Derivative Activities - Derivative Volumes Hedged and Average Hedge Prices (Parenthetical) (Detail) - 2023 Commodity Contract - Natural Gas	Jun. 30, 2022 MmbtuPerDay $ / MMBTU
Derivative [Line Items]
Volume Hedged \| MmbtuPerDay	40,000
Call Swaptions
Derivative [Line Items]
Weighted average price of hedge \| $ / MMBTU	2.91

Nominal number of units used to calculate payment on derivative.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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