Consolidated Entities and Equity Method Investments - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) investor	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity investments in unconsolidated subsidiaries	$ 1,425		$ 1,425		$ 1,416
Assets	148,853		148,853		145,180
Liabilities	111,511		111,511		108,506
Earnings from equity method investments	10	$ 31	43	$ 77
Southern Holdings Company
Schedule of Equity Method Investments [Line Items]
Equity investments in unconsolidated subsidiaries	115		115		128
Earnings from equity method investments	(14)	$ 0	(20)	$ 0
SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets	12,817		12,817		12,653
Liabilities	6,125		$ 6,125		5,971
SP Solar Holdings I, LP | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Distribution made to limited partner, cash distributions paid, percentage			67.00%
SP Solar Holdings I, LP | Financial Investors
Schedule of Equity Method Investments [Line Items]
Distribution made to limited partner, cash distributions paid, percentage			33.00%
Variable Interest Entity, Primary Beneficiary | SP Solar Holdings I, LP | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets	5,300		$ 5,300		5,400
Liabilities	360		360		372
Noncontrolling interests related to other partners' interests	1,000		1,000		1,000
Variable Interest Entity, Primary Beneficiary | SP Wind | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets	2,000		2,000		2,000
Liabilities	247		247		177
Noncontrolling interests related to other partners' interests	34		$ 34		35
Distribution made to limited partner, cash distributions paid, percentage			60.00%
Number of financial investors | investor			3
Variable Interest Entity, Primary Beneficiary | SP Wind | Financial Investors
Schedule of Equity Method Investments [Line Items]
Distribution made to limited partner, cash distributions paid, percentage			40.00%
Variable Interest Entity, Primary Beneficiary | Other Variable Interest Entities | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets	1,600		$ 1,600		1,600
Liabilities	229		229		224
Noncontrolling interests related to other partners' interests	$ 657		$ 657		$ 691