Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 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		373,121
Vested		(218,017	)
Forfeited		(98,311	)
Outstanding as of June 30, 2021		1,014,488

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		1,873,063		$	83.83
Exercised		(250,108	)	$	45.98
Forfeited		(816,023	)	$	138.19
Outstanding as of June 30, 2021		7,964,762		$	86.26		7.10	$	50,537
Exercisable as of June 30, 2021		4,467,182		$	83.13		5.77	$	43,822

Summary of Stock-Based Compensation Expense Recognized

Stock-based compensation expense recognized during the three and six months ended June 30, 2021 and 2020 was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
	(in thousands)
Research and development	$	13,453	$	10,120	$	22,734	$	22,344
Selling, general and administrative		14,210		12,124		26,905		31,010
Restructuring		—		1,788		—		1,788
	$	27,663	$	24,032	$	49,639	$	55,142

Summary of Stock-Based Compensation Expense by Award Type

Stock-based compensation expense recognized during the three and six months ended June 30, 2021 and 2020 by award type was as follows:

	Three Months Ended June 30,					Six Months Ended June 30,
	2021		2020			2021		2020
	(in thousands)
Stock options	$	21,545	$	23,418		$	41,224	$	53,636
Restricted stock units		5,920		750			7,975		750
Employee stock purchase plan		198		(136	)		440		756
	$	27,663	$	24,032		$	49,639	$	55,142