Revenue from Contracts with Customers - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Order shipments, description	A majority of the Company’s revenue is short cycle in nature with shipments within one year from order.
Payment terms, description	The Company's payment terms generally range between 30 to 90 days.
Refund liability	$ 142,000		$ 154,000
Contract assets	0		0
Contract with customer liability, revenue recognized	100,000	$ 100,000
Accrued Liabilities [Member]
Disaggregation Of Revenue [Line Items]
Refund liability	100,000		200,000
Contract liability	300,000		200,000
Inventories [Member]
Disaggregation Of Revenue [Line Items]
Product return asset	$ 100,000		$ 100,000