LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Troubled Debt Restructuring) (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($) contract	Jun. 30, 2019 USD ($) contract	Jun. 30, 2018 contract	Dec. 31, 2018 USD ($)
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	$ 6,594,000	$ 6,594,000		$ 13,422,000
TDRs on Nonaccrual Status	1,552,000	1,552,000		317,000
Total TDRs	8,146,000	8,146,000		13,739,000
Commitments to advance funds related to TDRs, maximum additional amounts	$ 49,000	$ 49,000		0
Number of Contracts | contract	2	3	0
Pre-modification Outstanding Recorded Investment	$ 756,000	$ 1,846,000
Post-modification Outstanding Recorded Investment	756,000	1,846,000
Commerical real estate - owner-occupied [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	0	0		200,000
TDRs on Nonaccrual Status	273,000	273,000		78,000
Total TDRs	273,000	273,000		278,000
Commercial real estate - investment properties [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	699,000	699,000		5,606,000
TDRs on Nonaccrual Status	1,077,000	1,077,000		0
Total TDRs	$ 1,776,000	$ 1,776,000		5,606,000
Number of Contracts | contract	0	1
Pre-modification Outstanding Recorded Investment	$ 0	$ 1,090,000
Post-modification Outstanding Recorded Investment	0	1,090,000
Commercial business [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	550,000	550,000		391,000
TDRs on Nonaccrual Status	0	0		0
Total TDRs	$ 550,000	$ 550,000		391,000
Number of Contracts | contract	1	1
Pre-modification Outstanding Recorded Investment	$ 160,000	$ 160,000
Post-modification Outstanding Recorded Investment	160,000	160,000
Agricultural business, including secured by farmland [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	2,320,000	2,320,000		2,561,000
TDRs on Nonaccrual Status	0	0		0
Total TDRs	$ 2,320,000	$ 2,320,000		2,561,000
Number of Contracts | contract	1	1
Pre-modification Outstanding Recorded Investment	$ 596,000	$ 596,000
Post-modification Outstanding Recorded Investment	596,000	596,000
One- to four-family residential [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	2,836,000	2,836,000		4,469,000
TDRs on Nonaccrual Status	202,000	202,000		239,000
Total TDRs	3,038,000	3,038,000		4,708,000
Consumer secured by one- to four-family [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	130,000	130,000		133,000
TDRs on Nonaccrual Status	0	0		0
Total TDRs	130,000	130,000		133,000
Consumer - other [Member]
Financing Receivable, Modifications [Line Items]
TDRs on Accrual Status	59,000	59,000		62,000
TDRs on Nonaccrual Status	0	0		0
Total TDRs	$ 59,000	$ 59,000		$ 62,000