FAIR VALUE - QUANTITATIVE INFORMATION (Details) $ in Thousands	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Fair Value Measurements
Mortgage servicing rights	$ 1,573	$ 1,536
Non-recurring
Fair Value Measurements
Impaired loans, at fair value	1,400	993
Other real estate owned	519	246
Mortgage servicing rights	1,100	430
Non-recurring | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Other real estate owned	1,107
Mortgage servicing rights		430
Non-recurring | Discounted cash flow | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Mortgage servicing rights	1,107	430
Non-recurring | 1-4 family residential | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Impaired loans, at fair value	200	993
Other real estate owned	40
Non-recurring | 1-4 family residential | Sales comparison | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Impaired loans, at fair value	200	993
Other real estate owned	40
Non-recurring | Multi-family residential | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Impaired loans, at fair value	1,242
Non-recurring | Multi-family residential | Income approach | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Impaired loans, at fair value	1,242
Non-recurring | Agricultural | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Other real estate owned	233
Non-recurring | Agricultural | Sales comparison | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Other real estate owned	233
Non-recurring | Commercial | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Other real estate owned	246	246
Non-recurring | Commercial | Sales comparison | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Other real estate owned	$ 246
Non-recurring | Commercial | Income approach | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Other real estate owned		$ 246
Non-recurring | Minimum | Discounted cash flow | Significant Unobservable Inputs (Level 3) | Measurement Input, Constant Prepayment Rate [Member]
Fair Value Measurements
Servicing asset, measurement input	9	7
Non-recurring | Minimum | 1-4 family residential | Sales comparison | Significant Unobservable Inputs (Level 3) | Measurement Input, Comparability Adjustment [Member]
Fair Value Measurements
Impaired loans - measurement input	(1)	(21)
Other real estate owned, measurement input	(4)
Non-recurring | Minimum | Multi-family residential | Income approach | Significant Unobservable Inputs (Level 3) | Measurement Input, Cap Rate [Member]
Fair Value Measurements
Impaired loans - measurement input	7
Non-recurring | Minimum | Agricultural | Sales comparison | Significant Unobservable Inputs (Level 3) | Measurement Input, Comparability Adjustment [Member]
Fair Value Measurements
Other real estate owned, measurement input	0
Non-recurring | Minimum | Commercial | Sales comparison | Significant Unobservable Inputs (Level 3) | Measurement Input, Comparability Adjustment [Member]
Fair Value Measurements
Other real estate owned, measurement input	(6)
Non-recurring | Minimum | Commercial | Income approach | Significant Unobservable Inputs (Level 3) | Measurement Input, Cap Rate [Member]
Fair Value Measurements
Other real estate owned, measurement input		10
Non-recurring | Maximum | Discounted cash flow | Significant Unobservable Inputs (Level 3) | Measurement Input, Constant Prepayment Rate [Member]
Fair Value Measurements
Servicing asset, measurement input	20	25
Non-recurring | Maximum | 1-4 family residential | Sales comparison | Significant Unobservable Inputs (Level 3) | Measurement Input, Comparability Adjustment [Member]
Fair Value Measurements
Impaired loans - measurement input	21	7
Other real estate owned, measurement input	11
Non-recurring | Maximum | Multi-family residential | Income approach | Significant Unobservable Inputs (Level 3) | Measurement Input, Cap Rate [Member]
Fair Value Measurements
Impaired loans - measurement input	7
Non-recurring | Maximum | Agricultural | Sales comparison | Significant Unobservable Inputs (Level 3) | Measurement Input, Comparability Adjustment [Member]
Fair Value Measurements
Other real estate owned, measurement input	26
Non-recurring | Maximum | Commercial | Sales comparison | Significant Unobservable Inputs (Level 3) | Measurement Input, Comparability Adjustment [Member]
Fair Value Measurements
Other real estate owned, measurement input	8
Non-recurring | Maximum | Commercial | Income approach | Significant Unobservable Inputs (Level 3) | Measurement Input, Cap Rate [Member]
Fair Value Measurements
Other real estate owned, measurement input		10
Non-recurring | Weighted average | Discounted cash flow | Significant Unobservable Inputs (Level 3) | Measurement Input, Constant Prepayment Rate [Member]
Fair Value Measurements
Servicing asset, measurement input	(12)	9
Non-recurring | Weighted average | 1-4 family residential | Sales comparison | Significant Unobservable Inputs (Level 3) | Measurement Input, Comparability Adjustment [Member]
Fair Value Measurements
Impaired loans - measurement input	1	(7)
Other real estate owned, measurement input	(29)
Non-recurring | Weighted average | Multi-family residential | Income approach | Significant Unobservable Inputs (Level 3) | Measurement Input, Cap Rate [Member]
Fair Value Measurements
Impaired loans - measurement input	(7)
Non-recurring | Weighted average | Agricultural | Sales comparison | Significant Unobservable Inputs (Level 3) | Measurement Input, Comparability Adjustment [Member]
Fair Value Measurements
Other real estate owned, measurement input	(14)
Non-recurring | Weighted average | Commercial | Sales comparison | Significant Unobservable Inputs (Level 3) | Measurement Input, Comparability Adjustment [Member]
Fair Value Measurements
Other real estate owned, measurement input	(62)
Non-recurring | Weighted average | Commercial | Income approach | Significant Unobservable Inputs (Level 3) | Measurement Input, Cap Rate [Member]
Fair Value Measurements
Other real estate owned, measurement input		(10)