Note 12 - Fair Value Measurements - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Held to maturity investment securities	$ 3,600,000	$ 3,597,000
Reported Value Measurement [Member]
Cash and cash equivalents	95,564,000	113,534,000
Held to maturity investment securities	3,475,000	3,488,000
Loans, net	980,326,000	961,631,000
Accrued interest receivable	4,585,000	5,019,000
Federal Home Loan Bank and Federal Reserve Bank Stock	13,410,000	9,840,000
Deposits	1,388,077,000	1,369,907,000
Federal funds purchased and short-term securities sold under agreements to repurchase	32,786,000	35,085
Securities sold under agreements to repurchase and other long-term borrowings	14,892,000	19,931,000
Subordinated notes payable to unconsolidated trusts	33,506,000	33,506,000
Accrued interest payable	289,000	321,000
Estimate of Fair Value Measurement [Member]
Cash and cash equivalents	95,564,000	113,534,000
Held to maturity investment securities	3,600,000	3,597,000
Loans, net	980,178,000	962,437,000
Accrued interest receivable	4,585,000	5,019,000
Federal Home Loan Bank and Federal Reserve Bank Stock	13,410,000	9,840,000
Deposits	1,388,247,000	1,369,567,000
Federal funds purchased and short-term securities sold under agreements to repurchase	32,786,000	35,085
Securities sold under agreements to repurchase and other long-term borrowings	15,215,000	20,410,000
Subordinated notes payable to unconsolidated trusts	21,521,000	21,234,000
Accrued interest payable	289,000	321,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	95,564,000	113,534,000
Held to maturity investment securities	0	0
Loans, net	0	0
Accrued interest receivable	0	0
Federal Home Loan Bank and Federal Reserve Bank Stock	0	0
Deposits	1,128,850,000	1,099,211,000
Federal funds purchased and short-term securities sold under agreements to repurchase	0	0
Securities sold under agreements to repurchase and other long-term borrowings	0	0
Subordinated notes payable to unconsolidated trusts	0	0
Accrued interest payable	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents	0	0
Held to maturity investment securities	3,600,000	3,597,000
Loans, net	0	0
Accrued interest receivable	4,585,000	5,019,000
Federal Home Loan Bank and Federal Reserve Bank Stock	0	0
Deposits	0	0
Federal funds purchased and short-term securities sold under agreements to repurchase	32,786,000	35,085
Securities sold under agreements to repurchase and other long-term borrowings	15,215,000	20,410,000
Subordinated notes payable to unconsolidated trusts	0	0
Accrued interest payable	289,000	321,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents	0	0
Held to maturity investment securities	0	0
Loans, net	980,178,000	962,437,000
Accrued interest receivable	0	0
Federal Home Loan Bank and Federal Reserve Bank Stock	13,410,000	9,840,000
Deposits	259,397,000	270,356,000
Federal funds purchased and short-term securities sold under agreements to repurchase	0	0
Securities sold under agreements to repurchase and other long-term borrowings	0	0
Subordinated notes payable to unconsolidated trusts	21,521,000	21,234,000
Accrued interest payable	$ 0	$ 0