Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of share option activity under the Plans

				Weighted
				Average
		Weighted		Remaining
		Average		Contractual	Aggregate
	Number of	Exercise		Term	Intrinsic
	Shares	Price		(in years)	Value
Outstanding as of December 31, 2019	8,491,734	$	11.17	7.88	$	27,217
Granted	3,794,735	$	16.50
Exercised	(1,324,429)	$	4.57
Forfeited	(1,003,182)	$	14.88
Outstanding as of December 31, 2020	9,958,858	$	13.53	8.15	$	52,394
Share options exercisable as of December 31, 2020	3,799,854	$	10.83	7.00	$	31,526
Share options unvested as of December 31, 2020	6,159,004	$	15.19	2.79	$	64,715

Schedule of share-based compensation expense was classified in the consolidated statements of operations and comprehensive loss

	Years Ended
	December 31,
	2020		2019		2018
Research and development expenses	$	8,866	$	5,746	$	2,285
Selling, general and administrative expenses		12,009		9,334		3,416
	$	20,875	$	15,080	$	5,701

Employees

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of stock option valuation assumptions presented on weighted-average basis

	Years Ended
	December 31,
	2020		2019		2018
Risk-free interest rate	0.55	%	2.07	%	2.82	%
Expected term (in years)	6.21		6.22		6.40
Expected volatility	80.81%	%	79.14	%	75.04	%
Expected dividend yield	—	%	—	%	—	%

Non-employees

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of stock option valuation assumptions presented on weighted-average basis

	Years Ended
	December 31,
	2019		2018
Risk-free interest rate	1.38	%	2.91	%
Expected term (in years)	2.77		7.35
Expected volatility	68.17	%	74.18	%
Expected dividend yield	—	%	—	%

Restricted Share Units (RSUs)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of restricted share activity

		Weighted
		Average
	Number of	Grant Date
	Shares	Fair Value
Unvested RSUs as of December 31, 2019	328,296	$	12.93
Granted	17,995	$	19.15
Vested	(80,701)	$	12.95
Forfeited	(60,278)	$	13.09
Unvested RSUs as of December 31, 2020	205,312	$	13.41