SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of Credit Risk (Narrative) (Details) - Atlanta Gas Light	Dec. 31, 2021 customer
Concentration Risk [Line Items]
Number of customers in Georgia	16
Percent of highest month's estimated bill	200.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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