Note 7 - Investments in Affordable Housing (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 7 - Investments in Affordable Housing (Details) [Line Items]
Affordable Housing Investments	$ 104,579,000	$ 84,108,000
Number of Limited Partnerships in Housing Investments	7	7
Increase in Total Assets and Liabilities from Consolidating Affordable Housing Equity Interest	24,800,000	23,800,000
Other Borrowings from Consolidating Affordable Housing Equity Interest	19,900,000	19,100,000
Other Liabilities from Affordable Housing Unfunded Commitments	22,000,000	7,000,000
Minimum Compliance Period Tax Credits Investments in Affordable Housing	15 years
Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Amount	10,200,000	9,800,000	9,200,000
Domestic Tax Authority [Member] | Affordable Housing Limited Partnerships [Member]
Note 7 - Investments in Affordable Housing (Details) [Line Items]
Remaining and Future Available Tax Credit	57,700,000
State and Local Jurisdiction [Member] | Affordable Housing Limited Partnerships [Member]
Note 7 - Investments in Affordable Housing (Details) [Line Items]
Remaining and Future Available Tax Credit	$ 1,400,000