Debt Repurchases and Calls (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Debt Repurchases and Calls [Line Items]
Loss on extinguishment of debt	$ (3)	$ (31)	$ (12)	$ (65)
Unsecured Debt [Member]
Debt Repurchases and Calls [Line Items]
Extinguishment of debt amount		804		2,300
Amount of debt extinguished that was due to mature in the current year		1		1
Loss on extinguishment of debt		(31)		(65)
Unsecured and Asset Backed Debt [Member]
Debt Repurchases and Calls [Line Items]
Extinguishment of debt amount	267		482
Amount of debt extinguished that was due to mature in the current year	0		0
Loss on extinguishment of debt	$ (3)		$ (12)