Share-Based Compensation - Options (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Shares
Outstanding, beginning of the period	8,491,734
Granted	3,794,735
Exercised	(1,324,429)
Forfeited	(1,003,182)
Outstanding, end of the period	9,958,858	8,491,734
Options exercisable	3,799,854
Options unvested	6,159,004
Weighted Average Grant Date Fair Value
Outstanding, beginning of the period	$ 11.17
Granted	16.50
Exercised	4.57
Forfeited	14.88
Outstanding, end of the period	13.53	$ 11.17
Options exercisable	10.83
Options unvested	$ 15.19
Weighted Average Remaining Contractual Term (in years)
Outstanding	8 years 1 month 24 days	7 years 10 months 17 days
Exercisable	7 years
Unvested	2 years 9 months 14 days
Aggregate Intrinsic Value
Outstanding	$ 52,394,000	$ 27,217,000
Exercisable	31,526,000
Unvested	64,715,000
Proceeds from exercise of options	$ 6,553,000	$ 1,119,000	$ 377,000
Class A common shares | Stock options
Number of Shares
Exercised	(1,324,429)	(150,253)	(25,683)
Aggregate Intrinsic Value
Intrinsic value of options exercised	$ 18,271,000	$ 1,776,000	$ 411,000
Weighted-average grant-date fair value per share of options granted	$ 11.38	$ 9.36	$ 11.96
Total fair value of options vested	$ 17,931	$ 13,997,000	$ 2,255,000
Proceeds from exercise of options	$ 6,058,000	$ 590,000	$ 87,000