Commitments and contingent liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Commitments Details
Construction in Xinxing, Guangdong, PRC	$ 41	$ 358
Total construction cost	$ 41	$ 358

The cash outflow from construction costs to date on capital projects that have not been completed and assets being constructed that are not ready to be placed into service.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

Name:	us-gaap_PaymentsForConstructionInProcess
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration