7. FINANCIAL INSTRUMENTS - Available-for-sale investments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019
Available-for-sale investments
Cost	$ 27,049
Total	27,140
Short-term investments
Available-for-sale investments
Cost	22,309	$ 19,367
Gross Unrealized Gains	46	4
Gross Unrealized Losses	(3)	(25)
Total	22,352	19,346
Short-term investments \| Agency bonds
Available-for-sale investments
Cost	6,798
Gross Unrealized Gains	20
Gross Unrealized Losses	(2)
Total	6,816
Short-term investments \| Supranational obligations
Available-for-sale investments
Cost	4,261	2,867
Gross Unrealized Losses	(1)	(1)
Total	4,260	2,866
Short-term investments \| Certificates of deposit
Available-for-sale investments
Cost	11,250	16,500
Gross Unrealized Gains	26	4
Gross Unrealized Losses		(24)
Total	11,276	16,480
Long-term investment
Available-for-sale investments
Cost	4,740	8,968
Gross Unrealized Gains	48	34
Gross Unrealized Losses		(5)
Total	4,788	8,997
Long-term investment \| Agency bonds
Available-for-sale investments
Cost		2,968
Gross Unrealized Gains		11
Gross Unrealized Losses		(1)
Total		2,978
Long-term investment \| Certificates of deposit
Available-for-sale investments
Cost	4,740	6,000
Gross Unrealized Gains	48	23
Gross Unrealized Losses		(4)
Total	$ 4,788	$ 6,019

Amount, before tax, of unrealized gain 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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-Topic 320
-SubTopic 10
-Section 50
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Amount, before tax, of unrealized 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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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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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 320
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-Paragraph 1
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