SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - General (Narrative) (Details)	Dec. 31, 2019 state electric_company
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of traditional electric operating companies \| electric_company	3
Traditional Operating Companies
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of states in which entity provides utilities \| state	3

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.

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