Shareholders' Equity (Tables)

9 Months Ended

Sep. 30, 2018

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

Summary of Stock Option Activity

The Company’s stock option activity under its option plans was comprised of the following for the nine months ended September 30, 2018:

	Shares Underlying Stock Options		Weighted- average Exercise Price per Share
Outstanding at December 31, 2017	6,037,302		$	24.19
Granted	1,130,700		$	29.48
Exercised	(106,370	)	$	17.95
Forfeited	(293,368	)	$	26.94
Outstanding at September 30, 2018	6,768,264		$	25.05

Summary of Share-based Compensation Expense

Total share-based compensation expense related to all share-based awards was comprised of the following for each of the periods below (in thousands):

	Three Months Ended   September 30,				Nine Months Ended   September 30,
	2018		2017		2018		2017
Research and development	$	5,895	$	3,092	$	16,992	$	8,141
Selling, general and administrative	3,985		2,390		12,134		7,035
Total share-based compensation expense	$	9,880	$	5,482	$	29,126	$	15,176