Stock-Based Compensation - Summary of Stock-Based Compensation Expense for Employees and Nonemployees (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 11,869,000	$ 1,414,000	$ 55,259,000	$ 4,743,000
Share-based payment arrangement, amount capitalized	200,000	0	500,000	0
Marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	2,328,000	261,000	4,946,000	919,000
Selling, general, and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 9,541,000	$ 1,153,000	$ 50,313,000	$ 3,824,000