Derivative Instruments - Notional Amounts of Derivative Instruments (Details) - Mcf Mcf in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Commodity Member
Derivative [Line Items]
Notional amount	1,502.4	1,484.4
Basis Swap
Derivative [Line Items]
Notional amount	1,240.5	1,056.6

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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