ACCOUNTING FOR DERIVATIVES - FAIR VALUE BY BALANCE SHEET LOCATION (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fixed index call options
Derivatives, Fair Value [Line Items]
Assets	$ 143.8	$ 203.8
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Assets	144.5	202.6
Liabilities	1,598.9	1,565.4
Not Designated as Hedging Instrument | Fixed index call options | Other invested assets:
Derivatives, Fair Value [Line Items]
Assets	143.8	203.8
Not Designated as Hedging Instrument | Reinsurance receivables | Other invested assets:
Derivatives, Fair Value [Line Items]
Assets	0.7	(1.2)
Not Designated as Hedging Instrument | Fixed index products | Future policy benefits:
Derivatives, Fair Value [Line Items]
Liabilities	$ 1,598.9	$ 1,565.4