Claim and Claim Adjustment Expense Reserves Net prior year claim and allocated claim adjustment expense reserve development for International segment (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development, excluding Life & Group	$ (5)	$ 24	$ (12)	$ 49
International [Member]
Medical Professional Liability	0	0	0	1
Other Professional Liability	(5)	(14)	(5)	(15)
Liability	(2)	(4)	(7)	(6)
Property & Marine	(8)	(7)	(14)	1
Other	7	0	14	(6)
Commutations	0	0	0	10
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development, excluding Life & Group	$ (8)	$ (25)	$ (12)	$ (15)

Net prior year claim and allocated claim adjustment expense reserve development, Medical Professional Liability

No definition available.

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Net prior year claim and allocated claim adjustment expense reserve development, Other

No definition available.

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Net Prior Year Claim and Allocated Claim Adjustment Expense Reserve Development, Commutations

No definition available.

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Net Prior Year Claim and Allocated Claim Adjustment Expense Reserve Development, Liability

No definition available.

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Net Prior Year Claim and Allocated Claim Adjustment Expense Reserve Development, Other Professional Liability

No definition available.

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Net Prior Year Claim and Allocated Claim Adjustment Expense Reserve Development, Property & Marine

No definition available.

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Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development, excluding Life & Group

No definition available.

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