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Environmental Matters - Additional Information (Detail)
 3 Months Ended
Mar. 31, 2025
USD ($)
Site Contingency [Line Items]  
Environmental Remediation Expense, before Recovery, Statement of Income or Comprehensive Income [Extensible Enumeration] Costs and Expenses
Environmental Restoration Costs  
Site Contingency [Line Items]  
Estimated Costs Accrued For Remediation $ 5,600,000
Fitchburg Manufactured Gas Plant Site [Member]  
Site Contingency [Line Items]  
Environmental Remediation Expense, before Recovery, Statement of Income or Comprehensive Income [Extensible Enumeration] Costs and Expenses
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