FAIR VALUE - Fair Value of Assets and Liabilities Measured on a Nonrecurring Basis - (Details) - Non-recurring basis - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Assets:
Total impaired loans	$ 2,775		$ 2,775		$ 1,140
Impaired servicing rights	1,145		1,145		531
Recorded investment of impaired loans	3,495		3,495		2,393
Valuation allowance of impaired loans	720		720		1,253
Provision expenses of impaired loans	354	$ 968	406	$ 1,056
Gross outstanding balance of servicing rights	1,395		1,395		731
Valuation allowance of servicing rights			250		200
Change occurred in the valuation allowance	50	$ 150	50	$ 150
Commercial and industrial
Assets:
Total impaired loans	256		256		58
Recorded investment of impaired loans	348		348
Valuation allowance of impaired loans	92		92
Agricultural
Assets:
Total impaired loans	1,179		1,179
Recorded investment of impaired loans	1,450		1,450
Valuation allowance of impaired loans	271		271
Farm
Assets:
Total impaired loans	880		880
Recorded investment of impaired loans	1,083		1,083
Valuation allowance of impaired loans	203		203
Other
Assets:
Total impaired loans	460		460		1,082
Recorded investment of impaired loans	614		614
Valuation allowance of impaired loans	154		154
Significant Unobservable Inputs (Level 3)
Assets:
Total impaired loans	2,775		2,775		1,140
Impaired servicing rights	1,145		1,145		531
Significant Unobservable Inputs (Level 3) | Commercial and industrial
Assets:
Total impaired loans	256		256		58
Significant Unobservable Inputs (Level 3) | Agricultural
Assets:
Total impaired loans	1,179		1,179
Significant Unobservable Inputs (Level 3) | Farm
Assets:
Total impaired loans	880		880
Significant Unobservable Inputs (Level 3) | Other
Assets:
Total impaired loans	$ 460		$ 460		$ 1,082