Investments (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
The scheduled maturities of available for sale fixed maturities
Fixed maturities amortized cost, One year or less	$ 867
Fixed maturities fair value, One year or less	887
Fixed maturities fair value, One year or less, Percent	4.00%
Fixed maturities amortized cost, After one year through five years	5,526
Fixed maturities fair value, After one year through five years	5,963
Fixed maturities fair value, After one year through five years, Percent	25.00%
Fixed maturities amortized cost, After five years through ten years	6,675
Fixed maturities fair value, After five years through ten years	7,394
Fixed maturities fair value, After five years through ten years, Percent	31.00%
Fixed maturities amortized cost, After ten years	2,511
Fixed maturities fair value, After ten years	2,752
Fixed maturities fair value, After ten years, Percent	11.00%
Fixed maturities amortized cost, Subtotal	15,579
Fixed maturities fair value, Subtotal	16,996
Fixed maturities fair value, Subtotal, Percent	71.00%
Fixed maturities amortized cost, MBS	6,504
Fixed maturities fair value, MBS	7,122
Fixed maturities fair value, MBS, Percent	29.00%
Fixed maturity [Member]
The scheduled maturities of available for sale fixed maturities
Amortized Cost	22,083
Fair Value	$ 24,118
Fair value, Total, Percent	100.00%

Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value, Percent.

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Available for sale securities debt maturities excluding MBS amortized cost.

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Available-for-sale Securities, Debt Maturities, within One Year, Fair Value, Percent.

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Mortgage-backed securities, amortized cost.

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

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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