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Property, Plant, and Equipment (Details ARO) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Asset Retirement Obligations    
Asset Retirement Obligations, Noncurrent $ 1,117 $ 968
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance 1,032 998
Liabilities incurred 15 21
Liabilities settled (8) (19)
Accretion expense 59 71
Revisions (1) [1] 67 (39)
Ending balance 1,165 $ 1,032
Asset Retirement Obligation Costs [Member]    
Unusual or Infrequent Item [Line Items]    
Transco's annual funding commitment for ARO $ 36  
[1]
Several factors are considered in the annual review process, including inflation rates, current estimates for removal cost, market risk premiums, discount rates, and the estimated remaining useful life of the assets. The 2019 revisions reflect changes in removal cost estimates, decreases in the estimated remaining useful life of certain assets, increases in inflation rates, and decreases in the discount rates used in the annual review process. The 2018 revisions reflect changes in removal cost estimates, decreases in the estimated remaining useful life of certain assets, and increases in the discount rates used in the annual review process.