Equity Incentive Plans - Summary of Stock Option Activity (Details) - Stock Option $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Options Outstanding
Outstanding at beginning of period | shares	7,490,000
Options exercised | shares	(1,105,000)
Options forfeited or canceled | shares	(70,000)
Outstanding at end of period | shares	6,315,000
Vested and expected to vest at end of period | shares	6,151,000
Exercisable at end of period | shares	4,120,000
Weighted Average Exercise Price per Share
Outstanding at beginning of period | $ / shares	$ 10.76
Options exercised | $ / shares	6.80
Options forfeited or canceled | $ / shares	14.16
Outstanding at end of period | $ / shares	11.42
Vested and expected to vest at end of period | $ / shares	11.33
Exercisable at end of period | $ / shares	$ 9.60
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding	6 years 7 months 6 days
Vested and expected to vest at end of period	6 years 6 months 21 days
Exercisable at end of period	5 years 9 months 18 days
Total Intrinsic Value | $	$ 106,863
Vested and expected to vest at end of period | $	104,638
Exercisable at end of period | $	$ 77,188