Variable Interest Entities and Other Investments (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012 Investment	Jun. 30, 2011	Jun. 30, 2012 Investment	Jun. 30, 2011
Variable interest entities and other investments (Textual) [Abstract]
Number of LIHC investment fund	2		2
Expenses related to consolidated VIEs	$ 101	$ 85	$ 200	$ 214
Impairment related to private capital investment			2
Low Income Housing Credit Investments [Member]
Variable interest entities and other investments (Textual) [Abstract]
Carrying amount of assets, consolidated VIEs	278		278
Carrying amount of liabilities, consolidated VIEs	9		9
Consolidated VIEs [Member]
Variable interest entities and other investments (Textual) [Abstract]
Expenses related to consolidated VIEs	8	6	15	12
Trust Owned and Lease Railcars [Member]
Variable interest entities and other investments (Textual) [Abstract]
Carrying amount of assets, consolidated VIEs	$ 61		$ 61