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Note 1 - Summary of Significant Accounting Policies - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Inputs, Level 1 [Member]
Total Assets	$ 3,656	$ 3,949
Fair Value, Inputs, Level 1 [Member] | Equity Funds [Member]
Investments	1,130	1,586
Fair Value, Inputs, Level 1 [Member] | Money Market and Mutual Funds [Member]
Other Assets	2,526	2,363
Fair Value, Inputs, Level 2 [Member]
Total Assets	8,221	8,184
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Investments	2,842	2,124
Fair Value, Inputs, Level 2 [Member] | Government-backed and Government-sponsored Enterprises' Debt Securities [Member]
Investments	$ 5,379	$ 6,060

X

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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X

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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X

- Definition

Fair value portion of other assets.

+ References

No definition available.

+ Details

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