SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION (Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	$ (47.9)	$ 104.3
Capital expenditures	(95.9)	(102.2)
Proceeds from disposition of non-consolidated affiliate		20.0
Net investing activities	(95.9)	(82.2)
Long-term debt:
Borrowings	225.0	0.0
Repayments	(75.4)	(50.2)
Common stock repurchased and retired	0.0	(13.2)
Stock options exercised	0.5	1.4
Dividends paid	(31.5)	(33.0)
Debt issuance costs	(0.4)	0.0
Intercompany financing activities		0.0
Net financing activities	118.2	(95.0)
Effect of exchange rate changes on cash and cash equivalents	(0.8)	(0.2)
Net increase (decrease) in cash and cash equivalents	(26.4)	(73.1)
Cash and cash equivalents, end of period	194.5	105.7
Cash and cash equivalents, beginning of period	220.9	178.8
Parent Guarantor
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	162.0	39.7
Capital expenditures	(32.1)	(50.7)
Proceeds from disposition of non-consolidated affiliate		20.0
Net investing activities	(32.1)	(30.7)
Long-term debt:
Borrowings	75.0
Repayments	(75.4)	(0.2)
Common stock repurchased and retired		(13.2)
Stock options exercised	0.5	1.4
Dividends paid	(31.5)	(33.0)
Debt issuance costs	(0.4)
Intercompany financing activities		(50.0)
Net financing activities	(31.8)	(95.0)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net increase (decrease) in cash and cash equivalents	98.1	(86.0)
Cash and cash equivalents, end of period	109.7	6.0
Cash and cash equivalents, beginning of period	11.6	92.0
Issuer
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	0.0	0.0
Capital expenditures	0.0	0.0
Proceeds from disposition of non-consolidated affiliate		0.0
Net investing activities	0.0	0.0
Long-term debt:
Borrowings	0.0
Repayments	0.0	(50.0)
Common stock repurchased and retired		0.0
Stock options exercised	0.0	0.0
Dividends paid	0.0	0.0
Debt issuance costs	0.0
Intercompany financing activities		50.0
Net financing activities	0.0	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net increase (decrease) in cash and cash equivalents	0.0	0.0
Cash and cash equivalents, end of period	0.0	0.0
Cash and cash equivalents, beginning of period	0.0	0.0
Subsidiary Non-Guarantor
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	(209.9)	64.6
Capital expenditures	(63.8)	(51.5)
Proceeds from disposition of non-consolidated affiliate		0.0
Net investing activities	(63.8)	(51.5)
Long-term debt:
Borrowings	150.0
Repayments	0.0	0.0
Common stock repurchased and retired		0.0
Stock options exercised	0.0	0.0
Dividends paid	0.0	0.0
Debt issuance costs	0.0
Intercompany financing activities		0.0
Net financing activities	150.0	0.0
Effect of exchange rate changes on cash and cash equivalents	(0.8)	(0.2)
Net increase (decrease) in cash and cash equivalents	(124.5)	12.9
Cash and cash equivalents, end of period	84.8	99.7
Cash and cash equivalents, beginning of period	209.3	86.8
Eliminations
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	0.0	0.0
Capital expenditures	0.0	0.0
Proceeds from disposition of non-consolidated affiliate		0.0
Net investing activities	0.0	0.0
Long-term debt:
Borrowings	0.0
Repayments	0.0	0.0
Common stock repurchased and retired		0.0
Stock options exercised	0.0	0.0
Dividends paid	0.0	0.0
Debt issuance costs	0.0
Intercompany financing activities		0.0
Net financing activities	0.0	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Net increase (decrease) in cash and cash equivalents	0.0	0.0
Cash and cash equivalents, end of period	0.0	0.0
Cash and cash equivalents, beginning of period	$ 0.0	$ 0.0