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Environmental Matters - Additional Information (Detail) | 9 Months Ended
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Sep. 30, 2025 USD ($)
Environmental Restoration Costs |
Site Contingency [Line Items] |
Estimated Costs Accrued For Remediation | $ 6,500,000
Fitchburg Manufactured Gas Plant Site [Member] |
Site Contingency [Line Items] |
Remediation costs | 3,500,000
Fitchburg Manufactured Gas Plant Site [Member] | Environmental Restoration Costs |
Site Contingency [Line Items] |
Estimated Costs Accrued For Remediation | $ 40,000

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