SHORT-TERM INVESTMENTS - Schedule of Short-Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Mar. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	$ 771,070	$ 646,786
Gross Unrealized Gain	1,713	645
Gross Unrealized Losses	(100)	(3,428)
Fair Value	772,683	644,003
Bank time deposits
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	118,000	191,000
Gross Unrealized Gain	0	0
Gross Unrealized Losses	0	0
Fair Value	118,000	191,000
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	508,431	337,752
Gross Unrealized Gain	1,617	307
Gross Unrealized Losses	(99)	(3,428)
Fair Value	509,949	334,631
US Treasuries
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	44,948	30,481
Gross Unrealized Gain	94	338
Gross Unrealized Losses	(1)	0
Fair Value	45,041	30,819
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	697
Gross Unrealized Gain	2
Gross Unrealized Losses	0
Fair Value	699
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	98,994	87,553
Gross Unrealized Gain	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 98,994	$ 87,553