Derivatives - Schedule of Pre-Tax Effects of Cash Flow and Fair Value Hedging on Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Derivative [Line Items]
Depreciation and amortization	$ 922	$ 896	$ 2,728	$ 2,658
Total interest expense, net of amounts capitalized	(511)	(451)	(1,461)	(1,352)
Total other income (expense), net	132	131	414	290
Natural gas
Derivative [Line Items]
Total cost of sales	294	129	1,840	943
Other Income (Expense)
Derivative [Line Items]
Amount excluded from effectiveness testing recognized in earnings	(21)	4	(17)	4
Cash Flow Hedging | Energy-related derivatives | Cost of Sales
Derivative [Line Items]
Gain (loss) on hedges	9	2	28	0
Cash Flow Hedging | Energy-related derivatives | Depreciation and Amortization
Derivative [Line Items]
Gain (loss) on hedges	(1)	3	5	6
Cash Flow Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(7)	(7)	(19)	(20)
Cash Flow Hedging | Foreign currency derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(3)	(6)	(16)	(18)
Cash Flow Hedging | Foreign currency derivatives | Other Income (Expense)
Derivative [Line Items]
Gain (loss) on hedges	(32)	(34)	(129)	(76)
Fair Value Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(102)	(4)	(300)	(16)
Fair Value Hedging | Foreign currency derivatives | Other Income (Expense)
Derivative [Line Items]
Gain (loss) on hedges	(59)	(32)	(180)	(32)
SOUTHERN POWER CO
Derivative [Line Items]
Depreciation and amortization	133	132	384	383
Total interest expense, net of amounts capitalized	(32)	(36)	(105)	(111)
Total other income (expense), net	3	2	5	10
SOUTHERN POWER CO | Cash Flow Hedging | Energy-related derivatives | Depreciation and Amortization
Derivative [Line Items]
Gain (loss) on hedges	(1)	3	5	6
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(3)	(6)	(16)	(18)
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives | Other Income (Expense)
Derivative [Line Items]
Gain (loss) on hedges	(32)	(34)	(129)	(76)
SOUTHERN Co GAS
Derivative [Line Items]
Depreciation and amortization	140	133	414	396
Total interest expense, net of amounts capitalized	(65)	(57)	(187)	(175)
Total other income (expense), net	15	13	47	(66)
SOUTHERN Co GAS | Natural gas
Derivative [Line Items]
Total cost of sales	294	129	1,840	943
SOUTHERN Co GAS | Cash Flow Hedging | Energy-related derivatives | Cost of Sales
Derivative [Line Items]
Gain (loss) on hedges	9	2	28	0
SOUTHERN Co GAS | Cash Flow Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(2)	(1)	(3)	(2)
SOUTHERN Co GAS | Fair Value Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	$ (30)	$ 0	$ (87)	$ 2