Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance at the beginning of the period	$ 319.0	$ 290.8	$ 290.8	$ 306.6
Acquisition costs deferred			460.0	398.3
Amortization of deferred acquisition costs	(192.9)	$ (216.5)	(431.8)	(414.1)	$ (465.7)
Balance at the end of the period	$ 353.1		$ 319.0	$ 290.8	$ 306.6

Amount of amortization expense (reversal of expense) for deferred policy acquisition costs.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration