FAIR VALUE (Fair value measurement non-recurring) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	$ 6,425	$ 6,153
Premises, furniture and equipment held for sale	3,251	7,258
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	35,427	52,577
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0	67,224
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	25,078	25,509
Loans held for sale	35,427	119,801
Other real estate owned	6,425	6,153
Fair Value, Measurements, Nonrecurring | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	5,039	7,143
Fair Value, Measurements, Nonrecurring | Premises, furniture and equipment held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Premises, furniture and equipment held for sale	3,251	7,258
Fair Value, Measurements, Nonrecurring | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	2,209	1,307
Loans held for sale	(1,234)	(1,870)
Other real estate owned	880	2,647
Fair Value, Measurements, Nonrecurring | Changes Measurement | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	1,579	58
Fair Value, Measurements, Nonrecurring | Changes Measurement | Premises, furniture and equipment held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Premises, furniture and equipment held for sale	954	59
Fair Value, Measurements, Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Loans held for sale	0	0
Other real estate owned	0	0
Fair Value, Measurements, Nonrecurring | Level 1 | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	0	0
Fair Value, Measurements, Nonrecurring | Level 1 | Premises, furniture and equipment held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Premises, furniture and equipment held for sale	0	0
Fair Value, Measurements, Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Loans held for sale	35,427	52,577
Other real estate owned	0	0
Fair Value, Measurements, Nonrecurring | Level 2 | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	0	0
Fair Value, Measurements, Nonrecurring | Level 2 | Premises, furniture and equipment held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Premises, furniture and equipment held for sale	0	0
Fair Value, Measurements, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	25,078	25,509
Loans held for sale	0	67,224
Other real estate owned	6,425	6,153
Fair Value, Measurements, Nonrecurring | Level 3 | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	5,039	7,143
Fair Value, Measurements, Nonrecurring | Level 3 | Premises, furniture and equipment held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Premises, furniture and equipment held for sale	3,251	7,258
Fair Value, Measurements, Nonrecurring | Agricultural and agricultural real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	11,536	11,070
Fair Value, Measurements, Nonrecurring | Agricultural and agricultural real estate | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,015	575
Fair Value, Measurements, Nonrecurring | Agricultural and agricultural real estate | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Fair Value, Measurements, Nonrecurring | Agricultural and agricultural real estate | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Fair Value, Measurements, Nonrecurring | Agricultural and agricultural real estate | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	11,536	11,070
Fair Value, Measurements, Nonrecurring | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,042	478
Fair Value, Measurements, Nonrecurring | Residential real estate | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	24	0
Fair Value, Measurements, Nonrecurring | Residential real estate | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Fair Value, Measurements, Nonrecurring | Residential real estate | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Fair Value, Measurements, Nonrecurring | Residential real estate | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,042	478
Fair Value, Measurements, Nonrecurring | Consumer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	645	624
Fair Value, Measurements, Nonrecurring | Consumer | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Fair Value, Measurements, Nonrecurring | Consumer | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Fair Value, Measurements, Nonrecurring | Consumer | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Fair Value, Measurements, Nonrecurring | Consumer | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	645	624
Commercial | Fair Value, Measurements, Nonrecurring | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	10,767	12,932
Commercial | Fair Value, Measurements, Nonrecurring | Commercial | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,098	660
Commercial | Fair Value, Measurements, Nonrecurring | Commercial | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial | Fair Value, Measurements, Nonrecurring | Commercial | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial | Fair Value, Measurements, Nonrecurring | Commercial | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	10,767	12,932
Commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,088	405
Commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	72	72
Commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	$ 1,088	$ 405