INCOME TAXES - Deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Allowance for loan losses	$ 1,919	$ 1,692
Nonaccrual interest	221	175
Deferred loan fees	119
Lease liabilities under operating leases	3,501
Unrealized losses on securities available for sale	1	46
Other	277
Total gross deferred tax assets	6,038	1,913
Deferred tax liabilities:
Deferred mortgage servicing fees	(2,535)	(1,389)
Deferred SBA servicing fees	(2,206)	(2,069)
Premises and equipment	(599)	(368)
Right-of-use assets under operating leases	(3,355)
Other	(254)	(16)
Total gross deferred tax liabilities	(8,949)	(3,842)
Net deferred tax liabilities	$ (2,911)	$ (1,929)