Investments (Details 18) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Mortgage loans, net [Member]
Purchased credit impaired investments, by invested asset class, held:
Outstanding principal and interest balance	$ 440	$ 471
Carrying value	199	173
Fixed maturity securities [Member]
Purchased credit impaired investments, by invested asset class, held:
Outstanding principal and interest balance	4,905	4,547
Carrying value	$ 3,900	$ 3,130

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and other-than-temporary impairments), for certain contractual rights to receive money on demand or on fixed or determinable dates. This relates to loans accounted for as available-for-sale debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans accounted for as available-for-sale debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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- Definition

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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- Definition

The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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