FAIR VALUE MEASUREMENTS (Details 2) - USD ($) $ in Millions |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Long-term Debt, Fair Value | $ 3,570.5 | $ 3,290.2 |
| Debt, Long-term and Short-term, Combined Amount | 3,340.8 | 3,230.3 |
| Quoted Prices In Active Markets for Identical Assets (Level 1) | ||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Long-term Debt, Fair Value | 0.0 | 0.0 |
| Significant Other Observable Inputs (Level 2) | ||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Long-term Debt, Fair Value | 3,417.5 | 3,137.2 |
| Significant Unobservable Inputs (Level 3) | ||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Long-term Debt, Fair Value | $ 153.0 | $ 153.0 |