Stock-Based Compensation - Summary of Stock Option Activity (Details) - $ / shares	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock options, Outstanding, balance	12,795,000
Stock options, Granted	2,974,000
Stock options, Exercised	(912,000)
Stock options, Cancelled/Forfeited	(866,000)
Stock options, Outstanding, Balance	13,991,000	12,795,000
Stock options, Options vested and exercisable	6,957,000
Weighted-average exercise price, Outstanding, Balance	$ 5.89
Weighted-average exercise price, Granted	5.70
Weighted-average exercise price, Exercised	2.81
Weighted-average exercise price, Cancelled/Forfeited	8.38
Weighted-average exercise price, Outstanding, Balance	5.90	$ 5.89
Weighted-average exercise price, Options vested and exercisable	$ 4.71
Weighted-average remaining contractual life, options outstanding	7 years 10 months 13 days	7 years 9 months 26 days
Weighted-average remaining contractual life, options vested and exercisable	6 years 9 months 7 days