FAIR VALUE MEASUREMENTS (Details 2) - USD ($) $ in Millions |
Jun. 30, 2018 |
Dec. 31, 2017 |
Jun. 30, 2017 |
|---|---|---|---|
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | |||
| Long-term Debt, Fair Value | $ 3,674.6 | $ 3,911.0 | $ 3,930.8 |
| Notes Payable | 3,513.5 | 3,612.0 | 3,600.6 |
| Fair Value, Inputs, Level 1 | |||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | |||
| Long-term Debt, Fair Value | 0.0 | 0.0 | 0.0 |
| Fair Value, Inputs, Level 2 | |||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | |||
| Long-term Debt, Fair Value | 3,521.6 | 3,758.0 | 3,777.8 |
| Fair Value, Inputs, Level 3 | |||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | |||
| Long-term Debt, Fair Value | $ 153.0 | $ 153.0 | $ 153.0 |