Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock Option Activity

The following is a summary of stock option activity for the three months ended March 31, 2019 (in thousands, except per share data):

	Shares	Weighted- Average Exercise Price per Share
Outstanding at December 31, 2018	3,744	$	20.69
Granted	770	51.86
Exercised	(349)	15.17
Canceled	(10)	29.94
Outstanding at March 31, 2019	4,155	$	26.91

Schedule of Restricted Stock Unit Activity

The following is a summary of restricted stock unit activity for the three months ended March 31, 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	167	52.66
Vested	(31)	42.65
Canceled	(7)	18.81
Outstanding at March 31, 2019	418	$	35.27

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 March 31,
	2019		2018
Research and development	$	1,435	$	681
Selling, general and administrative	2,788		1,231
Total	$	4,223	$	1,912