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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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.

+ References

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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.

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- Definition

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

+ References

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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 1.

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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.

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Fair Value Measurements - Transfers (Details) - Recurring Fair Value Measurements - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Fixed maturities \| Available-for-sale
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 1			$ 2.2
Transfers out of Level 2 into Level 3	$ 33.7	$ 12.4	33.7	$ 15.6
Transfers out of Level 3 into Level 2	2.3	52.3	28.3	100.3
U.S. government and agencies \| Available-for-sale
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 1			1.1
Corporate debt securities \| Available-for-sale
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3		0.4		1.0
Transfers out of Level 3 into Level 2		11.5		40.2
Commercial mortgage-backed securities \| Available-for-sale
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3	3.7		3.7	2.5
Transfers out of Level 3 into Level 2	2.3	0.9	2.3	0.9
Collateralized debt obligations \| Available-for-sale
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3	30.0	12.0	30.0	12.1
Transfers out of Level 3 into Level 2		39.9		59.2
Other debt obligations \| Available-for-sale
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 1			1.1
Transfers out of Level 3 into Level 2			26.0
Other investments
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3			10.0
Separate account assets
Fair Value Hierarchy Levels Transfers
Transfers out of Level 1 into Level 2	102.7	0.1	102.7	292.5
Transfers out of Level 2 into Level 1		0.1		0.8
Transfers out of Level 3 into Level 1		0.2		0.2
Transfers out of Level 3 into Level 2	$ 172.5	$ 0.2	$ 173.2	$ 0.2