FAIR VALUE (Quantitative Information about Level 3 fair value measurements) (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2019	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Premises, furniture and equipment held for sale		$ 3,251	$ 7,258
Interest rate lock commitments | Recurring Basis
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative assets		970	725
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale		0	67,224
Derivative assets		0	0
Level 3 | Interest rate lock commitments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative assets		970	725
Level 3 | Discounted cash flows
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale			67,224
Servicing rights		5,039	7,143
Level 3 | Modified appraised value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned		6,425	6,153
Level 3 | Modified appraised value | Commercial
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral dependent impaired loans		10,767	12,932
Level 3 | Modified appraised value | Commercial real estate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral dependent impaired loans		1,088	405
Level 3 | Modified appraised value | Agricultural and agricultural real estate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral dependent impaired loans		11,536	11,070
Level 3 | Modified appraised value | Residential real estate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral dependent impaired loans		1,042	478
Level 3 | Modified appraised value | Consumer
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral dependent impaired loans		645	624
Level 3 | Modified appraised value | Recurring Basis | Premises, furniture and equipment held for sale
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Premises, furniture and equipment held for sale		3,251	7,258
Level 3 | Interest rate lock commitments | Recurring Basis
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative assets		970	725
Level 3 | Interest rate lock commitments | Discounted cash flows
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative assets		$ 970	$ 725
Closing ratio | Level 3 | Weighted Average | Interest rate lock commitments | PrimeWest Mortgage Corporation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input		0.90
Closing ratio | Level 3 | Discounted cash flows | Weighted Average | Interest rate lock commitments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	0.91	0.90
Closing ratio | Level 3 | Discounted cash flows | Minimum | Interest rate lock commitments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	0	0
Closing ratio | Level 3 | Discounted cash flows | Maximum | Interest rate lock commitments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	0.99	0.99
Appraisal discount | Level 3 | Modified appraised value | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	0.00%	0.00%
Appraisal discount | Level 3 | Modified appraised value | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	10.00%	10.00%
Appraisal discount | Level 3 | Modified appraised value | Premises, furniture and equipment held for sale | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	0.00%	0.00%
Appraisal discount | Level 3 | Modified appraised value | Premises, furniture and equipment held for sale | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	10.00%	10.00%
Commercial | Appraisal discount | Level 3 | Modified appraised value | Commercial | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	0.00%	0.00%
Commercial | Appraisal discount | Level 3 | Modified appraised value | Commercial | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	8.00%	15.00%
Commercial | Appraisal discount | Level 3 | Modified appraised value | Commercial real estate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	0.00%	0.00%
Commercial | Appraisal discount | Level 3 | Modified appraised value | Commercial real estate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	19.00%	10.00%
Agricultural and agricultural real estate | Appraisal discount | Level 3 | Modified appraised value | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	0.00%	0.00%
Agricultural and agricultural real estate | Appraisal discount | Level 3 | Modified appraised value | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	24.00%	15.00%
Residential real estate | Appraisal discount | Level 3 | Modified appraised value | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	0.00%	0.00%
Residential real estate | Appraisal discount | Level 3 | Modified appraised value | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	24.00%	12.00%
Consumer | Valuation discount | Level 3 | Modified appraised value | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	0.00%	0.00%
Consumer | Valuation discount | Level 3 | Modified appraised value | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing assets, discount rate	14.00%	10.00%