Acquired Property Net (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Acquired Property, Net [Roll Forward]
Acquired Property, Net Beginning Balance	$ 10,266		$ 10,387		$ 10,489		$ 11,373
Acquired Property, Net Additions	4,422		4,090		12,185		11,957
Acquired Property, Net Disposals	(3,171)		(4,144)		(10,917)		(12,705)
Write-downs, net of recoveries	(137)		(55)		(377)		(347)
Acquired Property, Net Ending Balance	11,380	[1]	10,278	[1]	11,380	[1]	10,278	[1]
Real Estate Owned, Valuation Allowance	$ 564		$ 664		$ 564		$ 664

[1] Includes valuation allowance of $564 million and $664 million as of September 30, 2013 and 2012, respectively.