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Regulatory Matters, Commitments, Contingencies And Environmental Liabilities Regulatory Matters, Commitments, Contingencies And Environemental Liabilities (Environmental Liabilities) (Details) - USD ($)
$ in Millions
Dec. 31, 2019
Dec. 31, 2018
Environmental Remediation Obligations [Abstract]    
Current   $ 42
Non-current   295
Total environmental liabilities $ 320 $ 337