Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2019 USD ($) Derivative	Mar. 31, 2018 USD ($) Derivative
Significant Of Accounting Policies [Line Items]
Property, plant, and equipment, net	$ 6,000	$ 14,000
Allowance for doubtful accounts receivable, period increase (decrease)	(4,200)	2,100
Sales return reserve, period increase (decrease)	$ (159,200)	$ 12,500
Foreign exchange forward contracts held | Derivative	0	0
Advertising expenses	$ 121,000	$ 17,000
Income taxes penalties	3,000	1,000
Income taxes interest	$ 0	$ 51,000
Minimum
Significant Of Accounting Policies [Line Items]
Credit extended periods	10 days
Lease liabilities	$ 625,000
Right-of-use assets	$ 585,000
Maximum
Significant Of Accounting Policies [Line Items]
Credit extended periods	90 days
Lease liabilities	$ 764,000
Right-of-use assets	$ 715,000
Microwaves
Significant Of Accounting Policies [Line Items]
Warranty period	one year period
Audio Products
Significant Of Accounting Policies [Line Items]
Warranty period	90 day period