FAIR VALUE OF FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Fair Value Measurements within the Fair Value Hierarchy (Details) - Fair value measurements on recurring basis - USD ($) $ in Thousands	Sep. 30, 2023	Mar. 31, 2023
Fair value of assets and liabilities
Cash and Cash Equivalents	$ 492,169	$ 464,448
Short-Term Investments	31,920	32,807
Other Current Assets	12,405	12,110
Total assets	536,494	509,365
Cash
Fair value of assets and liabilities
Cash and Cash Equivalents	25,200	22,603
Short-Term Investments	0	0
Other Current Assets	0	0
Total assets	25,200	22,603
Level 1 | Money market funds
Fair value of assets and liabilities
Cash and Cash Equivalents	466,969	439,853
Short-Term Investments	0	0
Other Current Assets	0	0
Total assets	466,969	439,853
Level 1 | Assets of non-qualified retirement plan
Fair value of assets and liabilities
Cash and Cash Equivalents	0	0
Short-Term Investments	0	0
Other Current Assets	12,405	12,110
Total assets	12,405	12,110
Level 1 | U.S. Treasury securities
Fair value of assets and liabilities
Cash and Cash Equivalents	0	1,992
Short-Term Investments	24,420	25,307
Other Current Assets	0	0
Total assets	24,420	27,299
Level 1 | Certificates of deposit
Fair value of assets and liabilities
Cash and Cash Equivalents	0	0
Short-Term Investments	7,500	7,500
Other Current Assets	0	0
Total assets	$ 7,500	$ 7,500