7. FINANCIAL INSTRUMENTS - Available-for-sale investments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Mar. 31, 2021
Available-for-sale investments
Cost	$ 15,174
Total	15,169
Short-term investments
Available-for-sale investments
Cost	11,777	$ 9,679
Gross Unrealized Gains	4	38
Gross Unrealized Losses	(8)
Total	11,773	9,717
Short-term investments \| Certificates of deposit
Available-for-sale investments
Cost	5,750	1,495
Gross Unrealized Gains	2	13
Gross Unrealized Losses	(5)
Total	5,747	1,508
Short-term investments \| Supranational obligations
Available-for-sale investments
Cost	2,012	2,273
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(2)
Total	2,011	2,274
Short-term investments \| Agency bonds
Available-for-sale investments
Cost	4,015	5,911
Gross Unrealized Gains	1	24
Gross Unrealized Losses	(1)
Total	4,015	5,935
Long-term investment
Available-for-sale investments
Cost	3,397	5,774
Gross Unrealized Gains	6	20
Gross Unrealized Losses	(7)	(2)
Total	3,396	5,792
Long-term investment \| Certificates of deposit
Available-for-sale investments
Cost	1,750	3,750
Gross Unrealized Gains	5	19
Gross Unrealized Losses	(3)	(1)
Total	1,752	3,768
Long-term investment \| Supranational obligations
Available-for-sale investments
Cost	651	1,023
Gross Unrealized Losses	(2)	(1)
Total	649	1,022
Long-term investment \| Agency bonds
Available-for-sale investments
Cost	996	1,001
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(2)
Total	$ 995	$ 1,002

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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