Investment Securities (Schedule of Available-for-sale Securities Reconciliation) (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 15,565,000,000	$ 13,997,000,000
Available-for-sale Securities, Gross Unrealized Gains	258,000,000	262,000,000
Available-for-sale Securities, Gross Unrealized Losses	(71,000,000)	(81,000,000)
Available-for-sale Securities	15,752,000,000	14,178,000,000
Total agency backed bonds	6,217,000,000	4,983,000,000
Deposit Assets	15,000,000	15,000,000
Cash Equivalents, at Carrying Value	2,700,000,000	3,400,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	14,579,000,000	12,804,000,000
Available-for-sale Securities, Gross Unrealized Gains	210,000,000	230,000,000
Available-for-sale Securities, Gross Unrealized Losses	(22,000,000)	(8,000,000)
Available-for-sale Securities	14,767,000,000	13,026,000,000
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	2,097,000,000	2,212,000,000
Available-for-sale Securities, Gross Unrealized Gains	3,000,000	3,000,000
Available-for-sale Securities, Gross Unrealized Losses	(1,000,000)	(1,000,000)
Available-for-sale Securities	2,099,000,000	2,214,000,000
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	297,000,000	295,000,000
Available-for-sale Securities, Gross Unrealized Gains	9,000,000	8,000,000
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities	306,000,000	303,000,000
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	8,722,000,000	6,779,000,000
Available-for-sale Securities, Gross Unrealized Gains	111,000,000	130,000,000
Available-for-sale Securities, Gross Unrealized Losses	(18,000,000)	(3,000,000)
Available-for-sale Securities	8,815,000,000	6,906,000,000
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	2,191,000,000	2,309,000,000
Available-for-sale Securities, Gross Unrealized Gains	31,000,000	32,000,000
Available-for-sale Securities, Gross Unrealized Losses	(1,000,000)	(1,000,000)
Available-for-sale Securities	2,221,000,000	2,340,000,000
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,272,000,000	1,209,000,000
Available-for-sale Securities, Gross Unrealized Gains	56,000,000	57,000,000
Available-for-sale Securities, Gross Unrealized Losses	(2,000,000)	(3,000,000)
Available-for-sale Securities	1,326,000,000	1,263,000,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	986,000,000	1,193,000,000
Available-for-sale Securities, Gross Unrealized Gains	48,000,000	32,000,000
Available-for-sale Securities, Gross Unrealized Losses	(49,000,000)	(73,000,000)
Available-for-sale Securities	$ 985,000,000	$ 1,152,000,000

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details

- Definition

Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References+ Details