SECURITIES - Securities carrying amount (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) item	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) item
SECURITIES.
Securities sold during the year	$ 0
Carrying amount of securities sold in the period		$ 358,000
Carrying value of securities pledged	$ 51,500,000		$ 50,800,000
Securities held in a gross unrealized loss position | item	3		27
Immaterial amount threshold	$ 1,000
Impairment loss on securities	0	$ 0
Accrued interest receivable for securities	$ 674,000		$ 1,100,000