ALLOWANCE FOR LOAN AND LEASE LOSSES AND CREDIT QUALITY INFORMATION - Additional Information (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) loan SecurityLoan	Mar. 31, 2019 USD ($) loan	Dec. 31, 2019 USD ($) SecurityLoan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income	$ 200,000
Interest income on impaired loans		$ 200,000
Troubled debt restructuring related reserves	$ 700,000		$ 600,000
Usual sustained repayment performance period	6 months
TRD defaulted | loan	0	1
Subsequent default, loan amount		$ 100,000
Total TDRs	$ 17,943,000		$ 20,177,000
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of residential loans in the process of foreclosure | SecurityLoan	30		33
Total loans outstanding, residential loans	$ 2,700,000		$ 3,200,000
Commercial and industrial(1)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of residential loans in the process of foreclosure | SecurityLoan	24		29
Total loans outstanding, residential loans	$ 5,900,000		$ 9,500,000
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in allowance for loan losses	100,000	100,000
Troubled debt restructurings charged off	$ 0	$ 0
Total Residential and Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impairment loans, charge off period	90 days