Summary of Significant Accounting Policies - Components of Revenue from Contracts with Customers (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue from contracts with customers:
Total revenue from contracts with customers	$ 56,030	$ 65,016	$ 122,003	$ 129,845
Revenue recognized under ASC 842	702	2,087	908	3,293
Total revenues	56,732	67,103	122,911	133,138
Recurring Service Revenues [Member]
Revenue from contracts with customers:
Total revenue from contracts with customers	37,006	38,506	76,859	76,035
Other Service Revenues [Member]
Revenue from contracts with customers:
Total revenue from contracts with customers	1,423	1,232	2,094	2,710
Service [Member]
Revenue from contracts with customers:
Total revenue from contracts with customers	38,429	39,738	78,953	78,745
Product [Member]
Revenue from contracts with customers:
Total revenue from contracts with customers	17,601	25,278	43,050	51,100
Total revenues	$ 18,303	$ 27,365	$ 43,958	$ 54,393