Common Stock and Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Share-based Payment Arrangement [Abstract]

Summary of Stock Option Activity

The following is a summary of stock option activity for the six months ended June 30, 2019 (in thousands, except per share data):

	Shares	Weighted- Average Exercise Price per Share
Outstanding at December 31, 2018	3,744	$	20.69
Granted	924	50.28
Exercised	(386)	14.83
Canceled	(46)	34.57
Outstanding at June 30, 2019	4,236	$	27.53

Schedule of Restricted Stock Unit Activity

The following is a summary of restricted stock unit activity for the six months ended June 30, 2019 (in thousands, except per share data):

	Shares	Weighted- Average Fair Value per Share at Grant Date
Outstanding at December 31, 2018	289	$	25.56
Granted	169	52.56
Vested	(31)	42.65
Canceled	(16)	26.15
Outstanding at June 30, 2019	411	$	35.33

Stock-Based Compensation Expense

The following table summarizes the components of total stock-based compensation expense included in the condensed consolidated statements of operations (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Research and development	$	2,074	$	1,062	$	3,509	$	1,743
Selling, general and administrative	3,284		1,997		6,072		3,228
Total	$	5,358	$	3,059	$	9,581	$	4,971