Stock-based Compensation - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Number Of Options
Beginning balance (in shares)	13,291,684
Options granted (in shares)	1,137,046
Options exercised (in shares)	(744,215)
Options forfeited or canceled (in shares)	(503,565)
Ending balance (in shares)	13,180,950	13,291,684
Options exercisable at December 31, 2017 (in shares)	8,754,523
Weighted- Average Exercise Price
Beginning balance (in dollars per share)	$ 5.85
Options granted (in dollars per share)	10.78
Options exercised (in dollars per share)	4.03
Options forfeited or canceled (in dollars per share)	7.95
Ending balance (in dollars per share)	6.30	$ 5.85
Options exercisable at December 31, 2017 (in dollars per share)	$ 4.94
Stock Option Activity, Additional Disclosures
Weighted average remaining contractual life outstanding	7 years 7 days	7 years 8 months 27 days
Weighted average remaining contractual life exercisable	6 years 3 months
Options outstanding, Aggregate intrinsic value	$ 329,786	$ 61,774
Options exercised, Aggregate intrinsic value	20,308
Options exercisable, Aggregate intrinsic value	$ 230,914