INVESTMENTS IN VARIABLE INTEREST ENTITIES - CHANGES IN ALLOWANCE (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Variable Interest Entity [Line Items]
Beginning allowance	$ 19.9	$ 2.1
Additions for securities for which credit losses were not previously recorded	4.5	23.7
Additions for purchased securities with deteriorated credit	0.0	0.0
Additions (reductions) for securities where an allowance was previously recorded	(13.1)	(14.2)
Reduction for securities sold during the period	(0.5)	(0.8)
Reduction for securities for which the Company made the decision to sell where an allowance was previously recorded	0.0	0.0
Write-offs	0.0	0.0
Recoveries of previously written-off amount	0.0	0.0
Ending allowance	10.8	10.8
Corporate securities
Variable Interest Entity [Line Items]
Beginning allowance	18.2	2.1
Additions for securities for which credit losses were not previously recorded	4.2	21.7
Additions for purchased securities with deteriorated credit	0.0	0.0
Additions (reductions) for securities where an allowance was previously recorded	(11.9)	(13.0)
Reduction for securities sold during the period	(0.5)	(0.8)
Reduction for securities for which the Company made the decision to sell where an allowance was previously recorded	0.0	0.0
Write-offs	0.0	0.0
Recoveries of previously written-off amount	0.0	0.0
Ending allowance	10.0	10.0
Variable Interest Entity, Primary Beneficiary | Corporate securities
Variable Interest Entity [Line Items]
Beginning allowance	37.7	9.9
Additions for securities for which credit losses were not previously recorded	5.8	24.9
Additions for purchased securities with deteriorated credit	0.0	0.0
Additions (reductions) for securities where an allowance was previously recorded	(14.7)	(4.8)
Reduction for securities sold during the period	(1.1)	(2.3)
Reduction for securities for which the Company made the decision to sell where an allowance was previously recorded	0.0	0.0
Write-offs	0.0	0.0
Recoveries of previously written-off amount	0.0	0.0
Ending allowance	$ 27.7	$ 27.7