Note 3 - Fair Value Measurements - Financial Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Marketable Securities	$ 98,601	$ 128,233
Corporate Debt Securities [Member]
Marketable Securities	55,766	54,281
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Marketable Securities	14,302	28,534
Certificates of Deposit [Member]
Marketable Securities	15,728	18,866
US Treasury Securities [Member]
Marketable Securities	4,448	16,080
Asset-Backed Securities [Member]
Marketable Securities	8,357	10,472
Fair Value, Recurring [Member]
Total assets	98,601	128,808
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Marketable Securities	55,766	54,281
Fair Value, Recurring [Member] | Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Marketable Securities	14,302	28,534
Fair Value, Recurring [Member] | Certificates of Deposit [Member]
Marketable Securities	15,728	18,866
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Marketable Securities	4,448	16,080
Fair Value, Recurring [Member] | Asset-Backed Securities [Member]
Marketable Securities	8,357	10,472
Fair Value, Recurring [Member] | Money Market Funds [Member]
Money market funds (cash equivalents)		575
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total assets	18,750	45,189
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	14,302	28,534
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	4,448	16,080
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)		575
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total assets	79,851	83,619
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Marketable Securities	55,766	54,281
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	15,728	18,866
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	8,357	10,472
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Money market funds (cash equivalents)		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