FAIR VALUE MEASUREMENTS - BALANCE SHEET RECURRING (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Liabilities:
Fair value, measurement with unobservable inputs reconciliation, beginning balance				$ (905.5)
Purchases, sales, issuances and settlements, net				(60.2)
Total realized and unrealized gains (losses) included in net income				(26.5)
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)				0.0
Transfers into level 3				0.0
Transfers out of level 3				0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance		$ (992.2)		(992.2)
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date				(26.5)
Available-for-sale securities [Member] | Corporate securities [Member]
Assets:
Purchases, sales, issuances and settlements, net	$ 4.6	6.6	$ (21.7)	44.9
Available-for-sale securities [Member] | Corporate securities [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance	133.7	389.8	365.9	359.6
Purchases, sales, issuances and settlements, net	4.6	6.6	(21.7)	44.9
Total realized and unrealized gains (losses) included in net income	0.0	0.0	(2.2)	0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)	(3.8)	(0.9)	(10.0)	11.6
Transfers into level 3	11.8	37.5	21.0	52.7
Transfers out of level 3	0.0	(98.2)	(206.7)	(82.8)
Assets of CLIC sold				(51.2)
Fair value, measurement with unobservable inputs reconciliation, ending balance	146.3	334.8	146.3	334.8
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date	0.0	0.0	0.0	0.0
Available-for-sale securities [Member] | States and political subdivisions [Member]
Assets:
Assets of CLIC sold				(2.2)
Available-for-sale securities [Member] | States and political subdivisions [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance		28.7	35.5	0.0
Purchases, sales, issuances and settlements, net		0.0	0.0	0.0
Total realized and unrealized gains (losses) included in net income		0.0	0.0	0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)		0.0	0.0	0.1
Transfers into level 3		0.0	0.0	2.1
Transfers out of level 3		(28.7)	(35.5)	0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance	0.0	0.0	0.0	0.0
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date		0.0	0.0	0.0
Available-for-sale securities [Member] | Asset-backed Securities [Member]
Assets:
Purchases, sales, issuances and settlements, net	10.4	(0.1)	10.0	8.9
Available-for-sale securities [Member] | Asset-backed Securities [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance	53.3	52.7	59.2	42.2
Purchases, sales, issuances and settlements, net	10.4	(0.1)	10.0	8.9
Total realized and unrealized gains (losses) included in net income	0.0	0.0	0.0	0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)	0.2	0.2	(0.6)	4.0
Transfers into level 3	0.0	9.5	0.0	16.9
Transfers out of level 3	(23.9)	0.0	(28.6)	0.0
Assets of CLIC sold				(9.7)
Fair value, measurement with unobservable inputs reconciliation, ending balance	40.0	62.3	40.0	62.3
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date	0.0	0.0	0.0	0.0
Available-for-sale securities [Member] | Collateralized debt obligations [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance		14.2		246.7
Purchases, sales, issuances and settlements, net		0.0		0.0
Total realized and unrealized gains (losses) included in net income		0.0		0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)		0.0		0.0
Transfers into level 3		0.0		0.0
Transfers out of level 3		(14.2)		(246.7)
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance		0.0		0.0
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date		0.0		0.0
Available-for-sale securities [Member] | Commercial mortgage-backed securities [Member]
Assets:
Purchases, sales, issuances and settlements, net	14.6	1.1	14.5	1.1
Available-for-sale securities [Member] | Commercial mortgage-backed securities [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance	1.2	0.0	1.2	0.0
Purchases, sales, issuances and settlements, net	14.6	1.1	14.5	1.1
Total realized and unrealized gains (losses) included in net income	0.0	0.0	0.0	0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)	(0.2)	0.0	(0.1)	0.0
Transfers into level 3	0.0	0.0	0.0	0.0
Transfers out of level 3	0.0	0.0	0.0	0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance	15.6	1.1	15.6	1.1
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date	0.0	0.0	0.0	0.0
Available-for-sale securities [Member] | Mortgage pass-through securities [Member]
Assets:
Purchases, sales, issuances and settlements, net	(0.1)	(0.2)	(0.3)	(0.5)
Available-for-sale securities [Member] | Mortgage pass-through securities [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance	0.2	1.3	0.4	1.6
Purchases, sales, issuances and settlements, net	(0.1)	(0.2)	(0.3)	(0.5)
Total realized and unrealized gains (losses) included in net income	0.0	0.0	0.0	0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)	0.0	0.0	0.0	0.0
Transfers into level 3	0.0	0.0	0.0	0.0
Transfers out of level 3	0.0	0.0	0.0	0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance	0.1	1.1	0.1	1.1
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date	0.0	0.0	0.0	0.0
Available-for-sale securities [Member] | Collateralized mortgage obligations [Member]
Assets:
Purchases, sales, issuances and settlements, net				(0.1)
Available-for-sale securities [Member] | Collateralized mortgage obligations [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance		0.1		0.0
Purchases, sales, issuances and settlements, net		0.0		(0.1)
Total realized and unrealized gains (losses) included in net income		0.0		0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)		0.0		0.0
Transfers into level 3		0.0		0.2
Transfers out of level 3		0.0		0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance		0.1		0.1
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date		0.0		0.0
Available-for-sale securities [Member] | Total fixed maturities, available for sale [Member]
Assets:
Purchases, sales, issuances and settlements, net	29.5	7.4	2.5	54.3
Available-for-sale securities [Member] | Total fixed maturities, available for sale [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance	188.4	486.8	462.2	650.1
Purchases, sales, issuances and settlements, net	29.5	7.4	2.5	54.3
Total realized and unrealized gains (losses) included in net income	0.0	0.0	(2.2)	0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)	(3.8)	(0.7)	(10.7)	15.7
Transfers into level 3	11.8	47.0	21.0	71.9
Transfers out of level 3	(23.9)	(141.1)	(270.8)	(329.5)
Assets of CLIC sold				(63.1)
Fair value, measurement with unobservable inputs reconciliation, ending balance	202.0	399.4	202.0	399.4
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date	0.0	0.0	0.0	0.0
Equity securities classification [Member] | Corporate securities [Member]
Assets:
Purchases, sales, issuances and settlements, net	1.0	0.9	2.9	2.6
Equity securities classification [Member] | Corporate securities [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance	29.9	26.2	28.0	24.5
Purchases, sales, issuances and settlements, net	1.0	0.9	2.9	2.6
Total realized and unrealized gains (losses) included in net income	0.0	0.0	0.0	0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)	0.0	0.0	0.0	0.0
Transfers into level 3	0.0	0.0	0.0	0.0
Transfers out of level 3	0.0	0.0	0.0	0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance	30.9	27.1	30.9	27.1
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date	0.0	0.0	0.0	0.0
Equity securities classification [Member] | Asset-backed Securities [Member]
Assets:
Purchases, sales, issuances and settlements, net				29.1
Trading securities [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance		5.9		0.0
Purchases, sales, issuances and settlements, net		0.0		29.1
Total realized and unrealized gains (losses) included in net income		0.0		0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)		(0.3)		(0.2)
Transfers into level 3		29.1		5.8
Transfers out of level 3		0.0		0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance		34.7		34.7
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date		(0.3)		(0.2)
Investments held by variable interest entities [Member] | Corporate securities held by variable interest entities [Member]
Assets:
Purchases, sales, issuances and settlements, net		3.0		3.0
Investments held by variable interest entities [Member] | Corporate securities held by variable interest entities [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance		0.0		0.0
Purchases, sales, issuances and settlements, net		3.0		3.0
Total realized and unrealized gains (losses) included in net income		0.0		0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)		(0.1)		(0.1)
Transfers into level 3		1.0		1.0
Transfers out of level 3		0.0		0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance		3.9		3.9
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date		0.0		0.0
Collateralized mortgage obligations [Member] | Trading securities [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance		5.9		0.0
Purchases, sales, issuances and settlements, net		0.0		0.0
Total realized and unrealized gains (losses) included in net income		0.0		0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)		0.1		0.2
Transfers into level 3		0.0		5.8
Transfers out of level 3		0.0		0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance		6.0		6.0
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date		0.1		0.2
Commercial mortgage-backed securities [Member] | Trading securities [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Assets:
Fair value, measurement with unobservable inputs reconciliation, beginning balance	39.9	0.0	28.6	0.0
Purchases, sales, issuances and settlements, net	0.0	0.0	0.0	29.1
Total realized and unrealized gains (losses) included in net income	0.0	0.0	0.0	0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)	(0.6)	(0.4)	1.5	(0.4)
Transfers into level 3	0.0	29.1	0.0	0.0
Transfers out of level 3	(9.2)	0.0	0.0	0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance	30.1	28.7	30.1	28.7
Liabilities:
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date	(0.6)	(0.4)	1.5	(0.4)
Interest sensitive products [Member]
Liabilities:
Purchases, sales, issuances and settlements, net	16.1	(12.2)	6.1	(62.0)
Interest sensitive products [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Liabilities:
Fair value, measurement with unobservable inputs reconciliation, beginning balance	(1,074.0)	(980.3)	(1,081.5)	(903.7)
Purchases, sales, issuances and settlements, net	16.1	(12.2)	6.1	(62.0)
Total realized and unrealized gains (losses) included in net income	(21.2)	0.3	(3.7)	(26.5)
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)	0.0	0.0	0.0	0.0
Transfers into level 3	0.0	0.0	0.0	0.0
Transfers out of level 3	0.0	0.0	0.0	0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance	(1,079.1)	(992.2)	(1,079.1)	(992.2)
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date	$ (21.2)	0.3	$ (3.7)	(26.5)
Interest sensitive products, modified coinsurance agreement [Member]
Liabilities:
Purchases, sales, issuances and settlements, net				1.8
Interest sensitive products, modified coinsurance agreement [Member] | Fair value, measurements, recurring [Member] | Level 3 [Member]
Liabilities:
Fair value, measurement with unobservable inputs reconciliation, beginning balance				(1.8)
Purchases, sales, issuances and settlements, net				1.8
Total realized and unrealized gains (losses) included in net income				0.0
Total realized and unrealized gains (losses) included in accumulated other comprehensive income (loss)				0.0
Transfers into level 3				0.0
Transfers out of level 3				0.0
Assets of CLIC sold				0.0
Fair value, measurement with unobservable inputs reconciliation, ending balance		$ 0.0		0.0
Amount of total gains (losses) included in our net income relating to assets and liabilities still held as of the reporting date				$ 0.0