Equity (Activity of Stock Options) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Number of Shares
Outstanding, beginning of period (in shares)	15,375,960
Granted (in shares)	3,132,969
Exercised (in shares)	(1,653,690)
Unvested options forfeited (in shares)	(296,680)
Vested options expired (in shares)	(84,332)
Outstanding, end of period (in shares)	16,474,227
Vested at end of period (in shares)	9,280,650
Exercisable options, vested and expected to vest (in shares)	16,198,892	[1]
Weighted- Average Exercise Price
Outstanding, weighted average exercise price, beginning of period (in dollars per share)	$ 2.46
Granted, weighted average exercise price (in dollars per share)	$ 7.20
Exercised, weighted average exercise price (in dollars per share)	$ 1.49
Unvested options forfeited weighted-average exercise price (in dollars per share)	$ 4.09
Vested options expired weighted-average exercise price (in dollars per share)	$ 0.81
Outstanding, weighted average exercise price, end of period (in dollars per share)	$ 3.43
Vested at end of period weighted average exercise price (in dollars per share)	$ 1.97
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 3.38	[1]
Stock options, additional disclosures
Outstanding Options, weighted average remaining contractual term	7 years 3 months 18 days
Vested at end of period weighted average remaining contractual term	6 years 6 months
Vested and expected to vest, weighted average remaining contractual term	7 years 3 months 18 days	[1]
Outstanding intrinsic value	$ 133,360,210
Vested at end of period aggregate intrinsic value	88,716,569
Vested and expected to vest, aggregate intrinsic value	$ 131,953,654	[1]

[1] Includes forfeiture adjusted unvested shares.