Stock-Based Compensation - Summary of Stock Option Activity Under Plans (Details)	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Subject to Outstanding Options, Beginning Balance | shares	2,141,868
Shares Subject to Outstanding Options, granted | shares	1,685,575
Shares Subject to Outstanding Options, exercised | shares	(282,978)
Shares Subject to Outstanding Options, canceled | shares	(254,788)
Shares Subject to Outstanding Options, Ending Balance | shares	3,289,677
Weighted Average Exercise Price Per Share, Beginning Balance | $ / shares	$ 6.42
Weighted Average Exercise Price Per Share, granted | $ / shares	14.69
Weighted Average Exercise Price Per Share, exercised | $ / shares	4.46
Weighted Average Exercise Price Per Share, cancelled | $ / shares	9.13
Weighted Average Exercise Price Per Share, Ending Balance | $ / shares	$ 10.62