Note 4 - Marketable Securities - Investment in Marketable Securities (Details) $ in Thousands	Sep. 30, 2021 USD ($)
Amortized cost	$ 45,260
Gross unrealized gains	0
Gross unrealized losses	(9)
Fair value	45,479
Corporate Debt Securities [Member]
Amortized cost	30,963
Gross unrealized gains	0
Gross unrealized losses	(9)
Fair value	31,157
Commercial Paper [Member]
Amortized cost	11,471
Gross unrealized gains	0
Gross unrealized losses	0
Fair value	11,471
Debt Security, Corporate, Non-US [Member]
Amortized cost	2,826
Gross unrealized gains	0
Gross unrealized losses
Fair value	$ 2,851

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), including amounts presented in cash and cash equivalents.

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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-Topic 320
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Amortized cost 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 320
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-Publisher FASB
-Name Accounting Standards Codification
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