Investment Securities (Gross Unrealized Loss and Fair Value of Securities Available for Sale) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	$ (53)	$ (91)
Unrealized loss position 12 months or more - unrealized loss	(1,048)	(1,530)
Total unrealized loss	(1,101)	(1,621)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - fair value	2,967	5,028
Unrealized loss position 12 months or more - fair value	5,635	6,157
Total fair value	8,602	11,185
Debt Securities [Member] | 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	(8)	(24)
Unrealized loss position less than 12 months - fair value	934	2,165
Unrealized loss position 12 months or more - unrealized loss	(3)	(37)
Unrealized loss position 12 months or more - fair value	158	408
Total unrealized loss	(11)	(61)
Total fair value	1,092	2,573
Debt Securities [Member] | 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	(32)	(26)
Unrealized loss position less than 12 months - fair value	276	273
Unrealized loss position 12 months or more - unrealized loss	(864)	(1,242)
Unrealized loss position 12 months or more - fair value	4,344	4,378
Total unrealized loss	(896)	(1,268)
Total fair value	4,620	4,651
Debt Securities [Member] | 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	182	483
Unrealized loss position 12 months or more - unrealized loss	(2)
Unrealized loss position 12 months or more - fair value	60
Total unrealized loss	(3)	(17)
Total fair value	242	483
Debt Securities [Member] | Asset backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(4)	(13)
Unrealized loss position less than 12 months - fair value	1,044	1,355
Unrealized loss position 12 months or more - unrealized loss	(142)	(203)
Unrealized loss position 12 months or more - fair value	698	764
Total unrealized loss	(146)	(216)
Total fair value	1,742	2,119
Debt Securities [Member] | State and Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(6)	(6)
Unrealized loss position less than 12 months - fair value	423	512
Unrealized loss position 12 months or more - unrealized loss	(35)	(41)
Unrealized loss position 12 months or more - fair value	362	318
Total unrealized loss	(41)	(47)
Total fair value	785	830
Debt Securities [Member] | Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(2)	(5)
Unrealized loss position less than 12 months - fair value	108	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	(4)	(12)
Total fair value	$ 121	$ 529