Note 4 - Marketable Securities - Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Amortized Cost	$ 71,397	$ 83,029
Unrealized gains	203	230
Unrealized Losses	(13)	(20)
Fair Value	71,587	83,239
Marketable Securities	71,587	83,239
Corporate Debt Securities [Member]
Amortized Cost	50,744	44,794
Unrealized gains	177	175
Unrealized Losses	(7)	(6)
Fair Value	50,914	44,963
Marketable Securities	50,914	44,963
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Amortized Cost	5,427	12,081
Unrealized gains	2	5
Unrealized Losses	(2)	(2)
Fair Value	5,427	12,084
Marketable Securities	5,427	12,084
Certificates of Deposit [Member]
Amortized Cost	6,024	15,262
Unrealized gains	1	8
Unrealized Losses	0	(1)
Fair Value	6,025	15,269
Marketable Securities	6,025	15,269
US Treasury Securities [Member]
Amortized Cost	4,451	4,408
Unrealized gains	2	2
Unrealized Losses	(4)	(11)
Fair Value	4,449	4,399
Marketable Securities	4,449	4,399
Asset-Backed Securities [Member]
Amortized Cost	4,751	6,484
Unrealized gains	21	40
Unrealized Losses	0	0
Fair Value	4,772	6,524
Marketable Securities	$ 4,772	$ 6,524