Note 4 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Securities, fair value	$ 154,700	$ 182,817
US Government Agencies Debt Securities [Member]
Securities, fair value	55,804	57,155
Certificates of Deposit [Member]
Securities, fair value	6,200	8,524
Corporate Debt Securities [Member]
Securities, fair value	67,370	80,822
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Securities, fair value	10,612	22,275
Debt Security, Government, Non-US [Member]
Securities, fair value	2,336	2,146
Asset-Backed Securities [Member]
Securities, fair value	12,378	11,895
Fair Value, Recurring [Member]
Cash equivalents	19,848	21,042
Total financial assets	174,548	203,859
Fair Value, Recurring [Member] \| US Government Agencies Debt Securities [Member]
Securities, fair value	55,804	57,155
Fair Value, Recurring [Member] \| Certificates of Deposit [Member]
Securities, fair value	6,200	8,524
Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Securities, fair value	67,370	80,822
Fair Value, Recurring [Member] \| Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Securities, fair value	10,612	22,275
Fair Value, Recurring [Member] \| Debt Security, Government, Non-US [Member]
Securities, fair value	2,336	2,146
Fair Value, Recurring [Member] \| Asset-Backed Securities [Member]
Securities, fair value	12,378	11,895
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash equivalents	19,848	21,042
Total financial assets	75,652	78,197
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| US Government Agencies Debt Securities [Member]
Securities, fair value	55,804	57,155
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Certificates of Deposit [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Debt Security, Government, Non-US [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Asset-Backed Securities [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Cash equivalents	0	0
Total financial assets	98,896	125,662
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US Government Agencies Debt Securities [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Certificates of Deposit [Member]
Securities, fair value	6,200	8,524
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member]
Securities, fair value	67,370	80,822
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Securities, fair value	10,612	22,275
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Debt Security, Government, Non-US [Member]
Securities, fair value	2,336	2,146
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Asset-Backed Securities [Member]
Securities, fair value	12,378	11,895
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Cash equivalents	0	0
Total financial assets	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| US Government Agencies Debt Securities [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Certificates of Deposit [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Corporate Debt Securities [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Debt Security, Government, Non-US [Member]
Securities, fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Asset-Backed Securities [Member]
Securities, fair value	$ 0	$ 0