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)