Stock Based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity under our 2013 Equity Incentive Plan (the “2013 Plan”) and an Inducement Plan, and related information during the three months ended March 31, 2018:

	Shares
	Subject to			Weighted-
	Outstanding			Average Exercise
	Options			Price Per Share
Balance at December 31, 2017		6,514,538		$	31.36
Options granted		1,144,976			47.83
Options exercised		(185,664	)		22.30
Options canceled		(180,117	)		37.37
Balance at March 31, 2018		7,293,733		$	34.03

Summary of PSO Activities

The following table summarizes PSO activities under our 2013 Plan and related information during the three months ended March 31, 2018:

	Shares
	Subject to			Weighted-
	Outstanding			Average Exercise
	PSOs			Price Per Share
Balance at December 31, 2017		164,783		$	23.76
Options granted		—			—
Options exercised		(1,302	)		23.76
Options canceled		—			—
Balance at March 31, 2018		163,481		$	23.76

Summary of RSU Activity

The following table summarizes RSU activity under our 2013 Plan and Inducement Plan, and related information during the three months ended March 31, 2018:

	Shares
	Subject to			Weighted-
	Outstanding			Average Grant Date
	RSUs			Fair Value Per Share
Balance at December 31, 2017		600,334		$	27.87
RSUs granted		359,057			48.78
RSUs released		(279,555	)		28.49
RSUs canceled		(33,711	)		34.11
Balance at March 31, 2018		646,125		$	38.90

Summary of PSU Activity

	Shares
	Subject to			Weighted-
	Outstanding			Average Grant Date
	PSUs			Fair Value Per Share
Balance at December 31, 2017		304,754		$	25.34
PSUs granted		102,600			32.66
PSUs released		(6,004	)		49.83
PSUs canceled		(8,125	)		25.54
Balance at March 31, 2018		393,225		$	26.87

Classification of Stock-Based Compensation Expense

The table below sets forth the functional classification of stock-based compensation expense for the periods presented (in thousands):  

	Three Months Ended March 31,
	2018		2017
Research and development	$	4,452	$	4,150
Selling, general and administrative		6,528		4,884
Total stock-based compensation	$	10,980	$	9,034