Revenue Recognition - Summary of Revenues Disaggregated by Geography (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Total revenue		$ 35,942	$ 48,548
UNITED STATES
Disaggregation Of Revenue [Line Items]
Total revenue		22,619	32,877
Other
Disaggregation Of Revenue [Line Items]
Total revenue	[1]	$ 13,323	$ 15,671

[1] No single country outside of the United States represented 10% or more of the Company’s revenues in the periods presented.