DEBT - SUMMARY (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Debt
Capital leases	$ 0.1	$ 0.8
Total Debt	908.1	857.1
Less current portion	(42.1)	(30.8)
Total Long-term Debt	866.0	826.3
5.79%, payable through 2020
Debt
Total Debt	$ 14.0	$ 17.5
Interest rate (as a percent)	5.79%	5.79%
3.66%, payable through 2023
Debt
Total Debt	$ 45.6	$ 50.1
Interest rate (as a percent)	3.66%	3.66%
4.16%, payable through 2027
Debt
Total Debt	$ 47.1	$ 49.8
Interest rate (as a percent)	4.16%	4.16%
3.37 %, payable through 2027
Debt
Total Debt	$ 75.0	$ 75.0
Interest rate (as a percent)	3.37%	3.37%
3.14%, payable through 2031
Debt
Total Debt	$ 200.0	$ 200.0
Interest rate (as a percent)	3.14%	3.14%
4.31%, payable through 2032
Debt
Total Debt	$ 33.9	$ 35.1
Interest rate (as a percent)	4.31%	4.31%
4.35%, payable through 2044
Debt
Total Debt	$ 100.0	$ 100.0
Interest rate (as a percent)	4.35%	4.35%
3.92%, payable through 2045
Debt
Total Debt	$ 73.2	$ 73.2
Interest rate (as a percent)	3.92%	3.92%
5.34%, payable through 2028
Debt
Total Debt	$ 22.0	$ 24.2
Interest rate (as a percent)	5.34%	5.34%
5.27%, payable through 2029
Debt
Total Debt	$ 24.2	$ 26.4
Interest rate (as a percent)	5.27%	5.27%
Revolving Credit Facility
Debt
Total Debt	$ 273.0	$ 205.0
Funds available under the revolving credit facility	$ 243.2
Interest rate during period (as a percent)	3.52%