BUSINESS COMBINATIONS (Details)			1 Months Ended	12 Months Ended
	Aug. 31, 2016 USD ($) $ / shares shares	Apr. 29, 2016 USD ($) item $ / shares shares	Aug. 31, 2016 USD ($) item $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Business Acquisition [Line Items]
Assets				$ 985,367,000	$ 983,520,000
Purchase Price:
Shares outstanding (in Shares) | shares				6,294,930	6,263,371
Cash consideration					$ 1,900,000
Net assets acquired:
Goodwill				$ 5,694,000	5,694,000
Eagle River
Business Acquisition [Line Items]
Number of banking offices | item		3
Assets		$ 125,000,000
Purchase Price:
Shares outstanding (in Shares) | shares		85,776,000
Price per share / Cash Price | $ / shares		$ 145.73
Total purchase price		$ 12,500,000
Reimbursement of termination fees		(1,763,000)
Cash consideration		10,737,000
Net assets acquired:
Cash and cash equivalents		10,600,000
Securities available for sale, net of purchase accounting marks		23,296,000
FRB & FHLB Stock		575,000
Total Loans, net of purchase accounting marks		80,875,000
Premises and equipment		1,931,000
Other real estate owned		904,000
Deposit based intangible		993,000
Mortgage service rights		120,000
Deferred tax benefit - book for valuation marks		948,000
Bank owned life insurance		4,132,000
Other assets		323,000
Total assets		124,697,000
Non-interest bearing deposits		22,349,000
Interest bearing deposits		82,165,000
Total deposits		104,514,000
FHLB Borrowings		11,000,000
Other liabilities		285,000
Total liabilities		115,799,000
Net assets acquired		8,898,000
Goodwill		$ 1,839,000			$ 1,839,000
Number of days included into the pro-forma results					245 days
Data processing termination fees					$ 1,763,000
Other related expenses					954,000
Merger transaction related expenses before tax					2,717,000
Merger transaction related expenses after tax					1,793,000
Niagara Bancorporation
Business Acquisition [Line Items]
Number of banking offices | item			4
Assets	$ 67,000,000		$ 67,000,000
Purchase Price:
Shares outstanding (in Shares) | shares	4,354,000		4,354,000
Price per share / Cash Price | $ / shares	$ 1,682.36		$ 1,682.36
Total purchase price	$ 7,325,000
Net assets acquired:
Cash and cash equivalents	9,778,000		$ 9,778,000
Securities available for sale, net of purchase accounting marks	21,491,000		21,491,000
FRB & FHLB Stock	287,000		287,000
Total Loans, net of purchase accounting marks	31,707,000		31,707,000
Premises and equipment	926,000		926,000
Other real estate owned	301,000		301,000
Deposit based intangible	300,000		300,000
Mortgage service rights	87,000		87,000
Deferred tax benefit - book for valuation marks	397,000		397,000
Bank owned life insurance	1,109,000		1,109,000
Other assets	302,000		302,000
Total assets	66,685,000		66,685,000
Non-interest bearing deposits	5,396,000		5,396,000
Interest bearing deposits	53,788,000		53,788,000
Total deposits	59,184,000		59,184,000
Other liabilities	226,000		226,000
Total liabilities	59,410,000		59,410,000
Net assets acquired	7,275,000		7,275,000
Goodwill	$ 50,000		$ 50,000		$ 50,000
Number of days included into the pro-forma results					122 days
Merger transaction related expenses before tax					$ 384,000
Merger transaction related expenses after tax					253,000
Eagle River and Niagara
Unaudited proforma results
Net interest income				36,902,000	32,924,000
Noninterest income				5,129,000	4,865,000
Noninterest expense				30,857,000	26,851,000
Net income				$ 7,375,000	$ 7,219,000
Net income per diluted share | $ / shares				$ 1.18	$ 1.15
PARENT COMPANY
Business Acquisition [Line Items]
Assets				$ 101,445,000	$ 101,527,000
Net cash used in Eagle acquisition and reimbursement of contract termination fee					$ 19,825,000
Purchase Price:
Shares outstanding (in Shares) | shares				6,294,930	6,263,371