SCHEDULE IV - REINSURANCE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Assumed	$ 18.6	$ 20.7	$ 23.0
Reinsurance ceded	(214.6)	(231.3)	(247.8)
Premiums on traditional products with mortality or morbidity risk	2,309.9	2,342.8	2,340.3
Life insurance inforce:
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct	30,444.8	29,954.0	29,109.8
Assumed	86.5	93.8	99.5
Ceded	(2,820.0)	(2,930.8)	(3,042.4)
Net insurance inforce	$ 27,711.3	$ 27,117.0	$ 26,166.9
Percentage of assumed to net	0.30%	0.30%	0.40%
Insurance policy income:
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct	$ 2,483.1	$ 2,530.5	$ 2,542.4
Assumed	18.7	20.3	23.0
Reinsurance ceded	(191.9)	(208.0)	(225.1)
Premiums on traditional products with mortality or morbidity risk	$ 2,309.9	$ 2,342.8	$ 2,340.3
Percentage of assumed to net	0.80%	0.90%	1.00%