FAIR VALUE - Fair Value of Assets and Liabilities Measured on a Nonrecurring Basis - (Details) - Non-recurring basis - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Assets:
Total impaired loans	$ 2,751		$ 2,751		$ 1,140
Impaired servicing rights	3,161		3,161		531
Recorded investment of impaired loans	3,700		3,700		2,393
Valuation allowance of impaired loans	949		949		1,253
Provision expenses of impaired loans	228	$ 426	634	$ 1,281
Gross outstanding balance of servicing rights	3,536		3,536		731
Valuation allowance of servicing rights			375		200
Change occurred in the valuation allowance	125	$ 25	175	$ 25
Commercial and industrial
Assets:
Total impaired loans	259		259		58
Recorded investment of impaired loans	344		344
Valuation allowance of impaired loans	85		85
Agricultural
Assets:
Total impaired loans	1,081		1,081
Recorded investment of impaired loans	1,450		1,450
Valuation allowance of impaired loans	369		369
Farm
Assets:
Total impaired loans	823		823
Recorded investment of impaired loans	1,105		1,105
Valuation allowance of impaired loans	282		282
Other
Assets:
Total impaired loans	588		588		1,082
Recorded investment of impaired loans	801		801
Valuation allowance of impaired loans	213		213
Significant Unobservable Inputs (Level 3)
Assets:
Total impaired loans	2,751		2,751		1,140
Impaired servicing rights	3,161		3,161		531
Significant Unobservable Inputs (Level 3) | Commercial and industrial
Assets:
Total impaired loans	259		259		58
Significant Unobservable Inputs (Level 3) | Agricultural
Assets:
Total impaired loans	1,081		1,081
Significant Unobservable Inputs (Level 3) | Farm
Assets:
Total impaired loans	823		823
Significant Unobservable Inputs (Level 3) | Other
Assets:
Total impaired loans	$ 588		$ 588		$ 1,082