Basis of Presentation and Summary of Significant Accounting Policies - Revenue, Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Impairment losses on contract assets	$ 0	$ 0	$ 0
Right-of-use lease assets	83,600,000	77,200,000
Current lease liability	22,100,000	19,000,000.0
Long-term lease liability	$ 65,100,000	$ 61,100,000
Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues, percent	92.20%	92.00%	92.50%
Transferred over Time
Disaggregation of Revenue [Line Items]
Revenues, percent	7.80%	8.00%	7.50%