Equity (Common Stock) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Dividends Payable [Line Items]
Dividend Per Share					$ 1.01	$ 0.74	$ 0.74
Dividend Aggregate					$ 1,119	$ 811	$ 787
Common Stock [Member]
Dividends Payable [Line Items]
Declaration Date	Oct. 22, 2013	Jun. 25, 2013	Apr. 23, 2013	Jan. 04, 2013		Oct. 23, 2012	Oct. 25, 2011
Record Date	Nov. 08, 2013	Aug. 09, 2013	May 09, 2013	Feb. 06, 2013		Nov. 09, 2012	Nov. 09, 2011
Dividend Per Share	$ 0.275	$ 0.275	$ 0.275	$ 0.185		$ 0.74	$ 0.74
Dividend Aggregate	$ 311	$ 303	$ 302	$ 203	$ 1,119	$ 811	$ 787