LOANS AND ALLOWANCE FOR LOAN LOSSES - Loan Impairment average balance of impaired loans and interest income and cash basis interest - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Average recorded investment
Average Balance	$ 21,505	$ 17,695	$ 19,996
Commercial | Commercial and industrial
Average recorded investment
Average Balance	1,211	805	1,165
Commercial | Agricultural
Average recorded investment
Average Balance	1,668	998	31
Commercial real estate | Farm
Average recorded investment
Average Balance	1,442	933	401
Commercial real estate | Hotel
Average recorded investment
Average Balance	1,783	26	2,851
Commercial real estate | Construction and development
Average recorded investment
Average Balance	651	156	53
Commercial real estate | Other
Average recorded investment
Average Balance	4,635	4,800	5,734
Residential | 1-4 family
Average recorded investment
Average Balance	7,600	7,642	7,362
Residential | Home equity
Average recorded investment
Average Balance	1,699	2,212	2,268
Consumer | Direct
Average recorded investment
Average Balance	$ 816	$ 123	130
Consumer | Indirect
Average recorded investment
Average Balance			$ 1