Equity and Equity Compensation Plans - Allocation of Stock-based Compensation Expense (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 13,743,000	$ 7,205,000	$ 26,327,000	$ 14,416,000
Stock-based compensation capitalized in property and equipment	985,000	647,000	1,717,000	1,151,000
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	3,758,000	1,769,000	6,736,000	3,407,000
Technology and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	5,771,000	3,124,000	11,532,000	6,772,000
Marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	535,000	352,000	1,078,000	727,000
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 3,679,000	$ 1,960,000	$ 6,981,000	$ 3,510,000