Investment Securities (Gross Unrealized Loss and Fair Value of Securities Available for Sale) (Details) (Debt Securities [Member], USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	$ (15)	$ (91)
Unrealized loss position less than 12 months - fair value	1,695	5,028
Unrealized loss position 12 months or more - unrealized loss	(533)	(1,530)
Unrealized loss position 12 months or more - fair value	5,374	6,157
Total unrealized loss	(548)	(1,621)
Total fair value	7,069	11,185
Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(4)	(24)
Unrealized loss position less than 12 months - fair value	652	2,165
Unrealized loss position 12 months or more - unrealized loss	(3)	(37)
Unrealized loss position 12 months or more - fair value	134	408
Total unrealized loss	(7)	(61)
Total fair value	786	2,573
Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(3)	(26)
Unrealized loss position less than 12 months - fair value	58	273
Unrealized loss position 12 months or more - unrealized loss	(398)	(1,242)
Unrealized loss position 12 months or more - fair value	3,878	4,378
Total unrealized loss	(401)	(1,268)
Total fair value	3,936	4,651
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(1)	(17)
Unrealized loss position less than 12 months - fair value	88	483
Unrealized loss position 12 months or more - unrealized loss	(1)
Unrealized loss position 12 months or more - fair value	28
Total unrealized loss	(2)	(17)
Total fair value	116	483
Asset backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(3)	(13)
Unrealized loss position less than 12 months - fair value	676	1,355
Unrealized loss position 12 months or more - unrealized loss	(95)	(203)
Unrealized loss position 12 months or more - fair value	757	764
Total unrealized loss	(98)	(216)
Total fair value	1,433	2,119
State and Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(1)	(6)
Unrealized loss position less than 12 months - fair value	142	512
Unrealized loss position 12 months or more - unrealized loss	(34)	(41)
Unrealized loss position 12 months or more - fair value	564	318
Total unrealized loss	(35)	(47)
Total fair value	706	830
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(3)	(5)
Unrealized loss position less than 12 months - fair value	79	240
Unrealized loss position 12 months or more - unrealized loss	(2)	(7)
Unrealized loss position 12 months or more - fair value	13	289
Total unrealized loss	(5)	(12)
Total fair value	$ 92	$ 529