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

9 Months Ended

Sep. 30, 2024

Notes Tables

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

	September 30,		December 31,
	2024		2023
Cash	$	413,010	$	392,329
Money market funds		282,883		135,514
Certificates of deposit		171,065		127,123
Corporate debt securities		14,236		95,101
U.S. treasuries and government agency bonds		581,156		358,409
Auction-rate securities backed by student-loan notes		173		567
Total	$	1,462,523	$	1,109,043

	September 30,		December 31,
	2024		2023
Reported as:
Cash and cash equivalents	$	700,347	$	527,843
Short-term investments		762,003		580,633
Investment within other long-term assets		173		567
Total	$	1,462,523	$	1,109,043

Investments Classified by Contractual Maturity Date [Table Text Block]

	Amortized Cost		Fair Value
Due in less than 1 year	$	765,440	$	765,683
Due in 1 - 5 years		805		774
Due in greater than 5 years		175		173
Total	$	766,420	$	766,630

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

	September 30, 2024
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	282,883	$	-	$	-		$	282,883
Certificates of deposit		171,065		-		-			171,065
Corporate debt securities		14,522		-		(286	)		14,236
U.S. treasuries and government agency bonds		580,658		515		(17	)		581,156
Auction-rate securities backed by student-loan notes		175		-		(2	)		173
Total	$	1,049,303	$	515	$	(305	)	$	1,049,513

	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]

	September 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	$	-	$	-		$	14,236	$	(286	)	$	14,236	$	(286	)
U.S. treasuries and government agency bonds		45,331		(15	)		4,883		(2	)		50,214		(17	)
Auction-rate securities backed by student-loan notes		-		-			173		(2	)		173		(2	)
Total	$	45,331	$	(15	)	$	19,292	$	(290	)	$	64,623	$	(305	)

	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]

	September 30,		December 31,
	2024		2023
Cash and cash equivalents	$	700,347	$	527,843
Restricted cash included in other current assets (1)		-		33,204
Restricted cash included in other long-term assets (2)		134		134
Total cash, cash equivalents and restricted cash reported on the Condensed Consolidated Statements of Cash Flows	$	700,481	$	561,181