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Amount of transfers of assets measured on a recurring basis out of Level 1 into Level 2 of the fair value hierarchy.

No definition available.

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Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 3.

No definition available.

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Amount of transfers of assets measured on a recurring basis out of Level 2 into Level 1 of the fair value hierarchy.

No definition available.

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Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 3.

No definition available.

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Amount of transfers of assets measured on a recurring basis out of Level 3 of the fair value hierarchy into Level 2.

No definition available.

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Fair Value Measurements (Details 3) (Recurring Fair Value Measurements, USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Available-for-sale \| Fixed maturities
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3	$ 39.9		$ 86.4
Transfers out of Level 3 into Level 2	7.0		129.5
Available-for-sale \| Non-U.S. governments
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3			14.5
Available-for-sale \| States and political subdivisions
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3	1.8		1.8
Available-for-sale \| Corporate debt securities
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3	28.8		54.8
Transfers out of Level 3 into Level 2	2.8		98.3
Available-for-sale \| Collateralized debt obligations
Fair Value Hierarchy Levels Transfers
Transfers out of Level 3 into Level 2	4.2		31.2
Available-for-sale \| Other debt obligations
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3	9.3		15.3
Trading \| Fixed maturities
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3			9.5
Separate account assets
Fair Value Hierarchy Levels Transfers
Transfers out of Level 1 into Level 2	7.8	39.4	3,230.6	3,591.4
Transfers out of Level 1 into Level 3			0.3
Transfers out of Level 2 into Level 1	0.3		0.3
Transfers out of Level 2 into Level 3			1.3
Transfers out of Level 3 into Level 2			$ 1.8