Segment Information - Net Sales to Customers by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	$ 31,416	$ 29,972
Unaffiliated Customers by Geographic Area [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	31,416	29,972
United States [Member] | Unaffiliated Customers by Geographic Area [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	22,437	22,799
United Kingdom [Member] | Unaffiliated Customers by Geographic Area [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	3,792	3,037
Other International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	11,535	9,694
Other International [Member] | Unaffiliated Customers by Geographic Area [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales, Total	$ 5,187	$ 4,136