Summary of Significant Accounting Policies - Narrative (Details) shares in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($) shares	Mar. 31, 2017 USD ($) shares	Mar. 31, 2018 USD ($) Segment shares	Mar. 31, 2017 USD ($) shares	Jun. 30, 2018	Jun. 30, 2017 USD ($)
Summary Of Significant Accounting Policies
Foreign currency transaction gain (loss), realized	$ 14,000	$ 200,000	$ 5,000	$ (200,000)
Derivative instruments, gain (loss) realized in income, net	21,000	(200,000)	(100,000)	(100,000)
Bad debt expenses	0	0	0	0
Inventory valuation reserves	$ 1,500,000		$ 1,500,000			$ 900,000
Money back guarantee period			30 days
Percentage of products can be returned for a full refund by terminated distributors (up to)	30.00%		30.00%
Percent of restocking fee	10.00%		10.00%
Reserve for sales returns	$ 400,000		$ 400,000			400,000
Research and development	300,000	200,000	800,000	800,000
Income tax expenses	$ 598,000	$ (1,000)	$ 2,777,000	$ 626,000
Effective tax rate			50.10%
Deferred tax asset reduction			$ 1,200,000
Increase in effective tax rate			21.00%
Antidilutive securities excluded from EPS calculation (in shares) | shares	0.5	0.2	0.6	0.1
Number of operating segments | Segment			1
Number of geographic segments | Segment			2
United States
Summary Of Significant Accounting Policies
Long-lived assets	$ 9,300,000		$ 9,300,000			6,200,000
Japan
Summary Of Significant Accounting Policies
Long-lived assets	$ 900,000		900,000			$ 900,000
Cash accounts held primarily at One Financial Institution
Summary Of Significant Accounting Policies
Concentration of credit risk			7,700,000
Cash held primarily at Other Financial Institutions
Summary Of Significant Accounting Policies
Concentration of credit risk			$ 6,300,000
Forecast
Summary Of Significant Accounting Policies
Statutory tax blended rate					28.00%