FAIR VALUE MEASUREMENTS - Schedule of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Mar. 31, 2024
ASSETS:
Cash and cash equivalents	$ 363,355	$ 389,674
Available-for-sale securities	18,694	22,946
Equity investment in Napatech	19,827	11,507
Derivative financial instruments	132	11
Total assets	402,008	424,138
LIABILITIES:
Derivative financial instruments	(6)	(74)
Total liabilities	(6)	(74)
U.S. government and municipal obligations
ASSETS:
Available-for-sale securities	6,046	11,491
Commercial paper
ASSETS:
Available-for-sale securities	11,617	8,648
Certificates of deposit
ASSETS:
Available-for-sale securities	1,031	2,807
Level 1
ASSETS:
Cash and cash equivalents	336,539	381,829
Equity investment in Napatech	19,827	11,507
Derivative financial instruments	0	0
Total assets	360,406	402,321
LIABILITIES:
Derivative financial instruments	0	0
Total liabilities	0	0
Level 1 | U.S. government and municipal obligations
ASSETS:
Available-for-sale securities	4,040	8,985
Level 1 | Commercial paper
ASSETS:
Available-for-sale securities	0	0
Level 1 | Certificates of deposit
ASSETS:
Available-for-sale securities	0	0
Level 2
ASSETS:
Cash and cash equivalents	26,816	7,845
Equity investment in Napatech	0	0
Derivative financial instruments	132	11
Total assets	41,602	21,817
LIABILITIES:
Derivative financial instruments	(6)	(74)
Total liabilities	(6)	(74)
Level 2 | U.S. government and municipal obligations
ASSETS:
Available-for-sale securities	2,006	2,506
Level 2 | Commercial paper
ASSETS:
Available-for-sale securities	11,617	8,648
Level 2 | Certificates of deposit
ASSETS:
Available-for-sale securities	1,031	2,807
Level 3
ASSETS:
Cash and cash equivalents	0	0
Equity investment in Napatech	0	0
Derivative financial instruments	0	0
Total assets	0	0
LIABILITIES:
Derivative financial instruments	0	0
Total liabilities	0	0
Level 3 | U.S. government and municipal obligations
ASSETS:
Available-for-sale securities	0	0
Level 3 | Commercial paper
ASSETS:
Available-for-sale securities	0	0
Level 3 | Certificates of deposit
ASSETS:
Available-for-sale securities	$ 0	$ 0