FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2024

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 2024, 2023, and 2022 are shown in the table below.

	Southern Company		Alabama Power		Georgia Power
	(in millions)
Fair value increases (decreases)
2024	$	229	$	143	$	86
2023	281		157		124
2022	(360)		(171)		(189)
Unrealized gains (losses)
At December 31, 2024	$	113	$	64	$	49
At December 31, 2023	241		119		122
At December 31, 2022	(391)		(204)		(187)

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
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 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

	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)
Mississippi Power
Assets:
Energy-related derivatives	$	—	$	19	$	—	$	—	$	19
Liabilities:
Energy-related derivatives	$	—	$	34	$	—	$	—	$	34
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.

At December 31, 2023, 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, 2023:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Southern Company
Assets:
Energy-related derivatives(a)	$	6	$	49	$	—	$	—	$	55
Investments in trusts:(b)
Domestic equity	764		216		—		—		980
Foreign equity	145		171		—		—		316
U.S. Treasury and government agency securities	—		369		—		—		369
Municipal bonds	—		48		—		—		48
Pooled funds – fixed income	—		6		—		—		6
Corporate bonds	—		389		—		—		389
Mortgage and asset backed securities	—		89		—		—		89
Private equity	—		—		—		169		169
Cash and cash equivalents	3		—		—		—		3
Other	58		3		—		9		70
Cash equivalents and restricted cash	253		15		—		—		268
Other investments	9		27		8		—		44
Total	$	1,238	$	1,382	$	8	$	178	$	2,806
Liabilities:
Energy-related derivatives(a)	$	46	$	312	$	—	$	—	$	358
Interest rate derivatives	—		264		—		—		264
Foreign currency derivatives	—		122		—		—		122
Contingent consideration	3		—		16		—		19
Other	—		13		—		—		13
Total	$	49	$	711	$	16	$	—	$	776

	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, 2023:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Alabama Power
Assets:
Energy-related derivatives	$	—	$	15	$	—	$	—	$	15
Nuclear decommissioning trusts:(b)
Domestic equity	443		208		—		—		651
Foreign equity	145		—		—		—		145
U.S. Treasury and government agency securities	—		20		—		—		20
Municipal bonds	—		1		—		—		1
Corporate bonds	—		231		—		—		231
Mortgage and asset backed securities	—		25		—		—		25
Private equity	—		—		—		169		169
Other	8		—		—		9		17
Cash equivalents and restricted cash	119		15		—		—		134
Other investments	—		27		—		—		27
Total	$	715	$	542	$	—	$	178	$	1,435
Liabilities:
Energy-related derivatives	$	—	$	110	$	—	$	—	$	110
Georgia Power
Assets:
Energy-related derivatives	$	—	$	13	$	—	$	—	$	13
Nuclear decommissioning trusts:(b)
Domestic equity	321		1		—		—		322
Foreign equity	—		170		—		—		170
U.S. Treasury and government agency securities	—		349		—		—		349
Municipal bonds	—		47		—		—		47
Corporate bonds	—		158		—		—		158
Mortgage and asset backed securities	—		64		—		—		64
Other	50		3		—		—		53
Total	$	371	$	805	$	—	$	—	$	1,176
Liabilities:
Energy-related derivatives	$	—	$	124	$	—	$	—	$	124

	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, 2023:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Mississippi Power
Assets:
Energy-related derivatives	$	—	$	15	$	—	$	—	$	15
Cash equivalents	17		—		—		—		17
Total	$	17	$	15	$	—	$	—	$	32
Liabilities:
Energy-related derivatives	$	—	$	61	$	—	$	—	$	61
Southern Power
Assets:
Energy-related derivatives	$	—	$	3	$	—	$	—	$	3
Liabilities:
Energy-related derivatives	$	—	$	5	$	—	$	—	$	5
Foreign currency derivatives	—		22		—		—		22
Contingent consideration	3		—		16		—		19
Other	—		13		—		—		13
Total	$	3	$	40	$	16	$	—	$	59
Southern Company Gas
Assets:
Energy-related derivatives(a)	$	6	$	3	$	—	$	—	$	9
Non-qualified deferred compensation trusts:
Domestic equity	—		7		—		—		7
Foreign equity	—		1		—		—		1
Pooled funds - fixed income	—		6		—		—		6
Cash and cash equivalents	3		—		—		—		3
Total	$	9	$	17	$	—	$	—	$	26
Liabilities:
Energy-related derivatives(a)	$	46	$	12	$	—	$	—	$	58
Interest rate derivatives	—		79		—		—		79
Total	$	46	$	91	$	—	$	—	$	137

(a)Excludes cash collateral of $62 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

Financial instruments not having carrying amount equal to fair value

At December 31, 2024 and 2023, 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, 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
At December 31, 2023:
Long-term debt, including securities due within one year:
Carrying amount	$	59.4	$	11.2	$	16.5	$	1.6	$	2.7	$	7.8
Fair value	55.0		10.1		15.1		1.4		2.6		6.8

(*)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.