DEFERRED ACQUISITION COSTS, PRESENT VALUE OF FUTURE PROFITS AND SALES INDUCEMENTS - DEFERRED ACQUISITION COSTS (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	$ 2,220.7	$ 2,025.4
Capitalizations	222.8	212.5
Amortization expense	(128.2)	(116.7)
End of period	2,315.3	2,121.2
Fixed indexed annuities
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	497.4	450.0
Capitalizations	56.5	54.6
Amortization expense	(34.8)	(31.5)
End of period	519.1	473.1
Fixed interest annuities
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	41.8	35.9
Capitalizations	5.0	6.6
Amortization expense	(3.4)	(3.2)
End of period	43.4	39.3
Supplemental health
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	473.5	438.1
Capitalizations	37.6	35.4
Amortization expense	(20.2)	(18.6)
End of period	490.9	454.9
Medicare supplement
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	162.9	157.4
Capitalizations	20.3	14.6
Amortization expense	(12.5)	(12.5)
End of period	170.7	159.5
Long-term care
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	165.3	148.6
Capitalizations	17.4	14.6
Amortization expense	(8.4)	(7.7)
End of period	174.3	155.5
Interest-sensitive life
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	277.5	256.0
Capitalizations	20.9	18.1
Amortization expense	(9.0)	(8.3)
End of period	289.4	265.8
Traditional life
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	592.2	529.5
Capitalizations	62.9	68.6
Amortization expense	(37.7)	(33.3)
End of period	617.4	564.8
Funding agreements
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	10.1	9.9
Capitalizations	2.2	0.0
Amortization expense	(2.2)	(1.6)
End of period	$ 10.1	$ 8.3