7. FINANCIAL INSTRUMENTS - Available-for-sale investments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Available-for-sale investments
Cost	$ 19,033
Total	19,178
Short-term investments
Available-for-sale investments
Cost	14,989	$ 19,367
Gross Unrealized Gains	73	4
Gross Unrealized Losses	(1)	(25)
Total	15,061	19,346
Short-term investments \| Agency bonds
Available-for-sale investments
Cost	2,989
Gross Unrealized Gains	21
Total	3,010
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	12,000	16,500
Gross Unrealized Gains	52	4
Gross Unrealized Losses	(1)	(24)
Total	12,051	16,480
Long-term investment
Available-for-sale investments
Cost	4,044	8,968
Gross Unrealized Gains	73	34
Gross Unrealized Losses		(5)
Total	4,117	8,997
Long-term investment \| Agency bonds
Available-for-sale investments
Cost	2,029	2,968
Gross Unrealized Gains	42	11
Gross Unrealized Losses		(1)
Total	2,071	2,978
Long-term investment \| Supranational obligations
Available-for-sale investments
Cost	1,270
Gross Unrealized Gains	13
Total	1,283
Long-term investment \| Certificates of deposit
Available-for-sale investments
Cost	745	6,000
Gross Unrealized Gains	18	23
Gross Unrealized Losses		(4)
Total	$ 763	$ 6,019

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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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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
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562

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