Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE MEASUREMENTS (Fair Value of Assets and Liabilities) (Details)

v3.20.1
FAIR VALUE MEASUREMENTS (Fair Value of Assets and Liabilities) (Details) - USD ($)
$ in Millions
Mar. 31, 2020
Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Assets, Fair Value Disclosure $ 21.2 $ 233.4
Liabilities, Fair Value Disclosure 32.4 4.3
Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Assets, Fair Value Disclosure 0.0 0.0
Liabilities, Fair Value Disclosure 0.0 0.0
Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Assets, Fair Value Disclosure 1.6 187.6
Liabilities, Fair Value Disclosure 32.4 3.2
Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Assets, Fair Value Disclosure 19.6 45.8
Liabilities, Fair Value Disclosure 0.0 1.1
Cash and Cash Equivalents [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash equivalents   187.6
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash equivalents   0.0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash equivalents   187.6
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash equivalents   0.0
Commodity Contract [Member] | Other Current Assets [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset 1.6  
Commodity Contract [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset 0.0  
Commodity Contract [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset 1.6  
Commodity Contract [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset 0.0  
Commodity Contract [Member] | Other Current Liabilities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 26.5 3.2
Commodity Contract [Member] | Other Current Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0.0 0.0
Commodity Contract [Member] | Other Current Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 26.5 3.2
Commodity Contract [Member] | Other Current Liabilities [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0.0 0.0
Commodity Contract [Member] | Other Noncurrent Liabilities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 3.4  
Commodity Contract [Member] | Other Noncurrent Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 3.4  
Foreign Exchange Contract [Member] | Other Current Liabilities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 1.6  
Foreign Exchange Contract [Member] | Other Current Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 1.6  
Foreign Exchange Contract [Member] | Other Noncurrent Liabilities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0.9  
Foreign Exchange Contract [Member] | Other Noncurrent Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0.9  
Customer Supply Agreement [Member] | Other Current Assets [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset 19.0 44.5
Customer Supply Agreement [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset   0.0
Customer Supply Agreement [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset 19.0 44.5
Provisional Pricing Arrangements [Member] | Other Current Assets [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset 0.6 1.3
Provisional Pricing Arrangements [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset   0.0
Provisional Pricing Arrangements [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset   0.0
Provisional Pricing Arrangements [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Asset $ 0.6 1.3
Provisional Pricing Arrangements [Member] | Other Current Liabilities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability   1.1
Provisional Pricing Arrangements [Member] | Other Current Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability   0.0
Provisional Pricing Arrangements [Member] | Other Current Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability   0.0
Provisional Pricing Arrangements [Member] | Other Current Liabilities [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability   $ 1.1