Commitments and contingent liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Commitments Details
Construction in Xinxing, Guangdong, PRC	$ 358	$ 31
Mold	0	22
Total construction cost	$ 358	$ 48

The aggregate costs related to construction and development services during the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_ConstructionAndDevelopmentCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration