Note 17 - Regulatory Matters (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								3 Months Ended		12 Months Ended					3 Months Ended	39 Months Ended				1 Months Ended
	Dec. 31, 2009	Sep. 30, 2009	Jun. 30, 2010 Compliance [Member] Farmers Bank [Member]	Mar. 31, 2012 Compliance [Member] United Bank [Member]	Dec. 31, 2010 Compliance [Member] Citizens Northern [Member]	Sep. 30, 2010 Compliance [Member] Citizens Northern [Member]	Dec. 31, 2012 Safest Assets [Member]	Dec. 31, 2012 Riskier Assets [Member]	Sep. 30, 2012 Farmers Bank [Member]	Dec. 31, 2009 Farmers Bank [Member]	Dec. 31, 2010 Farmers Bank [Member]	Dec. 31, 2012 Farmers Bank [Member]		Dec. 31, 2011 Farmers Bank [Member]		Mar. 31, 2012 United Bank [Member]	Dec. 31, 2012 United Bank [Member]		Dec. 31, 2011 United Bank [Member]		Dec. 31, 2010 Citizens Northern [Member]	Dec. 31, 2012 Citizens Northern [Member]		Dec. 31, 2011 Citizens Northern [Member]
Risk Weighting of Assets							0.00%	100.00%
Common Stock, Dividends, Per Share, Declared (in Dollars per share)	$ 0.10	$ 0.25
Tier One Leverage Capital to Average Assets			8.00%	9.00%	8.00%	7.50%						9.68%	[1],[2]	9.47%	[1],[2]		9.45%	[1],[2]	8.44%	[1],[2]	8.04%	9.36%	[1],[2]	8.48%	[1],[2]
Payments for (Proceeds from) Other Investing Activities (in Dollars)										$ 11,000	$ 200					$ 2,500	$ 18,900				$ 250
Cash Dividends Paid to Parent Company (in Dollars)									$ 4,000
Capital to Risk Weighted Assets				13.00%								19.20%	[1],[3]	18.84%	[1],[3]		16.69%	[1],[3]	14.79%	[1],[3]		14.22%	[1],[3]	13.49%	[1],[3]

[1] See discussion below under the caption "Summary of Regulatory Agreements" for minimum capital ratios required as part of the bank's regulatory agreement.

[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.

[3] Tier 1 Risk-based and Total Risk-based Capital ratios are computed by dividing a bank's 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. The safest assets (e.g., government obligations) are assigned a weighting of 0% with riskier assets receiving higher ratings (e.g., ordinary commercial loans are assigned a weighting of 100%).