SHORT-TERM INVESTMENTS (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	$ 878,172	$ 646,786
Gross Unrealized Gain	2,919	645
Gross Unrealized Losses	(266)	(3,428)
Fair Value	880,825	644,003
Bank-time deposits
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	352,026	191,000
Gross Unrealized Gain	0	0
Gross Unrealized Losses	0	0
Fair Value	352,026	191,000
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	398,792	337,752
Gross Unrealized Gain	2,672	307
Gross Unrealized Losses	(266)	(3,428)
Fair Value	401,198	334,631
US Treasuries
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	28,444	30,481
Gross Unrealized Gain	240	338
Gross Unrealized Losses	0	0
Fair Value	28,684	30,819
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	1,000
Gross Unrealized Gain	7
Gross Unrealized Losses	0
Fair Value	1,007
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	97,910	87,553
Gross Unrealized Gain	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 97,910	$ 87,553