Environmental Matters - Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Site Contingency [Line Items]
Accrued liabilities	$ 1,029	$ 1,037
Regulatory assets	5,672	5,664
Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	939	941
Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	90	96
Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	1,029	1,037
Regulatory assets	1,024	1,038
CECONY
Site Contingency [Line Items]
Accrued liabilities	935	942
CECONY | Subsidiaries
Site Contingency [Line Items]
Regulatory assets	5,307	5,264
CECONY | Manufactured gas plant sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	845	846
CECONY | Other Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	90	96
CECONY | Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	935	942
Regulatory assets	$ 937	$ 952