Changes in Deferred Revenue (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Revenue From Contract With Customer [Abstract]
Deferred revenue	$ 2,810
Fair value of deferred revenue acquired in acquisition, net of recognition	4
Deferral of revenue billed in current period, net of recognition	2,567
Recognition of revenue deferred in prior periods	(1,816)
Deferred revenue	$ 3,565