SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION (Balance Sheet)(Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	$ 255.9	$ 184.5	$ 127.0	$ 392.0
Receivables, net	729.5	675.0	744.1
Intercompany receivables	0.0	0.0	0.0
Income taxes receivable	15.9	25.5	49.0
Inventories	689.5	630.4	617.0
Other Assets, Current	27.1	30.8	16.1
Total current assets	1,717.9	1,546.2	1,553.2
Property, Plant and Equipment, Net	3,579.2	3,704.9	3,713.9
Investment in subsidiaries	0.0	0.0	0.0
Deferred income taxes	141.1	119.5	112.2
Other Assets, Noncurrent	1,215.6	644.4	640.3
Long-term receivables—affiliates	0.0	0.0	0.0
Intangible Assets, Net	592.9	629.6	653.8
Goodwill	2,119.8	2,118.0	2,119.4	2,174.1
Total assets	9,366.5	8,762.6	8,792.8
Current installments of long-term debt	81.7	80.5	80.3
Accounts payable	613.5	570.8	509.7
Intercompany payables	0.0	0.0	0.0
Income taxes payable	9.6	7.5	13.3
Accrued Liabilities, Current	294.5	263.8	291.5
Total current liabilities	999.3	922.6	894.8
Long-term Debt, Excluding Current Maturities	3,663.5	3,537.1	3,597.5
Accrued pension liability	618.7	638.1	597.7
Deferred income taxes	1,055.5	1,032.5	1,036.6
Long-term payables—affiliates	0.0	0.0	0.0
Other Liabilities, Noncurrent	731.0	359.3	335.5
Total liabilities	7,068.0	6,489.6	6,462.1
Commitments and contingencies
Common Stock, Value, Issued	166.4	165.4	165.3
Additional Paid in Capital, Common Stock	2,267.7	2,243.8	2,242.8
Accumulated other comprehensive loss	(470.0)	(510.0)	(466.7)	(492.5)
Retained Earnings (Accumulated Deficit)	334.4	373.8	389.3
Total shareholders' equity	2,298.5	2,273.0	2,330.7	2,418.8
Total liabilities and shareholders' equity	9,366.5	8,762.6	8,792.8
Parent Guarantor
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	36.9	25.2	15.5	119.4
Receivables, net	106.0	88.3	64.4
Intercompany receivables	0.0	0.0	0.0
Income taxes receivable	13.4	19.0	38.5
Inventories	172.2	167.7	163.8
Other Assets, Current	180.5	164.7	145.5
Total current assets	509.0	464.9	427.7
Property, Plant and Equipment, Net	513.0	510.1	451.4
Investment in subsidiaries	6,155.3	6,035.2	6,000.5
Deferred income taxes	140.9	133.5	153.7
Other Assets, Noncurrent	45.5	48.1	40.4
Long-term receivables—affiliates	0.0	0.0	0.0
Intangible Assets, Net	0.3	0.4	0.4
Goodwill	0.0	0.0	0.0
Total assets	7,364.0	7,192.2	7,074.1
Current installments of long-term debt	0.7	0.6	0.6
Accounts payable	69.6	45.3	55.4
Intercompany payables	1,948.4	1,882.8	1,740.8
Income taxes payable	0.0	0.0	0.0
Accrued Liabilities, Current	146.0	124.9	158.1
Total current liabilities	2,164.7	2,053.6	1,954.9
Long-term Debt, Excluding Current Maturities	944.1	913.9	1,154.9
Accrued pension liability	405.7	453.7	141.3
Deferred income taxes	0.0	0.0	0.0
Long-term payables—affiliates	1,267.2	1,209.1	1,226.0
Other Liabilities, Noncurrent	283.8	288.9	266.3
Total liabilities	5,065.5	4,919.2	4,743.4
Common Stock, Value, Issued	166.4	165.4	165.3
Additional Paid in Capital, Common Stock	2,267.7	2,243.8	2,242.8
Accumulated other comprehensive loss	(470.0)	(510.0)	(466.7)
Retained Earnings (Accumulated Deficit)	334.4	373.8	389.3
Total shareholders' equity	2,298.5	2,273.0	2,330.7
Total liabilities and shareholders' equity	7,364.0	7,192.2	7,074.1
Issuer
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	0.0	0.0	0.0	0.0
Receivables, net	0.0	0.0	0.0
Intercompany receivables	0.0	0.0	8.3
Income taxes receivable	0.0	0.0	0.0
Inventories	0.0	0.0	0.0
Other Assets, Current	0.0	3.4	0.0
Total current assets	0.0	3.4	8.3
Property, Plant and Equipment, Net	0.0	0.0	0.0
Investment in subsidiaries	3,828.7	3,734.7	3,690.5
Deferred income taxes	0.0	0.0	0.0
Other Assets, Noncurrent	0.0	0.0	0.0
Long-term receivables—affiliates	2,174.0	2,194.2	2,211.1
Intangible Assets, Net	5.7	5.7	5.7
Goodwill	966.3	966.3	966.3
Total assets	6,974.7	6,904.3	6,881.9
Current installments of long-term debt	68.8	67.5	67.5
Accounts payable	0.0	0.0	0.0
Intercompany payables	0.0	29.5	0.0
Income taxes payable	0.0	0.0	0.0
Accrued Liabilities, Current	0.0	0.0	0.0
Total current liabilities	68.8	97.0	67.5
Long-term Debt, Excluding Current Maturities	2,470.1	2,413.3	2,430.3
Accrued pension liability	0.0	0.0	0.0
Deferred income taxes	250.5	223.6	241.5
Long-term payables—affiliates	0.0	0.0	0.0
Other Liabilities, Noncurrent	5.6	6.6	0.0
Total liabilities	2,795.0	2,740.5	2,739.3
Common Stock, Value, Issued	0.0	0.0	0.0
Additional Paid in Capital, Common Stock	4,125.7	4,125.7	4,125.7
Accumulated other comprehensive loss	0.0	0.0	0.0
Retained Earnings (Accumulated Deficit)	54.0	38.1	16.9
Total shareholders' equity	4,179.7	4,163.8	4,142.6
Total liabilities and shareholders' equity	6,974.7	6,904.3	6,881.9
Subsidiary Non-Guarantor
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	219.0	159.3	111.5	272.6
Receivables, net	623.5	586.7	679.7
Intercompany receivables	1,948.4	1,912.3	1,732.5
Income taxes receivable	4.6	7.3	11.1
Inventories	517.3	462.7	453.2
Other Assets, Current	5.0	1.2	4.2
Total current assets	3,317.8	3,129.5	2,992.2
Property, Plant and Equipment, Net	3,066.2	3,194.8	3,262.5
Investment in subsidiaries	0.0	0.0	0.0
Deferred income taxes	127.0	103.5	90.2
Other Assets, Noncurrent	1,170.1	596.3	599.9
Long-term receivables—affiliates	0.0	0.0	0.0
Intangible Assets, Net	586.9	623.5	647.7
Goodwill	1,153.5	1,151.7	1,153.1
Total assets	9,421.5	8,799.3	8,745.6
Current installments of long-term debt	12.2	12.4	12.2
Accounts payable	548.3	527.4	456.4
Intercompany payables	0.0	0.0	0.0
Income taxes payable	11.7	8.3	13.9
Accrued Liabilities, Current	305.0	277.5	266.8
Total current liabilities	877.2	825.6	749.3
Long-term Debt, Excluding Current Maturities	249.3	209.9	12.3
Accrued pension liability	213.0	184.4	456.4
Deferred income taxes	931.8	926.4	926.8
Long-term payables—affiliates	906.8	985.1	985.1
Other Liabilities, Noncurrent	441.6	63.8	69.2
Total liabilities	3,619.7	3,195.2	3,199.1
Common Stock, Value, Issued	14.6	14.6	15.1
Additional Paid in Capital, Common Stock	4,808.2	4,808.2	4,750.5
Accumulated other comprehensive loss	(5.7)	(7.0)	(20.7)
Retained Earnings (Accumulated Deficit)	984.7	788.3	801.6
Total shareholders' equity	5,801.8	5,604.1	5,546.5
Total liabilities and shareholders' equity	9,421.5	8,799.3	8,745.6
Eliminations
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	0.0	0.0	0.0	$ 0.0
Receivables, net	0.0	0.0	0.0
Intercompany receivables	(1,948.4)	(1,912.3)	(1,740.8)
Income taxes receivable	(2.1)	(0.8)	(0.6)
Inventories	0.0	0.0	0.0
Other Assets, Current	(158.4)	(138.5)	(133.6)
Total current assets	(2,108.9)	(2,051.6)	(1,875.0)
Property, Plant and Equipment, Net	0.0	0.0	0.0
Investment in subsidiaries	(9,984.0)	(9,769.9)	(9,691.0)
Deferred income taxes	(126.8)	(117.5)	(131.7)
Other Assets, Noncurrent	0.0	0.0	0.0
Long-term receivables—affiliates	(2,174.0)	(2,194.2)	(2,211.1)
Intangible Assets, Net	0.0	0.0	0.0
Goodwill	0.0	0.0	0.0
Total assets	(14,393.7)	(14,133.2)	(13,908.8)
Current installments of long-term debt	0.0	0.0	0.0
Accounts payable	(4.4)	(1.9)	(2.1)
Intercompany payables	(1,948.4)	(1,912.3)	(1,740.8)
Income taxes payable	(2.1)	(0.8)	(0.6)
Accrued Liabilities, Current	(156.5)	(138.6)	(133.4)
Total current liabilities	(2,111.4)	(2,053.6)	(1,876.9)
Long-term Debt, Excluding Current Maturities	0.0	0.0	0.0
Accrued pension liability	0.0	0.0	0.0
Deferred income taxes	(126.8)	(117.5)	(131.7)
Long-term payables—affiliates	(2,174.0)	(2,194.2)	(2,211.1)
Other Liabilities, Noncurrent	0.0	0.0	0.0
Total liabilities	(4,412.2)	(4,365.3)	(4,219.7)
Common Stock, Value, Issued	(14.6)	(14.6)	(15.1)
Additional Paid in Capital, Common Stock	(8,933.9)	(8,933.9)	(8,876.2)
Accumulated other comprehensive loss	5.7	7.0	20.7
Retained Earnings (Accumulated Deficit)	(1,038.7)	(826.4)	(818.5)
Total shareholders' equity	(9,981.5)	(9,767.9)	(9,689.1)
Total liabilities and shareholders' equity	$ (14,393.7)	$ (14,133.2)	$ (13,908.8)