Note 11 - Regulatory Matters - Regulatory Ratios of the Consolidated Company and Its Subsidiary Banks (Details)		Jun. 30, 2016	Dec. 31, 2015
Consolidated Entities [Member]
Common Equity Tier 1 Risk-based Capital	[1]	15.89%	14.91%
Tier 1 Risk-based Capital	[1]	18.74%	19.00%
Total Risk-based Capital	[1]	19.56%	19.89%
Tier 1 Leverage	[2]	12.13%	12.46%
Farmers Bank [Member]
Common Equity Tier 1 Risk-based Capital	[1]	15.87%	15.57%
Tier 1 Risk-based Capital	[1]	15.87%	15.57%
Total Risk-based Capital	[1]	16.58%	16.35%
Tier 1 Leverage	[2]	9.17%	9.20%
United Bank [Member]
Common Equity Tier 1 Risk-based Capital	[1]	17.23%	18.67%
Tier 1 Risk-based Capital	[1]	17.23%	18.67%
Total Risk-based Capital	[1]	18.20%	19.68%
Tier 1 Leverage	[2]	12.05%	12.89%
First Citizens Bank [Member]
Common Equity Tier 1 Risk-based Capital	[1]	13.80%	13.55%
Tier 1 Risk-based Capital	[1]	13.80%	13.55%
Total Risk-based Capital	[1]	14.41%	14.17%
Tier 1 Leverage	[2]	9.63%	9.20%
Citizens Northern [Member]
Common Equity Tier 1 Risk-based Capital	[1]	14.72%	14.42%
Tier 1 Risk-based Capital	[1]	14.72%	14.42%
Total Risk-based Capital	[1]	15.82%	15.67%
Tier 1 Leverage	[2]	10.25%	10.79%

[1] Common Equity Tier 1 Risked-based, Tier 1 Risk-based, and Total Risk-based Capital ratios are computed by dividing a bank's Common Equity Tier 1, Tier 1 or Total Capital, as defined by regulation, by a risk-weighted sum of the bank's assets, with the risk weighting determined by general standards established by regulation.

[2] Tier 1 Leverage ratio is computed by dividing a bank's Tier 1 Capital by its total quarterly average assets, as defined by regulation.