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Introduction - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025	Dec. 31, 2024
Restricted Cash and Cash Equivalent Item [Line Items]
Cash and cash equivalents	$ 2,984	$ 1,639
Restricted cash:
Total cash, cash equivalents, and restricted cash	2,990	1,640	$ 1,265	$ 1,101
Other current assets
Restricted cash:
Restricted cash	5	1
GEORGIA POWER CO
Restricted Cash and Cash Equivalent Item [Line Items]
Cash and cash equivalents	72	59
Restricted cash:
Total cash, cash equivalents, and restricted cash	72	59	94	118
SOUTHERN POWER CO
Restricted Cash and Cash Equivalent Item [Line Items]
Cash and cash equivalents	278	105
Restricted cash:
Total cash, cash equivalents, and restricted cash	278	105	143	168
SOUTHERN Co GAS
Restricted Cash and Cash Equivalent Item [Line Items]
Cash and cash equivalents	214	15
Restricted cash:
Total cash, cash equivalents, and restricted cash	218	15	$ 225	$ 44
SOUTHERN Co GAS \| Other current assets
Restricted cash:
Restricted cash	4	0
Southern Holdings Company \| Collateral For Life Insurance And Long-Term Disability Insurance
Restricted cash:
Restricted cash	$ 1	$ 1