Investment Securities (Schedule of Available-for-sale Securities Reconciliation) (Details) (USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 17,716,000,000	$ 16,107,000,000
Available-for-sale Securities, Gross Unrealized Gains	251,000,000	213,000,000
Available-for-sale Securities, Gross Unrealized Losses	(138,000,000)	(183,000,000)
Available-for-sale Securities	17,829,000,000us-gaap_AvailableForSaleSecurities	16,137,000,000us-gaap_AvailableForSaleSecurities
Total agency backed bonds	7,312,000,000	7,557,000,000
Deposit Assets	15,000,000us-gaap_DepositAssets	15,000,000us-gaap_DepositAssets
Cash Equivalents, at Carrying Value	2,300,000,000us-gaap_CashEquivalentsAtCarryingValue	2,000,000,000us-gaap_CashEquivalentsAtCarryingValue
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	16,732,000,000	15,216,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	223,000,000	164,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(93,000,000)	(149,000,000)
Available-for-sale Securities, Debt Securities	16,862,000,000	15,231,000,000
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	2,673,000,000	1,195,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	19,000,000	1,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(4,000,000)	(18,000,000)
Available-for-sale Securities, Debt Securities	2,688,000,000	1,178,000,000
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	506,000,000	389,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	19,000,000	17,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(1,000,000)	0
Available-for-sale Securities, Debt Securities	524,000,000	406,000,000
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	202,000,000	224,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	13,000,000	8,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	0	0
Available-for-sale Securities, Debt Securities	215,000,000	232,000,000
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	10,246,000,000	10,431,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	144,000,000	119,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(85,000,000)	(125,000,000)
Available-for-sale Securities, Debt Securities	10,305,000,000	10,425,000,000
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	313,000,000	254,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	0	0
Available-for-sale Debt Securities, Gross Unrealized Loss	(1,000,000)	(1,000,000)
Available-for-sale Securities, Debt Securities	312,000,000	253,000,000
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	2,061,000,000	1,989,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	6,000,000	5,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(1,000,000)	(3,000,000)
Available-for-sale Securities, Debt Securities	2,066,000,000	1,991,000,000
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	731,000,000	734,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	22,000,000	14,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(1,000,000)	(2,000,000)
Available-for-sale Securities, Debt Securities	752,000,000	746,000,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis	984,000,000	891,000,000
Available-for-sale Equity Securities, Gross Unrealized Gain	28,000,000	49,000,000
Available-for-sale Equity Securities, Gross Unrealized Loss	(45,000,000)	(34,000,000)
Available-for-sale Securities, Equity Securities	$ 967,000,000	$ 906,000,000

Total agency backed bonds, available for sale.

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