FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Assets and liabilities measured at fair value on a recurring basis

The fair value increases (decreases) of the Funds, including unrealized gains (losses) and reinvested interest and dividends and excluding the Funds' expenses, for 2025, 2024, and 2023 are shown in the table below.

	Southern Company		Alabama Power		Georgia Power
	(in millions)
Fair value increases
2025	$	348	$	191	$	157
2024	229		143		86
2023	281		157		124
Unrealized gains
At December 31, 2025	$	216	$	111	$	105
At December 31, 2024	113		64		49
At December 31, 2023	241		119		122

At December 31, 2025, assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows:

	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
At December 31, 2025:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Southern Company
Assets:
Energy-related derivatives(a)	$	4	$	60	$	—	$	—	$	64
Interest rate derivatives	—		8		—		—		8
Foreign currency derivatives	—		21		—		—		21
Investments in trusts:(b)
Domestic equity	935		278		—		—		1,213
Foreign equity	182		225		—		—		407
U.S. Treasury and government agency securities	—		398		—		—		398
Municipal bonds	—		50		—		—		50
Pooled funds – fixed income	—		6		—		—		6
Corporate bonds	—		520		—		—		520
Mortgage- and asset-backed securities	—		114		—		—		114
Private equity	—		—		—		192		192
Cash and cash equivalents	1		—		—		—		1
Other	50		3		—		9		62
Investments, available for sale:
U.S. Treasury and government agency securities	3		12		—		—		15
Corporate bonds	1		2		—		—		3
Mortgage- and asset-backed securities	—		5		—		—		5
Cash equivalents	1,080		19		—		—		1,099
Other investments	10		34		8		—		52
Other	—		—		11		—		11
Total	$	2,266	$	1,755	$	19	$	201	$	4,241
Liabilities:
Energy-related derivatives(a)	$	12	$	100	$	—	$	—	$	112
Interest rate derivatives	—		187		—		—		187
Foreign currency derivatives	—		22		—		—		22
Contingent consideration	3		—		11		—		14
Other	—		13		11		—		24
Total	$	15	$	322	$	22	$	—	$	359

	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
At December 31, 2025:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Alabama Power
Assets:
Energy-related derivatives	$	—	$	19	$	—	$	—	$	19
Nuclear decommissioning trusts:(b)
Domestic equity	514		267		—		—		781
Foreign equity	182		—		—		—		182
U.S. Treasury and government agency securities	—		15		—		—		15
Municipal bonds	—		1		—		—		1
Corporate bonds	—		316		—		—		316
Mortgage- and asset-backed securities	—		31		—		—		31
Private equity	—		—		—		192		192
Other	12		1		—		9		22
Cash equivalents	273		19		—		—		292
Other investments	—		34		—		—		34
Total	$	981	$	703	$	—	$	201	$	1,885
Liabilities:
Energy-related derivatives	$	—	$	31	$	—	$	—	$	31
Georgia Power
Assets:
Energy-related derivatives	$	—	$	18	$	—	$	—	$	18
Nuclear decommissioning trusts:(b)
Domestic equity	421		1		—		—		422
Foreign equity	—		224		—		—		224
U.S. Treasury and government agency securities	—		383		—		—		383
Municipal bonds	—		49		—		—		49
Corporate bonds	—		204		—		—		204
Mortgage- and asset-backed securities	—		83		—		—		83
Other	38		2		—		—		40
Cash equivalents	20		—		—		—		20
Total	$	479	$	964	$	—	$	—	$	1,443
Liabilities:
Energy-related derivatives	$	—	$	33	$	—	$	—	$	33

	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
At December 31, 2025:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Mississippi Power
Assets:
Energy-related derivatives	$	—	$	14	$	—	$	—	$	14
Cash equivalents	12		—		—		—		12
Total	$	12	$	14	$	—	$	—	$	26
Liabilities:
Energy-related derivatives	$	—	$	27	$	—	$	—	$	27
Southern Power
Assets:
Energy-related derivatives	$	—	$	4	$	—	$	—	$	4
Foreign currency derivatives	—		17		—		—		17
Other	—		—		11		—		11
Total	$	—	$	21	$	11	$	—	$	32
Liabilities:
Energy-related derivatives	$	—	$	1	$	—	$	—	$	1
Contingent consideration	3		—		11		—		14
Other	—		13		11		—		24
Total	$	3	$	14	$	22	$	—	$	39
Southern Company Gas
Assets:
Energy-related derivatives(a)	$	4	$	5	$	—	$	—	$	9
Non-qualified deferred compensation trusts:
Domestic equity	—		10		—		—		10
Foreign equity	—		1		—		—		1
Pooled funds - fixed income	—		6		—		—		6
Cash and cash equivalents	1		—		—		—		1
Total	$	5	$	22	$	—	$	—	$	27
Liabilities:
Energy-related derivatives(a)	$	12	$	8	$	—	$	—	$	20
Interest rate derivatives	—		59		—		—		59
Total	$	12	$	67	$	—	$	—	$	79

(a)Excludes cash collateral of $33 million.

(b)Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. See Note 6 under "Nuclear Decommissioning" for additional information.

At December 31, 2024, assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows:

	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
At December 31, 2024:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Southern Company
Assets:
Energy-related derivatives(a)	$	12	$	77	$	—	$	—	$	89
Investments in trusts:(b)
Domestic equity	849		250		—		—		1,099
Foreign equity	148		175		—		—		323
U.S. Treasury and government agency securities	—		371		—		—		371
Municipal bonds	—		47		—		—		47
Pooled funds – fixed income	—		7		—		—		7
Corporate bonds	—		452		—		—		452
Mortgage- and asset-backed securities	—		106		—		—		106
Private equity	—		—		—		181		181
Cash and cash equivalents	1		—		—		—		1
Other	39		3		—		9		51
Investment, available for sale:
U.S. Treasury and government agency securities	2		7		—		—		9
Corporate bonds	1		2		—		—		3
Mortgage- and asset-backed securities	—		10		—		—		10
Cash equivalents and restricted cash	533		19		—		—		552
Other investments	9		31		8		—		48
Total	$	1,594	$	1,557	$	8	$	190	$	3,349
Liabilities:
Energy-related derivatives(a)	$	5	$	124	$	—	$	—	$	129
Interest rate derivatives	—		269		—		—		269
Foreign currency derivatives	—		218		—		—		218
Contingent consideration	3		—		16		—		19
Other	—		13		11		—		24
Total	$	8	$	624	$	27	$	—	$	659

	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
At December 31, 2024:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Alabama Power
Assets:
Energy-related derivatives	$	—	$	26	$	—	$	—	$	26
Nuclear decommissioning trusts:(b)
Domestic equity	459		241		—		—		700
Foreign equity	148		—		—		—		148
U.S. Treasury and government agency securities	—		16		—		—		16
Municipal bonds	—		1		—		—		1
Corporate bonds	—		287		—		—		287
Mortgage- and asset-backed securities	—		31		—		—		31
Private equity	—		—		—		181		181
Other	11		1		—		9		21
Cash equivalents and restricted cash	334		19		—		—		353
Other investments	—		31		—		—		31
Total	$	952	$	653	$	—	$	190	$	1,795
Liabilities:
Energy-related derivatives	$	—	$	42	$	—	$	—	$	42
Georgia Power
Assets:
Energy-related derivatives	$	—	$	19	$	—	$	—	$	19
Nuclear decommissioning trusts:(b)
Domestic equity	390		1		—		—		391
Foreign equity	—		174		—		—		174
U.S. Treasury and government agency securities	—		355		—		—		355
Municipal bonds	—		46		—		—		46
Corporate bonds	—		165		—		—		165
Mortgage- and asset-backed securities	—		75		—		—		75
Other	28		2		—		—		30
Cash equivalents	35		—		—		—		35
Total	$	453	$	837	$	—	$	—	$	1,290
Liabilities:
Energy-related derivatives	$	—	$	42	$	—	$	—	$	42
Mississippi Power
Assets:
Energy-related derivatives	$	—	$	19	$	—	$	—	$	19
Liabilities:
Energy-related derivatives	$	—	$	34	$	—	$	—	$	34

	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
At December 31, 2024:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Southern Power
Assets:
Energy-related derivatives	$	—	$	4	$	—	$	—	$	4
Cash equivalents	51		—		—		—		51
Total	$	51	$	4	$	—	$	—	$	55
Liabilities:
Foreign currency derivatives	—		51		—		—		51
Contingent consideration	3		—		16		—		19
Other	—		13		11		—		24
Total	$	3	$	64	$	27	$	—	$	94
Southern Company Gas
Assets:
Energy-related derivatives(a)	$	12	$	9	$	—	$	—	$	21
Non-qualified deferred compensation trusts:
Domestic equity	—		8		—		—		8
Foreign equity	—		1		—		—		1
Pooled funds - fixed income	—		7		—		—		7
Cash and cash equivalents	1		—		—		—		1
Investments, available-for-sale:
U.S. Treasury and government agency securities	2		7		—		—		9
Corporate bonds	1		2		—		—		3
Mortgage- and asset-backed securities	—		10		—		—		10
Cash equivalents	22		—		—		—		22
Total	$	38	$	44	$	—	$	—	$	82
Liabilities:
Energy-related derivatives(a)	$	5	$	6	$	—	$	—	$	11
Interest rate derivatives	—		84		—		—		84
Total	$	5	$	90	$	—	$	—	$	95

(a)Excludes cash collateral of $17 million.

(b)Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. See Note 6 under "Nuclear Decommissioning" for additional information

Schedule of financial instruments not having carrying amount equal to fair value

At December 31, 2025 and 2024, other financial instruments for which the carrying amount did not equal fair value were as follows:

	Southern    Company(*)		Alabama Power		Georgia Power		Mississippi Power		Southern Power		Southern Company    Gas(*)
	(in billions)
At December 31, 2025:
Long-term debt, including securities due within one year:
Carrying amount	$	71.1	$	12.0	$	20.8	$	1.8	$	2.9	$	9.3
Fair value	67.2		10.9		19.4		1.6		2.9		8.4
At December 31, 2024:
Long-term debt, including securities due within one year:
Carrying amount	$	63.2	$	11.2	$	18.1	$	1.7	$	2.7	$	8.5
Fair value	57.7		9.8		16.2		1.5		2.6		7.4

(*)The carrying amount of Southern Company Gas' long-term debt includes fair value adjustments from the effective date of the 2016 merger with Southern Company. Southern Company Gas amortizes the fair value adjustments over the remaining lives of the respective bonds, the latest being through 2043.