Note 10 - Cash, Cash Equivalents, Investments and Restricted Cash (Tables)

6 Months Ended

Jun. 30, 2024

Notes Tables

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

	June 30,		December 31,
	2024		2023
Cash	$	357,743	$	392,329
Money market funds		192,732		135,514
Certificates of deposit		165,120		127,123
Corporate debt securities		22,729		95,101
U.S. treasuries and government agency bonds		568,921		358,409
Auction-rate securities backed by student-loan notes		345		567
Total	$	1,307,590	$	1,109,043

	June 30,		December 31,
	2024		2023
Reported as:
Cash and cash equivalents	$	550,475	$	527,843
Short-term investments		756,770		580,633
Investment within other long-term assets		345		567
Total	$	1,307,590	$	1,109,043

Investments Classified by Contractual Maturity Date [Table Text Block]

	Amortized Cost		Fair Value
Due in less than 1 year	$	722,601	$	721,901
Due in 1 - 5 years		34,969		34,869
Due in greater than 5 years		350		345
Total	$	757,920	$	757,115

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

	June 30, 2024
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	192,732	$	-	$	-		$	192,732
Certificates of deposit		165,120		-		-			165,120
Corporate debt securities		23,285		1		(557	)		22,729
U.S. treasuries and government agency bonds		569,165		5		(249	)		568,921
Auction-rate securities backed by student-loan notes		350		-		(5	)		345
Total	$	950,652	$	6	$	(811	)	$	949,847

	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]

	June 30, 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	$	-	$	-		$	22,278	$	(557	)	$	22,278	$	(557	)
U.S. treasuries and government agency bonds		474,947		(214	)		17,351		(35	)		492,298		(249	)
Auction-rate securities backed by student-loan notes		-		-			345		(5	)		345		(5	)
Total	$	474,947	$	(214	)	$	39,974	$	(597	)	$	514,921	$	(811	)

	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]

	June 30,		December 31,
	2024		2023
Cash and cash equivalents	$	550,475	$	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 Condensed Consolidated Statements of Cash Flows	$	550,600	$	561,181