Acquired Property Net (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Acquired Property, Net [Roll Forward]
Acquired Property, Net Beginning Balance	$ 10,149		$ 10,619		$ 10,489		$ 11,373
Acquired Property, Net Additions	4,087		4,162		7,763		7,867
Acquired Property, Net Disposals	(3,845)		(4,261)		(7,746)		(8,561)
Write-downs, net of recoveries	(125)		(133)		(240)		(292)
Acquired Property, Net Ending Balance	10,266	[1]	10,387	[1]	10,266	[1]	10,387	[1]
Real Estate Owned, Valuation Allowance	$ 540		$ 648		$ 540		$ 648

[1] Includes valuation allowance of $540 million and $648 million as of June 30, 2013 and 2012, respectively.