FAIR VALUE - Quantitative Information about Level 3 Value Measurements - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Impaired Loans | Minimum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	0.00%
Impaired Loans | Maximum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	50.00%
Impaired Loans | Commercial and industrial | Sales comparison approach | Minimum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	10.00%
Impaired Loans | Commercial and industrial | Sales comparison approach | Maximum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	30.00%
Impaired Loans | Commercial and industrial | Sales comparison approach | Average
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	18.00%
Impaired Loans | Agricultural | Sales comparison approach
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	10.00%
Impaired Loans | Agricultural | Sales comparison approach | Average
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	10.00%
Impaired Loans | Farm | Sales comparison approach
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	10.00%	10.00%
Impaired Loans | Farm | Sales comparison approach | Average
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	10.00%	10.00%
Impaired Loans | Other real estate | Sales comparison approach | Minimum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	16.00%
Impaired Loans | Other real estate | Sales comparison approach | Maximum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	31.00%
Impaired Loans | Other real estate | Sales comparison approach | Average
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	27.00%
Impaired Loans | Other | Sales comparison approach | Average
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)		10.00%
Other real estate owned | Minimum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	0.00%
Other real estate owned | Maximum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)	50.00%
Mortgage servicing rights | Cash flow analysis
Unobservable Inputs
Discount rate (as a percent)	10.00%	10.00%
Non-recurring basis | Significant Unobservable Inputs (Level 3) | Impaired Loans
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value
Fair Value	$ 2,537	$ 1,140
Non-recurring basis | Significant Unobservable Inputs (Level 3) | Impaired Loans | Commercial and industrial
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value
Fair Value	260
Non-recurring basis | Significant Unobservable Inputs (Level 3) | Impaired Loans | Farm
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value
Fair Value		58
Non-recurring basis | Significant Unobservable Inputs (Level 3) | Impaired Loans | Other
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value
Fair Value	560	$ 1,082
Non-recurring basis | Significant Unobservable Inputs (Level 3) | Impaired Loans | Other | Sales comparison approach | Minimum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)		0.00%
Non-recurring basis | Significant Unobservable Inputs (Level 3) | Impaired Loans | Other | Sales comparison approach | Maximum
Unobservable Inputs
Adjustment for differences between comparable sales, type of property, current status of property (as a percent)		20.00%
Non-recurring basis | Significant Unobservable Inputs (Level 3) | Mortgage servicing rights
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value
Fair Value	$ 1,083	$ 531