Property, Plant and Equipment (Schedule of Nonregulated Solar Projects) (Parenthetical) (Detail) - MW	1 Months Ended
Jan. 31, 2021	Dec. 31, 2020
Acquisition of Solar Project Hardin I in Ohio
Property Plant And Equipment [Line Items]
Capacity of project commenced commercial operations	53	97

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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