Property, plant and equipment, net (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
Cost	$ 29,436	$ 30,166
Less: accumulated depreciation	(19,845)	(19,732)
Property, plant and equipment, net	9,591	10,434
Building [Member]
Cost	16,890	17,863
Construction-in-progress [Member]
Cost	597	260
Plant And Machinery [Member]
Cost	9,838	9,932
Furniture, fixtures and equipment [Member]
Cost	1,475	1,468
Motor vehicles [Member]
Cost	$ 636	$ 643

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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