Fair Value Measurements - Summary of Financial Instruments Measured at Fair Value (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Balance Sheet Location	Deferred acquisition costs, current	Deferred acquisition costs, current
Financial Assets	$ 825,759	$ 12,093
Convertible security	$ 25,000	$ 46,500
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Balance Sheet Location	Cash and cash equivalents	Cash and cash equivalents
Financial Assets	$ 820,594	$ 6,413
Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Balance Sheet Location	Prepaid expenses and other current assets
Financial Assets	$ 5,165
Embedded derivative
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Balance Sheet Location		Long-term debt
Financial Assets		$ 5,680
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets	825,759	6,413
Convertible security	25,000	0
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets	820,594	6,413
Level 1 | Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets	5,165
Level 1 | Embedded derivative
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets		0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets	0	0
Convertible security	0	0
Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets	0	0
Level 2 | Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets
Level 2 | Embedded derivative
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets		0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets	0	5,680
Convertible security	0	46,500
Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets	0	0
Level 3 | Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets
Level 3 | Embedded derivative
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Assets		$ 5,680