Regulatory Matters - Summary of Utilities Rate Plans (CECONY - Steam) (Details) - Steam - CECONY $ in Millions	9 Months Ended	36 Months Ended
	Sep. 30, 2023 USD ($)	Oct. 31, 2026 USD ($)
Public Utilities, General Disclosures [Line Items]
Annual cap of surcharge recoveries	0.005
Property tax deferrals rate difference (in percent)	90.00%
Recovery deferral (percent)	80.00%
Maximum deferral (percent)	30.00%
Scenario, Forecast | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Authorized return on common equity (percent)		9.25%
Earnings sharing (percent)		9.75%
Common equity ratio (percent)		48.00%
Unprotected Portion
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA	$ 24.0
Year 1
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount	77.8
Late payment charges and fees	$ 2.5
Deferral, annual maximum (not more than) (percent)	0.10%
Year 1 | Scenario, Forecast | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Base rate changes		$ 110.0
Capital expenditures		106.0
Amortization to income of net regulatory (assets) and liabilities		15.0
Negative revenue adjustments		3.7
Net utility plant reconciliations		$ 2,025.0
Weighted average cost of capital (after-tax) (percent)		6.78%
Cost of long-term debt (percent)		4.51%
Average rate base		$ 1,799.0
Year 1 | Protected Portion
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA	$ 3.0
Non-plant regulatory asset	11.0
Year 2
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount	77.8
Late payment charges and fees	$ 3.0
Deferral, annual maximum (not more than) (percent)	0.075%
Year 2 | Scenario, Forecast | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Base rate changes		44.0
Capital expenditures		107.0
Amortization to income of net regulatory (assets) and liabilities		3.0
Negative revenue adjustments		3.8
Net utility plant reconciliations		$ 2,029.0
Weighted average cost of capital (after-tax) (percent)		6.81%
Cost of long-term debt (percent)		4.58%
Average rate base		$ 1,848.0
Year 2 | Protected Portion
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA	$ 5.0
Year 3
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount	77.8
Late payment charges and fees	$ 3.5
Deferral, annual maximum (not more than) (percent)	0.05%
Year 3 | Scenario, Forecast | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Base rate changes		45.0
Capital expenditures		105.0
Amortization to income of net regulatory (assets) and liabilities		3.0
Negative revenue adjustments		3.8
Net utility plant reconciliations		$ 2,015.0
Weighted average cost of capital (after-tax) (percent)		6.83%
Cost of long-term debt (percent)		4.62%
Average rate base		$ 1,882.0
Year 3 | Protected Portion
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA	$ 6.0