Note 4 - Cash, Cash Equivalents, Investments and Restricted Cash - Unrealized Gains and Losses on Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Amortized Cost	$ 183,214	$ 718,024
Unrealized Gains	0	331
Unrealized Losses	(69)	(1,641)
Total Fair Value	183,145	716,714
Money Market Funds [Member]
Amortized Cost	11,867	135,514
Unrealized Gains	0	0
Unrealized Losses	0	0
Total Fair Value	11,867	135,514
Certificates of Deposit [Member]
Amortized Cost	164,418	127,123
Unrealized Gains	0	0
Unrealized Losses	0	0
Total Fair Value	164,418	127,123
Corporate Debt Securities [Member]
Amortized Cost	6,779	96,636
Unrealized Gains	0	4
Unrealized Losses	(67)	(1,539)
Total Fair Value	6,712	95,101
Auction Rate Securities [Member]
Amortized Cost	150	574
Unrealized Gains	0	0
Unrealized Losses	(2)	(7)
Total Fair Value	$ 148	567
US Government Agencies Short-Term Debt Securities [Member]
Amortized Cost		358,177
Unrealized Gains		327
Unrealized Losses		(95)
Total Fair Value		$ 358,409