Stock-Based Compensation and Employee Benefit Plans - Stock Option and Restricted Stock Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Outstanding Options/RSUs, Number of Shares
Outstanding (in shares)	14,558,420	11,604,403
Granted (in shares)	4,956,064	4,202,284
Exercised (in shares)	(358,564)	(398,704)
Cancelled (in shares)	(1,318,604)	(849,563)
Outstanding (in shares)	17,837,316	14,558,420	11,604,403
Outstanding Options Weighted Average Exercise Price
Outstanding (in dollars per share)	$ 25.93	$ 26.42
Granted (in dollars per share)	5.60	19.79
Exercised (in dollars per share)	4.26	3.98
Cancelled (in dollars per share)	25.33	12.51
Outstanding (in dollars per share)	$ 20.76	$ 25.93	$ 26.42
Outstanding, remaining contractual life	6 years 11 months 9 days	6 years 9 months 11 days	6 years 4 days
Outstanding, aggregate intrinsic value	$ 14,964,000	$ 3,084,000	$ 52,682,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Vested and expected to vest (in shares)	17,159,824
Exercisable (in shares)	9,161,918
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 21.17
Exercisable, weighted average exercise price (in dollars per share)	$ 28.82
Vested and expected to vest, remaining contractual life	6 years 10 months 6 days
Exercisable, remaining contractual life	4 years 10 months 21 days
Vested and expected to vest, aggregate intrinsic value	$ 13,471,000
Exercisable, aggregate intrinsic value	$ 500,000