Organization and Basis of Presentation (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Noncontrolling Interest [Line Items]
Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses	$ 1,353	$ 1,434	$ 2,692	$ 2,853
Accounting Standards Update [Extensible List]					us-gaap:AccountingStandardsUpdate201613Member
Current Liabilities: Other	2,898		2,898		$ 2,367
ACP
Noncontrolling Interest [Line Items]
Current Liabilities: Other	920		920
Piedmont Natural Gas
Noncontrolling Interest [Line Items]
Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses	79	$ 83	159	$ 163
Current Liabilities: Other	56		56		67
Piedmont Natural Gas | Other
Noncontrolling Interest [Line Items]
Income taxes receivable	22		22		14
Prepaid assets	19		19		$ 3
Incremental COVID-19 costs
Noncontrolling Interest [Line Items]
Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses	34		$ 40
Waived Late Payment Fees	$ 25