Note 9 - Fair Value Measurements - Financial Assets and Liabilities, Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Assets, fair value	$ 510,245	$ 362,450
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	206,017	205,158
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	304,179	157,243
Fair Value, Inputs, Level 3 [Member]
Assets, fair value	49	49
Money Market Funds [Member]
Available for sale securities, fair value	130,786	129,674
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Available for sale securities, fair value	130,786	129,674
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Available for sale securities, fair value	0	0
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Available for sale securities, fair value	0	0
Certificates of Deposit [Member]
Available for sale securities, fair value	304,179	157,243
Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member]
Available for sale securities, fair value	0	0
Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Available for sale securities, fair value	304,179	157,243
Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member]
Available for sale securities, fair value	0	0
Auction Rate Securities [Member]
Available for sale securities, fair value	49	49
Auction Rate Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available for sale securities, fair value	0	0
Auction Rate Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available for sale securities, fair value	0	0
Auction Rate Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available for sale securities, fair value	49	49
Mutual Fund [Member]
Available for sale securities, fair value	75,231	75,484
Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Available for sale securities, fair value	75,231	75,484
Mutual Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Available for sale securities, fair value	0	0
Mutual Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Available for sale securities, fair value	$ 0	$ 0