Investment Securities (Schedule of Unrealized Loss on Investments) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	$ 10,341	$ 1,391
Available-for-sale Securities, Unrealized Loss Less than 12 months	(380)	(45)
Available-for-sale Securities, Fair value 12 months or longer	162	257
Available-for-sale Securities, Unrealized Loss 12 months or longer	(29)	(36)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	10,014	1,011
Available-for-sale Securities, Unrealized Loss Less than 12 months	(338)	(6)
Available-for-sale Securities, Fair value 12 months or longer	16	39
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	(2)
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	1,648	244
Available-for-sale Securities, Unrealized Loss Less than 12 months	(51)	(1)
Available-for-sale Securities, Fair value 12 months or longer	0	0
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	0
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	113	11
Available-for-sale Securities, Unrealized Loss Less than 12 months	(2)	0
Available-for-sale Securities, Fair value 12 months or longer	0	0
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	0
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	7,326	493
Available-for-sale Securities, Unrealized Loss Less than 12 months	(269)	(2)
Available-for-sale Securities, Fair value 12 months or longer	13	23
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	(1)
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	426	143
Available-for-sale Securities, Unrealized Loss Less than 12 months	(4)	(1)
Available-for-sale Securities, Fair value 12 months or longer	1	1
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	0
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	501	120
Available-for-sale Securities, Unrealized Loss Less than 12 months	(12)	(2)
Available-for-sale Securities, Fair value 12 months or longer	2	15
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	(1)
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	327	380
Available-for-sale Securities, Unrealized Loss Less than 12 months	(42)	(39)
Available-for-sale Securities, Fair value 12 months or longer	146	218
Available-for-sale Securities, Unrealized Loss 12 months or longer	$ (29)	$ (34)