Regulatory Capital (Details) - AuburnBank [Member] $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital	$ 96,096	$ 92,778
Tier One Leverage Capital to Average Assets	0.1032	0.1123
Tier One Leverage Capital Required for Capital Adequacy	$ 37,263	$ 33,043
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	0.0400	0.0400
Tier One Leverage Capital Required to be Well Capitalized	$ 46,579	$ 41,303
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	0.0500	0.0500
Common Equity Tier One Capital [Abstract]
Common Equity Tier One Capital Amount	$ 96,096	$ 92,778
Common Equity Tier One Captial To Risk Weighted Assets	0.1727	0.1728
Common Equity Tier One Captial Required For Capital Adequacy	$ 25,042	$ 24,162
Common Equity Tier One Captial Required for Capital Adequacy To Risk Weighted Assets	4.50%	4.50%
Common Equity Tier One Captial Required For Well Capitalized	$ 36,171	$ 34,901
Common Equity Tier One Captial Required For Well Capitalized To Risk Weighted Assets	6.50%	6.50%
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital	$ 96,096	$ 92,778
Tier One Risk Based Capital to Risk Weighted Assets	0.1727	0.1728
Tier One Risk Based Capital Required for Capital Adequacy	$ 33,389	$ 32,216
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	0.0600	0.0600
Tier One Risk Based Capital Required to be Well Capitalized	$ 44,519	$ 42,955
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	0.0800	0.0800
Total Risk-Based Capital [Abstract]
Total Risk Based Capital	$ 101,906	$ 97,291
Total Risk Based Capital to Risk Weighted Assets	0.1831	0.1812
Total Risk Based Capital Required for Capital Adequacy	$ 44,519	$ 42,955
Total Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	0.0800	0.0800
Total Risk Based Capital Required to be Well Capitalized	$ 55,648	$ 53,693
Total Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	0.1000	0.1000

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