Investment Securities (Schedule of Unrealized Loss on Investments) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	$ 7,400	$ 2,701
Available-for-sale Securities, Unrealized Loss Less than 12 months	(134)	(42)
Available-for-sale Securities, Fair value 12 months or longer	3,132	4,016
Available-for-sale Securities, Unrealized Loss 12 months or longer	(123)	(141)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	6,681	2,470
Available-for-sale Securities, Unrealized Loss Less than 12 months	(78)	(18)
Available-for-sale Securities, Fair value 12 months or longer	3,103	3,976
Available-for-sale Securities, Unrealized Loss 12 months or longer	(116)	(131)
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	1,562	297
Available-for-sale Securities, Unrealized Loss Less than 12 months	(24)	(3)
Available-for-sale Securities, Fair value 12 months or longer	569	859
Available-for-sale Securities, Unrealized Loss 12 months or longer	(5)	(15)
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	295	50
Available-for-sale Securities, Unrealized Loss Less than 12 months	(5)	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
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	6	0
Available-for-sale Securities, Unrealized Loss Less than 12 months	0	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	3,508	1,172
Available-for-sale Securities, Unrealized Loss Less than 12 months	(39)	(10)
Available-for-sale Securities, Fair value 12 months or longer	2,504	3,098
Available-for-sale Securities, Unrealized Loss 12 months or longer	(111)	(116)
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	830	819
Available-for-sale Securities, Unrealized Loss Less than 12 months	(2)	(3)
Available-for-sale Securities, Fair value 12 months or longer	26	8
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	480	132
Available-for-sale Securities, Unrealized Loss Less than 12 months	(8)	(2)
Available-for-sale Securities, Fair value 12 months or longer	4	11
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	719	231
Available-for-sale Securities, Unrealized Loss Less than 12 months	(56)	(24)
Available-for-sale Securities, Fair value 12 months or longer	29	40
Available-for-sale Securities, Unrealized Loss 12 months or longer	$ (7)	$ (10)