LOANS, ALLOWANCE FOR LOAN LOSSES AND IMPAIRED LOANS - Loans by Loan Segment (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021 USD ($) contract	Mar. 31, 2020 USD ($) contract	Jun. 30, 2020 TDR	Dec. 31, 2020 USD ($)
Troubled Debt Restructuring
Number of Modifications	6	6	0
Recorded Investment | $	$ 17,442			$ 18,477
Commercial/agriculture real estate
Troubled Debt Restructuring
Number of Modifications	2	3
C&I/Agricultural operating
Troubled Debt Restructuring
Number of Modifications	1	0
Residential mortgage
Troubled Debt Restructuring
Number of Modifications	2	1
Consumer installment
Troubled Debt Restructuring
Number of Modifications	1	2
Originated Loans
Troubled Debt Restructuring
Number of Modifications	105	92
Recorded Investment | $	$ 17,442	$ 12,088
Originated Loans | Commercial/agriculture real estate
Troubled Debt Restructuring
Number of Modifications	30	28
Recorded Investment | $	$ 8,656	$ 6,415
Originated Loans | C&I/Agricultural operating
Troubled Debt Restructuring
Number of Modifications	14	14
Recorded Investment | $	$ 4,800	$ 2,065
Originated Loans | Residential mortgage
Troubled Debt Restructuring
Number of Modifications	52	42
Recorded Investment | $	$ 3,937	$ 3,539
Originated Loans | Consumer installment
Troubled Debt Restructuring
Number of Modifications	9	8
Recorded Investment | $	$ 49	$ 69