Investment Securities (Schedule of Available-for-sale Securities Reconciliation) (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 18,243,000,000	$ 13,997,000,000
Available-for-sale Securities, Gross Unrealized Gains	153,000,000	262,000,000
Available-for-sale Securities, Gross Unrealized Losses	(429,000,000)	(81,000,000)
Available-for-sale Securities	17,967,000,000	14,178,000,000
Total agency backed bonds	8,702,000,000	4,983,000,000
Deposit Assets	15,000,000	15,000,000
Cash Equivalents, at Carrying Value	3,200,000,000	3,400,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	17,314,000,000	12,804,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	121,000,000	230,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(385,000,000)	(8,000,000)
Available-for-sale Securities, Debt Securities	17,050,000,000	13,026,000,000
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	2,075,000,000	2,212,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	1,000,000	3,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(54,000,000)	(1,000,000)
Available-for-sale Securities, Debt Securities	2,022,000,000	2,214,000,000
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	178,000,000	0
Available-for-sale Debt Securities Gross Unrealized Gain	1,000,000	0
Available-for-sale Debt Securities, Gross Unrealized Loss	0	0
Available-for-sale Securities, Debt Securities	179,000,000	0
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	299,000,000	295,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	4,000,000	8,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(3,000,000)	0
Available-for-sale Securities, Debt Securities	300,000,000	303,000,000
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	11,444,000,000	6,779,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	78,000,000	130,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(316,000,000)	(3,000,000)
Available-for-sale Securities, Debt Securities	11,206,000,000	6,906,000,000
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	20,000,000	0
Available-for-sale Debt Securities Gross Unrealized Gain	0	0
Available-for-sale Debt Securities, Gross Unrealized Loss	0	0
Available-for-sale Securities, Debt Securities	20,000,000	0
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	2,251,000,000	2,309,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	17,000,000	32,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(3,000,000)	(1,000,000)
Available-for-sale Securities, Debt Securities	2,265,000,000	2,340,000,000
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,047,000,000	1,209,000,000
Available-for-sale Debt Securities Gross Unrealized Gain	20,000,000	57,000,000
Available-for-sale Debt Securities, Gross Unrealized Loss	(9,000,000)	(3,000,000)
Available-for-sale Securities, Debt Securities	1,058,000,000	1,263,000,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis	929,000,000	1,193,000,000
Available-for-sale Equity Securities, Gross Unrealized Gain	32,000,000	32,000,000
Available-for-sale Equity Securities, Gross Unrealized Loss	(44,000,000)	(73,000,000)
Available-for-sale Securities, Equity Securities	$ 917,000,000	$ 1,152,000,000