FAIR VALUE - Summary of carrying amounts and estimated fair values for financial instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets:
Cash and cash equivalents	$ 254,442	$ 196,512	$ 386,983
Held-to-maturity securities, net of ACL	66,617	74,718
Financing receivable loan	2,530,915	2,469,413
Accrued interest receivable	11,428	10,445
Liabilities:
FHLB borrowings – fixed rate	125,711	146,886
Subordinated notes	52,340	52,132
Accrued interest payable	3,793	1,125
Loans accounted for under the fair value option	13,726	23,321
Carrying Amount
Assets:
Cash and cash equivalents	254,442	196,512
Held-to-maturity securities, net of ACL	74,102	81,056
Financing receivable loan	2,493,258	2,428,909
Accrued interest receivable	11,428	10,445
Liabilities:
Term deposits	496,452	224,090
Non-term deposits	2,032,587	2,181,139
FHLB borrowings – fixed rate	41,175	141,498
FHLB borrowings – floating rate	50,000
FHLB borrowings – fixed rate	34,536	5,388
Accrued interest payable	3,793	1,125
Subordinated Notes | Carrying Amount
Liabilities:
Subordinated notes	52,340	52,132
Level 1
Liabilities:
Term deposits due within one year	414,600	181,000
Level 1 | Estimate of Fair Value Measurement
Assets:
Cash and cash equivalents	254,442	196,512
Held-to-maturity securities, net of ACL	243	234
Accrued interest receivable	11,428	10,445
Liabilities:
Term deposits	414,613	181,036
Non-term deposits	2,032,587	2,181,139
FHLB borrowings – fixed rate	3,539	5,388
Accrued interest payable	3,793	1,125
Level 2 | Estimate of Fair Value Measurement
Assets:
Held-to-maturity securities, net of ACL	58,229	67,433
Liabilities:
FHLB borrowings – fixed rate	41,372	141,867
FHLB borrowings – floating rate	49,986
FHLB borrowings – fixed rate	30,936
Significant Unobservable Inputs (Level 3) | Estimate of Fair Value Measurement
Assets:
Held-to-maturity securities, net of ACL	8,144	7,051
Financing receivable loan	2,395,468	2,356,085
Liabilities:
Term deposits	82,564	43,586
Significant Unobservable Inputs (Level 3) | Subordinated Notes | Estimate of Fair Value Measurement
Liabilities:
Subordinated notes	$ 48,228	$ 60,384