Reinsurance - Effects Of Reinsurance (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Premiums and other considerations:
Premiums and other considerations, Direct	$ 1,436.7	$ 1,431.1	$ 2,477.2	$ 2,407.5
Premiums and other considerations, Ceded	(70.5)	(161.4)	(223.6)	(302.7)
Net premiums and other considerations	1,366.2	1,269.7	2,253.6	2,104.8
Benefits, claims and settlement expenses:
Benefits, claims and settlement expenses, Direct	1,884.2	1,986.6	3,521.5	3,493.9
Benefits, claims and settlement expenses, Ceded	(605.6)	(173.8)	(783.0)	(306.4)
Net benefits, claims and settlement expenses	$ 1,278.6	$ 1,812.8	$ 2,738.5	$ 3,187.5

Amount, before premiums ceded to other entities, of premiums earned and premiums assumed by the entity.

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Amount, before effect of policies ceded, of expense related to provision for policy benefits and costs incurred and policies assumed.

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Amount of earned premiums ceded to other entities.

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Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred.

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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

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