Note 3 - Debt Securities - Held to Maturity Securities in Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Securities held to maturity, less than 12 months fair value		$ 25,084
Securities held to maturity, less than 12 months unrealized losses		(65)
Securities held to maturity, 12 months or longer fair value	24,990
Securities held to maturity, 12 months or longer unrealized losses	(23)
Securities held to maturity, total fair value	24,990	25,084
Securities held to maturity, unrealized losses	(23)	(65)
US Government Agencies Debt Securities [Member]
Securities held to maturity, less than 12 months fair value		17,888
Securities held to maturity, less than 12 months unrealized losses		(49)
Securities held to maturity, 12 months or longer fair value	17,867
Securities held to maturity, 12 months or longer unrealized losses	(20)
Securities held to maturity, total fair value	17,867	17,888
Securities held to maturity, unrealized losses	(20)	(49)
Corporate Debt Securities [Member]
Securities held to maturity, less than 12 months fair value		7,196
Securities held to maturity, less than 12 months unrealized losses		(16)
Securities held to maturity, 12 months or longer fair value	7,123
Securities held to maturity, 12 months or longer unrealized losses	(3)
Securities held to maturity, total fair value	7,123	7,196
Securities held to maturity, unrealized losses	$ (3)	$ (16)

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

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- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

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- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for less than 12 months.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer.

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