Note 11 - Regulatory Matters (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended
		Jun. 08, 2015	Jan. 31, 2009	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Note 11 - Regulatory Matters (Details) [Line Items]
Dividends Payable (in Dollars)				$ 0	$ 113	$ 225
Safest Assets [Member]
Note 11 - Regulatory Matters (Details) [Line Items]
Risk Weighting of Assets				0.00%
Riskier Assets [Member]
Note 11 - Regulatory Matters (Details) [Line Items]
Risk Weighting of Assets				100.00%
Series A Preferred Stock [Member]
Note 11 - Regulatory Matters (Details) [Line Items]
Stock Redeemed or Called During Period, Shares (in Shares)		10,000
Preferred Stock, Liquidation Preference Per Share (in Dollars per share)		$ 1,000
Dividends Payable (in Dollars)		$ 58
Stock Issued During Period, Shares, New Issues (in Shares)			30,000
Citizens Northern [Member]
Note 11 - Regulatory Matters (Details) [Line Items]
Tier One Leverage Capital to Average Assets	[1]			10.31%	10.11%
Citizens Northern [Member] | Compliance [Member]
Note 11 - Regulatory Matters (Details) [Line Items]
Tier One Leverage Capital to Average Assets				9.00%

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