Note 8 - Marketable Securities - Short-term and Long-term Available for Sale Securities (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Amortized Cost	$ 26,039
Unrealized Gains	7
Unrealized Losses	(126)
Fair Value	25,920
Bank Time Deposits [Member]
Amortized Cost	1,687
Unrealized Gains	7
Unrealized Losses	0
Fair Value	1,694
US Government Agencies Debt Securities [Member]
Amortized Cost	2,500
Unrealized Gains	0
Unrealized Losses	(12)
Fair Value	2,488
Corporate Debt Securities [Member]
Amortized Cost	9,303
Unrealized Gains	0
Unrealized Losses	(44)
Fair Value	9,259
US States and Political Subdivisions Debt Securities [Member]
Amortized Cost	12,549
Unrealized Gains	0
Unrealized Losses	(70)
Fair Value	12,479
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Amortized Cost	0
Unrealized Gains	0
Unrealized Losses	0
Fair Value	$ 0

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).

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Amount, before tax, of unrealized loss 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).

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