Regulatory Matters - GAS Narrative (Details) $ in Millions	Oct. 14, 2021 USD ($)	Sep. 14, 2021 USD ($)	Jul. 21, 2021 USD ($)	Apr. 28, 2021 USD ($)	Nov. 01, 2020 USD ($)	Apr. 06, 2021 mi
Atlanta Gas Light
Loss Contingencies [Line Items]
Integrated capacity delivery plan, capital budgets and related operations and maintenance spending, term				10 years
Approved rate increase (decrease)			$ 49
Atlanta Gas Light | Minimum
Loss Contingencies [Line Items]
Integrated capacity delivery plan, capital forecast plan, amount, years one through ten				$ 500
Atlanta Gas Light | Maximum
Loss Contingencies [Line Items]
Integrated capacity delivery plan, capital forecast plan, amount, years one through ten				$ 600
Atlanta Gas Light | Subsequent Event
Loss Contingencies [Line Items]
Requested revenues increase (decrease) percentage	(10.00%)
Requested rate increase (decrease) amount	$ 5
Integrated capacity delivery plan, capital forecast plan, amount, years one through three	$ 1,700
Virginia Natural Gas
Loss Contingencies [Line Items]
Requested rate increase (decrease) amount					$ 50
Motion filed to withdraw project application, header improvement project, scope of project (in miles) | mi						9.5
Approved rate increase (decrease)		$ 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%