Note 10 - Cash, Cash Equivalents, Investments and Restricted Cash - Unrealized Gains and Losses on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Amortized Cost	$ 925,092	$ 718,024
Unrealized Gains	8	331
Unrealized Losses	(1,231)	(1,641)
Total Fair Value	923,869	716,714
Money Market Funds [Member]
Amortized Cost	125,235	135,514
Unrealized Gains	0	0
Unrealized Losses	0	0
Total Fair Value	125,235	135,514
Certificates of Deposit [Member]
Amortized Cost	166,157	127,123
Unrealized Gains	0	0
Unrealized Losses	0	0
Total Fair Value	166,157	127,123
Corporate Debt Securities [Member]
Amortized Cost	61,353	96,636
Unrealized Gains	1	4
Unrealized Losses	(974)	(1,539)
Total Fair Value	60,380	95,101
US Government Agencies Short-Term Debt Securities [Member]
Amortized Cost	571,822	358,177
Unrealized Gains	7	327
Unrealized Losses	(250)	(95)
Total Fair Value	571,579	358,409
Auction Rate Securities [Member]
Amortized Cost	525	574
Unrealized Gains	0	0
Unrealized Losses	(7)	(7)
Total Fair Value	$ 518	$ 567