Revenue Recognition - Summary of Impact of Adoption of New Revenue Standard on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2018	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	$ 94,376	$ 68,642		$ 31,699
Deferred costs	14,500	9,900		2,429
Deferred costs (non-current)	15,900	14,200
Other current liabilities	15,602	4,819		808
Deferred revenue (current and non-current)				73,072
Accumulated deficit	$ (293,316)	$ (199,920)		$ (109,252)
Accounting Standards Update 2014-09
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net			$ 31,799
Deferred costs			4,561
Deferred costs (non-current)			6,965
Other current liabilities			908
Deferred revenue (current and non-current)			73,072
Accumulated deficit			(100,155)
Accounting Standards Update 2014-09 | Adjustments Due to ASC 606
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net			100
Deferred costs			2,132
Deferred costs (non-current)			6,965
Other current liabilities			100
Accumulated deficit			$ 9,097