Note 4 - Investment Securities Available-for-sale (Details) - Investment Securities Pledged as Collateral (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financial Instruments Owned and Pledged as Collateral [Line Items]
Investment securities available for sale pledged	$ 123,351	$ 133,195
Municpal and Other Secured Deposit [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Investment securities available for sale pledged	85,252	84,255
Retail Purchase Agreements [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Investment securities available for sale pledged	25,701	36,629
Federal Reserve Line of Credit [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Investment securities available for sale pledged	1,339	1,352
Correspondent Banks Line of Credit [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Investment securities available for sale pledged	$ 11,059	$ 10,959