Liability for Future Policyholder Benefits - Reconciliation of the Net Liability for Future Benefits to Life and Health Insurance Reserves (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021
Insurance [Abstract]
Present Value of Expected Future Policyholder benefits	$ 3,699.5	$ 4,348.7	$ 3,561.0	$ 4,933.1
Net Liability for Future Policyholder benefits	2,977.1	3,687.7	$ 3,687.7
Deferred Profit Liability	272.6	213.9
A&H and Other Reserves	149.9	202.6
Total Life and Health Insurance Reserves	3,399.6	4,104.2
Liability for Future Policy Benefit, Expected Net Premium, before Reinsurance, after Discount Rate Change	103.8	101.4
Liability for Future Policy Benefit, Interest Expense	$ 35.4	$ 35.6