Note 12 - Pension and Other Postretirement Benefit Plans - Amounts Recognized In Accumulated Other Comprehensive Income, On a Pre-tax Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net Actuarial loss (gain)	$ 2,707	$ 6,917	$ 8,151
Prior Service cost (credit)	(283)	(356)	(401)
Total	2,424	6,561	7,750
Retirement Plan [Member]
Net Actuarial loss (gain)	3,238	6,166	8,055
Prior Service cost (credit)	0	0	0
Total	3,238	6,166	8,055
Other Postretirement Benefits Plan [Member]
Net Actuarial loss (gain)	35	1,223	636
Prior Service cost (credit)	(283)	(368)	(453)
Total	(248)	855	183
Directors' Plan [Member]
Net Actuarial loss (gain)	(566)	(472)	(540)
Prior Service cost (credit)		12	52
Total	$ (566)	$ (460)	$ (488)

Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (i-k)
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580

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- Definition

Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Publisher FASB
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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