Stock-Based Compensation - Summary of The Activity of Restricted Stock And Restricted Stock Units Granted By The Company (Detail)	9 Months Ended
	Sep. 30, 2021 $ / shares shares
Share-based Payment Arrangement, Disclosure [Abstract]
Non-vested as of January 1, 2021 | shares	85,903,970
Granted | shares	9,112,569
Vested | shares	(9,300,893)
Forfeited | shares	(4,700,102)
Cancelled | shares	(16,655,197)
Modified | shares	(68,986,297)
Modified and reissued | shares	68,986,297
Non-vested as of September 30, 2021 | shares	64,360,347
Non-vested as of January 1, 2021 | $ / shares	$ 2.80
Granted | $ / shares	8.62
Vested | $ / shares	11.04
Forfeited | $ / shares	9.46
Cancelled | $ / shares	3.60
Modified | $ / shares	2.78
Modified and reissued | $ / shares	11.36
Non-vested as of September 30, 2021 | $ / shares	$ 10.94