Note 10 - Regulatory Matters (Detail) (USD $)	3 Months Ended						3 Months Ended		12 Months Ended			3 Months Ended	36 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]	Sep. 30, 2012 Farmers Bank [Member]	Dec. 31, 2009 Farmers Bank [Member]	Dec. 31, 2010 Farmers Bank [Member]	Sep. 30, 2012 Farmers Bank [Member]	Dec. 31, 2011 Farmers Bank [Member]	Mar. 31, 2012 United Bank [Member]	Sep. 30, 2012 United Bank [Member]	Dec. 31, 2011 United Bank [Member]	Dec. 31, 2010 Citizens Northern [Member]	Sep. 30, 2012 Citizens Northern [Member]	Dec. 31, 2011 Citizens Northern [Member]
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%				9.47%	9.47%		9.41%	8.44%	8.04%	9.01%	8.48%
Payments for (Proceeds from) Other Investing Activities (in Dollars)								$ 11,000,000	$ 200,000			$ 2,500,000	$ 18,900,000		$ 250,000
Cash Dividends Paid to Parent Company (in Dollars)							$ 4,000,000
Capital to Risk Weighted Assets				13.00%						18.96%	18.84%		16.60%	14.79%		14.09%	13.49%