Note 4 - Cash, Cash Equivalents, Investments and Restricted Cash - Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Continuous Unrealized Loss Position, Less than 12 Months	$ 0	$ 118,391
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(114)
Continuous Unrealized Loss Position, 12 Months or Longer	6,860	71,373
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(69)	(1,527)
Unrealized Loss Position, Total	6,860	189,764
Unrealized Loss Position, Accumulated Loss, Total	(69)	(1,641)
Corporate Debt Securities [Member]
Continuous Unrealized Loss Position, Less than 12 Months	0	20,792
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(19)
Continuous Unrealized Loss Position, 12 Months or Longer	6,712	70,806
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(67)	(1,520)
Unrealized Loss Position, Total	6,712	91,598
Unrealized Loss Position, Accumulated Loss, Total	(67)	(1,539)
US Treasury and Government Short-Term Debt Securities [Member]
Continuous Unrealized Loss Position, Less than 12 Months	0
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0
Continuous Unrealized Loss Position, 12 Months or Longer	0
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Unrealized Loss Position, Total	0
Unrealized Loss Position, Accumulated Loss, Total	0
US Government Agencies Short-Term Debt Securities [Member]
Continuous Unrealized Loss Position, Less than 12 Months		97,599
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(95)
Continuous Unrealized Loss Position, 12 Months or Longer		0
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Unrealized Loss Position, Total		97,599
Unrealized Loss Position, Accumulated Loss, Total		(95)
Auction Rate Securities [Member]
Continuous Unrealized Loss Position, Less than 12 Months	0	0
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Continuous Unrealized Loss Position, 12 Months or Longer	148	567
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2)	(7)
Unrealized Loss Position, Total	148	567
Unrealized Loss Position, Accumulated Loss, Total	$ (2)	$ (7)