Summary of Stock Option Activity (Detail) - Employee Stock Option - 2013 Equity Incentive Plan	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Shares Subject to Outstanding Stock Options
Beginning balance | shares	5,817,116
Options granted | shares	1,259,150
Options exercised | shares	(757,573)
Options canceled | shares	(142,391)
Ending balance | shares	6,176,302
Weighted-Average Exercise Price Per Share
Beginning balance | $ / shares	$ 25.26
Options granted | $ / shares	29.05
Options exercised | $ / shares	11.42
Options canceled | $ / shares	33.90
Ending balance | $ / shares	$ 27.53