Servicing Activities (Schedule Of Sensitivity Analysis of Fair Value) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012 Y	Dec. 31, 2011 Y
Servicing Activities [Abstract]
Weighted average life (in years)	4.8	4.7
Weighted average prepayment speed	13.10%	15.70%
Impact on fair value of 10% adverse change	$ (78)	$ (135)
Impact on fair value of 20% adverse change	(147)	(257)
Weighted average discount rate	8.00%	10.20%
Impact on fair value of 10% adverse change, discount rate	(14)	(59)
Impact on fair value of 20% adverse change, discount rate	$ (26)	$ (114)