XML 158 R105.htm IDEA: XBRL DOCUMENT
v3.25.0.1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Provision for Uncollectible Accounts (Narrative) (Details) | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Accounting Policies [Abstract] |  |  |
Uncollectible accounts, average percent of revenues (less than) | 1.00% | 1.00% | 1.00%

X
- Definition Uncollectible accounts + References No definition available. + Details
Name: | so_UncollectibleAccounts
Namespace Prefix: | so_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration