Loans and ACL (Changes in Carrying Amount and Accretable Yield for Covered Loans) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Purchased Impaired Loans [Member]
Accretable yield for purchased loans, beginning balance	$ 187	$ 264
Accretion	(58)	(149)
Other, net	35	72
Accretable yield for purchased loans, ending balance	164	187
Carrying amount of loans, beginning balance	863	1,400
Accretion	58	149
Payments received, net	(222)	(686)
Carrying amount of loans, ending balance	699	863
Outstanding UPB at end of period	1,023	1,266
Purchased Nonimpaired Loans [Member]
Accretable yield for purchased loans, beginning balance	351	617
Accretion	(101)	(301)
Other, net	35	35
Accretable yield for purchased loans, ending balance	285	351
Carrying amount of loans, beginning balance	1,172	1,894
Accretion	101	301
Payments received, net	(319)	(1,023)
Carrying amount of loans, ending balance	954	1,172
Outstanding UPB at end of period	$ 1,234	$ 1,516