Employee Stock Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2017

Table Text Blocks

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 and six months ended June 30, 2017 and 2016 (in thousands):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2017		2016		2017		2016
Research and development	$	3,568	$	3,265	$	6,192	$	5,764
Selling, general and administrative		5,572		4,832		10,227		9,139
	$	9,140	$	8,097	$	16,419	$	14,903

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				Six Months Ended
	June 30,				June 30,
	2017		2016		2017		2016
Expected volatility	46.1	%	45.9	%	46.1	%	46.0	%
Expected term (in years)	6.0		6.0		6.0		6.0
Risk-free interest rate	2.0	%	1.5	%	2.0	%	1.5	%
Expected dividend yield	—	%	—	%	—	%	—	%

Summary of stock option activity

		Weighted-
		Average
	Number of Shares	Fair Value
	(in thousands)
Outstanding at December 31, 2016	20,455	$	11.92
Granted	3,160		16.63
Exercised	(1,598)		9.57
Cancelled	(396)		13.27
Outstanding at June 30, 2017	21,621	$	12.75

Summary of RSU activity

		Weighted-
		Average
	Number	Grant Date
	of Shares	Fair Value
	(in thousands)
Unvested as of December 31, 2016	1,299	$	12.53
Granted	1,267	$	16.71
Vested	(224)	$	12.86
Forfeited	(72)	$	14.43
Unvested as of June 30, 2017	2,270	$	14.77