Derivatives - Schedule of Foreign Currency Derivatives (Details) - 6 months ended Jun. 30, 2022 - Foreign currency derivatives € in Millions, $ in Millions	USD ($)	EUR (€)
Derivative [Line Items]
Pay Notional	$ 2,040
Receive Notional | €		€ 1,750
Fair Value Gain (Loss)	(228)
Fair Value Hedges of Existing Debt | Southern Company parent
Derivative [Line Items]
Pay Notional	$ 1,476
Pay Rate	3.39%
Receive Notional | €		1,250
Receive Rate	1.88%
Fair Value Gain (Loss)	$ (183)
Cash Flow Hedges of Existing Debt | SOUTHERN POWER CO | April 2030
Derivative [Line Items]
Pay Notional	$ 564
Pay Rate	3.78%
Receive Notional | €		€ 500
Receive Rate	1.85%
Fair Value Gain (Loss)	$ (45)