Note 3 - Fair Value Measurements - Financial Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Mar. 31, 2025	Dec. 31, 2024
Marketable Securities	$ 71,587,000	$ 83,239,000
Corporate Debt Securities [Member]
Marketable Securities	50,914,000	44,963,000
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Marketable Securities	5,427,000	12,084,000
Certificates of Deposit [Member]
Marketable Securities	6,025,000	15,269,000
US Treasury Securities [Member]
Marketable Securities	4,449,000	4,399,000
Asset-Backed Securities [Member]
Marketable Securities	4,772,000	6,524,000
Fair Value, Recurring [Member]
Marketable Securities	4,772,000
Total assets	90,373,000	107,119,000
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Marketable Securities	50,914,000	44,963,000
Fair Value, Recurring [Member] | Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Marketable Securities	5,427,000	12,084,000
Fair Value, Recurring [Member] | Certificates of Deposit [Member]
Marketable Securities	6,025,000	15,269,000
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Marketable Securities	4,449,000	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)	18,786	23,880,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total assets	28,662,000	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	5,427,000	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	4,449,000	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)	18,786	23,880,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total assets	61,711,000	66,756,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Marketable Securities	50,914,000	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	6,025,000	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	4,772,000	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