Related Party Transactions - Additional Information (Details) MMBTU in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2025 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) MMBTU	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Related Party Transaction [Line Items]
Common shareholders’ equity	$ 23,783,000,000	$ 24,168,000,000	$ 21,898,000,000	$ 24,168,000,000	$ 21,898,000,000	$ 21,962,000,000	$ 23,756,000,000	$ 21,560,000,000	$ 21,615,000,000	$ 21,158,000,000
Other income		208,000,000	157,000,000	623,000,000	476,000,000
Unconditional charitable contribution, accrued amount	12,000,000
CECONY
Related Party Transaction [Line Items]
Common shareholders’ equity	$ 21,649,000,000	21,997,000,000	19,873,000,000	21,997,000,000	19,873,000,000	19,971,000,000	$ 21,615,000,000	$ 19,570,000,000	$ 19,597,000,000	$ 19,146,000,000
Income taxes due to Con Edison				35,000,000		344,000,000
Funding limit of CECONY to O&R (not to exceed)				$ 250,000,000
CECONY | Related Party, Lending of Funds
Related Party Transaction [Line Items]
Lending period (not more than) (months)				12 months
CECONY | Equity Method Investee | Mountain Valley Pipeline LLC
Related Party Transaction [Line Items]
Contract term (years)				20 years
Generating capacity per day (in dekatherms) | MMBTU				200
CECONY | Mountain Valley Pipeline LLC | Related Party
Related Party Transaction [Line Items]
Other income		14,000,000		$ 41,000,000
CECONY | Subsidiaries
Related Party Transaction [Line Items]
Sale of natural gas		16,000,000	14,000,000	80,000,000	52,000,000
O&R
Related Party Transaction [Line Items]
Common shareholders’ equity		1,291,000,000		1,291,000,000
Outstanding loans		0		0		$ 0
CET Electric | NY Transco | Related Party
Related Party Transaction [Line Items]
Other income		$ 0	$ 0	$ 0	$ 0