Stock-Based Compensation (Tables)

12 Months Ended

Dec. 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 Plan and 2017 Plan, and related information during the year ended December 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		2,452,738			36.36
Options exercised		(699,974	)		16.92
Options canceled		(759,612	)		42.12
Balance at December 31, 2018		7,507,690		$	33.25

Additional Information Related to the Status of Stock Options

Additional information related to the status of stock options at December 31, 2018, is as follows (aggregate intrinsic value in thousands):  

			Weighted-
			Average		Remaining
			Exercise Price		Contractual		Aggregate
	Shares		Per Share		Life		Intrinsic Value
Outstanding		7,507,690	$	33.25		6.5	$	4,833
Vested		4,149,238	$	31.05		5.0	$	4,819

Summary of PSO Activities

The following table summarizes PSO activities under our 2013 Plan and related information

	Shares
	Subject to			Weighted-
	Outstanding			Average Exercise
	PSOs			Price Per Share
Balance at December 31, 2017		164,783		$	23.76
Options granted		—			—
Options exercised		(17,448	)		23.76
Options canceled		(4,000	)		23.76
Balance at December 31, 2018		143,335		$	23.76

Additional Information Related to the Status of PSOs

Additional information related to the status of PSOs at December 31, 2018, is as follows (aggregate intrinsic value in thousands):

			Weighted-
			Average		Remaining
			Exercise Price		Contractual		Aggregate
	Shares		Per Share		Life		Intrinsic Value
Outstanding and Vested		143,335	$	23.76		4.0	$	-

Summary of RSU Activities

The following table summarizes RSU activities under our 2013 Plan and 2017 Plan and related information:

	Shares
	Subject to			Weighted-
	Outstanding			Average Grant Date
	RSUs			Fair Value Per Share
Balance at December 31, 2017		600,334		$	27.87
RSUs granted		758,156			37.62
RSUs released		(279,555	)		28.49
RSUs canceled		(99,657	)		40.13
Balance at December 31, 2018		979,278		$	34.00

Additional Information Related to the Status of RSUs

Additional information related to the status of RSUs at December 31, 2018, is as follows (aggregate intrinsic value in thousands):

			Remaining
			Contractual		Aggregate
	Shares		Life		Intrinsic Value
Outstanding		979,278		1.2	$	19,116

Summary of PSU Activities

The following table summarizes PSU activities under our 2013 Plan and related information:

	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		(218,107	)		25.26
PSUs canceled		(35,744	)		27.48
Balance at December 31, 2018		153,503		$	29.85

Additional Information Related to the Status of PSUs

Additional information related to the status of PSUs at December 31, 2018, is as follows (aggregate intrinsic value in thousands):

			Remaining
			Contractual		Aggregate
	Shares		Life		Intrinsic Value
Outstanding		153,503		0.7	$	2,996

Classification of Stock-Based Compensation Expense

Stock-based compensation expense is reflected in the consolidated statements of operations as follows (in thousands):

	Year Ended December 31,
	2018			2017		2016
Research and development	$	27,694		$	19,779	$	12,905
Selling, general and administrative		28,712			23,505		17,457
Subtotal	$	56,406		$	43,284	$	30,362
Capitalized stock-based compensation costs		(1,046	)		—		—
Stock-based compensation expense included in total expenses	$	55,360		$	43,284	$	30,362

Summary of Weighted-Average Assumptions of Fair Value Awards

The following table illustrates the weighted-average assumptions for the Black-Scholes option-pricing model used in determining the fair value of these awards:

	Year Ended December 31,
	2018	2017	2016
Risk-free interest rate
Stock options	2.55% - 3.03%	1.70% - 2.27%	1.01% - 2.10%
Performance stock options	–	–	1.34% - 1.50%
ESPP	1.10% - 2.28%	0.47% - 1.10%	0.26% - 0.50%
Expected term
Stock options	5.0 - 6.1 years	5.0 - 6.1 years	5.0 - 6.1 years
Performance stock options	–	–	5.4 - 6.4 years
ESPP	0.5 years	0.5 years	0.5 years
Expected volatility
Stock options	59% - 62%	60% - 65%	62% - 66%
Performance stock options	–	–	65% - 66%
ESPP	49% - 65%	61% - 80%	54% - 99%
Dividend yield
Stock options	–	–	–
Performance stock options	–	–	–
ESPP	–	–	–