Note 8 - Components of Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Income (Loss) (Details) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	$ 1,209	$ (706)
Reclassification adjustment for gain included in net income, taxes	(3)
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
AOCI Attributable to Parent [Member]
Unrealized holding gain (loss) on available for sale securities, tax	1,209	$ (706)
Reclassification adjustment for gain included in net income, taxes	$ (3)

Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e640-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 17A
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL34724391-108580

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 20
-Section 45
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e39076-109324

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration