Acquired Property Net (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Acquired Property [Roll Forward]
Acquired Property, Beginning Balance	$ 11,409		$ 16,928		$ 12,401		$ 18,054
Acquired Property, Additions	4,282		4,998		8,108		9,887
Acquired Property, Disposals	(4,656)		(7,011)		(9,474)		(13,026)
Acquired Property, Ending Balance	11,035		14,915		11,035		14,915
Valuation Allowance [Roll Forward]
Valuation Allowance, Beginning Balance	(790)	[1]	(1,664)	[1]	(1,028)	[1]	(1,881)	[1]
Valuation Allowance, Additions	(120)	[1]	(149)	[1]	(241)	[1]	(278)	[1]
Valuation Allowance, Disposals	395	[1]	788	[1]	913	[1]	1,518	[1]
Valuation Allowance, Write-downs, net of recoveries	(133)	[1]	(298)	[1]	(292)	[1]	(682)	[1]
Valuation Allowance, Ending Balance	(648)	[1]	(1,323)	[1]	(648)	[1]	(1,323)	[1]
Acquired Property, Net [Roll Forward]
Acquired Property, Net Beginning Balance	10,619		15,264		11,373		16,173
Acquired Property, Net Additions	4,162		4,849		7,867		9,609
Acquired Property, Net Disposals	(4,261)		(6,223)		(8,561)		(11,508)
Valuation Allowance, Write-downs, net of recoveries	(133)	[1]	(298)	[1]	(292)	[1]	(682)	[1]
Acquired Property, Net Ending Balance	$ 10,387		$ 13,592		$ 10,387		$ 13,592

[1] Reflects activities in the valuation allowance for acquired properties held primarily by our single-family segment.