v3.20.2

Note 2 - Investments and Fair Value Measurement - Fair Value of Financial Assets and Liabilities by Level Within Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets, fair value	$ 41,666	$ 64,180
Liabilities, fair value	506	437
Contingent Put Option Liability [Member]
Liabilities, fair value	506	437
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	1,415	598
Liabilities, fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Contingent Put Option Liability [Member]
Liabilities, fair value	0	0
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	40,251	63,582
Liabilities, fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Contingent Put Option Liability [Member]
Liabilities, fair value	0	0
Fair Value, Inputs, Level 3 [Member]
Assets, fair value	0	0
Liabilities, fair value	506	437
Fair Value, Inputs, Level 3 [Member] | Contingent Put Option Liability [Member]
Liabilities, fair value	506	437
Money Market Funds [Member]
Assets, fair value	1,415	598
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	1,415	598
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	0	0
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value	0	0
U.S. Government Agency Securities [Member]
Assets, fair value	18,855	14,268
U.S. Government Agency Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	0	0
U.S. Government Agency Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	18,855	14,268
U.S. Government Agency Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value	0	0
Commercial Paper [Member]
Assets, fair value	21,396	39,260
Commercial Paper [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	0	0
Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	21,396	39,260
Commercial Paper [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value	$ 0	0
Corporate Debt Securities [Member]
Assets, fair value		10,054
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value		0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value		10,054
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value		$ 0

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

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X

- Definition

Fair value of financial and nonfinancial obligations.

+ 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

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