FAIR VALUE MEASUREMENTS - Level 3 inputs for financial instruments measured at fair value (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2021	Mar. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Debt Securities, Available-for-sale, Measurement Input [Extensible List]	us-gaap:MeasurementInputDiscountRateMember
Adjustments to the appraised values of impaired loans	$ 0	$ 0
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	5.375%	5.375%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	8.00%	8.00%