Note 8 - Fair Value Measurements - Estimated Fair Values and Related Carrying Amounts of Financial Instruments (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Reported Value Measurement [Member]
Financial Assets:
Cash and due from banks	$ 11,302,000	$ 12,152,000
Interest-bearing deposits	80,170,000	130,811,000
Securities	429,324,000	388,159,000
Restricted securities	1,170,000	1,129,000
Mortgage loans held for sale	434,000	634,000
Loans, net	627,940,000	610,711,000
Accrued interest receivable	5,138,000	5,769,000
Bank-owned life insurance	22,848,000	22,401,000
Financial Liabilities:
Deposits	1,010,008,000	1,018,859,000
Accrued interest payable	48,000	56,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Cash and due from banks	11,302,000	12,152,000
Interest-bearing deposits	80,170,000	130,811,000
Securities	0	0
Restricted securities	0	0
Mortgage loans held for sale		0
Loans, net	0	0
Accrued interest receivable	0	0
Bank-owned life insurance	0	0
Financial Liabilities:
Deposits	0	0
Accrued interest payable	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Securities	436,555,000	394,163,000
Restricted securities	1,170,000	1,129,000
Mortgage loans held for sale	434,000	634,000
Loans, net	0	0
Accrued interest receivable	5,138,000	5,769,000
Bank-owned life insurance	22,848,000	22,401,000
Financial Liabilities:
Deposits	834,219,000	826,476,000
Accrued interest payable	48,000	56,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Securities	0	0
Restricted securities	0	0
Mortgage loans held for sale		0
Loans, net	642,859,000	621,590,000
Accrued interest receivable	0	0
Bank-owned life insurance	0	0
Financial Liabilities:
Deposits	174,388,000	193,912,000
Accrued interest payable	$ 0	$ 0