Investment Securities (Schedule of Unrealized Loss on Investments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	$ 2,701	$ 10,118
Available-for-sale Securities, Unrealized Loss Less than 12 months	(42)	(482)
Available-for-sale Securities, Fair value 12 months or longer	4,016	204
Available-for-sale Securities, Unrealized Loss 12 months or longer	(141)	(26)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	2,470	9,951
Available-for-sale Securities, Unrealized Loss Less than 12 months	(18)	(470)
Available-for-sale Securities, Fair value 12 months or longer	3,976	104
Available-for-sale Securities, Unrealized Loss 12 months or longer	(131)	(10)
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	297	1,405
Available-for-sale Securities, Unrealized Loss Less than 12 months	(3)	(69)
Available-for-sale Securities, Fair value 12 months or longer	859	0
Available-for-sale Securities, Unrealized Loss 12 months or longer	(15)	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	50	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	0	114
Available-for-sale Securities, Unrealized Loss Less than 12 months	0	(3)
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	1,172	7,503
Available-for-sale Securities, Unrealized Loss Less than 12 months	(10)	(388)
Available-for-sale Securities, Fair value 12 months or longer	3,098	100
Available-for-sale Securities, Unrealized Loss 12 months or longer	(116)	(10)
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	819	407
Available-for-sale Securities, Unrealized Loss Less than 12 months	(3)	(3)
Available-for-sale Securities, Fair value 12 months or longer	8	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	132	310
Available-for-sale Securities, Unrealized Loss Less than 12 months	(2)	(6)
Available-for-sale Securities, Fair value 12 months or longer	11	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	231	167
Available-for-sale Securities, Unrealized Loss Less than 12 months	(24)	(12)
Available-for-sale Securities, Fair value 12 months or longer	40	100
Available-for-sale Securities, Unrealized Loss 12 months or longer	$ (10)	$ (16)