Common Equity (Details 1) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Jan. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock option activity
Outstanding, Shares, Beginning Balance	8,089,710
Outstanding, Weighted-Average Exercise Price, Beginning	$ 26.84
Granted, shares	899,500
Granted, Weighted-Average Exercise Price		$ 3.45	$ 3.34	$ 3.17
Outstanding, Shares, Ending Balance		8,089,710
Outstanding, Weighted-Average Exercise Price, Ending		$ 26.84
Exercisable, shares		5,708,920
Exercisable, Weighted-Average Exercise Price		$ 23.16
Stock Options [Member]
Stock option activity
Outstanding, Shares, Beginning Balance		8,919,669
Outstanding, Weighted-Average Exercise Price, Beginning		$ 23.86
Granted, Weighted-Average Exercise Price		$ 37.46
Exercised, shares		(2,238,489)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price		$ 21.67
Forfeited, shares		(10,030)
Forfeited, Weighted-Average Exercise Price		$ 35.37
Outstanding, Shares, Ending Balance		8,089,710
Outstanding, Weighted-Average Exercise Price, Ending		$ 26.84
Outstanding, Weighted-Average Remaining Contractual Life (Years)		5 years 5 months
Outstanding, Aggregate Intrinsic Value		$ 117.3
Exercisable, shares		5,708,920
Exercisable, Weighted-Average Exercise Price		$ 23.16
Exercisable, Weighted-Average Remaining Contractual Life (Years)		4 years 1 month
Exercisable, Aggregate Intrinsic Value		$ 103.8