Fair Value of Financial Instruments - Schedule of warrant liability (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 83,652	$ 1,738
Issuance of warrant on Series E convertible preferred stock		12,620
Increase in fair value of warrant	47,061	69,294
Exercise of preferred stock warrants prior to Business Combination	(130,714)
Public and Private placement Warrants acquired in Business Combination	45,623
Decrease in fair value of Public and Private placement Warrants	(38,929)
Balance, end of period	$ 6,693	$ 83,652