Note 4 - Cash, Cash Equivalents, Investments and Restricted Cash (Tables)

12 Months Ended

Dec. 31, 2024

Notes Tables

Fair Value, by Balance Sheet Grouping [Table Text Block]

	December 31,
	2024		2023
Cash	$	679,949	$	392,329
Money market funds		11,867		135,514
Certificates of deposit		164,418		127,123
Corporate debt securities		6,712		95,101
U.S. treasuries and government agency bonds		-		358,409
Auction-rate securities backed by student-loan notes		148		567
Total	$	863,094	$	1,109,043

	December 31,
	2024		2023
Reported as:
Cash and cash equivalents	$	691,816	$	527,843
Short-term investments		171,130		580,633
Investment within other long-term assets		148		567
Total	$	863,094	$	1,109,043

Investments Classified by Contractual Maturity Date [Table Text Block]

	Amortized Cost		Fair Value
Due in less than 1 year	$	171,197	$	171,130
Due in 1 - 5 years		-		-
Due in greater than 5 years		150		148
Total	$	171,347	$	171,278

Unrealized Gain (Loss) on Investments [Table Text Block]

	December 31, 2024
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	11,867	$	-	$	-		$	11,867
Certificates of deposit		164,418		-		-			164,418
Corporate debt securities		6,779		-		(67	)		6,712
Auction-rate securities backed by student-loan notes		150		-		(2	)		148
Total	$	183,214	$	-	$	(69	)	$	183,145

	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	135,514	$	-	$	-		$	135,514
Certificates of deposit		127,123		-		-			127,123
Corporate debt securities		96,636		4		(1,539	)		95,101
U.S. treasuries and government agency bonds		358,177		327		(95	)		358,409
Auction-rate securities backed by student-loan notes		574		-		(7	)		567
Total	$	718,024	$	331	$	(1,641	)	$	716,714

Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table Text Block]

	December 31, 2024
	Less than 12 Months				Greater than 12 Months					Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate debt securities	$	-	$	-	$	6,712	$	(67	)	$	6,712	$	(67	)
U.S. treasuries and government agency bonds		-		-		-		-			-		-
Auction-rate securities backed by student-loan notes		-		-		148		(2	)		148		(2	)
Total	$	-	$	-	$	6,860	$	(69	)	$	6,860	$	(69	)

	December 31, 2023
	Less than 12 Months					Greater than 12 Months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate debt securities	$	20,792	$	(19	)	$	70,806	$	(1,520	)	$	91,598	$	(1,539	)
U.S. treasuries and government agency bonds		97,599		(95	)		-		-			97,599		(95	)
Auction-rate securities backed by student-loan notes		-		-			567		(7	)		567		(7	)
Total	$	118,391	$	(114	)	$	71,373	$	(1,527	)	$	189,764	$	(1,641	)

Restrictions on Cash and Cash Equivalents [Table Text Block]

	December 31,
	2024		2023
Cash and cash equivalents	$	691,816	$	527,843
Restricted cash included in other current assets		-		33,204
Restricted cash included in other long-term assets		125		134
Total cash, cash equivalents and restricted cash reported on the Consolidated Statements of Cash Flows	$	691,941	$	561,181