INVESTMENTS (SCHEDULE OF REALIZED GAIN (LOSS) ON INVESTMENTS) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investment [Line Items]
Net impairment losses recognized	$ (32.3)	$ (39.9)	$ (27.3)
Other-than-temporary impairment losses recognized in accumulated other comprehensive income	3.6	3.0	0.0
Net realized investment gains (losses)	8.3	(36.6)	36.7
Gain (loss) on dissolution of variable interest entities	(7.3)	11.3	0.0
Total fixed maturities, available for sale [Member]
Investment [Line Items]
Gross realized gains on sale	137.7	95.7	64.4
Gross realized losses on sale	(95.2)	(88.4)	(13.0)
Net impairment losses recognized	(15.2)	(17.9)	0.0
Other-than-temporary impairment losses recognized in accumulated other comprehensive income	3.6	3.0	0.0
Net impairment losses recognized	(11.6)	(14.9)	0.0
Net realized investment gains (losses)	30.9	(7.6)	51.4
Equity securities [Member]
Investment [Line Items]
Net realized investment gains (losses)	20.9	3.7	10.1
Commercial mortgage loans [Member]
Investment [Line Items]
Net realized investment gains (losses)	0.0	(2.3)	(0.1)
Impairments of preferred stock and other investments [Member]
Investment [Line Items]
Net realized investment gains (losses)	(20.7)	(25.0)	(27.3)
Other [Member]
Investment [Line Items]
Net realized investment gains (losses)	(15.5)	(16.7)	2.6
Investments [Member]
Investment [Line Items]
Change in estimated fair value of trading securities	$ (0.5)	$ (9.2)	$ 7.8

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Line items represent reporting concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments.

+ References

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The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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Amount of increase (decrease) in the fair value of equity or debt securities classified as trading.

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Amount before tax of other than temporary impairment (OTTI) on investment in available-for-sale debt security, recognized in other comprehensive loss.

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The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis.

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