Note 10 - Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in unfunded portion of postretirement benefit obligation, tax	$ 211	$ (74)	$ (382)
Net unrealized securities (losses) gains	(3,545)	(1,052)	4,737
Total income tax (benefit) expense recorded directly to shareholders’ equity	$ (3,334)	$ (1,126)	$ 4,355