 0
Estimated Fair Value | 87,619 | 59,341
U.S. Government agency obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 23,462 | 19,787
Gross Unrealized Gains | 46 | 89
Gross Unrealized Losses | (179) | (201)
Estimated Fair Value | 23,329 | 19,675
Obligations issued by U.S. states and their political subdivisions |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 19,172 | 23,280
Gross Unrealized Gains | 1,152 | 1,515
Gross Unrealized Losses | 0 | 0
Estimated Fair Value | 20,324 | 24,795
Residential one-to-four family |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 116,166 | 71,773
Gross Unrealized Gains | 140 | 951
Gross Unrealized Losses | (1,905) | (8)
Estimated Fair Value | 114,401 | 72,716
Multifamily |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 35,412 | 56,563
Gross Unrealized Gains | 598 | 1,499
Gross Unrealized Losses | (94) | (2)
Estimated Fair Value | 35,916 | $ 58,060
Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 6,538 |
Gross Unrealized Gains | 3 |
Gross Unrealized Losses | (70) |
Estimated Fair Value | $ 6,471 |

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- Definition 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). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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