FAIR VALUE MEASUREMENTS (Details 2) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Long-term Debt, Fair Value	$ 3,484.9	$ 3,911.0	$ 4,073.5
Notes Payable	3,337.3	3,612.0	3,745.2
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	3,331.9	3,758.0	3,920.5
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