Loans and Leases (Changes in Carrying Amount and Accretable Yield for Purchased Impaired and Nonimpaired Loans) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Purchased Impaired Loans [Member]
Accretable yield for purchased loans, beginning balance	$ 521	$ 835
Accretion recognized during the period for purchased loans	(177)	(359)
Other, net	(107)	45
Accretable yield for purchased loans, ending balance	237	521
Carrying amount of loans, beginning balance	2,124	2,858
Change in carrying amount of loans, accretion recognized during period	177	359
Change in carrying amount of loans, payments received, net	(736)	(1,093)
Carrying amount of loans, ending balance	1,565	2,124
Purchased Nonimpaired Loans [Member]
Accretable yield for purchased loans, beginning balance	1,239	1,611
Accretion recognized during the period for purchased loans	(429)	(706)
Other, net	(26)	334
Accretable yield for purchased loans, ending balance	784	1,239
Carrying amount of loans, beginning balance	2,782	3,394
Change in carrying amount of loans, accretion recognized during period	429	706
Change in carrying amount of loans, payments received, net	(1,061)	(1,318)
Carrying amount of loans, ending balance	$ 2,150	$ 2,782