CONTRIBUTING EMPLOYEE OWNERSHIP PLAN (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 7.0	$ 7.1	$ 22.4	$ 20.5
Employer matching contributions to employee ownership plan	$ 3.0	$ 3.0	$ 8.7	$ 8.7
Minimum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation	5.00%		5.00%
Maximum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation	10.00%		10.00%