CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Mar. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 12,088	$ 50,414
Unrealized Gains	39	168
Fair Value	12,127	50,582
Short-term Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	12,088	47,852
Unrealized Gains	39	117
Fair Value	12,127	47,969
Short-term Marketable Securities \| U.S. government and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,585	28,621
Unrealized Gains	29	107
Fair Value	3,614	28,728
Short-term Marketable Securities \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	6,595	14,644
Unrealized Gains	0	0
Fair Value	6,595	14,644
Short-term Marketable Securities \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,908	4,587
Unrealized Gains	10	10
Fair Value	1,918	4,597
Long-term Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	2,562
Unrealized Gains	0	51
Fair Value	$ 0	2,613
Long-term Marketable Securities \| U.S. government and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		2,562
Unrealized Gains		51
Fair Value		$ 2,613

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 320
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Amount, before tax, of unrealized gain (loss) in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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