Equity Equity - Dividends (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($)
5.75% Cumulative Convertible Preferred Stock [Member]
Dividends Payable [Line Items]
Preferred Stock, Amount of Preferred Dividends in Arrears	$ 21
5.75% Cumulative Convertible Preferred Stock Series A [Member]
Dividends Payable [Line Items]
Preferred Stock, Amount of Preferred Dividends in Arrears	16
4.50% Cumulative Convertible Preferred Stock [Member]
Dividends Payable [Line Items]
Preferred Stock, Amount of Preferred Dividends in Arrears	3
5.0% Cumulative Convertible Preferred Stock Series 2005 B [Member]
Dividends Payable [Line Items]
Preferred Stock, Amount of Preferred Dividends in Arrears	$ 3