INVESTMENTS IN VARIABLE INTEREST ENTITIES - NARRATIVE (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) investment	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Variable Interest Entity [Line Items]
Total amortized cost	$ 1,198.9
Variable interest entity, gross unrealized gains fixed maturity securities	0.9
Variable interest entity gross unrealized losses fixed maturity securities	13.1
Variable interest entity, allowance for credit losses fixed maturity securities	5.9
Estimated fair value of fixed maturity securities	1,180.8
Variable interest entities net realized gain (losses) on investments	(3.2)	$ 4.1
Variable interest entities net loss from sale of fixed maturity investments	(0.8)	(5.6)
Variable interest entities, net loss from change in market value of other investments	(0.2)
Variable interest entities, change in allowance for credit losses	(2.2)	9.7
Variable interest entity, gross investment losses from sale	0.8	5.6
Variable interest entities, investments sold	$ 11.7	$ 27.2
Number of investments held by VIE, in default | investment	0
Fair value, less than 12 months	$ 5,155.3		$ 1,698.6
Gross unrealized losses, less than 12 months	251.2		15.1
Fair value, 12 months or greater	149.5		122.2
Gross unrealized losses, 12 months or greater	8.9		3.4
Investments held in limited partnerships	620.7
Unfunded commitments to limited partnerships	244.9
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Fair value, less than 12 months	504.1		417.7
Gross unrealized losses, less than 12 months	5.5		2.2
Fair value, 12 months or greater	390.0		279.7
Gross unrealized losses, 12 months or greater	$ 6.6		$ 3.1