SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Fair Value
Assets and Liabilities:
Deferred Compensation Plan Assets	$ 35.5
Deferred Compensation Plan Liability	(35.5)
Total assets and liabilities	0.0
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets and Liabilities:
Deferred Compensation Plan Assets	35.5
Deferred Compensation Plan Liability	0.0
Total assets and liabilities	35.5
Significant Other Observable Inputs (Level 2)
Assets and Liabilities:
Deferred Compensation Plan Assets	0.0
Deferred Compensation Plan Liability	(35.5)
Total assets and liabilities	(35.5)
Significant Unobservable Inputs (Level 3)
Assets and Liabilities:
Deferred Compensation Plan Assets	0.0
Deferred Compensation Plan Liability	0.0
Total assets and liabilities	$ 0.0