Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment	$ 200,752	$ 135,674
Accumulated depreciation and amortization	(42,118)	(32,412)
Property and Equipment, net	158,634	103,262
Computer and Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	29,570	23,834
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	143,246	93,239
Website and Software
Property Plant And Equipment [Line Items]
Total property and equipment	8,323	6,510
Office Equipment and Furniture
Property Plant And Equipment [Line Items]
Total property and equipment	$ 19,613	$ 12,091