Contract Assets and Liabilities - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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	43,200,000	53,500,000	$ 113,100,000	111,600,000
Revenue expected to be recognized	309,800,000		309,800,000
Amortization expense related to deferred commissions	$ 9,000,000.0	$ 8,900,000	$ 17,200,000	$ 16,000,000.0
Maximum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with customer, expected payment term			one year