Servicing Activities (Narrative - Mortgage Servicing Advances) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Servicing Activities [Abstract]
Mortgage Servicing Advances Included In Other Assets	$ 76	$ 1,900
Allowance for uncollected primary servicing advances	1	43
Outstanding servicer advances related to subserviced loans	0	125
Reserve for uncollected subservicer advances	0	1
Outstanding master-servicing advances	$ 0	$ 158