Equity (Preferred Stock - Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Jul. 01, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 12, 2015	Jun. 01, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Preferred Stock, Shares Issued		25,500,000		25,500,000				84,000,000
Payments of Stock Issuance Costs				$ 17
Tender Offer Number Of Shares						59,850,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01		$ 0.01				$ 0.01
Preferred Stock, Liquidation Preference Per Share		$ 2,100		$ 2,100				$ 2,100
Stock Redeemed or Called During Period, Shares	22,807,587			37,192,413
Proceeds from Issuance of Preferred Stock and Preference Stock				$ 1,483	$ 0
Preferred Stock, Shares Outstanding		25,500,000		25,500,000				84,000,000
Preferred Stock, Redemption Amount	$ 570	$ 932		$ 932
Other liabilities relating to variable interest entities		27,977		27,977				$ 24,437
Preferred stock repurchase premium		$ 0	$ 0	$ 42	$ 0
Series B Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Issued		0		0				60,000,000
Preferred Stock, Liquidation Preference Per Share						$ 25
Preferred Stock, Shares Outstanding		0		0		60,000,000		60,000,000
Preferred Stock, Dividend Rate, Percentage				6.50%
Series C Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Issued		1,500,000		1,500,000			1,500,000	0
Preferred Stock, Dividend Payment Rate, Variable				5.25% Fixed-to-Floating Rate
Preferred Stock, Par or Stated Value Per Share							$ 0.01
Preferred Stock, Liquidation Preference Per Share							$ 1,000
Preferred Stock, Shares Outstanding		1,500,000		1,500,000				0
Junior Subordinated Debt Instrument One [Member]
Class of Stock [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		10.75%		10.75%
Debt Instrument, Maturity Date				Aug. 01, 2069
Fixed Rate [Member] | Series C Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Dividend Payment Rate, Variable				0.0525
Variable Rate [Member] | Series C Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Dividend Payment Rate, Variable				LIBOR plus 3.575%