Accounting for Shared-Based Payments (Details 2) (USD $)	12 Months Ended			110 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2011
Intrinsic Value
Stock based compensation expense	$ 4,722,000	$ 4,614,000	$ 2,515,000
Amount of excess tax benefits recognized (in dollars)	0
Stock options | Contingent vesting
Intrinsic Value
Grant date fair value	28,918,822			28,918,822
Stock based compensation expense				0
Stock options | Exercise price per Share 0.50 - 4.30
Number of Options
Balance outstanding, end of period (in shares)					5,964,039
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)					$ 0.50
Exercise price, high end of the range (in dollars per share)					$ 4.30
Weighted Average Exercise Price Per Share
Balance outstanding, end of period (in dollars per share)					$ 1.77
Intrinsic Value
Intrinsic value of options outstanding (in dollars)					6,027,000
Stock options | Exercise price per Share 3.40 - 5.20
Number of Options
Granted (in shares)			3,875,229
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)			$ 5.20
Weighted Average Exercise Price Per Share
Granted (in dollars per share)			$ 4.29
Stock options | Exercise price per Share 3.40 - 4.38
Number of Options
Forfeited (in shares)			(105,000)
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)			$ 4.38
Weighted Average Exercise Price Per Share
Forfeited (in dollars per share)			$ 4.10
Stock options | Exercise price per Share 0.50 - 5.20
Number of Options
Balance outstanding, end of period (in shares)			9,734,268
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)			$ 0.50
Exercise price, high end of the range (in dollars per share)			$ 5.20
Weighted Average Exercise Price Per Share
Balance outstanding, end of period (in dollars per share)			$ 2.75
Intrinsic Value
Intrinsic value of options outstanding (in dollars)			24,482,000
Stock options | Exercise price per Share 0.44 - 20.01
Number of Options
Granted (in shares)		2,545,965
Balance outstanding, end of period (in shares)		11,324,049
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)		$ 20.01
Weighted Average Exercise Price Per Share
Granted (in dollars per share)		$ 6.41
Balance outstanding, end of period (in dollars per share)		$ 3.31
Intrinsic Value
Intrinsic value of options outstanding (in dollars)		37,521,000
Stock options | Exercise price per Share 0.50 - 4.28
Number of Options
Exercised (in shares)		(61,787)
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)		$ 0.50
Exercise price, high end of the range (in dollars per share)		$ 4.28
Weighted Average Exercise Price Per Share
Exercised (in dollars per share)		$ 1.91
Intrinsic Value
Intrinsic value of options exercised (in dollars)		221,000
Stock options | Exercise price per Share 4.42 - 13.90
Number of Options
Forfeited (in shares)		(894,397)
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)		$ 4.42
Exercise price, high end of the range (in dollars per share)		$ 13.90
Weighted Average Exercise Price Per Share
Forfeited (in dollars per share)		$ 6.05
Stock options | Exercise price per Share 2.83 - 4.24
Number of Options
Granted (in shares)	5,528,000
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)	$ 2.83
Exercise price, high end of the range (in dollars per share)	$ 4.24
Weighted Average Exercise Price Per Share
Granted (in dollars per share)	$ 3.47
Stock options | Exercise price per Share 3.40 - 3.95
Number of Options
Exercised (in shares)	(9,999)
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)	$ 3.95
Weighted Average Exercise Price Per Share
Exercised (in dollars per share)	$ 3.58
Stock options | Exercise price per Share 4.24 - 20.01
Number of Options
Forfeited (in shares)	(275,030)
Exercise Price Per Share
Exercise price, low end of the range (in dollars per share)	$ 4.24
Exercise price, high end of the range (in dollars per share)	$ 20.01
Weighted Average Exercise Price Per Share
Forfeited (in dollars per share)	$ 13.42
Stock options | Exercise Price Range 0.44 To 17.79
Number of Options
Balance outstanding, end of period (in shares)	16,567,020			16,567,020
Exercisable at the end of the period (in shares)	7,028,499			7,028,499
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			$ 3.20
Exercisable at the end of the period (in dollars per share)	$ 3.13			$ 3.13
Intrinsic Value
Intrinsic value of options outstanding (in dollars)	8,949,000			8,949,000
Intrinsic value of options exercisable (in dollars)	$ 5,071,000			$ 5,071,000