DERIVATIVES (SCHEDULE PRE-TAX GAINS (LOSSES) RECOGNIZED IN NET INCOME FOR DERIVATIVE INSTRUMENTS) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Gains (losses) on derivative instruments not designated as hedging instruments	$ 89.7	$ (9.6)	$ (10.4)
Investment Income [Member]
Derivative [Line Items]
Gains (losses) on derivative instruments not designated as hedging instruments	29.2	(36.2)	68.1
Investment Income [Member] | Equity Swap [Member]
Derivative [Line Items]
Gains (losses) on derivative instruments not designated as hedging instruments	29.2	(36.2)	69.5
Investment Income [Member] | Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Gains (losses) on derivative instruments not designated as hedging instruments	0.0	0.0	(1.4)
Gain (Loss) on Investments [Member]
Derivative [Line Items]
Gains (losses) on derivative instruments not designated as hedging instruments	(0.3)	(9.7)	(5.0)
Gain (Loss) on Investments [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Gains (losses) on derivative instruments not designated as hedging instruments	(1.1)	(2.7)	(7.0)
Gain (Loss) on Investments [Member] | Embedded Derivative Financial Instruments [Member] | Coinsurance [Member]
Derivative [Line Items]
Gains (losses) on derivative instruments not designated as hedging instruments	0.8	(7.0)	2.0
Insurance Policy Benefits [Member] | Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Gains (losses) on derivative instruments not designated as hedging instruments	$ 60.8	$ 36.3	$ (73.5)