Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based 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, 2019:

	Shares Subject to Outstanding Options		Weighted- Average Exercise Price Per Share
Balance at December 31, 2018	7,507,690		$	33.25
Options granted	2,199,307		27.74
Options exercised	(916,157	)	21.32
Options canceled	(1,242,404	)	38.62
Balance at December 31, 2019	7,548,436		$	32.21

Additional Information Related to the Status of Stock Options

Additional information related to the status of stock options at December 31, 2019, is as follows (aggregate intrinsic value in thousands):

	Shares	Weighted- Average Exercise Price Per Share		Weighted-Average Remaining Contractual Life	Aggregate Intrinsic Value
Outstanding	7,548,436	$	32.21	6.64	$	5,913
Vested	4,361,497	$	32.75	5.33	$	4,514

Summary of PSO Activities

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

	Shares Subject to Outstanding PSOs		Weighted- Average Exercise Price Per Share
Balance at December 31, 2018	143,335		$	23.76
Options granted	490,986		33.29
Options exercised	(35,624	)	23.76
Options canceled	(46,687	)	33.29
Balance at December 31, 2019	552,010		$	31.43

Additional Information Related to the Status of PSOs

Additional information related to the status of PSOs at December 31, 2019, is as follows (aggregate intrinsic value in thousands):

	Shares	Weighted- Average Exercise Price Per Share		Weighted-Average Remaining Contractual Life	Aggregate Intrinsic Value
Outstanding	552,010	$	31.43	7.78	$	34
Vested	107,711	$	23.76	3.00	$	34

Summary of RSU Activities

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

	Shares Subject to Outstanding RSUs		Weighted- Average Grant Date Fair Value Per Share
Balance at December 31, 2018	979,278		$	34.00
RSUs granted	882,646		27.86
RSUs released	(401,393	)	33.62
RSUs canceled	(186,314	)	34.02
Balance at December 31, 2019	1,274,217		$	29.86

Additional Information Related to the Status of RSUs

Additional information related to the status of RSUs at December 31, 2019, is as follows (aggregate intrinsic value in thousands):

	Shares	Weighted-Average Remaining Contractual Life	Aggregate Intrinsic Value
Outstanding	1,274,217	1.16	$	30,428

Summary of PSU Activities

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

	Shares Subject to Outstanding PSUs		Weighted- Average Grant Date Fair Value Per Share
Balance at December 31, 2018	153,503		$	29.85
PSUs granted	—		—
PSUs released	(52,670	)	28.29
PSUs canceled	(88,908	)	30.4
Balance at December 31, 2019	11,925		32.66

Additional Information Related to the Status of PSUs

Additional information related to the status of PSUs at December 31, 2019, is as follows (aggregate intrinsic value in thousands):

	Shares	Weighted-Average Remaining Contractual Life	Aggregate Intrinsic Value
Outstanding	11,925	0.03	$	285

Classification of Stock-Based Compensation Expense

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

	Year Ended December 31,
	2019			2018			2017
Research and development	$	19,340		$	27,694		$	19,779
Selling, general and administrative	32,735			28,712			23,505
Stock-based compensation expense included in total expenses	$	52,075		$	56,406		$	43,284
							—
Capitalized stock-based compensation costs	$	(1,657	)	$	(1,046	)	$	—

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,
	2019	2018	2017
Risk-free interest rate
Stock options	1.39% - 2.56%	2.55% - 3.03%	1.70% - 2.27%
Performance stock options	2.43%	—	—
ESPP	1.89% - 2.52%	1.10% - 2.28%	0.47% - 1.10%
Expected term
Stock options	5.0 - 6.1 years	5.0 - 6.1 years	5.0 - 6.1 years
Performance stock options	6.0 years	—	—
ESPP	0.5 years	0.5 years	0.5 years
Expected volatility
Stock options	59% - 61%	59% - 62%	60% - 65%
Performance stock options	61%	—	—
ESPP	43% - 67%	49% - 65%	61% - 80%
Dividend yield
Stock options	—	—	—
Performance stock options	—	—	—
ESPP	—	—	—