FAIR VALUE MEASUREMENTS (FAIR VALUE MEASUREMENTS OF FINANCIAL INSTRUMENTS MEASURED ON A RECURRING BASIS - SECURITIES) (Details) (USD $) | Dec. 31, 2014 | Dec. 31, 2013 |
In Millions, unless otherwise specified |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | $20,634.90 | $23,204.60 |
Trading securities | 244.9 | 247.6 |
Investments held by variable interest entities - corporate securities | 1,367.10 | 1,046.70 |
Assets held in separate accounts | 5.6 | 10.3 |
Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Trading securities | 3.5 | 2.4 |
Investments held by variable interest entities - corporate securities | 0 | 0 |
Assets held in separate accounts | 0 | 0 |
Total assets carried at fair value by category | 221.8 | 82.6 |
Total liabilities carried at fair value by category | | 0 |
Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Trading securities | 212.8 | 245.2 |
Investments held by variable interest entities - corporate securities | 1,367.10 | 1,046.70 |
Assets held in separate accounts | 5.6 | 10.3 |
Total assets carried at fair value by category | 22,039.50 | 24,131.80 |
Total liabilities carried at fair value by category | | 0 |
Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Trading securities | 28.6 | 0 |
Investments held by variable interest entities - corporate securities | 0 | 0 |
Assets held in separate accounts | 0 | 0 |
Total assets carried at fair value by category | 518.8 | 674.6 |
Total liabilities carried at fair value by category | | 905.5 |
Corporate debt securities [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Equity securities - corporate securities | 216.9 | 79.6 |
Trading securities | 0 | 0 |
Corporate debt securities [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 13,605.10 | 15,340.10 |
Equity securities - corporate securities | 174.1 | 118.9 |
Trading securities | 24.3 | 45.2 |
Corporate debt securities [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 365.9 | 359.6 |
Equity securities - corporate securities | 28 | 24.5 |
Trading securities | 0 | 0 |
US treasury and government [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Trading securities | 0 | 0 |
US treasury and government [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 168.9 | 73.1 |
Trading securities | 3.7 | 4.6 |
US treasury and government [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Trading securities | 0 | 0 |
US States and Political Subdivisions Debt Securities [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Trading securities | | 0 |
US States and Political Subdivisions Debt Securities [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 2,242.20 | 2,204.40 |
Trading securities | | 14.1 |
US States and Political Subdivisions Debt Securities [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 35.5 | 0 |
Trading securities | | 0 |
Foreign Government Debt Securities [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | |
Foreign Government Debt Securities [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 1.9 | |
Foreign Government Debt Securities [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | |
Asset-backed securities [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Trading securities | 0 | 0 |
Asset-backed securities [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 1,209.80 | 1,419.90 |
Trading securities | 24 | 24.3 |
Asset-backed securities [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 59.2 | 42.2 |
Trading securities | 0 | 0 |
Collateralized debt obligations [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Collateralized debt obligations [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 324.5 | 47.3 |
Collateralized debt obligations [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 246.7 |
Commercial Mortgage Backed Securities [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Trading securities | 0 | 0 |
Commercial Mortgage Backed Securities [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 1,275.10 | 1,609 |
Trading securities | 131 | 125.8 |
Commercial Mortgage Backed Securities [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 1.2 | 0 |
Trading securities | 28.6 | 0 |
Mortgage pass-through securities [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Trading securities | 0 | 0 |
Mortgage pass-through securities [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 4.2 | 11.8 |
Trading securities | 0.1 | 0.1 |
Mortgage pass-through securities [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0.4 | 1.6 |
Trading securities | 0 | 0 |
Collateralized mortgage obligations [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Trading securities | 0 | 0 |
Collateralized mortgage obligations [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 1,341 | 1,848.90 |
Trading securities | 29.7 | 31.1 |
Collateralized mortgage obligations [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Trading securities | 0 | 0 |
Total fixed maturities, available for sale [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 0 | 0 |
Total fixed maturities, available for sale [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 20,172.70 | 22,554.50 |
Total fixed maturities, available for sale [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 462.2 | 650.1 |
Equity Securities [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Trading securities | 3.5 | 2.4 |
Equity Securities [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Trading securities | 0 | 0 |
Equity Securities [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Trading securities | 0 | 0 |
Derivatives [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Other invested assets - derivatives | 1.4 | 0.6 |
Derivatives [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Other invested assets - derivatives | 107.2 | 156.2 |
Derivatives [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Other invested assets - derivatives | 0 | 0 |
Embedded derivatives associated with fixed index annuity products [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total liabilities for insurance products | 0 | 0 |
Embedded derivatives associated with fixed index annuity products [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total liabilities for insurance products | 0 | 0 |
Embedded derivatives associated with fixed index annuity products [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total liabilities for insurance products | 1,081.50 | 903.7 |
Embedded derivative associated with modified coinsurance agreement [Member] | Level 1 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total liabilities for insurance products | | 0 |
Embedded derivative associated with modified coinsurance agreement [Member] | Level 2 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total liabilities for insurance products | | 0 |
Embedded derivative associated with modified coinsurance agreement [Member] | Level 3 [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total liabilities for insurance products | | 1.8 |
Estimate of fair value measurement [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Trading securities | 244.9 | 247.6 |
Investments held by variable interest entities - corporate securities | 1,367.10 | 1,046.70 |
Assets held in separate accounts | 5.6 | 10.3 |
Total assets carried at fair value by category | 22,780.10 | 24,889 |
Total liabilities carried at fair value by category | | 905.5 |
Estimate of fair value measurement [Member] | Corporate debt securities [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 13,971 | 15,699.70 |
Equity securities - corporate securities | 419 | 223 |
Trading securities | 24.3 | 45.2 |
Estimate of fair value measurement [Member] | US treasury and government [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 168.9 | 73.1 |
Trading securities | 3.7 | 4.6 |
Estimate of fair value measurement [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 2,277.70 | 2,204.40 |
Trading securities | | 14.1 |
Estimate of fair value measurement [Member] | Foreign Government Debt Securities [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 1.9 | |
Estimate of fair value measurement [Member] | Asset-backed securities [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 1,269 | 1,462.10 |
Trading securities | 24 | 24.3 |
Estimate of fair value measurement [Member] | Collateralized debt obligations [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 324.5 | 294 |
Estimate of fair value measurement [Member] | Commercial Mortgage Backed Securities [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 1,276.30 | 1,609 |
Trading securities | 159.6 | 125.8 |
Estimate of fair value measurement [Member] | Mortgage pass-through securities [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 4.6 | 13.4 |
Trading securities | 0.1 | 0.1 |
Estimate of fair value measurement [Member] | Collateralized mortgage obligations [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 1,341 | 1,848.90 |
Trading securities | 29.7 | 31.1 |
Estimate of fair value measurement [Member] | Total fixed maturities, available for sale [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total fixed maturities, available for sale | 20,634.90 | 23,204.60 |
Estimate of fair value measurement [Member] | Equity Securities [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Trading securities | 3.5 | 2.4 |
Estimate of fair value measurement [Member] | Derivatives [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Other invested assets - derivatives | 108.6 | 156.8 |
Estimate of fair value measurement [Member] | Embedded derivatives associated with fixed index annuity products [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total liabilities for insurance products | 1,081.50 | 903.7 |
Estimate of fair value measurement [Member] | Embedded derivative associated with modified coinsurance agreement [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total liabilities for insurance products | | $1.80 |