Investment Securities (Schedule of Unrealized Loss on Investments) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	$ 2,393	$ 2,701
Available-for-sale Securities, Unrealized Loss Less than 12 months	(46)	(42)
Available-for-sale Securities, Fair value 12 months or longer	3,242	4,016
Available-for-sale Securities, Unrealized Loss 12 months or longer	(92)	(141)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	2,019	2,470
Available-for-sale Securities, Unrealized Loss Less than 12 months	(9)	(18)
Available-for-sale Securities, Fair value 12 months or longer	3,214	3,976
Available-for-sale Securities, Unrealized Loss 12 months or longer	(84)	(131)
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	277	297
Available-for-sale Securities, Unrealized Loss Less than 12 months	0	(3)
Available-for-sale Securities, Fair value 12 months or longer	670	859
Available-for-sale Securities, Unrealized Loss 12 months or longer	(4)	(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	120	50
Available-for-sale Securities, Unrealized Loss Less than 12 months	(1)	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	1,064	1,172
Available-for-sale Securities, Unrealized Loss Less than 12 months	(6)	(10)
Available-for-sale Securities, Fair value 12 months or longer	2,537	3,098
Available-for-sale Securities, Unrealized Loss 12 months or longer	(80)	(116)
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	524	819
Available-for-sale Securities, Unrealized Loss Less than 12 months	(1)	(3)
Available-for-sale Securities, Fair value 12 months or longer	1	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	34	132
Available-for-sale Securities, Unrealized Loss Less than 12 months	(1)	(2)
Available-for-sale Securities, Fair value 12 months or longer	6	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	374	231
Available-for-sale Securities, Unrealized Loss Less than 12 months	(37)	(24)
Available-for-sale Securities, Fair value 12 months or longer	28	40
Available-for-sale Securities, Unrealized Loss 12 months or longer	$ (8)	$ (10)

Amount of unrealized loss on securities classified as available-for-sale that have been in a loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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Amount of unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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