Consolidated Entities and Equity Method Investments - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($) investor	Dec. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Assets	$ 134,005	$ 127,534
Liabilities	98,287	94,967
Equity investments in unconsolidated subsidiaries	1,292	1,282
SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets	13,283	13,390
Liabilities	6,403	6,792
Equity investments in unconsolidated subsidiaries	49	86
Proceeds from sale of equity method investments	$ 38
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	$ 6,000	6,100
Liabilities	400	400
Noncontrolling interests related to other partners' interests	1,100	1,100
Variable Interest Entity, Primary Beneficiary | SP Wind | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets	2,300	2,300
Liabilities	191	130
Noncontrolling interests related to other partners' interests	$ 40	41
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	$ 1,900	1,900
Liabilities	200	300
Noncontrolling interests related to other partners' interests	$ 800	$ 900