CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 58,766	$ 77,339
Unrealized Gains	69	17
Fair Value	58,835	77,356
Short-term marketable securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	56,217	76,332
Unrealized Gains	57	12
Fair Value	56,274	76,344
Short-term marketable securities \| U.S. government and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	27,139	27,610
Unrealized Gains	48	12
Fair Value	27,187	27,622
Short-term marketable securities \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	24,911	48,722
Unrealized Gains	0	0
Fair Value	24,911	48,722
Short-term marketable securities \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,167
Unrealized Gains	9
Fair Value	4,176
Long-term marketable securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,549	1,007
Unrealized Gains	12	5
Fair Value	2,561	1,012
Long-term marketable securities \| U.S. government and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,549
Unrealized Gains	12
Fair Value	$ 2,561
Long-term marketable securities \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		1,007
Unrealized Gains		5
Fair Value		$ 1,012

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=118939692&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=118942338&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 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562

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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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