Revenue Recognition - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Revenue Recognition [Abstract]
Period of revenue from services	1 month
Subscription revenue term, minimum	1 year
Subscription revenue term, maximum	3 years
Aggregate amount of transaction price from contractual obligations	$ 16,377	$ 17,496