Note 6 - Fair Value Measurements - Fair Value of Financial Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Marketable securities	$ 47,041
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	40,694	$ 72,225
Marketable securities	17,951	0
Total	59,860	127,603
Contingent consideration	0	0
Total	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Money Market Funds [Member]
Cash and cash equivalents	1,215	55,378
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents	0	0
Marketable securities	29,090	0
Total	29,090	0
Contingent consideration	0	0
Total	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Money Market Funds [Member]
Cash and cash equivalents	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents	0	0
Marketable securities	0	0
Total	0	0
Contingent consideration	5,629	0
Total	5,629	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Money Market Funds [Member]
Cash and cash equivalents	$ 0	$ 0

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

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 2
-Subparagraph (a)
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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Amount of liability recognized arising from contingent consideration in a business combination.

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-Publisher FASB
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

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Fair value of financial and nonfinancial obligations.

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