Capital Stock (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.25	$ 0.25
Proceeds from Issuance of Common Stock	$ 799
Preferred Stock, Dividend Rate, Percentage	11.125%
Preferred Stock, Par or Stated Value Per Share	$ 0.01
Adjustments to Additional Paid in Capital, Preferred Dividends in Excess of Retained Earnings	$ 67
Proceeds from Issuance of Preferred Stock and Preference Stock	1,866
Restricted Cash and Cash Equivalents, Current	8,440
Restricted Cash For Equity Offering	1,955
Proceeds from Equity, Net of Issuance Costs	$ 2,665
Common Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period Shares Excluding Over Allotment New Issues	150,000,000
Stock Issued During Period, Shares, New Issues	165,000,000
Common stock, par value (in dollars per share)	$ 0.25
Shares Issued, Price Per Share	$ 5.00
Over Allotment Option Shares Issued	15,000,000
Preferred Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues	19,250,000
Shares Issued Excluding Over Allotment	17,500,000
Over Allotment Option Shares Issued	1,750,000
Preferred Stock, Dividend Rate, Percentage	11.125%
Preferred Stock, Par or Stated Value Per Share	$ 0.01
Preferred Stock, Liquidation Preference Per Share	$ 100
Additional Paid-in Capital [Member]
Class of Stock [Line Items]
Adjustments to Additional Paid in Capital, Preferred Dividends in Excess of Retained Earnings	$ 67
Proceeds from Issuance of Preferred Stock and Preference Stock	$ 1,866
Minimum [Member] | Preferred Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion	17.0213
Maximum [Member] | Preferred Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion	20.000