Note 16 - Accumulated Other Comprehensive Income - Components of Accumulated Other Comprehensive Income, Net of Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Balance	$ 350,714	[1]	$ 339,057		$ 343,017
Other comprehensive income (loss), net	(589)		1,415		3,236
Balance	332,857		350,714	[1]	339,057
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance	975		(544)		(3,885)
Other comprehensive income (loss) before reclassifications	(1,748)		972		647
Reclassified from AOCI	488		413		2,694
Other comprehensive income (loss), net	(1,260)		1,385		3,341
Reclassification of certain tax effects			134
Balance	(285)		975		(544)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(1,815)		(1,467)		(1,362)
Other comprehensive income (loss) before reclassifications	446		(132)		(276)
Reclassified from AOCI	225		162		171
Other comprehensive income (loss), net	671		30		(105)
Reclassification of certain tax effects			(378)
Balance	(1,144)		(1,815)		(1,467)
AOCI Attributable to Parent [Member]
Balance	(840)		(2,011)		(5,247)
Other comprehensive income (loss) before reclassifications	(1,302)		840		371
Reclassified from AOCI	713		575		2,865
Other comprehensive income (loss), net	(589)		1,415		3,236
Reclassification of certain tax effects			(244)
Balance	$ (1,429)		$ (840)		$ (2,011)

[1] Derived from audited financial statements