Organization, Basis of Presentation and Summary of Significant Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Basis Of Presentation [Line Items]
Common Stock, par value	$ 0.001		$ 0.001		$ 0.001
Preferred Stock, par value	$ 0.001		$ 0.001
Inventory obsolescence reserved	$ 336		$ 336		$ 187
Sales return maximum duration			18 months
Offered period for sales return prior to expiration			6 months
Offered period for sales return subsequent to expiration			12 months
Discount for prompt payment	2.00%		2.00%
Research and development expense		$ 854		$ 3,338
Dividend Income	$ 100		$ 100
Threshold Limit For Liquid Investments			90 days
Minimum [Member]
Basis Of Presentation [Line Items]
Accrual to payment cycle period			1 month
Maximum [Member]
Basis Of Presentation [Line Items]
Accrual to payment cycle period			3 months