Note 8 - Components of Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Details) (Parentheticals) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Unrealized holding gain on securities transferred from held to maturity to available for sale, tax	$ 237
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	(1,378)	1,235
Reclassification adjustment for gain included in net income, taxes		(1)
Unrealized holding gain on securities transferred from held to maturity to available for sale, tax	237
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	0	0
Reclassification adjustment for gain included in net income, taxes		0
Unrealized holding gain on securities transferred from held to maturity to available for sale, tax	0
AOCI Attributable to Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	(1,378)	1,235
Reclassification adjustment for gain included in net income, taxes		$ (1)
Unrealized holding gain on securities transferred from held to maturity to available for sale, tax	$ 237