Investments (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Available for Sale Securities
Amortized cost	$ 73,925	$ 73,379
Gross unrealized gains	5,129	4,404
Gross unrealized losses	(1,128)	(1,670)
Fair value	77,926	76,113
U.S. government and agencies
Schedule of Available for Sale Securities
Amortized cost	4,872	5,966
Gross unrealized gains	374	349
Fair value	5,246	6,315
Municipal
Schedule of Available for Sale Securities
Amortized cost	13,087	13,634
Gross unrealized gains	991	863
Gross unrealized losses	(186)	(256)
Fair value	13,892	14,241
Corporate
Schedule of Available for Sale Securities
Amortized cost	44,229	41,217
Gross unrealized gains	3,251	2,743
Gross unrealized losses	(226)	(379)
Fair value	47,254	43,581
Foreign government
Schedule of Available for Sale Securities
Amortized cost	1,942	1,866
Gross unrealized gains	227	216
Gross unrealized losses		(1)
Fair value	2,169	2,081
Residential mortgage-backed securities ("RMBS")
Schedule of Available for Sale Securities
Amortized cost	3,887	4,532
Gross unrealized gains	118	110
Gross unrealized losses	(330)	(521)
Fair value	3,675	4,121
Commercial mortgage-backed securities ("CMBS")
Schedule of Available for Sale Securities
Amortized cost	1,831	1,962
Gross unrealized gains	56	48
Gross unrealized losses	(171)	(226)
Fair value	1,716	1,784
Asset-backed securities ("ABS")
Schedule of Available for Sale Securities
Amortized cost	4,054	4,180
Gross unrealized gains	110	73
Gross unrealized losses	(215)	(287)
Fair value	3,949	3,966
Redeemable preferred stock
Schedule of Available for Sale Securities
Amortized cost	23	22
Gross unrealized gains	2	2
Fair value	$ 25	$ 24

Amount of debt 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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-Publisher FASB

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-Number 115

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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+ 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