Accounting for Shared-Based Payments (Details 2) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended	81 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Sep. 30, 2015
Number of Options
Exercised (in shares)	(248,387)
Weighted Average Remaining Contractual Term
Stock based compensation expense	$ (69,000)	$ 922,000	$ 7,724,000	$ 3,187,000
Stock options | Contingent vesting
Weighted Average Exercise Price Per Share
Balance outstanding, end of period (in dollars per share)	$ 0.70		$ 0.70		$ 0.70	$ 0.70
Weighted Average Remaining Contractual Term
Stock based compensation expense						$ 0
Stock options | Exercise Price Per Share $0.44 - $17.79
Number of Options
Balance outstanding, beginning of period (in shares)			16,567,020
Balance outstanding, end of period (in shares)					16,567,020
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)					$ 0.44
Exercise price, high end of the range (in dollars per share)					17.79
Weighted Average Exercise Price Per Share
Balance outstanding, end of period (in dollars per share)					$ 3.20
Intrinsic Value
Intrinsic value of options outstanding (in dollars)					$ 8,949,000
Weighted Average Remaining Contractual Term
Balance at the end of the period					7 years 3 months 15 days
Stock options | Exercise Price Per Share $0.44 - $17.79 | Contingent vesting
Number of Options
Balance outstanding, beginning of period (in shares)			4,364,000
Balance outstanding, end of period (in shares)					4,364,000
Stock options | Exercise Price Per Share $3.33 - $9.33
Number of Options
Granted (in shares)			3,706,112
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)			$ 3.33
Exercise price, high end of the range (in dollars per share)			9.33
Weighted Average Exercise Price Per Share
Granted (in dollars per share)			$ 6.70
Stock options | Exercise Price Per Share $3.40 - $6.28
Number of Options
Exercised (in shares)			(248,387)
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)			$ 3.40
Exercise price, high end of the range (in dollars per share)			6.28
Weighted Average Exercise Price Per Share
Exercised (in dollars per share)			$ 4.34
Stock options | Exercise Price Per Share $3.33 - $9.45
Number of Options
Forfeited (in shares)			(256,789)
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)			$ 3.33
Exercise price, high end of the range (in dollars per share)			9.45
Weighted Average Exercise Price Per Share
Forfeited (in dollars per share)			$ 6.93
Stock options | Exercise Price Per Share $0.44 - $9.12
Number of Options
Balance outstanding, end of period (in shares)	19,767,956		19,767,956			19,767,956
Exercisable at the end of the period (in shares)	7,560,758		7,560,758			7,560,758
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)			$ 0.44
Exercise price, high end of the range (in dollars per share)			9.12
Weighted Average Exercise Price Per Share
Balance outstanding, end of period (in dollars per share)	$ 3.74		3.74			$ 3.74
Exercisable at the end of the period (in dollars per share)	$ 3.19		$ 3.19			$ 3.19
Intrinsic Value
Intrinsic value of options outstanding (in dollars)	$ 36,270,000		$ 36,270,000			$ 36,270,000
Intrinsic value of options exercisable (in dollars)	$ 16,387,000		$ 16,387,000			$ 16,387,000
Weighted Average Remaining Contractual Term
Balance at the end of the period			7 years 2 months 19 days
Exercisable at the end of the period			5 years 7 months 10 days
Stock options | Exercise Price Per Share $0.44 - $9.12 | Contingent vesting
Number of Options
Balance outstanding, end of period (in shares)	4,364,000		4,364,000			4,364,000