Regulatory Matters - Rate Plans (Details) $ in Millions				1 Months Ended			36 Months Ended
	Jan. 01, 2024 USD ($)	Aug. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Aug. 31, 2023 USD ($) substation	Jul. 31, 2023 USD ($)	Apr. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2023 USD ($)	May 31, 2023 USD ($)
Brooklyn Clean Energy Hub
Public Utilities, General Disclosures [Line Items]
Estimated cost recovery						$ 810.0
Eastern Queens Reliability Project
Public Utilities, General Disclosures [Line Items]
Estimated cost recovery				$ 1,200.0
CECONY
Public Utilities, General Disclosures [Line Items]
Number of substations | substation				2
Deferred costs								$ 3.0
CECONY | Electric | Year 1
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount					$ 442.0		$ 457.0
CECONY | Electric | Year 2
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount					518.0		457.0
CECONY | Electric | Year 3
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount					$ 382.0		457.0
CECONY | Electric | Subsidiaries
Public Utilities, General Disclosures [Line Items]
Return on common equity (as a percent)					9.25%
Common equity ratio (percent)					48.00%
Capital expenditures					$ 8,513.0
CECONY | Gas | Year 1
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount					217.0		187.0
CECONY | Gas | Year 2
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount					173.0		187.0
CECONY | Gas | Year 3
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount					122.0		$ 187.0
CECONY | Gas | Subsidiaries
Public Utilities, General Disclosures [Line Items]
Capital expenditures					$ 3,297.0
CECONY | Electric and Gas Transmission Projects | Subsidiaries
Public Utilities, General Disclosures [Line Items]
Rate plan, term (in years)					3 years
RECO
Public Utilities, General Disclosures [Line Items]
Deferred costs									$ 5.1
RECO | Electric
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount		$ 18.2	$ 16.9
RECO | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount	$ 20.7