Note 16 - Components of Accumulated Other Comprehensive Income (Loss) - Reclassifications Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Component of Accumulated Other Comprehensive Income (Loss)
Reclassification adjustment for gain included in net income, tax		$ (4)	$ (4)	$ (65)
Realized gain on available-for-sale securities, net of tax, reclassified out of accumulated other comprehensive income (loss)		(13)	(6)	(121)
Amortization of prior service cost included in net periodic pension cost, tax		(24)	(38)	(38)
Amortization of defined benefit pension items, net of tax, reclassified out of accumulated other comprehensive income (loss)		(86)	(71)	(72)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Component of Accumulated Other Comprehensive Income (Loss)
Realized securities gain, net		(17)	(10)	(186)
Reclassification adjustment for gain included in net income, tax		(4)	(4)	(65)
Realized gain on available-for-sale securities, net of tax, reclassified out of accumulated other comprehensive income (loss)		(13)	(6)	(121)
Prior service costs(1)	[1]	(110)	(109)	(110)
Amortization of prior service cost included in net periodic pension cost, tax		(24)	(38)	(38)
Amortization of defined benefit pension items, net of tax, reclassified out of accumulated other comprehensive income (loss)		$ (86)	$ (71)	$ (72)

[1] This accumulated other comprehensive income (loss) component is included in the computation of net periodic benefit cost. (For additional information, see Note 8, "Employee Benefit Plans.")