Servicing Activities (Schedule Of Sensitivity Analysis of Fair Value) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012 Y	Dec. 31, 2011 Y
Servicing Activities [Abstract]
Weighted average life (in years)	4.1	4.7
Weighted average prepayment speed	17.00%	15.70%
Impact on fair value of 10% adverse change	$ (81)	$ (135)
Impact on fair value of 20% adverse change	(152)	(257)
Weighted average discount rate	5.90%	10.20%
Impact on fair value of 10% adverse change, discount rate	(7)	(59)
Impact on fair value of 20% adverse change, discount rate	$ (12)	$ (114)