v3.19.3.a.u2
Asset Retirement Obligations and Accrued Environmental Costs - Textuals (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Environmental Liabilities [Line Items]    
Accrued environmental costs $ 171 $ 178
Accrued Enviornmental Costs Discounted $ 97  
Maximum number of years accrued environmental liabilities will be paid over 30 years  
Expected expenditures for acquired environmental obligations, weighted-average discount factor rate 5.00%  
Accrued environmental costs, undiscounted due 2020 $ 10  
Accrued environmental costs, undiscounted due 2021 7  
Accrued environmental costs, undiscounted due 2022 10  
Accrued environmental costs, undiscounted due 2023 3  
Accrued environmental costs, undiscounted due 2024 2  
Accrued environmental costs, undiscounted due after 2025 108  
Cleanup Remediation Activities [Member]    
Environmental Liabilities [Line Items]    
Accrued environmental costs 112 100
Corporate and Other Environmental Liabilities [Member]    
Environmental Liabilities [Line Items]    
Accrued environmental costs 47 67
Federal Comprehensive Environmental Response Compensation and Liability Act or Similar State Laws [Member]    
Environmental Liabilities [Line Items]    
Accrued environmental costs $ 12 $ 11