Net Loss Per Share Attributable to Common Stockholders - Summary of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net loss	$ (69,129)	$ (94,922)	$ (24,374)	$ (13,003)	$ (15,054)	$ (16,380)	$ (188,425)	$ (44,437)
Cumulative redeemable convertible preferred stock dividends				3,774			7,060	11,150
Net loss available to common stockholders	$ (69,129)			$ (16,777)			$ (195,485)	$ (55,587)
Denominator:
Denominator for Basic and Dilutive Loss per share-Weighted-average Common Stock	129,731,980			32,607,357			75,313,520	32,607,373
Basic loss per share	$ (0.53)			$ (0.51)			$ (2.60)	$ (1.70)
Diluted loss per share	$ (0.53)			$ (0.51)			$ (2.60)	$ (1.70)
Class A Common Stock [Member]
Denominator:
Denominator for Basic and Dilutive Loss per share-Weighted-average Common Stock	111,312,720						50,027,683
Class B Common Stock [Member]
Denominator:
Denominator for Basic and Dilutive Loss per share-Weighted-average Common Stock	18,419,260						7,300,725
Series A Common Stock [Member]
Denominator:
Denominator for Basic and Dilutive Loss per share-Weighted-average Common Stock				26,108,711			14,420,964	26,108,727
Series B common stock [Member]
Denominator:
Denominator for Basic and Dilutive Loss per share-Weighted-average Common Stock				3,054,318			1,664,380	3,054,318
Warrant [Member]
Denominator:
Denominator for Basic and Dilutive Loss per share-Weighted-average Common Stock				3,444,328			1,899,768	3,444,328