Environmental Matters - Schedule of Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Site Contingency [Line Items]
Total	$ 1,081	$ 1,079
Regulatory assets	6,035	5,702
Manufactured gas plant sites
Site Contingency [Line Items]
Total	978	980
Other Superfund Sites
Site Contingency [Line Items]
Total	103	99
Superfund Sites
Site Contingency [Line Items]
Total	1,081	1,079
Regulatory assets	1,082	1,079
CECONY
Site Contingency [Line Items]
Total	983	980
CECONY | Manufactured gas plant sites
Site Contingency [Line Items]
Total	881	882
CECONY | Other Superfund Sites
Site Contingency [Line Items]
Total	102	98
CECONY | Superfund Sites
Site Contingency [Line Items]
Total	983	980
Regulatory assets	$ 990	$ 987