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Derivatives (Tables)

9 Months Ended

Sep. 30, 2025

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Energy-Related Derivatives

At September 30, 2025, the net volume of energy-related derivative contracts for natural gas positions, together with the longest hedge date over which the respective entity is hedging its exposure to the variability in future cash flows for forecasted transactions and the longest non-hedge date for derivatives not designated as hedges, were as follows:

			Net Purchased mmBtu						Longest Hedge Date						Longest Non-Hedge Date
			(in millions)
Southern Company(*)			443						2030						2028
Alabama Power			132						2028						—
Georgia Power			123						2028						—
Mississippi Power			101						2029						—
Southern Power			9						2030						2025
Southern Company Gas(*)			78						2028						2028

(*)Southern Company Gas' derivative instruments include both long and short natural gas positions. A long position is a contract to purchase natural gas and a short position is a contract to sell natural gas. Southern Company Gas' volume represents the net of 96 million mmBtu long natural gas positions and 18 million mmBtu short natural gas positions at September 30, 2025, which is also included in Southern Company's total volume.

Schedule of Interest Rate Derivatives

At September 30, 2025, the following interest rate derivatives were outstanding:

			Notional Amount			Weighted Average Interest Rate Paid			Interest Rate Received			Hedge Maturity Date			Fair Value Gain (Loss) at September 30, 2025
			(in millions)												(in millions)
Fair Value Hedges of Existing Debt
Southern Company parent			$	400		1-day SOFR + 0.80%			1.75%			March 2028			$	(23)
Southern Company parent			1,000			1-day SOFR + 2.48%			3.70%			April 2030			(108)
Southern Company parent			565			1-day SOFR + 1.56%			6.50%			March 2045			3
Southern Company Gas			500			1-day SOFR + 0.49%			1.75%			January 2031			(56)
Southern Company			$	2,465											$	(184)

Schedule of Foreign Currency Derivatives

At September 30, 2025, the following foreign currency derivatives were outstanding:

			Pay Notional			Pay Rate			Receive Notional			Receive Rate			Hedge Maturity Date			Fair Value Gain (Loss) at September 30, 2025
			(in millions)						(in millions)									(in millions)
Cash Flow Hedges of Existing Debt
Southern Power			$	564		3.78%			€	500		1.85%			June 2026			$	20
Fair Value Hedges of Existing Debt
Southern Company parent			1,476			3.39%			1,250			1.88%			September 2027			(10)
Southern Company			$	2,040					€	1,750								$	10

Schedule of Derivative Category and Balance Sheet Location

The fair value of energy-related derivatives, interest rate derivatives, and foreign currency derivatives was reflected as either assets or liabilities in the balance sheets (included in "Other" or shown separately as "Risk Management Activities") as follows:

			At September 30, 2025						At December 31, 2024
Derivative Category and Balance Sheet Location			Assets			Liabilities			Assets			Liabilities
			(in millions)
Southern Company
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current			$	34		$	44		$	33		$	82
Non-current			51			32			42			40
Total derivatives designated as hedging instruments for regulatory purposes			85			76			75			122
Derivatives designated as hedging instruments in cash flow and fair value hedges
Energy-related derivatives:
Current			2			6			4			3
Non-current			4			—			4			—
Interest rate derivatives:
Current			7			53			—			61
Non-current			—			138			—			208
Foreign currency derivatives:
Current			20			21			—			36
Non-current			11			—			—			182
Total derivatives designated as hedging instruments in cash flow and fair value hedges			44			218			8			490
Energy-related derivatives not designated as hedging instruments
Current			13			7			5			3
Non-current			—			—			1			—
Total derivatives not designated as hedging instruments			13			7			6			3
Gross amounts recognized			142			301			89			615
Gross amounts offset(a)			(54)			(63)			(44)			(61)
Net amounts recognized in the Balance Sheets(b)			$	88		$	238		$	45		$	554
Alabama Power
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current			$	13		$	13		$	11		$	30
Non-current			18			12			15			12
Total derivatives designated as hedging instruments for regulatory purposes			31			25			26			42
Gross amounts offset			(17)			(17)			(19)			(19)
Net amounts recognized in the Balance Sheets			$	14		$	8		$	7		$	23

			At September 30, 2025						At December 31, 2024
Derivative Category and Balance Sheet Location			Assets			Liabilities			Assets			Liabilities
			(in millions)
Georgia Power
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current			$	8		$	15		$	6		$	32
Non-current			17			9			13			9
Total derivatives designated as hedging instruments for regulatory purposes			25			24			19			41
Energy-related derivatives not designated as hedging instruments
Current			2			—			—			1
Gross amounts recognized			27			24			19			42
Gross amounts offset			(16)			(16)			(15)			(15)
Net amounts recognized in the Balance Sheets			$	11		$	8		$	4		$	27
Mississippi Power
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current			$	4		$	12		$	5		$	15
Non-current			16			11			14			19
Total derivatives designated as hedging instruments for regulatory purposes			20			23			19			34
Gross amounts offset			(15)			(15)			(17)			(17)
Net amounts recognized in the Balance Sheets			$	5		$	8		$	2		$	17
Southern Power
Derivatives designated as hedging instruments in cash flow hedges
Energy-related derivatives:
Current			$	1		$	1		$	1		$	—
Non-current			3			—			3			—
Foreign currency derivatives:
Current			20			—			—			11
Non-current			—			—			—			40
Total derivatives designated as hedging instruments in cash flow hedges			24			1			4			51
Net amounts recognized in the Balance Sheets			$	24		$	1		$	4		$	51

			At September 30, 2025						At December 31, 2024
Derivative Category and Balance Sheet Location			Assets			Liabilities			Assets			Liabilities
			(in millions)
Southern Company Gas
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current			$	9		$	4		$	11		$	5
Derivatives designated as hedging instruments in cash flow and fair value hedges
Energy-related derivatives:
Current			1			5			3			3
Non-current			1			—			1			—
Interest rate derivatives:
Current			—			13			—			17
Non-current			—			43			—			67
Total derivatives designated as hedging instruments in cash flow and fair value hedges			2			61			4			87
Energy-related derivatives not designated as hedging instruments
Current			11			7			5			2
Non-current			—			—			1			—
Total derivatives not designated as hedging instruments			11			7			6			2
Gross amounts recognized			22			72			21			94
Gross amounts offset(a)			(6)			(15)			7			(10)
Net amounts recognized in the Balance Sheets(b)			$	16		$	57		$	28		$	84

(a)Gross amounts offset includes cash collateral held on deposit in broker margin accounts of $10 million and $17 million at September 30, 2025 and December 31, 2024, respectively.

(b)Net amounts of derivative instruments outstanding exclude immaterial premium and intrinsic value associated with weather derivatives at September 30, 2025 and December 31, 2024.

Schedule of Pre-tax Effects of Unrealized Derivative Gains (Losses)

At September 30, 2025 and December 31, 2024, the pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments designated as regulatory hedging instruments and deferred were as follows:

Regulatory Hedge Unrealized Gain (Loss) Recognized in the Balance Sheet
Derivative Category and Balance Sheet Location			Southern Company			Alabama Power			Georgia Power			Mississippi Power			Southern Company Gas
			(in millions)
At September 30, 2025:
Energy-related derivatives:
Other regulatory assets, current			$	(24)		$	(7)		$	(8)		$	(8)		$	(1)
Other regulatory assets, deferred			(1)			(1)			—			—			—
Other regulatory liabilities, current			13			7			1			—			5
Other regulatory liabilities, deferred			20			7			8			5			—
Total energy-related derivative gains (losses)			$	8		$	6		$	1		$	(3)		$	4
At December 31, 2024:
Energy-related derivatives:
Other regulatory assets, current			$	(61)		$	(23)		$	(26)		$	(11)		$	(1)
Other regulatory assets, deferred			(5)			—			—			(5)			—
Other regulatory liabilities, current			8			4			—			—			4
Other regulatory liabilities, deferred			8			3			4			1			—
Total energy-related derivative gains (losses)			$	(50)		$	(16)		$	(22)		$	(15)		$	3

Schedule of Pre-Tax Effects of Hedging on AOCI

For the three and nine months ended September 30, 2025 and 2024, the pre-tax effects of cash flow and fair value hedge accounting on accumulated OCI for the applicable Registrants were as follows:

Gain (Loss) Recognized in OCI on Derivatives			Three Months Ended September 30,						Nine Months Ended September 30,
			2025			2024			2025			2024
			(in millions)
Southern Company
Cash flow hedges:
Energy-related derivatives			$	(12)		$	(7)		$	(6)		$	(11)
Interest rate derivatives			(1)			(8)			6			16
Foreign currency derivatives			(6)			15			60			(4)
Fair value hedges(*):
Foreign currency derivatives			1			(2)			(12)			(8)
Total			$	(18)		$	(2)		$	48		$	(7)
Georgia Power
Cash flow hedges:
Interest rate derivatives			$	—		$	1		$	3		$	17
Mississippi Power
Cash flow hedges:
Interest rate derivatives			$	—		$	—		$	—		$	7
Southern Power
Cash flow hedges:
Energy-related derivatives			$	(2)		$	(2)		$	—		$	(2)
Foreign currency derivatives			(6)			15			60			(4)
Total			$	(8)		$	13		$	60		$	(6)
Southern Company Gas
Cash flow hedges:
Energy-related derivatives			$	(10)		$	(4)		$	(6)		$	(9)
Interest rate derivatives			(1)			(6)			3			(5)
Total			$	(11)		$	(10)		$	(3)		$	(14)

(*)Represents amounts excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI.

Schedule of Pre-Tax Effects of Cash Flow and Fair Value Hedging on Income

For the three and nine months ended September 30, 2025 and 2024, the pre-tax effects of cash flow and fair value hedge accounting on income were as follows:

						Gain (Loss)
Statements of Income Location			Derivative Category			Three Months Ended September 30,						Nine Months Ended September 30,
						2025			2024			2025			2024
						(in millions)
Southern Company
Fuel			Energy-related cash flow hedges			$	—		$	(3)		$	1		$	(5)
Cost of natural gas			Energy-related cash flow hedges			(1)			(4)			(1)			(34)
Other operations and maintenance			Energy-related cash flow hedges			—			—			—			(1)
Interest expense, net of amounts capitalized			Interest rate cash flow hedges			(4)			(4)			(10)			(12)
			Foreign currency cash flow hedges			(2)			(3)			(8)			(9)
			Interest rate fair value hedges			16			78			85			47
Other income (expense), net			Foreign currency cash flow hedges			1			24			68			7
			Foreign currency fair value hedges			5			58			160			79
			Amount excluded from effectiveness testing recognized in earnings			(1)			3			12			8
Southern Power
Fuel			Energy-related cash flow hedges			$	—		$	(3)		$	1		$	(5)
Interest expense, net of amounts capitalized			Foreign currency cash flow hedges			(2)			(3)			(8)			(9)
Other income (expense), net			Foreign currency cash flow hedges			1			24			68			7
Southern Company Gas
Cost of natural gas			Energy-related cash flow hedges			$	(1)		$	(4)		$	(1)		$	(34)
Operations and maintenance			Energy-related cash flow hedges			—			—			—			(1)
Interest expense, net of amounts capitalized			Interest rate cash flow hedges			—			—			(1)			—
			Interest rate fair value hedges			7			28			28			18

Schedule of Cumulative Basis Adjustments for Fair Value Hedges

At September 30, 2025 and December 31, 2024, the following amounts were recorded on the balance sheets related to cumulative basis adjustments for fair value hedges:

			Carrying Amount of the Hedged Item						Cumulative Amount of Fair Value Hedging Adjustment included in Carrying Amount of the Hedged Item
Balance Sheet Location of Hedged Items			At September 30, 2025			At December 31, 2024			At September 30, 2025			At December 31, 2024
			(in millions)
Southern Company
Long-term debt			$	(3,733)		$	(2,936)		$	164		$	242
Southern Company Gas
Long-term debt			$	(445)		$	(422)		$	52		$	75

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