Consolidated Entities and Equity Method Investments - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) investor	Dec. 31, 2022 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity investments in unconsolidated subsidiaries	$ 1,408	$ 1,443
Assets	134,756	134,891
Liabilities	100,194	100,359
Southern Holdings Company
Schedule of Equity Method Investments [Line Items]
Equity investments in unconsolidated subsidiaries	120	112
SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Equity investments in unconsolidated subsidiaries	0	49
Assets	13,134	13,081
Liabilities	6,276	6,165
Proceeds from sale of equity method investments	$ 50
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 | Global Atlantic
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	$ 5,800	5,900
Liabilities	400	400
Noncontrolling interests related to other partners' interests	1,000	1,100
Variable Interest Entity, Primary Beneficiary | SP Wind | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets	2,200	2,200
Liabilities	172	169
Noncontrolling interests related to other partners' interests	$ 39	39
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	$ 1,800	1,800
Liabilities	200	200
Noncontrolling interests related to other partners' interests	$ 800	$ 800