DERIVATIVES - SCHEDULE PRE-TAX GAINS (LOSSES) RECOGNIZED IN NET INCOME FOR DERIVATIVE INSTRUMENTS (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Derivative [Line Items]
Gains on derivatives not designated as hedging instruments	$ 161.1	$ 81.1	$ 95.9	$ 11.7
Net pre-tax impact	45.0	21.4	6.8	(35.1)
Embedded derivatives
Derivative [Line Items]
Embedded derivatives related to fixed indexed annuities	0.5	0.8	3.4	(7.2)
Embedded derivatives \| Embedded derivatives related to fixed indexed annuities
Derivative [Line Items]
Embedded derivatives related to fixed indexed annuities	116.1	59.7	89.1	46.8
Income Statement Location [Axis]: us-gaap:GainLossOnInvestments \| Embedded derivatives \| Embedded derivative related to modified coinsurance agreement
Derivative [Line Items]
Gains on derivatives not designated as hedging instruments	(0.2)	0.1	(0.6)	1.3
Income Statement Location [Axis]: us-gaap:InvestmentIncomeInvestmentExpense \| Fixed indexed call options
Derivative [Line Items]
Gains on derivatives not designated as hedging instruments	$ 161.3	$ 81.0	$ 96.5	$ 10.4

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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