LOANS - Average Recorded Investment and Interest Income Recognized on Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Business Activities Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	$ 6,924	$ 6,774
Cash Basis Interest Income Recognized	121	246
Business Activities Loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	3,913	4,387
Cash Basis Interest Income Recognized	66	157
Business Activities Loans | Commercial real estate | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	0	0
Cash basis interest income recognized, with no related allowance	0	0
Recorded investment, with related allowance	637	0
Cash basis interest income recognized, with related allowance	0	0
Business Activities Loans | Commercial real estate | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	2,541	2,768
Cash basis interest income recognized, with no related allowance	66	157
Recorded investment, with related allowance	735	1,619
Cash basis interest income recognized, with related allowance	0	0
Business Activities Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	600	513
Cash Basis Interest Income Recognized	8	13
Business Activities Loans | Commercial and industrial | Other Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	382	239
Cash basis interest income recognized, with no related allowance	6	4
Recorded investment, with related allowance	105	118
Cash basis interest income recognized, with related allowance	1	0
Business Activities Loans | Commercial and industrial | Agricultural and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	113	156
Cash basis interest income recognized, with no related allowance	1	9
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Business Activities Loans | Commercial and industrial | Tax exempt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	0	0
Cash basis interest income recognized, with no related allowance	0	0
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Business Activities Loans | Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	2,331	1,839
Cash Basis Interest Income Recognized	44	73
Business Activities Loans | Residential real estate | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	2,174	1,514
Cash basis interest income recognized, with no related allowance	39	73
Recorded investment, with related allowance	157	325
Cash basis interest income recognized, with related allowance	5	0
Business Activities Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	80	35
Cash Basis Interest Income Recognized	3	3
Business Activities Loans | Consumer | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	27	17
Cash basis interest income recognized, with no related allowance	0	1
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Business Activities Loans | Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	53	2
Cash basis interest income recognized, with no related allowance	3	2
Recorded investment, with related allowance	0	16
Cash basis interest income recognized, with related allowance	0	0
Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	598	0
Cash Basis Interest Income Recognized	2	0
Acquired Loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	136	0
Cash Basis Interest Income Recognized	0	0
Acquired Loans | Commercial real estate | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	0	0
Cash basis interest income recognized, with no related allowance	0	0
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Acquired Loans | Commercial real estate | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	136	0
Cash basis interest income recognized, with no related allowance	0	0
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Acquired Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	264	0
Cash Basis Interest Income Recognized	1	0
Acquired Loans | Commercial and industrial | Other Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	264	0
Cash basis interest income recognized, with no related allowance	1	0
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Acquired Loans | Commercial and industrial | Agricultural and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	0	0
Cash basis interest income recognized, with no related allowance	0	0
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Acquired Loans | Commercial and industrial | Tax exempt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	0	0
Cash basis interest income recognized, with no related allowance	0	0
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Acquired Loans | Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	140	0
Cash Basis Interest Income Recognized	1	0
Acquired Loans | Residential real estate | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	140	0
Cash basis interest income recognized, with no related allowance	1	0
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Acquired Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	58	0
Cash Basis Interest Income Recognized	0	0
Acquired Loans | Consumer | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	58	0
Cash basis interest income recognized, with no related allowance	0	0
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	0	0
Acquired Loans | Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment, with no related allowance	0	0
Cash basis interest income recognized, with no related allowance	0	0
Recorded investment, with related allowance	0	0
Cash basis interest income recognized, with related allowance	$ 0	$ 0