GOODWILL AND OTHER INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Oct. 01, 2018	Jun. 07, 2018	May 31, 2018	May 18, 2018	Aug. 31, 2016	Apr. 29, 2016	Dec. 05, 2014
Goodwill	$ 19,574	$ 22,024	$ 19,574
Deposit based intangible assets	5,212	5,720	6,746
Amortization expense	509	450
Future Amortization Expense	675
Amortization expense year one	675
Amortization expense year two	675
Amortization expense year three	675
Amortization expense year four	675
Amortization expense year five	675
PFC
Goodwill									$ 3,805
Deposit based intangible assets	624	714							$ 1,206
Amortization expense	90	121
Future Amortization Expense	121
Eagle River
Goodwill								$ 1,839
Deposit based intangible assets	654	728						$ 993
Amortization expense	74	99
Future Amortization Expense	99
Niagara Bancorporation
Goodwill							$ 50
Deposit based intangible assets	208	230					$ 300
Amortization expense	23	30
Future Amortization Expense	30
FFNM
Goodwill					$ 12,628	$ 12,628
Deposit based intangible assets	2,508	2,735				$ 2,894
Amortization expense	227	159
Future Amortization Expense	290
Lincoln Community Bank
Goodwill			1,252	$ 1,252
Deposit based intangible assets	1,218	1,313	$ 1,353
Amortization expense	95	$ 41
Future Amortization Expense	$ 135