Revenues from Contracts with Customers - Disaggregation of Revenue by Identified Revenue Stream (Parenthetical) (Detail) $ in Millions	9 Months Ended
Sep. 30, 2021 USD ($)
Brokered Natural Gas, Marketing and Other \| Other marketing revenue
Disaggregation of Revenue [Line Items]
Revenue received as part of capacity release agreement	$ 8.8

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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