Income Taxes - Domestic and Foreign Components of Income Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
United States	$ (113,689)	$ (105,961)	$ (38,078)
(Loss) income before provision for (benefit from) income taxes	(105,128)	(93,226)	(24,174)
Israel
Income Tax Contingency [Line Items]
Foreign	2,214	2,791	3,163
United Kingdom
Income Tax Contingency [Line Items]
Foreign	536	5,377	3,690
Netherlands
Income Tax Contingency [Line Items]
Foreign	3,398	(465)	3,235
Australia
Income Tax Contingency [Line Items]
Foreign	1,663	716	686
Germany
Income Tax Contingency [Line Items]
Foreign	243	3,854	2,900
Other
Income Tax Contingency [Line Items]
Foreign	$ 507	$ 462	$ 230