ALLOWANCE FOR CREDIT LOSSES - Allowance for credit losses for unfunded commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Beginning balance	$ 25,280	$ 23,693	$ 24,778
Ending balance	40,637	25,280	23,693
Unfunded Commitment
Financing Receivable, Recorded Investment [Line Items]
Beginning balance	378
Impact of implementation	2,981
Provision for credit losses for unfunded commitments	818	0	$ 0
Ending balance	$ 4,177	$ 378