Equity (Summary of Unvested Stock Options) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Number of Shares
Unvested at (in shares)	8,568,228
Granted (in shares)	3,132,969
Called/expired (in shares)	(296,680)
Vested (in shares)	(4,210,940)
Unvested at (in shares)	7,193,577	8,568,228
Weighted- Average Grant Date Fair Value
Unvested at (in dollars per share)	$ 1.94
Granted (in dollars per share)	$ 4.18	$ 3.08	$ 1.07
Cancelled/expired (in dollars per share)	$ 4.09
Vested (in dollars per share)	$ 1.58
Unvested at (in dollars per share)	$ 3.08	$ 1.94