Regulatory Matters - Other Regulatory Matters (Details) - USD ($) $ in Millions	Dec. 31, 2023	Apr. 30, 2023	Dec. 31, 2022
CECONY
Public Utilities, General Disclosures [Line Items]
Public utilities, requested capitalization of billing system costs	$ 75.0
Public utilities, billing system costs	496.0
Net regulatory assets	1,113.0		$ 1,150.0
CECONY | Maximum
Public Utilities, General Disclosures [Line Items]
Public utilities, limit for capitalization	421.0	$ 421.0
O&R
Public Utilities, General Disclosures [Line Items]
Net regulatory assets	$ 18.0		$ 22.0