CONSOLIDATED STATEMENT OF CASH FLOWS - SCHEDULE OF THE RECONCILIATION FOR NET INCOME PROVIDED BY OPERATING ACTIVITIES (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net income	$ 43.4	$ 105.0	$ 136.1	$ 112.3	$ 115.8	$ 99.8	$ 78.0	$ 147.4	$ 396.8	$ 441.0	$ 301.8
Adjustments to reconcile net income to net cash from operating activities:
Amortization and depreciation									345.3	319.5	303.9
Income taxes									86.6	146.5	14.1
Insurance liabilities									(175.6)	346.2	397.6
Accrual and amortization of investment income									138.7	(347.6)	(125.2)
Deferral of policy acquisition costs									(332.2)	(298.8)	(275.8)
Net investment (gains) losses									135.4	(19.1)	36.2
Other									(99.6)	10.6	82.9
Net cash from operating activities									495.4	598.3	735.5
Stock options, restricted stock and performance units									$ 25.2	$ 26.0	$ 24.5