7. FINANCIAL INSTRUMENTS - Available-for-sale investments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Available-for-sale investments
Cost	$ 25,589
Total	25,665
Short-term investments
Available-for-sale investments
Cost	20,293	$ 19,367
Gross Unrealized Gains	50	4
Gross Unrealized Losses		(25)
Total	20,343	19,346
Short-term investments \| Agency bonds
Available-for-sale investments
Cost	6,793
Gross Unrealized Gains	18
Total	6,811
Short-term investments \| Supranational obligations
Available-for-sale investments
Cost		2,867
Gross Unrealized Losses		(1)
Total		2,866
Short-term investments \| Certificates of deposit
Available-for-sale investments
Cost	13,500	16,500
Gross Unrealized Gains	32	4
Gross Unrealized Losses		(24)
Total	13,532	16,480
Long-term investment
Available-for-sale investments
Cost	5,296	8,968
Gross Unrealized Gains	29	34
Gross Unrealized Losses	(3)	(5)
Total	5,322	8,997
Long-term investment \| Agency bonds
Available-for-sale investments
Cost	2,033	2,968
Gross Unrealized Gains		11
Gross Unrealized Losses	(2)	(1)
Total	2,031	2,978
Long-term investment \| Supranational obligations
Available-for-sale investments
Cost	1,273
Gross Unrealized Losses	(1)
Total	1,272
Long-term investment \| Certificates of deposit
Available-for-sale investments
Cost	1,990	6,000
Gross Unrealized Gains	29	23
Gross Unrealized Losses		(4)
Total	$ 2,019	$ 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).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
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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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+ References

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-Name Accounting Standards Codification
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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).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 45
-Paragraph 1
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