Convertible Preferred Shares (Details) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	May 31, 2018 $ / shares shares	Feb. 28, 2018 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) director $ / shares shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 Vote director $ / shares shares	May 29, 2018 shares
Convertible Preferred Shares
Payment of offering expenses | $			$ 1,136	$ 118	$ 3,657
Preferred stock, cash dividends declared or paid | $					$ 0
Convertible Preferred Shares
Convertible Preferred Shares
Preferred shares designated		35,670,093	0	0		22,885,492
Preferred stock, shares issued (in shares)			0	0
Convertible preferred shares, par value (in dollars per share) | $ / shares		$ 0.000273235				$ 0.000273235
Number of directors entitled to elect | director						2
Series A convertible preferred shares
Convertible Preferred Shares
Preferred shares designated						17,128,120
Number of votes for each Class B common share | Vote						10
Original issue price (per share) | $ / shares	$ 4.6707
Convertible ratio to Class B common share	1
Series B convertible preferred shares
Convertible Preferred Shares
Preferred shares designated						5,757,372
Number of votes for each Class A common share | Vote						1
Original issue price (per share) | $ / shares	$ 6.9475
Convertible ratio to Class A common share	1
Series C convertible preferred shares
Convertible Preferred Shares
Preferred shares designated		12,784,601
Preferred stock, shares issued (in shares)		12,784,601
Share price per share | $ / shares		$ 15.6438
Proceeds from issuance of shares | $		$ 190,822
Payment of offering expenses | $		$ 9,178
Number of votes for each Class A common share | Vote						1
Original issue price (per share) | $ / shares	$ 15.6438
Convertible ratio to Class A common share	1
Common Class A and Class B
Convertible Preferred Shares
Number of directors entitled to elect | director				1
Class A common shares
Convertible Preferred Shares
Number of shares issued on conversion of convertible preferred shares	5,546,019						5,546,019
Class B common shares
Convertible Preferred Shares
Number of shares issued on conversion of convertible preferred shares	1,070,502						1,070,502
Class A1 common shares
Convertible Preferred Shares
Number of shares issued on conversion of convertible preferred shares	12,995,954						12,995,954
Class B1 common shares
Convertible Preferred Shares
Number of shares issued on conversion of convertible preferred shares	16,057,618						16,057,618
Common Class A or Class B | Minimum
Convertible Preferred Shares
Share price per share | $ / shares				$ 15.6438
Gross proceeds from IPO | $				$ 100,000