Note 9 - Fair Value Measurements and Disclosures (Details) - Estimated Fair Values and Carrying Amounts of Financial and Off-Balance Sheet Instruments (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Financial assets
Cash and cash equivalents, carrying amount	$ 19,524,000	$ 15,453,000	$ 11,662,000	$ 10,555,000
Cash and cash equivalents, fair value	19,524,000	15,453,000
Investment securities available-for-sale, fair value	407,248,000	401,502,000
Investment securities held-to-maturity, carrying amount	146,000	146,000
Investment securities held-to-maturity, fair value	162,000	166,000
Restricted investment in bank stocks, carrying amount	1,868,000	2,244,000
Restricted investment in bank stocks, fair value	1,868,000	2,244,000
Loans held-for-sale, carrying amount	385,000	1,616,000
Loans held-for-sale, fair value	400,000	1,674,000
Net loans, carrying amount	478,542,000	467,961,000
Net loans, fair value	475,868,000	474,330,000
Mortgage servicing rights, carrying amount	523,000	448,000
Mortgage servicing rights, fair value	635,000	464,000
Accrued interest receivable, carrying amount	2,644,000	2,803,000
Accrued interest receivable, fair value	2,644,000	2,803,000
Financial liabilities
Deposits, carrying amount	827,952,000	801,638,000
Short-term borrowings, carrying amount	28,058,000	32,488,000
Short-term borrowings, fair value	28,058,000	32,488,000
Long-term debt, carrying amount	5,000,000	5,287,000
Long-term debt, fair value	5,111,000	5,694,000
Accrued interest payable, carrying amount	383,000	487,000
Accrued interest payable, fair value	383,000	487,000
With No Stated Maturities [Member] | Fair Value, Inputs, Level 1 [Member]
Financial liabilities
Deposits, fair value	583,893,000	532,404,000
With No Stated Maturities [Member]
Financial liabilities
Deposits, carrying amount	583,893,000	532,404,000
Deposits, fair value	583,893,000	532,404,000
With Stated Maturities [Member] | Fair Value, Inputs, Level 2 [Member]
Financial liabilities
Deposits, fair value	246,142,000	273,878,000
With Stated Maturities [Member]
Financial liabilities
Deposits, carrying amount	244,059,000	269,234,000
Deposits, fair value	246,142,000	273,878,000
Investment Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets
Investment securities available-for-sale, fair value	4,884,000	4,055,000
Investment Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets
Investment securities available-for-sale, fair value	400,195,000	395,485,000
Investment Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets
Investment securities available-for-sale, fair value	2,169,000	1,962,000
Investment Securities [Member]
Financial assets
Investment securities available-for-sale, carrying amount	407,248,000	401,502,000
Investment securities available-for-sale, fair value	407,248,000	401,502,000
Fair Value, Inputs, Level 1 [Member]
Financial assets
Cash and cash equivalents, fair value	19,524,000	15,453,000
Investment securities available-for-sale, fair value	4,884,000	4,055,000
Financial liabilities
Short-term borrowings, fair value	28,058,000	32,488,000
Fair Value, Inputs, Level 2 [Member]
Financial assets
Investment securities available-for-sale, fair value	400,195,000	395,485,000
Investment securities held-to-maturity, fair value	162,000	166,000
Restricted investment in bank stocks, fair value	1,868,000	2,244,000
Loans held-for-sale, fair value	400,000	1,674,000
Accrued interest receivable, fair value	2,644,000	2,803,000
Financial liabilities
Long-term debt, fair value	5,111,000	5,694,000
Accrued interest payable, fair value	383,000	487,000
Fair Value, Inputs, Level 3 [Member]
Financial assets
Investment securities available-for-sale, fair value	2,169,000	1,962,000
Net loans, fair value	475,868,000	474,330,000
Mortgage servicing rights, fair value	$ 635,000	$ 464,000