FAIR VALUE (Fair value measurement non-recurring) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	$ 4,744	$ 6,624
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	37,078	57,949
Significant Unobservable Inputs (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	38,179	34,488
Loans held for sale	37,078	57,949
Other real estate owned	4,744	6,624
Fair Value, Measurements, Nonrecurring | Servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	5,801	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	2,699	6,499
Fair Value, Measurements, Nonrecurring | Year-to- Date (Gains) Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,885	12,082
Loans held for sale	(1,335)	(982)
Other real estate owned	(119)	1,044
Fair Value, Measurements, Nonrecurring | Year-to- Date (Gains) Losses | Servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	(586)	1,778
Fair Value, Measurements, Nonrecurring | Year-to- Date (Gains) Losses | 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	(86)	3,288
Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (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 | Quoted Prices in Active Markets for Identical Assets (Level 1) | Servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	0	0
Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (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 | Significant Other Observable Inputs (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	37,078	57,949
Other real estate owned	0	0
Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2) | Servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	0	0
Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (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 | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	38,179	34,488
Loans held for sale	0	0
Other real estate owned	4,744	6,624
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3) | Servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	5,801	5,189
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (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	2,699	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	9,145	12,451
Fair Value, Measurements, Nonrecurring | Agricultural and agricultural real estate | Year-to- Date (Gains) Losses
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 | Quoted Prices in Active Markets for Identical Assets (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 | Significant Other Observable Inputs (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 | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	9,145	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	10,270	11,256
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Year-to- Date (Gains) Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	248	451
Commercial and industrial | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Quoted Prices in Active Markets for Identical Assets (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 | Significant Other Observable Inputs (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 | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	10,270	11,256
Owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	3,552	5,874
Owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Year-to- Date (Gains) Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	11,631
Owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	3,552	5,874
Non-owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	15,212	4,907
Non-owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Year-to- Date (Gains) Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,637	0
Non-owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Non-owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Non-owner occupied commercial real estate | Fair Value, Measurements, Nonrecurring | Commercial and industrial | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	$ 15,212	$ 4,907