Investment Securities (Schedule of Unrealized Loss on Investments) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	$ 6,506	$ 10,118
Available-for-sale Securities, Unrealized Loss Less than 12 months	(242)	(482)
Available-for-sale Securities, Fair value 12 months or longer	607	204
Available-for-sale Securities, Unrealized Loss 12 months or longer	(33)	(26)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	6,326	9,951
Available-for-sale Securities, Unrealized Loss Less than 12 months	(226)	(470)
Available-for-sale Securities, Fair value 12 months or longer	547	104
Available-for-sale Securities, Unrealized Loss 12 months or longer	(30)	(10)
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	1,246	1,405
Available-for-sale Securities, Unrealized Loss Less than 12 months	(27)	(69)
Available-for-sale Securities, Fair value 12 months or longer	0	0
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	0
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	3	212
Available-for-sale Securities, Unrealized Loss Less than 12 months	0	(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	32	114
Available-for-sale Securities, Unrealized Loss Less than 12 months	0	(3)
Available-for-sale Securities, Fair value 12 months or longer	11	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	4,705	7,503
Available-for-sale Securities, Unrealized Loss Less than 12 months	(197)	(388)
Available-for-sale Securities, Fair value 12 months or longer	531	100
Available-for-sale Securities, Unrealized Loss 12 months or longer	(30)	(10)
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	276	407
Available-for-sale Securities, Unrealized Loss Less than 12 months	(1)	(3)
Available-for-sale Securities, Fair value 12 months or longer	0	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	64	310
Available-for-sale Securities, Unrealized Loss Less than 12 months	(1)	(6)
Available-for-sale Securities, Fair value 12 months or longer	5	3
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	0
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	180	167
Available-for-sale Securities, Unrealized Loss Less than 12 months	(16)	(12)
Available-for-sale Securities, Fair value 12 months or longer	60	100
Available-for-sale Securities, Unrealized Loss 12 months or longer	$ (3)	$ (16)