Contract Assets and Liabilities - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract assets	$ 0	$ 0	$ 0	$ 0
Contract with customer, contract duration			1 year
Deferred revenue recognized	25,500,000	21,200,000	$ 138,600,000	132,800,000
Revenue expected to be recognized	301,000,000.0		301,000,000.0
Amortization expense related to deferred commissions	$ 9,900,000	$ 8,100,000	$ 27,100,000	$ 24,100,000
Maximum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with customer, expected payment term			one year