Note 8 - Components of Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Loss) (Details) (Parentheticals) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	$ 580,000	$ 1,802,000
Reclassification adjustment for gain included in net income, taxes	0	(2,000)
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	0
AOCI Attributable to Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	580,000	1,802,000
Reclassification adjustment for gain included in net income, taxes	$ 0	$ (2,000)