Equity Incentive Plans - Summary of Options Outstanding and Vested (Details)	9 Months Ended
	Sep. 30, 2018 $ / shares shares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Option Outstanding, Number Outstanding	11,367,104
Options Vested and Exercisable, Number Vested and Exercisable	6,597,314
Options Vested and Exercisable, Weighted Average Life (in Years)	5 years 7 months 20 days
$0.70 to 1.90
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 0.70
Exercise Prices, High | $ / shares	$ 1.90
Option Outstanding, Number Outstanding	1,112,182
Options Outstanding, Weighted Average Life (in Years)	2 years 4 months 17 days
Options Vested and Exercisable, Number Vested and Exercisable	1,112,182
Options Vested and Exercisable, Weighted Average Life (in Years)	2 years 4 months 17 days
2.86 to 6.40
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 2.86
Exercise Prices, High | $ / shares	$ 6.40
Option Outstanding, Number Outstanding	1,209,521
Options Outstanding, Weighted Average Life (in Years)	4 years 5 months 1 day
Options Vested and Exercisable, Number Vested and Exercisable	1,209,521
Options Vested and Exercisable, Weighted Average Life (in Years)	4 years 5 months 1 day
8.04 to 11.72
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 8.04
Exercise Prices, High | $ / shares	$ 11.72
Option Outstanding, Number Outstanding	1,519,571
Options Outstanding, Weighted Average Life (in Years)	5 years 4 months 13 days
Options Vested and Exercisable, Number Vested and Exercisable	1,500,509
Options Vested and Exercisable, Weighted Average Life (in Years)	5 years 4 months 13 days
12.20 to 15.06
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 12.20
Exercise Prices, High | $ / shares	$ 15.06
Option Outstanding, Number Outstanding	4,767,480
Options Outstanding, Weighted Average Life (in Years)	7 years 9 months 14 days
Options Vested and Exercisable, Number Vested and Exercisable	2,684,808
Options Vested and Exercisable, Weighted Average Life (in Years)	7 years 6 months 29 days
16.06 to 42.21
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Low | $ / shares	$ 16.06
Exercise Prices, High | $ / shares	$ 42.21
Option Outstanding, Number Outstanding	2,758,350
Options Outstanding, Weighted Average Life (in Years)	9 years 4 months 28 days
Options Vested and Exercisable, Number Vested and Exercisable	90,294
Options Vested and Exercisable, Weighted Average Life (in Years)	9 years 2 months 4 days