Investments (Details 3) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
The scheduled maturities of available for sale fixed maturities
Fixed maturities amortized cost, One year or less	$ 634
Fixed maturities fair value, One year or less	648
Fixed maturities fair value, One year or less, Percent	3.00%
Fixed maturities amortized cost, After one year through five years	5,265
Fixed maturities fair value, After one year through five years	5,599
Fixed maturities fair value, After one year through five years, Percent	25.00%
Fixed maturities amortized cost, After five years through ten years	6,425
Fixed maturities fair value, After five years through ten years	7,001
Fixed maturities fair value, After five years through ten years, Percent	31.00%
Fixed maturities amortized cost, After ten years	1,950
Fixed maturities fair value, After ten years	2,105
Fixed maturities fair value, After ten years, Percent	10.00%
Fixed maturities amortized cost, Subtotal	14,274
Fixed maturities fair value, Subtotal	15,353
Fixed maturities fair value, Subtotal, Percent	69.00%
Fixed maturities amortized cost, MBS	6,720
Fixed maturities fair value, MBS	7,018
Fixed maturities fair value, MBS, Percent	31.00%
Fixed maturity securities [Member]
The scheduled maturities of available for sale fixed maturities
Amortized Cost	20,994	20,562
Fair Value	$ 22,371	$ 21,807
Fair value, Total, Percent	100.00%

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

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Mortgage-backed securities, amortized cost.

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