Note 3 - Fair Value Measurements - Available-for-sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Amortized Cost	$ 27,450	$ 4,924
Unrealized Gains	1	1
Unrealized Losses	(7)
Fair Value	27,444	4,925
US Government Agencies Debt Securities [Member]
Amortized Cost	27,450	4,924
Unrealized Gains	1	1
Unrealized Losses	(7)
Fair Value	$ 27,444	$ 4,925

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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