LOANS (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Loans
Total loans	$ 1,044,177,000	$ 1,045,428,000	$ 1,058,776,000
Acquired portfolio
Acquired with deteriorated credit quality	5,331,000	5,960,000
Balance at the beginning of period	3,176,000	5,051,000
Accretion	(759,000)	(541,000)
Reclassification from nonaccretable difference	293,000	12,000
Balance at the end of period	2,710,000	4,522,000
Changes in the allowance for loan losses
Net charge off activity	116,000	129,000
Provision for loan losses	100,000	100,000
PFC
Acquired portfolio
Loans acquired - contractual payments	67,139,000
Nonaccretable difference	(2,234,000)
Expected cash flows	64,905,000
Accretable yield	(2,844,000)
Carrying balance at acquisition date	62,061,000
Balance at the beginning of period	105,000	128,000
Accretion	(90,000)
Reclassification from nonaccretable difference	52,000
Balance at the end of period	67,000	128,000
Eagle River
Acquired portfolio
Loans acquired - contractual payments	84,138,000
Nonaccretable difference	(1,172,000)
Expected cash flows	82,966,000
Accretable yield	(2,091,000)
Carrying balance at acquisition date	80,875,000
Balance at the beginning of period	209,000	229,000
Accretion	(77,000)	(16,000)
Reclassification from nonaccretable difference	58,000
Balance at the end of period	190,000	213,000
Niagara Bancorporation
Acquired portfolio
Loans acquired - contractual payments	32,660,000
Nonaccretable difference	(265,000)
Expected cash flows	32,395,000
Accretable yield	(688,000)
Carrying balance at acquisition date	31,707,000
Balance at the beginning of period	19,000	95,000
Accretion	(4,000)	(51,000)
Reclassification from nonaccretable difference	3,000
Balance at the end of period	18,000	44,000
FFNM
Acquired portfolio
Loans acquired - contractual payments	192,742,000
Nonaccretable difference	(2,100,000)
Expected cash flows	190,642,000
Accretable yield	(5,198,000)
Carrying balance at acquisition date	185,444,000
Balance at the beginning of period	2,471,000	4,017,000
Accretion	(547,000)	(410,000)
Reclassification from nonaccretable difference	177,000
Balance at the end of period	2,101,000	3,607,000
Lincoln Community Bank
Acquired portfolio
Loans acquired - contractual payments	39,601,000
Nonaccretable difference	(421,000)
Expected cash flows	39,180,000
Accretable yield	(633,000)
Carrying balance at acquisition date	38,547,000
Balance at the beginning of period	372,000	582,000
Accretion	(41,000)	(64,000)
Reclassification from nonaccretable difference	3,000	12,000
Balance at the end of period	334,000	530,000
Commercial real estate
Loans
Total loans	522,659,000	498,471,000	514,394,000
Acquired portfolio
Acquired with deteriorated credit quality	1,739,000	2,763,000
Changes in the allowance for loan losses
Provision for loan losses	623,000	(109,000)
Commercial, financial, and agricultural
Loans
Total loans	207,727,000	201,089,000	211,023,000
Acquired portfolio
Acquired with deteriorated credit quality	2,416,000	1,419,000
Changes in the allowance for loan losses
Provision for loan losses	502,000	372,000
Commercial construction
Loans
Total loans	29,971,000	33,118,000	40,107,000
Acquired portfolio
Acquired with deteriorated credit quality	367,000	365,000
Changes in the allowance for loan losses
Provision for loan losses	27,000	(1,000)
One to four family residential real estate
Loans
Total loans	244,059,000	281,104,000	253,918,000
Acquired portfolio
Acquired with deteriorated credit quality	808,000	1,161,000
Changes in the allowance for loan losses
Provision for loan losses	291,000	60,000
Consumer
Loans
Total loans	20,375,000	19,624,000	21,238,000
Acquired portfolio
Acquired with deteriorated credit quality	1,000	39,000
Changes in the allowance for loan losses
Provision for loan losses	33,000	49,000
Consumer construction
Loans
Total loans	19,386,000	12,022,000	$ 18,096,000
Acquired portfolio
Acquired with deteriorated credit quality		213,000
Changes in the allowance for loan losses
Provision for loan losses	7,000
Acquired Impaired
Acquired portfolio
Balance at the beginning of period	959,000	1,078,000
Accretion	(411,000)	(15,000)
Reclassification from nonaccretable difference	293,000	12,000
Balance at the end of period	841,000	1,075,000
Acquired Impaired | PFC
Acquired portfolio
Loans acquired - contractual payments	13,290,000
Nonaccretable difference	(2,234,000)
Expected cash flows	11,056,000
Accretable yield	(744,000)
Carrying balance at acquisition date	10,312,000
Balance at the beginning of period	105,000	128,000
Accretion	(90,000)
Reclassification from nonaccretable difference	52,000
Balance at the end of period	67,000	128,000
Acquired Impaired | Eagle River
Acquired portfolio
Loans acquired - contractual payments	3,401,000
Nonaccretable difference	(1,172,000)
Expected cash flows	2,229,000
Accretable yield	(391,000)
Carrying balance at acquisition date	1,838,000
Balance at the beginning of period	209,000	213,000
Accretion	(77,000)
Reclassification from nonaccretable difference	58,000
Balance at the end of period	190,000	213,000
Acquired Impaired | Niagara Bancorporation
Acquired portfolio
Loans acquired - contractual payments	2,105,000
Nonaccretable difference	(265,000)
Expected cash flows	1,840,000
Accretable yield	(88,000)
Carrying balance at acquisition date	1,752,000
Balance at the beginning of period	19,000	26,000
Accretion	(4,000)
Reclassification from nonaccretable difference	3,000
Balance at the end of period	18,000	26,000
Acquired Impaired | FFNM
Acquired portfolio
Loans acquired - contractual payments	5,440,000
Nonaccretable difference	(2,100,000)
Expected cash flows	3,340,000
Accretable yield	(700,000)
Carrying balance at acquisition date	2,640,000
Balance at the beginning of period	518,000	571,000
Accretion	(237,000)
Reclassification from nonaccretable difference	177,000
Balance at the end of period	458,000	571,000
Acquired Impaired | Lincoln Community Bank
Acquired portfolio
Loans acquired - contractual payments	1,901,000
Nonaccretable difference	(421,000)
Expected cash flows	1,480,000
Accretable yield	(140,000)
Carrying balance at acquisition date	1,340,000
Balance at the beginning of period	108,000	140,000
Accretion	(3,000)	(15,000)
Reclassification from nonaccretable difference	3,000	12,000
Balance at the end of period	108,000	137,000
Acquired Non-impaired
Acquired portfolio
Balance at the beginning of period	2,217,000	3,973,000
Accretion	(348,000)	(526,000)
Balance at the end of period	1,869,000	3,447,000
Acquired Non-impaired | PFC
Acquired portfolio
Loans acquired - contractual payments	53,849,000
Expected cash flows	53,849,000
Accretable yield	(2,100,000)
Carrying balance at acquisition date	51,749,000
Acquired Non-impaired | Eagle River
Acquired portfolio
Loans acquired - contractual payments	80,737,000
Expected cash flows	80,737,000
Accretable yield	(1,700,000)
Carrying balance at acquisition date	79,037,000
Balance at the beginning of period		16,000
Accretion		(16,000)
Acquired Non-impaired | Niagara Bancorporation
Acquired portfolio
Loans acquired - contractual payments	30,555,000
Expected cash flows	30,555,000
Accretable yield	(600,000)
Carrying balance at acquisition date	29,955,000
Balance at the beginning of period		69,000
Accretion		(51,000)
Balance at the end of period		18,000
Acquired Non-impaired | FFNM
Acquired portfolio
Loans acquired - contractual payments	187,302,000
Expected cash flows	187,302,000
Accretable yield	(4,498,000)
Carrying balance at acquisition date	182,804,000
Balance at the beginning of period	1,953,000	3,446,000
Accretion	(310,000)	(410,000)
Balance at the end of period	1,643,000	3,036,000
Acquired Non-impaired | Lincoln Community Bank
Acquired portfolio
Loans acquired - contractual payments	37,700,000
Expected cash flows	37,700,000
Accretable yield	(493,000)
Carrying balance at acquisition date	37,207,000
Balance at the beginning of period	264,000	442,000
Accretion	(38,000)	(49,000)
Balance at the end of period	$ 226,000	$ 393,000