Regulatory Matters - MEC (Details) $ in Millions	Sep. 30, 2021 USD ($)
MEC
Schedule Of Regulatory Assets and Liabilities [Line Items]
Adjustment clause, cost increase	$ 245

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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration