Summary of Stock Option Activity (Detail) - Employee Stock Option - 2013 Equity Incentive Plan	3 Months Ended
	Mar. 31, 2017 $ / shares shares
Shares Subject to Outstanding Stock Options
Beginning balance | shares	5,817,116
Options granted | shares	1,036,100
Options exercised | shares	(196,871)
Options canceled | shares	(71,202)
Ending balance | shares	6,585,143
Weighted-Average Exercise Price Per Share
Beginning balance | $ / shares	$ 25.26
Options granted | $ / shares	27.04
Options exercised | $ / shares	15.86
Options canceled | $ / shares	33.34
Ending balance | $ / shares	$ 25.73