Note 6 - Marketable Securities - Portfolio of Available-for-sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortized cost basis, current	$ 2	$ 401
Accumulated gross unrealized gains, current		11,394
Accumulated gross unrealized losses, current	(1)
Fair value, current	1	11,795
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Amortized cost basis, current		400
Accumulated gross unrealized gains, current		11,394
Accumulated gross unrealized losses, current
Fair value, current		11,794
Equity Securities, Debt Securities [Member]
Amortized cost basis, current	2	1
Accumulated gross unrealized gains, current
Accumulated gross unrealized losses, current	(1)
Fair value, current	$ 1	$ 1

Represents the current amount of accumulated gross unrealized gains on available-for-sale debt securities.

No definition available.

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- Definition

Represents the current amount of accumulated gross unrealized losses on available-for-sale debt securities.

+ References

No definition available.

+ Details

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- Definition

Amortized cost basis of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

No definition available.

+ Details

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26626-111562

+ Details

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- Details

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- Details

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