LOANS - Summary of Impaired Loans, Excluding Purchased Impaired (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Impaired loans
Loans with allowance allocation	$ 21,688		$ 21,688		$ 27,437
Loans without allowance allocation	9,145		9,145		8,138
Carrying balance	30,833		30,833		35,575
Contractual balance	33,357		33,357		38,362
Specifically allocated allowance	1,834		1,834		$ 3,874
Average carrying balance of individually assessed loans	31,500	$ 8,800	34,100	$ 4,200
Interest income on individually assessed loans	$ 0	$ 0	$ 0	$ 0