Changes in Deferred Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenue From Contract With Customer [Abstract]
Deferred revenue	$ 2,366	$ 2,833
Deferral of revenue billed in current period, net of recognition	1,905	1,591
Recognition of revenue deferred in prior periods	(1,838)	(2,058)
Deferred revenue	$ 2,433	$ 2,366