Revenues - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2018
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Additions in deferred revenue	$ 8,000
Additional Invoicing	159,800
Total revenues	151,798		$ 114,556
Deferred revenue, revenue recognized		$ 94,400
Revenue remaining performance obligation, contracts exceeds one year	$ 134,400
Revenue remaining performance obligation contract period	1 year
Revenue remaining performance obligation percentage recognized	94.00%
Short-term deferred revenue	$ 191,193			$ 183,305
Increase in deferred commission expense	3,100
Incremental costs of deferred sales commission expense	9,900
Amortization of deferred commission expense	$ 6,800
Minimum [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Amortization period of deferred commissions	1 year
Maximum [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Amortization period of deferred commissions	3 years
Accrued Expenses and Other Current Liabilities [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Short-term deferred revenue	$ 1,300			$ 1,600