EMPLOYEE BENEFITS - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Employee stock ownership plan, maximum employer contribution as a percentage of participant's qualified compensation	5.00%
Employee stock ownership plan, total contributions accrued or paid	$ 1,146	$ 1,031
Employee stock ownership plan, shares held under plan (in shares)	1,287,897
Employee stock ownership plan, unallocated shares (in shares)	0
Cash surrender value of life insurance	$ 36,582		$ 35,510
Gain on proceeds from life insurance policies	277,000	0
Bonus expense	3,529	1,610
Executive Incentive Retirement Plan | Postretirement Life Insurance | Nonqualified Plan | Unfunded Plan
Defined Benefit Plan Disclosure [Line Items]
Cash surrender value of life insurance	36,582		35,510
Plan cost	588	$ 500	592
Plan obligation	$ 4,861		$ 4,383