Summary of Significant Accounting Policies - Narrative (Details) shares in Thousands	3 Months Ended
	Sep. 30, 2017 USD ($) Segment shares	Sep. 30, 2016 USD ($) shares	Jun. 30, 2017 USD ($)
Summary Of Significant Accounting Policies
Foreign currency transaction gain (loss), realized	$ 100,000	$ (100,000)
Derivative instruments, gain (loss) realized in income, net	3,000	(100,000)
Bad debt expenses	0	0
Inventory valuation reserves	$ 1,100,000		$ 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%
Percent of restocking fee	10.00%
Reserve for sales returns	$ 300,000		400,000
Research and development	300,000	300,000
Income tax expense	$ 441,000	$ 498,000
Effective tax rate	35.10%
Statutory tax rate	35.00%
Antidilutive securities excluded from EPS calculation (in shares) | shares	200	46
Number of operating segments | Segment	1
Number of geographic segments | Segment	2
United States
Summary Of Significant Accounting Policies
Long-lived assets	$ 8,300,000		6,200,000
Japan
Summary Of Significant Accounting Policies
Long-lived assets	900,000		$ 900,000
Cash accounts held primarily at One Financial Institution
Summary Of Significant Accounting Policies
Concentration of credit risk	8,500,000
Cash held primarily at Other Financial Institutions
Summary Of Significant Accounting Policies
Concentration of credit risk	$ 3,800,000