Segment Information - Net Sales to Customers by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	$ 36,244	$ 33,809	$ 102,456	$ 98,067
Unaffiliated Customers by Geographic Area [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	36,244	33,809	102,456	98,067
United States [Member] | Unaffiliated Customers by Geographic Area [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	24,970	25,424	71,604	73,497
United Kingdom [Member] | Unaffiliated Customers by Geographic Area [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	4,433	3,445	12,756	9,885
Other International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	14,581	10,996	39,938	31,623
Other International [Member] | Unaffiliated Customers by Geographic Area [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	$ 6,841	$ 4,940	$ 18,096	$ 14,685