GOODWILL AND OTHER INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Oct. 01, 2018	May 18, 2018	Aug. 31, 2016	Apr. 29, 2016	Dec. 05, 2014
Goodwill	$ 19,574	$ 19,574	$ 19,574
Deposit based intangible assets	4,537	5,043	6,746
Amortization expense	506	677
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	503	594					$ 1,206
Amortization expense	90	121
Future Amortization Expense	121
Eagle River
Goodwill						$ 1,839
Deposit based intangible assets	554	629				$ 993
Amortization expense	74	99
Future Amortization Expense	99
Niagara Bancorporation
Goodwill					$ 50
Deposit based intangible assets	178	200			$ 300
Amortization expense	23	30
Future Amortization Expense	30
FFNM
Goodwill				$ 12,628
Deposit based intangible assets	2,219	2,436		$ 2,894
Amortization expense	217	299
Future Amortization Expense	290
Lincoln Community Bank
Goodwill			1,252
Deposit based intangible assets	1,083	1,184	$ 1,353
Amortization expense	102	$ 128
Future Amortization Expense	$ 135