Capital stock - Additional Information (Detail) - USD ($)					12 Months Ended
	Oct. 19, 2020	Dec. 23, 2019	Sep. 19, 2018	Aug. 16, 2018	Dec. 31, 2019	Mar. 31, 2021	Dec. 31, 2020	Oct. 20, 2020
Number of shares of common stock authorized						320,000,000	320,000,000	320,000,000
Number of shares of preferred stock authorized							10,000,000	10,000,000
Preferred stock authorized par value								$ 0.0001
Common stock voting right		one
Preferred Stock, Conversion split				one-for-one
Preferred Stock, Shares Issued							0
Voting Common Stock [Member]
Number of shares of common stock authorized								300,000,000
Non-Voting Common Stock [Member]
Number of shares of common stock authorized								20,000,000
Series A Preferred Stock [Member]
Sale of stock issue price per share				$ 9.32
Sale of stock, consideration received on transaction			$ 20,000,000	$ 75,000,000
Series A [Member]
Conversion of convertible notes to redeemable convertible preferred stock				5,600,000
Stock issuance costs				$ 194,000
Series B Preferred Stock [Member]
Sale of stock, consideration received on transaction		$ 125,000,000
Series B One Preferred Stock [Member]
Sale of stock issue price per share		$ 10.18690
Sale of stock, consideration received on transaction		$ 85,000,000
Stock issuance costs					$ 442,000
Sale of Stock, Number of Shares Issued in Transaction		8,344,034
Series B Two Preferred Stock [Member]
Sale of stock issue price per share		$ 11.20563
Sale of Stock, Number of Shares Issued in Transaction	3,569,630	3,569,630
Cummulative stock issued						0