FAIR VALUE OF OTHER FINANCIAL INSTRUMENTS - CARRYING VALUES AND FAIR VALUES OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019 |
Estimate of Fair Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | $ 2,602.6 | $ 2,278.5 |
Total Liabilities at Fair Value | 0 | 0 |
Estimate of Fair Value Measurement | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 2,591.8 | 2,248.9 |
Total Liabilities at Fair Value | 0 | 0 |
Estimate of Fair Value Measurement | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 10.6 | 29.4 |
Total Liabilities at Fair Value | 0 | 0 |
Estimate of Fair Value Measurement | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0.2 | 0.2 |
Total Liabilities at Fair Value | 0 | 0 |
Bonds | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Bonds | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 1,927.8 | 1,423.5 |
Bonds | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 13.6 | 9.6 |
Bonds | Estimate of Fair Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 1,941.4 | 1,433.1 |
Bonds | Reported Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 1,731.8 | 1,350.9 |
Preferred Stock | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 2.3 | 2.3 |
Preferred Stock | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 23.1 | 0 |
Preferred Stock | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Preferred Stock | Estimate of Fair Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 25.4 | 2.3 |
Preferred Stock | Reported Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 22.9 | 2.3 |
Common Stock | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Common Stock | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Common Stock | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 87.6 | 78.5 |
Common Stock | Estimate of Fair Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 87.6 | 78.5 |
Common Stock | Reported Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 65.7 | 58.9 |
Mortgage Loans on Real Estate | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Mortgage Loans on Real Estate | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Mortgage Loans on Real Estate | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 17.7 | 17.6 |
Mortgage Loans on Real Estate | Estimate of Fair Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 17.7 | 17.6 |
Mortgage Loans on Real Estate | Reported Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 17 | 17 |
Derivatives | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 17 | 13.1 |
Derivatives | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 3.6 | 15.1 |
Derivatives | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Derivatives | Estimate of Fair Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 20.6 | 28.2 |
Derivatives | Reported Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 20.6 | 28.2 |
Separate Accounts | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 2,606.6 | 2,276.5 |
Separate Accounts | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 485.6 | 441.9 |
Separate Accounts | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Separate Accounts | Estimate of Fair Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 3,092.2 | 2,718.4 |
Separate Accounts | Reported Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 3,055.9 | 2,699.3 |
Policy loans | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Policy loans | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 0 | 0 |
Policy loans | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 136.2 | 89.1 |
Policy loans | Estimate of Fair Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 136.2 | 89.1 |
Policy loans | Reported Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Assets at Fair Value | 112.1 | 88.5 |
Policyholders liabilities: Investment contracts | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Liabilities at Fair Value | 0 | 0 |
Policyholders liabilities: Investment contracts | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Liabilities at Fair Value | 0 | 0 |
Policyholders liabilities: Investment contracts | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Liabilities at Fair Value | 4.5 | 3.7 |
Policyholders liabilities: Investment contracts | Estimate of Fair Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Liabilities at Fair Value | 4.5 | 3.7 |
Policyholders liabilities: Investment contracts | Reported Value Measurement | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Total Liabilities at Fair Value | $ 4.5 | $ 3.7 |