Net Loss per Share - Schedule of Potentially Dilutive Securities not Included in Calculation of Diluted Net Loss per Share (Detail) - shares		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in calculation of dilutive net loss per share		30,830,705	29,512,766
Class B Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in calculation of dilutive net loss per share	[1]	23,093,860	23,093,860
Common Stock Options Granted Under the Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in calculation of dilutive net loss per share		5,722,342	4,404,403
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in calculation of dilutive net loss per share		2,014,503	2,014,503

[1] Shares of Class B Common Stock do not share in the Company’s earnings and are not participating securities.  Accordingly, separate presentation of loss per share of Class B Common Stock under the two-class method has not been provided.  Each share of Class B Common Stock (together with a corresponding vTv Unit) is exchangeable for one share of Class A Common Stock