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DEBT (Narrative) (Detail) (USD $)
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Debt Instrument [Line Items]      
Line of Credit Facility, Current Borrowing Capacity $ 425,000,000    
Line of Credit Facility, Maximum Borrowing Capacity 600,000,000    
Line Of Credit Facility Capacity Available 1,200,000,000    
Line of Credit Facility, Amount Outstanding 0 110,000,000  
Line of Credit Facility, Remaining Borrowing Capacity 373,000,000 258,000,000  
Interest Paid 17,000,000 21,000,000 24,000,000
Industrial Revenue Bonds, due 2012-2023 [Member]
     
Debt Instrument [Line Items]      
Debt, Weighted Average Interest Rate 0.47% 0.57%  
Revolving Credit Agreement, due 2012 [Member]
     
Debt Instrument [Line Items]      
Debt, Weighted Average Interest Rate 0.77% 0.80%  
Debt Instrument, Covenant Description 60%    
Two Thousand Eleven Notes [Member]
     
Debt Instrument [Line Items]      
Debt Instrument, Issuance Date Dec. 08, 2011    
Debt Instrument, Face Amount 300,000,000    
Debt Instrument, Covenant Description Debt to capitalization limit 60%    
Senior Notes Three Eighty Four [Member]
     
Debt Instrument [Line Items]      
Debt Instrument, Issuance Date 2011-12-08    
Debt Instrument, Maturity Date Dec. 01, 2021    
Debt Instrument, Face Amount 100,000,000    
Debt Instrument, Interest Rate, Stated Percentage 3.84%    
Senior Notes Four Twenty Four [Member]
     
Debt Instrument [Line Items]      
Debt Instrument, Issuance Date Dec. 08, 2011    
Debt Instrument, Maturity Date Dec. 01, 2026    
Debt Instrument, Face Amount 200,000,000    
Debt Instrument, Interest Rate, Stated Percentage 4.24%    
Two Thousand Three Notes [Member]
     
Debt Instrument [Line Items]      
Debt Instrument, Issuance Date 2003-09-25    
Debt Instrument, Face Amount 200,000,000    
Debt Instrument, Covenant Description Debt to capitalization limit 60%    
Senior Notes Five Thirteen [Member]
     
Debt Instrument [Line Items]      
Debt Instrument, Issuance Date Sep. 25, 2003    
Debt Instrument, Maturity Date Sep. 25, 2010    
Debt Instrument, Face Amount 75,000,000    
Debt Instrument, Interest Rate, Stated Percentage 5.13%    
Senior Notes Five Seventy Four [Member]
     
Debt Instrument [Line Items]      
Debt Instrument, Issuance Date Sep. 25, 2003    
Debt Instrument, Maturity Date Sep. 25, 2013    
Debt Instrument, Face Amount 125,000,000    
Debt Instrument, Interest Rate, Stated Percentage 5.74%    
Senior Notes Five Fifty One [Member]
     
Debt Instrument [Line Items]      
Debt Instrument, Issuance Date Dec. 01, 2005    
Debt Instrument, Maturity Date Dec. 01, 2017    
Debt Instrument, Face Amount $ 150,000,000    
Debt Instrument, Interest Rate, Stated Percentage 5.51%    
Debt Instrument, Covenant Description Debt to capitalization limit 60%