Accounting for Shared-Based Payments (Details 2) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended	78 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Jun. 30, 2015
Weighted Average Remaining Contractual Term
Stock based compensation expense	$ 5,389,000	$ 999,000	$ 7,794,000	$ 2,264,000
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 Range 2.94 - 9.33
Number of Options
Granted (in shares)			625,000
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)			$ 2.94
Exercise price, high end of the range (in dollars per share)			9.33
Weighted Average Exercise Price Per Share
Granted (in dollars per share)			$ 6.54
Stock options | Exercise Price Range 2.94 - 9.45
Number of Options
Forfeited (in shares)			(153,631)
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)			$ 2.94
Exercise price, high end of the range (in dollars per share)			9.45
Weighted Average Exercise Price Per Share
Forfeited (in dollars per share)			$ 6.26
Stock options | Exercise Price Range 0.44 - 9.12
Number of Options
Balance outstanding, beginning of period (in shares)
Balance outstanding, end of period (in shares)	17,038,389		17,038,389			17,038,389
Exercisable at the end of the period (in shares)	7,703,334		7,703,334			7,703,334
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)	$ 3.30		3.30			$ 3.30
Exercisable at the end of the period (in dollars per share)	$ 3.20		$ 3.20			$ 3.20
Intrinsic Value
Intrinsic value of options outstanding (in dollars)	$ 80,864,000		$ 80,864,000			$ 80,864,000
Intrinsic value of options exercisable (in dollars)	$ 35,550,000		$ 35,550,000			$ 35,550,000
Weighted Average Remaining Contractual Term
Balance at the end of the period			7 years 1 month 21 days
Exercisable at the end of the period			5 years 9 months 11 days
Stock options | Exercise Price Range 0.44 - 9.12 | Contingent vesting
Number of Options
Balance outstanding, beginning of period (in shares)
Balance outstanding, end of period (in shares)	4,364,000		4,364,000			4,364,000