Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Activity Relating to Restricted Stock Units

The table below summarizes activity relating to time-based restricted stock units and performance restricted stock units:

	Shares
Outstanding as of December 31, 2020		957,695
Granted		341,721
Vested		—
Forfeited		(13,241	)
Outstanding as of March 31, 2021		1,286,175

Summary of Activity Relating to Time Based and Performance Based Stock Options

The table below summarizes activity related to time-based and performance-based stock options:

	Shares			Weighted Average Exercise Price		Weighted Average Remaining Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2020		7,157,830		$	91.41		6.91	$	167,242
Granted		1,740,263			84.43
Exercised		(81,588	)		58.34
Forfeited		(78,155	)		139.01
Outstanding as of March 31, 2021		8,738,350		$	89.90		7.28	$	114,140
Exercisable as of March 31, 2021		4,846,143		$	90.10		5.95	$	86,826

Summary of Stock-Based Compensation Expense Recognized

Stock-based compensation expense recognized during the three months ended March 31, 2021 and 2020 was as follows:

	Three Months Ended March 31,
	2021		2020
	(in thousands)
Research and development	$	9,281	$	12,224
Selling, general and administrative		12,695		18,886
	$	21,976	$	31,110

Summary of Stock-Based Compensation Expense by Award Type

Stock-based compensation expense recognized during the three months ended March 31, 2021 and 2020 by award type was as follows:

	Three Months Ended March 31,
	2021		2020
	(in thousands)
Stock options	$	19,679	$	30,218
Restricted stock units		2,055		—
Employee stock purchase plan		242		892
	$	21,976	$	31,110