Regulatory Matters - GAS Narrative (Details) $ in Millions	Jul. 21, 2021 USD ($)	May 10, 2021 USD ($)	Apr. 28, 2021 USD ($)	Nov. 01, 2020 USD ($)	Apr. 06, 2021 mi
Virginia Natural Gas
Loss Contingencies [Line Items]
Motion filed to withdraw project application, header improvement project, scope of project (in miles) | mi					9.5
Approved rate increase		$ 43
Public utilities, approved rate increase amount recovery of investments		$ 14
Public utilities, approved return on equity percentage		9.50%
Public utilities, approved equity capital structure percentage		51.90%
Requested revenues increase amount				$ 50
Atlanta Gas Light
Loss Contingencies [Line Items]
Integrated capacity delivery plan, capital budgets and related operations and maintenance spending, term			10 years
Atlanta Gas Light | Minimum
Loss Contingencies [Line Items]
Integrated capacity delivery plan, capital forecast plan, amount, years one through three			$ 500
Atlanta Gas Light | Maximum
Loss Contingencies [Line Items]
Integrated capacity delivery plan, capital forecast plan, amount, years one through three			$ 600
Atlanta Gas Light | Subsequent Event
Loss Contingencies [Line Items]
Approved rate increase	$ 49