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SUBORDINATED DEBENTURES (Details) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Sep. 30, 2015 | Mar. 31, 2021 | Mar. 31, 2020 | Dec. 31, 2017 | Dec. 31, 2020
Debt Instrument [Line Items] |  |  |  |  |
Fixed-to-floating rate subordinated debentures | $ 80.0 |  |  |  |
Subordinated notes payable, net |  | $ 197.2 |  |  | $ 114.1
Interest expense related to the subordinated debt |  | $ 1.9 | $ 1.3 |  |
Subordinated Debentures |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Fixed-to-floating rate subordinated debentures |  |  |  | $ 115.0 |
Fixed annual interest rate |  |  |  | 4.50% |
Basis points |  |  |  | 266.00% |
Callable Notes After Five Years | Subordinated Debentures |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Fixed-to-floating rate subordinated debentures | $ 40.0 |  |  |  |
Debt Instrument, Term | 5 years |  |  |  |
Fixed annual interest rate | 5.25% |  |  |  |
Debt instrument variable rate description | three-month LIBOR |  |  |  |
Basis points | 360.00% |  |  |  |
Callable Notes After Ten Years | Subordinated Debentures |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Fixed-to-floating rate subordinated debentures | $ 40.0 |  |  |  |
Debt Instrument, Term | 10 years |  |  |  |
Fixed annual interest rate | 5.75% |  |  |  |
Debt instrument variable rate description | three-month LIBOR |  |  |  |
Basis points | 345.00% |  |  |  |

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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
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