Financial instruments at fair value (Details) - Equity investment - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
Fair Value of Investment	$ 102	$ 78
Fair Value, Inputs, Level 1 [Member]
Fair Value of Investment	102	78
Fair Value, Inputs, Level 2 [Member]
Fair Value of Investment
Fair Value, Inputs, Level 3 [Member]
Fair Value of Investment

Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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Name:	us-gaap_InvestmentOwnedAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant