Environmental Matters - Schedule of Environmental Remediation Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 3	$ 9
Environmental Remediation Expense, before Recovery, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Expense	Other Nonoperating Expense
CECONY
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 3	$ 9
Environmental Remediation Expense, before Recovery, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Nonoperating Expense