LOANS (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Oct. 01, 2018	May 18, 2018	Aug. 31, 2016	Apr. 29, 2016	Dec. 05, 2014
Loans
Total loans	$ 1,144,325,000	$ 1,059,942,000	$ 1,144,325,000	$ 1,059,942,000	$ 1,058,776,000
Acquired portfolio
Acquired with deteriorated credit quality	3,202,000	5,793,000	3,202,000	5,793,000
Balance at the beginning of period			3,176,000	5,051,000
Accretion			(1,570,000)	(1,746,000)
Reclassification from nonaccretable difference			455,000	275,000
Balance at the end of period	2,061,000	3,580,000	2,061,000	3,580,000
Changes in the allowance for loan losses
Net charge off activity			76,000	225,000
Provision for loan losses	400,000	50,000	600,000	350,000
PFC
Acquired portfolio
Loans acquired - contractual payments	67,139,000		67,139,000
Nonaccretable difference	(2,234,000)		(2,234,000)
Expected cash flows	64,905,000		64,905,000
Accretable yield	(2,844,000)		(2,844,000)
Carrying balance at acquisition date	62,061,000		62,061,000
Balance at the beginning of period			105,000	128,000
Accretion			(202,000)	(81,000)
Reclassification from nonaccretable difference			151,000	(60,000)
Balance at the end of period	54,000	107,000	54,000	107,000
Eagle River
Acquired portfolio
Loans acquired - contractual payments	84,138,000		84,138,000
Nonaccretable difference	(1,172,000)		(1,172,000)
Expected cash flows	82,966,000		82,966,000
Accretable yield	(2,091,000)		(2,091,000)
Carrying balance at acquisition date	80,875,000		80,875,000
Balance at the beginning of period			209,000	229,000
Accretion			(104,000)	(33,000)
Reclassification from nonaccretable difference			78,000	(13,000)
Balance at the end of period	183,000	209,000	183,000	209,000
Niagara Bancorporation
Acquired portfolio
Loans acquired - contractual payments	32,660,000		32,660,000
Nonaccretable difference	(265,000)		(265,000)
Expected cash flows	32,395,000		32,395,000
Accretable yield	(688,000)		(688,000)
Carrying balance at acquisition date	31,707,000		31,707,000
Balance at the beginning of period			19,000	95,000
Accretion			(27,000)	(83,000)
Reclassification from nonaccretable difference			20,000	11,000
Balance at the end of period	12,000	23,000	12,000	23,000
FFNM
Acquired portfolio
Loans acquired - contractual payments	192,742,000		192,742,000
Nonaccretable difference	(2,100,000)		(2,100,000)
Expected cash flows	190,642,000		190,642,000
Accretable yield	(5,198,000)		(5,198,000)
Carrying balance at acquisition date	185,444,000		185,444,000
Balance at the beginning of period			2,471,000	4,017,000
Accretion			(1,125,000)	(1,302,000)
Reclassification from nonaccretable difference			200,000	109,000
Balance at the end of period	1,546,000	2,824,000	1,546,000	2,824,000
Lincoln Community Bank
Acquired portfolio
Loans acquired - contractual payments	39,601,000		39,601,000
Nonaccretable difference	(421,000)		(421,000)
Expected cash flows	39,180,000		39,180,000
Accretable yield	(633,000)		(633,000)
Carrying balance at acquisition date	38,547,000		38,547,000
Balance at the beginning of period			372,000	582,000
Accretion			(112,000)	(247,000)
Reclassification from nonaccretable difference			6,000	82,000
Balance at the end of period	266,000	417,000	266,000	417,000
Commercial real estate | Commercial Real Estate Portfolio Segment [Member]
Loans
Total loans	499,793,000	508,332,000	499,793,000	508,332,000	514,394,000
Acquired portfolio
Acquired with deteriorated credit quality	1,853,000	2,189,000	1,853,000	2,189,000
Changes in the allowance for loan losses
Provision for loan losses	28,000	(6,000)	586,000	(594,000)
Commercial, financial, and agricultural | Commercial loan portfolio
Loans
Total loans	326,771,000	209,872,000	326,771,000	209,872,000	211,023,000
Acquired portfolio
Acquired with deteriorated credit quality	248,000	2,207,000	248,000	2,207,000
Changes in the allowance for loan losses
Provision for loan losses	(77,000)	326,000	772,000	638,000
Commercial construction loan receivables [Member] | Commercial construction loan receivables [Member]
Loans
Total loans	39,162,000	34,511,000	39,162,000	34,511,000	40,107,000
Acquired portfolio
Acquired with deteriorated credit quality	181,000	377,000	181,000	377,000
Changes in the allowance for loan losses
Provision for loan losses	(83,000)		(27,000)	(25,000)
One to four family residential real estate | Residential Portfolio Segment [Member]
Loans
Total loans	237,336,000	268,333,000	237,336,000	268,333,000	253,918,000
Acquired portfolio
Acquired with deteriorated credit quality	903,000	991,000	903,000	991,000
Changes in the allowance for loan losses
Provision for loan losses	(12,000)	(29,000)	261,000	109,000
Consumer | Consumer Portfolio Segment [Member]
Loans
Total loans	19,575,000	20,214,000	19,575,000	20,214,000	21,238,000
Acquired portfolio
Acquired with deteriorated credit quality	17,000	29,000	17,000	29,000
Changes in the allowance for loan losses
Provision for loan losses	5,000	207,000	30,000	293,000
Consumer construction | Consumer construction
Loans
Total loans	21,688,000	18,680,000	21,688,000	18,680,000	$ 18,096,000
Changes in the allowance for loan losses
Provision for loan losses		6,000	(1,000)	5,000
Acquired Impaired
Acquired portfolio
Balance at the beginning of period			959,000	1,078,000
Accretion			(627,000)	(366,000)
Reclassification from nonaccretable difference			470,000	275,000
Balance at the end of period	802,000	987,000	802,000	987,000
Acquired Impaired | PFC
Acquired portfolio
Loans acquired - contractual payments	13,290,000		13,290,000							$ 13,290,000
Nonaccretable difference	(2,234,000)		(2,234,000)
Expected cash flows	11,056,000		11,056,000
Accretable yield	(744,000)		(744,000)
Carrying balance at acquisition date	10,312,000		10,312,000
Balance at the beginning of period			105,000	128,000
Accretion			(202,000)	(81,000)
Reclassification from nonaccretable difference			151,000	(60,000)
Balance at the end of period	54,000	107,000	54,000	107,000
Acquired Impaired | Eagle River
Acquired portfolio
Loans acquired - contractual payments	3,401,000		3,401,000						$ 3,401,000
Nonaccretable difference	(1,172,000)		(1,172,000)
Expected cash flows	2,229,000		2,229,000
Accretable yield	(391,000)		(391,000)
Carrying balance at acquisition date	1,838,000		1,838,000
Balance at the beginning of period			209,000	213,000
Accretion			(104,000)	(17,000)
Reclassification from nonaccretable difference			78,000	(13,000)
Balance at the end of period	183,000	209,000	183,000	209,000
Acquired Impaired | Niagara Bancorporation
Acquired portfolio
Loans acquired - contractual payments	2,105,000		2,105,000					$ 2,105,000
Nonaccretable difference	(265,000)		(265,000)
Expected cash flows	1,840,000		1,840,000
Accretable yield	(88,000)		(88,000)
Carrying balance at acquisition date	1,752,000		1,752,000
Balance at the beginning of period			19,000	26,000
Accretion			(27,000)	(14,000)
Reclassification from nonaccretable difference			20,000	11,000
Balance at the end of period	12,000	23,000	12,000	23,000
Acquired Impaired | FFNM
Acquired portfolio
Loans acquired - contractual payments	5,440,000		5,440,000				$ 5,440,000
Nonaccretable difference	(2,100,000)		(2,100,000)
Expected cash flows	3,340,000		3,340,000
Accretable yield	(700,000)		(700,000)
Carrying balance at acquisition date	2,640,000		2,640,000
Balance at the beginning of period			518,000	571,000
Accretion			(287,000)	(145,000)
Reclassification from nonaccretable difference			215,000	109,000
Balance at the end of period	446,000	535,000	446,000	535,000
Acquired Impaired | Lincoln Community Bank
Acquired portfolio
Loans acquired - contractual payments	1,901,000		1,901,000			$ 1,901,000
Nonaccretable difference	(421,000)		(421,000)
Expected cash flows	1,480,000		1,480,000
Accretable yield	(140,000)		(140,000)
Carrying balance at acquisition date	1,340,000		1,340,000
Balance at the beginning of period			108,000	140,000
Accretion			(7,000)	(109,000)
Reclassification from nonaccretable difference			6,000	82,000
Balance at the end of period	107,000	113,000	107,000	113,000
Acquired Non-impaired
Acquired portfolio
Balance at the beginning of period			2,217,000	3,973,000
Accretion			(943,000)	(1,380,000)
Reclassification from nonaccretable difference			(15,000)
Balance at the end of period	1,259,000	2,593,000	1,259,000	2,593,000
Acquired Non-impaired | PFC
Acquired portfolio
Loans acquired - contractual payments	53,849,000		53,849,000
Expected cash flows	53,849,000		53,849,000
Accretable yield	(2,100,000)		(2,100,000)
Carrying balance at acquisition date	51,749,000		51,749,000
Acquired Non-impaired | Eagle River
Acquired portfolio
Loans acquired - contractual payments	80,737,000		80,737,000
Expected cash flows	80,737,000		80,737,000
Accretable yield	(1,700,000)		(1,700,000)
Carrying balance at acquisition date	79,037,000		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		30,555,000
Expected cash flows	30,555,000		30,555,000
Accretable yield	(600,000)		(600,000)
Carrying balance at acquisition date	29,955,000		29,955,000
Balance at the beginning of period				69,000
Accretion				(69,000)
Acquired Non-impaired | FFNM
Acquired portfolio
Loans acquired - contractual payments	187,302,000		187,302,000
Expected cash flows	187,302,000		187,302,000
Accretable yield	(4,498,000)		(4,498,000)
Carrying balance at acquisition date	182,804,000		182,804,000
Balance at the beginning of period			1,953,000	3,446,000
Accretion			(838,000)	(1,157,000)
Reclassification from nonaccretable difference			(15,000)
Balance at the end of period	1,100,000	2,289,000	1,100,000	2,289,000
Acquired Non-impaired | Lincoln Community Bank
Acquired portfolio
Loans acquired - contractual payments	37,700,000		37,700,000
Expected cash flows	37,700,000		37,700,000
Accretable yield	(493,000)		(493,000)
Carrying balance at acquisition date	37,207,000		37,207,000
Balance at the beginning of period			264,000	442,000
Accretion			(105,000)	(138,000)
Balance at the end of period	$ 159,000	$ 304,000	$ 159,000	$ 304,000