INVESTMENTS IN VARIABLE INTEREST ENTITIES - NARRATIVE (Details) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($) investment	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Variable Interest Entity [Line Items]
Variable interest entity amortized cost securities held	$ 1,828.8
Variable interest entity, gross unrealized gains fixed maturity securities	3.7
Variable interest entity gross unrealized losses fixed maturity securities	24.7
Estimated fair value of fixed maturity securities	1,807.8
Variable interest entities net realized gain (loss) on investments	$ (6.4)	$ (0.9)
Number of investments held by VIE, in default | investment	1
Investment held by VIE, in default, amortized cost	$ 2.3
Investment held by VIE, in default, carrying value	1.5
Variable interest entities, investments sold	150.8	40.3
Variable interest entity, gross investment losses from sale	14.2	$ 1.1
Investments held in limited partnerships	185.3
Unfunded commitments to limited partnerships	130.7
Less than twelve months [Member]
Variable Interest Entity [Line Items]
Fair value investments held by variable interest entity that had been in an unrealized loss position	931.6		$ 1,178.7
Gross unrealized losses for a period	9.8		23.9
Greater than twelve months [Member]
Variable Interest Entity [Line Items]
Fair value investments held by variable interest entity that had been in an unrealized loss position	369.2		294.3
Gross unrealized losses for a period	$ 14.9		$ 22.3