Implemented Accounting Pronouncements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Bad debt expense	$ 1,343,000	$ 1,013,000	$ 581,000
Allowance for doubtful accounts	2,100,000	1,883,000	$ 1,883,000
Net investment in sales-type leases	1,800,000	$ 2,900,000
Credit loss expense	$ 0
Minimum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Sales-type leases terms	12 months
Maximum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Sales-type leases terms	36 months