Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2016

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 statements of operations as follows:

	THREE MONTHS ENDED   MARCH 31,
(in thousands)	2016		2015
Research and development	$	712	$	511
General and administrative	2,822		2,230
Total	$	3,534	$	2,741

Schedule of Stock Options Activity

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

	NUMBER OF SHARES		WEIGHTED AVERAGE EXERCISE PRICE		WEIGHTED AVERAGE REMAINING CONTRACTUAL LIFE (YEARS)	AGGREGATE INTRINSIC VALUE (000’s)
Options outstanding at December 31, 2015	4,583,586		$	12.86
Granted	672,636		15.85
Exercised	(25,121	)	2.61
Canceled	(29,682	)	22.57
Options outstanding at March 31, 2016	5,201,419		$	13.24	8.0	$	21,177
Options vested and expected to vest at March 31, 2016	5,110,809		$	13.14	8.0	$	21,096
Options exercisable at March 31, 2016	2,500,586		$	9.02	7.2	$	16,299

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, 2015	119,993		$	20.31
Granted	100,755		15.57
Vested	(30,078	)	18.57
Canceled	—		—
RSAs outstanding at March 31, 2016	190,670		$	18.07