Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2015

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

Stock-Based Compensation Expense for Options Granted, Restricted Stock and Stock Purchase Rights as Reflected in Statement of Operations

Stock-based compensation expense for options granted and restricted stock awards (“RSAs”) is reflected in the consolidated statement of operations as follows:

	THREE MONTHS ENDED   SEPTEMBER 30,				NINE MONTHS ENDED   SEPTEMBER 30,
(in thousands)	2015		2014		2015		2014
Research and development	$	597	$	220	$	1,691	$	1,072
General and administrative	2,719		2,172		7,842		5,624
Total	$	3,316	$	2,392	$	9,533	$	6,696

Schedule of Stock Options Activity

The following table summarizes the stock option activity under the Plans:

	NUMBER OF SHARES		WEIGHTED AVERAGE EXERCISE PRICE		AGGREGATE INTRINSIC VALUE
					(000’s)
Options outstanding at December 31, 2014	3,826,459		$	8.39	$	79,792
Granted	1,081,000		25.50		—
Exercised	(287,193	)	4.49		—
Canceled	(255,323	)	17.11		—
Options outstanding at September 30, 2015	4,364,943		$	12.33	$	23,614
Options exercisable at September 30, 2015	2,006,263		$	7.27	$	21,006

Restricted Stock and Restricted Stock Units Activity

The following table summarizes the RSA activity under the Plans:

	NUMBER OF SHARES		WEIGHTED AVERAGE FAIR VALUE PER SHARE
RSAs outstanding at December 31, 2014	103,064		$	2.47
Granted	99,027		28.00
Vested	(58,165	)	3.10
Canceled	(11,304	)	28.54
RSAs outstanding at September 30, 2015	132,622		$	19.03