Employee Stock Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2015

Employee Stock Benefit Plans

Share-based compensation expense reflected in the condensed consolidated statements of operations

The following table summarizes share-based compensation expense reflected in the condensed consolidated statements of operations for the three months ended March 31, 2015 and 2014 (in thousands):

	Three Months Ended
	March 31,
	2015		2014
Research and development	$	2,054	$	2,690
Selling, general and administrative	3,372		3,384
	$	5,426	$	6,074

Summary of stock option activity

	Number of Shares		Weighted-Average Exercise Price
	(in thousands)
Outstanding at December 31, 2014	19,957		$	10.07
Granted	2,542		15.61
Exercised	(1,240	)	5.95
Cancelled	(169	)	13.01
Outstanding at March 31, 2015	21,090		$	10.96

Schedule of weighted-average assumptions used to estimate the fair value of the stock options using the Black-Scholes option-pricing model

	Three Months Ended
	March 31,
	2015		2014
Expected volatility	46.0	%	46.6	%
Expected term (in years)	6.0		6.1
Risk-free interest rate	1.7	%	1.8	%
Expected dividend yield	—	%	—	%

Summary of RSU activity

	Number of Shares		Weighted- Average Fair Value
	(in thousands)
Unvested as of December 31, 2014	—		—
Granted (1)	493		$	15.62
Vested	—		—
Forfeited	(2	)	15.62
Unvested as of March 31, 2015	491		$	15.62

(1) RSUs granted in the three months ended March 31, 2015 primarily represent awards made in connection with the Company’s annual equity grants in March 2015.