FAIR VALUE - Significant unobservable inputs (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Minimum | Fair value of collateral | Estimated cost of disposal/market adjustment
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Other real estate owned, measurement input	0.090
Maximum | Fair value of collateral | Estimated cost of disposal/market adjustment
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Other real estate owned, measurement input	0.738
Level 3 | Estimated cost of disposal/market adjustment
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Individually assessed loans, Valuation Technique [Extensible List]	Fair value of collateral	Fair value of collateral
Other real estate owned, valuation technique [Extensible List]	Fair value of collateral	Fair value of collateral
Level 3 | Embedded servicing value
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Commitments to originate real estate loans for sale, Valuation Technique [Extensible List]	Discounted cash flow	Discounted cash flow
Level 3 | Weighted average constant prepayment rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Mortgage servicing rights, Valuation Technique [Extensible List]	Discounted cash flow	Discounted cash flow
Level 3 | Weighted average discount rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Contingent consideration, Valuation Technique [Extensible List]	Discounted cash flow	Discounted cash flow
Level 3 | Fair value of collateral | Estimated cost of disposal/market adjustment
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Individually assessed loans	$ 9,224,000	$ 3,014,000
Individually assessed loans, measurement input	0.272	0.272
Individually assessed loans, Measurement Input [Extensible List]	Estimated cost of disposal/market adjustment	Estimated cost of disposal/market adjustment
Other real estate owned	$ 1,742,000	$ 1,159,000
Other real estate owned, measurement input [Extensible List]	Estimated cost of disposal/market adjustment	Estimated cost of disposal/market adjustment
Level 3 | Discounted cash flow | Embedded servicing value
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Commitments to originate real estate loans for sale	$ 32,000	$ 2,000
Commitments to originate real estate loans for sale, measurement input	0.010	0.010
Level 3 | Discounted cash flow | Weighted average constant prepayment rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Mortgage servicing rights	$ 76,000	$ 162,000
Mortgage servicing rights, Measurement Input [Extensible List]	Weighted average constant prepayment rate	Weighted average constant prepayment rate
Level 3 | Discounted cash flow | Weighted average discount rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Mortgage servicing rights, Measurement Input [Extensible List]	Weighted average discount rate	Weighted average discount rate
Contingent consideration	$ (8,216,000)	$ (5,150,000)
Level 3 | Discounted cash flow | Adequate compensation
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Business loans held for sale, measurement input	7	7
Mortgage servicing rights, Measurement Input [Extensible List]	Adequate compensation	Adequate compensation
Contingent consideration, Measurement Input [Extensible List]	Weighted average discount rate	Weighted average discount rate
Level 3 | Discounted cash flow | Probability of achievement
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Contingent consideration, Measurement Input [Extensible List]	Probability of achievement	Probability of achievement
Level 3 | Minimum | Fair value of collateral | Estimated cost of disposal/market adjustment
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Other real estate owned, measurement input	0.090	0.090
Level 3 | Minimum | Discounted cash flow | Weighted average constant prepayment rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Mortgage servicing rights, measurement input	0.050	0.042
Level 3 | Minimum | Discounted cash flow | Weighted average discount rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Mortgage servicing rights, measurement input	0.050	0.046
Contingent consideration, measurement input	0.067	0.067
Level 3 | Minimum | Discounted cash flow | Probability of achievement
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Contingent consideration, measurement input	0.820	1
Level 3 | Maximum | Fair value of collateral | Estimated cost of disposal/market adjustment
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Other real estate owned, measurement input	0.738	0.738
Level 3 | Maximum | Discounted cash flow | Weighted average constant prepayment rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Mortgage servicing rights, measurement input	0.144	0.051
Level 3 | Maximum | Discounted cash flow | Weighted average discount rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Mortgage servicing rights, measurement input	0.052	0.050
Contingent consideration, measurement input	0.191	0.069
Level 3 | Maximum | Discounted cash flow | Probability of achievement
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Contingent consideration, measurement input	1.000
Level 3 | Weighted Average | Fair value of collateral | Estimated cost of disposal/market adjustment
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Other real estate owned, measurement input	(0.588)	(0.458)
Level 3 | Weighted Average | Discounted cash flow | Weighted average constant prepayment rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Mortgage servicing rights, measurement input	(0.052)	(0.042)
Level 3 | Weighted Average | Discounted cash flow | Weighted average discount rate
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Mortgage servicing rights, measurement input	(0.052)	(0.049)
Contingent consideration, measurement input	(0.121)	(0.069)
Level 3 | Weighted Average | Discounted cash flow | Probability of achievement
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Contingent consideration, measurement input	(0.941)
Commitments to originate real estate loans for sale | Level 3 | Discounted cash flow | Embedded servicing value
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3
Commitments to originate real estate loans for sale, Measurement Input [Extensible List]	Embedded servicing value	Embedded servicing value