CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES - Summary of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Cash and cash equivalents	$ 468,470	$ 467,176	$ 415,719	$ 338,489
Restricted cash	0	0	748	1,748
Total cash, cash equivalents and restricted cash	$ 468,470	$ 467,176	$ 416,467	$ 340,237