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Note 7 - Investment and Equity Securities (Details Textual) - USD ($)		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2018	Dec. 31, 2018
Equity Securities, FV-NI, Unrealized Gain (Loss), Total	[1]	$ 58,000	$ 18,000
Equity Securities, FV-NI, Realized Gain (Loss), Total		0	0
Proceeds from Sale of Available-for-sale Securities, Total		0		$ 0
Security Owned and Pledged as Collateral, Fair Value, Total		$ 59,500,000			$ 63,500,000
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Total		39
Available-for-sale Securities, Percentage of Portfolio		100.00%
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held, Ending Balance		$ 0
Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Total		$ 0	$ 0
[1] Not within scope of ASC 606

X

- Definition

Represents a percentage of the available-for-sale securities portfolio.

+ References

No definition available.

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X

- Definition

Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ 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 (b)(3)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

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- Definition

Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117546-209714

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- Definition

Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117546-209714

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- Definition

The cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (a component of shareholders' equity).

+ References

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-Paragraph 8B
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- Definition

Amount of other-than-temporary impairment (OTTI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), recognized in earnings and other comprehensive loss (OCI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=118954083&loc=SL6284422-111562

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- Definition

The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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