Concentration Risk - Additional Information (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Customer Concentration Risk | Net Revenues
Concentration Risk [Line Items]
Concentration risk, percentage	88.00%	90.00%	87.00%	85.00%
Product Concentration Risk | Net Revenues | Microwave Ovens
Concentration Risk [Line Items]
Concentration risk, percentage	40.00%	62.00%	45.00%	66.00%
Product Concentration Risk | Net Revenues | Audio Products
Concentration Risk [Line Items]
Concentration risk, percentage	56.00%	29.00%	50.00%	25.00%
Credit Concentration Risk | Accounts Receivable | Customer One
Concentration Risk [Line Items]
Concentration risk, percentage			46.00%		64.00%
Credit Concentration Risk | Accounts Receivable | Customer Two
Concentration Risk [Line Items]
Concentration risk, percentage			33.00%		21.00%
Supplier Concentration Risk | Products for Resale
Concentration Risk [Line Items]
Concentration risk, percentage	67.00%	47.00%	61.00%	61.00%
Supplier Concentration Risk | Products for Resale | Two Largest Factory Suppliers
Concentration Risk [Line Items]
Concentration risk, percentage	87.00%	81.00%	85.00%	91.00%