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Amount of asset position for contract or contract feature in long-duration contract issued by insurance entity that both protects contract holder from other-than-nominal capital market risk and exposes insurance entity to other-than-nominal capital market risk.

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Long-Duration Insurance Contracts - Market Risk Benefits by Asset and Liability Balance (Details) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Dec. 31, 2020
Market Risk Benefit [Line Items]
Net	$ (4.5)	$ (3.6)	$ 0.2	$ 2.9	$ 4.6	$ 4.8	$ 8.6
Deferred variable annuities
Market Risk Benefit [Line Items]
(Asset)	(6.4)		(4.4)
Liability	1.9		4.7
Net	$ (4.5)		$ 0.3