Note 10 - Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2025

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	September 30, 2025
	Total		Level 1		Level 2		Level 3
Money market funds	$	500,259	$	500,259	$	-	$	-
Certificates of deposit		154,489		-		154,489		-
U.S. treasuries and government agency bonds		33,249		-		33,249		-
Auction-rate securities backed by student-loan notes		74		-		-		74
Mutual funds and money market funds under deferred compensation plan		70,994		70,994		-		-
Total	$	759,065	$	571,253	$	187,738	$	74

	December 31, 2024
	Total		Level 1		Level 2		Level 3
Money market funds	$	11,867	$	11,867	$	-	$	-
Certificates of deposit		164,418		-		164,418		-
Corporate debt securities		6,712		-		6,712		-
Auction-rate securities backed by student-loan notes		148		-		-		148
Mutual funds and money market funds under deferred compensation plan		65,337		65,337		-		-
Total	$	248,482	$	77,204	$	171,130	$	148