Changes in Deferred Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenue From Contract With Customer [Abstract]
Deferred revenue	$ 2,433	$ 2,366
Deferral of revenue billed in current period, net of recognition	381	392
Recognition of revenue deferred in prior periods	(1,030)	(793)
Deferred revenue	$ 1,784	$ 1,965