Note 16 - Income Taxes - Difference Between Statutory and Effective Tax Rates (Details)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
U.S. federal statutory tax rate	35.00%	35.00%
Tax exempt interest income	(1.30%)	(1.40%)
Tax credits	(9.50%)	(2.50%)
Cash surrender value of life insurance	(0.90%)	(0.90%)
State income taxes, net of federal benefit	0.90%	0.90%
Other, net	2.70%	0.40%
Effective tax rate	26.90%	31.50%