FAIR VALUE (Fair value measurement non-recurring) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	$ 6,236	$ 6,624
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	43,037	57,949
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0	0
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	31,175	34,488
Loans held for sale	43,037	57,949
Other real estate owned	6,236	6,624
Fair Value, Measurements, Nonrecurring | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	6,218	5,189
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	7,633	6,499
Fair Value, Measurements, Nonrecurring | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	859	12,082
Loans held for sale	(1,121)	(982)
Other real estate owned	(154)	1,044
Fair Value, Measurements, Nonrecurring | Changes Measurement | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	(917)	1,778
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	0	3,288
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	43,037	57,949
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	31,175	34,488
Loans held for sale	0	0
Other real estate owned	6,236	6,624
Fair Value, Measurements, Nonrecurring | Level 3 | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	6,218	5,189
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	7,633	6,499
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	7,271	12,451
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	0	0
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	7,271	12,451
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Commercial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	10,621	11,256
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	859	451
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	10,621	11,256
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Owner occupied commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,233	5,874
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Owner occupied commercial real estate | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	11,631
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Owner occupied commercial real estate | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Owner occupied commercial real estate | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Owner occupied commercial real estate | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,233	5,874
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Non-owner occupied commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	12,050	4,907
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Non-owner occupied commercial real estate | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Non-owner occupied commercial real estate | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Non-owner occupied commercial real estate | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Non-owner occupied commercial real estate | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	12,050	4,907
Real estate construction | Fair Value, Measurements, Nonrecurring | Commercial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Real estate construction | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Real estate construction | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Real estate construction | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Real estate construction | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	$ 0	$ 0