INVESTMENTS - NARRATIVE (Details) $ in Millions	3 Months Ended
Mar. 31, 2026 USD ($) mortgage_loan loan	Mar. 31, 2025 USD ($)
Debt Securities, Available-for-sale [Line Items]
Value of available for sale securities sold	$ 1,657.1	$ 230.3
Amortized cost of fixed maturities that were non-income producing	5.7
Carrying value of fixed maturities that were non-income producing	3.5
Total fixed maturities, available for sale
Debt Securities, Available-for-sale [Line Items]
Gross realized losses on sales of fixed maturities, available for sale	$ (56.3)	$ (2.8)
Financial Asset, Past Due
Debt Securities, Available-for-sale [Line Items]
Number of mortgage loans noncurrent \| loan	38
Commercial Portfolio Segment
Debt Securities, Available-for-sale [Line Items]
Number of mortgage loans in process of foreclosure \| mortgage_loan	0
Carrying value of loans	$ 1,852.9
Residential Portfolio Segment
Debt Securities, Available-for-sale [Line Items]
Number of mortgage loans noncurrent \| mortgage_loan	0
Residential Portfolio Segment \| Financial Asset, Past Due
Debt Securities, Available-for-sale [Line Items]
Carrying value of loans	$ 28.4
Residential Portfolio Segment \| Financial Asset, Past Due \| Foreclosure
Debt Securities, Available-for-sale [Line Items]
Number of mortgage loans noncurrent \| loan	12
Carrying value of loans	$ 8.0
Total carrying amount \| Residential Mortgage
Debt Securities, Available-for-sale [Line Items]
Mortgage loans	1,511.9
Total carrying amount \| Commercial Portfolio Segment \| Commercial Mortgage
Debt Securities, Available-for-sale [Line Items]
Mortgage loans	1,852.9
Total estimated fair value \| Residential Mortgage
Debt Securities, Available-for-sale [Line Items]
Mortgage loans	1,527.8
Total estimated fair value \| Commercial Portfolio Segment \| Commercial Mortgage
Debt Securities, Available-for-sale [Line Items]
Mortgage loans	$ 1,752.6

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