Earnings Per Share Cumulative Convertible Stock Adjustments (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
5.75% Cumulative Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income Adjustments	$ 43
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	56
5.75% Cumulative Convertible Preferred Stock Series A
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income Adjustments	32
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	39
5.0% Cumulative Convertible Preferred Stock Series Two Thousand And Five B [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income Adjustments	5
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	5
4.50% Cumulative Comvertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income Adjustments	6
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	6
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income Adjustments	$ 11
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	5