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Debt (Details) - USD ($)
$ in Millions
Mar. 31, 2018
Dec. 31, 2017
Debt Instrument [Line Items]    
Total debt $ 1,089 $ 1,089
Deferred financing fees 11 11
Long term debt net of unamortized debt issuance costs $ 1,078 1,078
4.875% senior notes due 2027    
Debt Instrument [Line Items]    
Debt instrument interest rate 4.875%  
Total debt $ 500 500
5.5% senior notes due 2025    
Debt Instrument [Line Items]    
Debt instrument interest rate 5.50%  
Total debt $ 350 350
Industrial revenue bonds (due 2028 through 2034)    
Debt Instrument [Line Items]    
Total debt $ 239 $ 239