Liability for Unpaid Claims and CAE - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2021	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Liability for Unpaid Claims and CAE
Reinsurance Recoverables, Incurred but Not Reported Claims		$ 8,372.3	$ 8,697.8	$ 9,042.2	$ 8,378.9
Phase 2 | Closed Block Individual Disability Reinsurance Transaction
Liability for Unpaid Claims and CAE
Increase in Benefits and Change in Reserves for Future Benefits	$ 133.1	133.1
Reinsurance Recoverables, Incurred but Not Reported Claims	$ 990.0	$ 990.0