Equity Incentive Plans - Summary of Stock Option Activity (Details) - Stock Option $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Options Outstanding
Outstanding at beginning of period | shares	7,490,000
Options exercised | shares	(1,747,000)
Options forfeited or canceled | shares	(224,000)
Outstanding at end of period | shares	5,519,000
Vested and expected to vest at end of period | shares	5,390,000
Exercisable at end of period | shares	3,804,000
Weighted Average Exercise Price per Share
Outstanding at beginning of period | $ / shares	$ 10.76
Options exercised | $ / shares	7.98
Options forfeited or canceled | $ / shares	15.36
Outstanding at end of period | $ / shares	11.46
Vested and expected to vest at end of period | $ / shares	11.38
Exercisable at end of period | $ / shares	$ 9.90
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding	6 years 3 months 29 days
Vested and expected to vest at end of period	6 years 3 months 14 days
Exercisable at end of period	5 years 7 months 17 days
Total Intrinsic Value | $	$ 136,542
Vested and expected to vest at end of period | $	133,804
Exercisable at end of period | $	$ 100,037