Redeemable Convertible Preferred Stock Warrant Liability - Narrative (Details) - $ / shares	3 Months Ended					9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jun. 30, 2017	Jul. 31, 2015
Class of Warrant or Right [Line Items]
Issuance upon exercise of warrants (in shares)	62,000	4,448,000	531,000	45,000	75,000
Series D, Redeemable Convertible Preferred Stock
Class of Warrant or Right [Line Items]
Warrants exercised for redeemable convertible preferred stock (in shares)									108,145	869,842
Exercise price of warrants (in dollars per share)										$ 5.08
Warrant term (in years)										5 years
Series D, Redeemable Convertible Preferred Stock | Common Stock Warrants
Class of Warrant or Right [Line Items]
Issuance upon exercise of warrants (in shares)			531,423				651,328
Warrants outstanding (in shares)								0
Series E, Redeemable Convertible Preferred Stock Warrants
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)										$ 13.73
Warrants outstanding (in shares)	0					0		72,000
Series E, Redeemable Convertible Preferred Stock Warrants | Common Stock Warrants
Class of Warrant or Right [Line Items]
Issuance upon exercise of warrants (in shares)	62,454		0			62,454	0
Warrants outstanding (in shares)	0					0