Share-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of non-cash share-based compensation expense

Non-cash share-based compensation expense, consisting of expense for both stock options and RSUs, was classified in the condensed consolidated statements of operations and comprehensive loss as follows:

	Three Months Ended March 31,
	2020		2019
Research and development expenses	$	6,251	$	3,700
General and administrative expenses	10,628		3,630
	$	16,879	$	7,330

Schedule of stock option activity

The following table is a summary of the Company's stock option activity for the three months ended March 31, 2020:

	Number of Shares	Weighted Average Exercise Price	Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2019	9,423,015	$24.58
Granted	88,838	$45.63
Exercised	(350,461)	$7.44
Forfeited	(24,563)	$36.95
Outstanding at March 31, 2020	9,136,829	$25.41	7.51	$	119,446
Options exercisable at March 31, 2020	5,315,110	$16.47	6.65	$	106,407
Vested at March 31, 2020 and expected to vest in the future	9,136,829	$25.41	7.51	$	119,446

Schedule of RSU activity

The following table is a summary of the RSU activity for the three months ended March 31, 2020:

	Number of Shares	Weighted Average Grant Date Fair Value
Unvested outstanding as of December 31, 2019	88,950	$57.40
Granted	482,175	$54.92
Forfeited	(4,750)	$54.28
Vested	(86,508)	$55.82
Unvested outstanding as of March 31, 2020	479,867	$55.22