Accounts Receivable - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Receivables [Abstract]
Amount billed but not received under retainage provisions in contracts	$ 1,500,000		$ 1,500,000
Retainage receivables on contracts period	1 year
Bad debt (recoveries) expense	$ (41,000)	$ 46,000