Note 3 - Fair Value Measurements - Financial Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Jun. 30, 2025	Dec. 31, 2024
Marketable Securities	$ 78,093,000	$ 83,239,000
Corporate Debt Securities [Member]
Marketable Securities	61,175,000	44,963,000
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Marketable Securities	9,415,000	12,084,000
Certificates of Deposit [Member]
Marketable Securities	918,000	15,269,000
US Treasury Securities [Member]
Marketable Securities	2,734,000	4,399,000
Asset-Backed Securities [Member]
Marketable Securities	3,851,000	6,524,000
Fair Value, Recurring [Member]
Marketable Securities	3,851,000
Total assets	81,823,000	107,119,000
Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Marketable Securities	61,175,000	44,963,000
Fair Value, Recurring [Member] \| Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Marketable Securities	9,415,000	12,084,000
Fair Value, Recurring [Member] \| Certificates of Deposit [Member]
Marketable Securities	918,000	15,269,000
Fair Value, Recurring [Member] \| US Treasury Securities [Member]
Marketable Securities	2,734,000	4,399,000
Fair Value, Recurring [Member] \| Asset-Backed Securities [Member]
Marketable Securities		6,524,000
Fair Value, Recurring [Member] \| Money Market Funds [Member]
Money market funds (cash equivalents)	3,730	23,880,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Total assets	15,879,000	40,363,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Marketable Securities	9,415,000	12,084,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Certificates of Deposit [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities [Member]
Marketable Securities	2,734,000	4,399,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Asset-Backed Securities [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Money Market Funds [Member]
Money market funds (cash equivalents)	3,730	23,880,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Total assets	65,944,000	66,756,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member]
Marketable Securities	61,175,000	44,963,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Certificates of Deposit [Member]
Marketable Securities	918,000	15,269,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US Treasury Securities [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Asset-Backed Securities [Member]
Marketable Securities	3,851,000	6,524,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Money Market Funds [Member]
Money market funds (cash equivalents)	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Total assets	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Corporate Debt Securities [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Certificates of Deposit [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| US Treasury Securities [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Asset-Backed Securities [Member]
Marketable Securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Money Market Funds [Member]
Money market funds (cash equivalents)	$ 0	$ 0