Note 8 - Components of Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Details) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	$ (706)	$ 580
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	0	0
AOCI Attributable to Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	$ (706)	$ 580