Note 13 - Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019		Mar. 31, 2018
Beginning balance	$ 332,857	[1]	$ 350,714
Other comprehensive income (loss), net	696		(1,641)
Ending balance	333,102		342,037
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Beginning balance	(285)		975
Other comprehensive loss before reclassifications	962		(1,697)
Reclassified from AOCI
Other comprehensive income (loss), net	962		(1,697)
Ending balance	677		(722)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Beginning balance	(1,144)		(1,815)
Other comprehensive loss before reclassifications	(321)
Reclassified from AOCI	55		56
Other comprehensive income (loss), net	(266)		56
Ending balance	(1,410)		(1,759)
AOCI Attributable to Parent [Member]
Beginning balance	(1,429)		(840)
Other comprehensive loss before reclassifications	641		(1,697)
Reclassified from AOCI	55		56
Other comprehensive income (loss), net	696		(1,641)
Ending balance	$ (733)		$ (2,481)

[1] Derived from audited financial statements