Regulatory Matters - GAS Schedule of Infrastructure Replacement Programs and Capital Projects (Details) - SOUTHERN Co GAS $ in Millions	6 Months Ended
	Jun. 30, 2022 USD ($)
Public Utilities, General Disclosures [Line Items]
Capital expenditures	$ 240
Investing in Illinois
Public Utilities, General Disclosures [Line Items]
Capital expenditures	177
Steps to Advance Virginia's Energy
Public Utilities, General Disclosures [Line Items]
Capital expenditures	33
System Reinforcement Rider
Public Utilities, General Disclosures [Line Items]
Capital expenditures	28
Pipeline Replacement Program
Public Utilities, General Disclosures [Line Items]
Capital expenditures	$ 2