Regulatory Matters - Summary of Utilities Rate Plans (CECONY-Electric) (Details) - USD ($)	1 Months Ended	12 Months Ended					36 Months Ended
	Dec. 31, 2016	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2022	Dec. 31, 2019	Dec. 31, 2016	Dec. 31, 2023
Public Utilities, General Disclosures [Line Items]
Revenues		$ 12,246,000,000	$ 12,574,000,000	$ 12,337,000,000	$ 12,033,000,000
Deferred revenues		41,000,000	17,000,000	20,000,000	87,000,000			$ 17,000,000
Deferred revenues		$ (599,000,000)	(599,000,000)					(599,000,000)
NYSPSC
Public Utilities, General Disclosures [Line Items]
Percentage of total consolidated revenues		15.00%
Maximum | NYSPSC
Public Utilities, General Disclosures [Line Items]
Percentage of total consolidated revenues		15.00%
Percentage of debt to total consolidated debt		20.00%
CECONY
Public Utilities, General Disclosures [Line Items]
Actual earnings adjustment mechanism incentives		$ 46,000,000
Revenues		10,647,000,000	10,821,000,000	10,680,000,000
Deferred revenues		(523,000,000)	(477,000,000)					(477,000,000)
CECONY | Electric
Public Utilities, General Disclosures [Line Items]
Retention of annual transmission congestion revenues								75,000,000
Actual earnings adjustment mechanism incentives		34,000,000	43,000,000	25,000,000	13,000,000
Other earnings incentives		5,000,000	5,000,000	5,000,000
Deferred revenues		242,000,000	169,000,000	(6,000,000)	45,000,000			169,000,000
Negative revenue adjustments		5,000,000	15,000,000	0	0
Cost reconciliation, deferred net regulatory liabilities		288,000,000	10,000,000	189,000,000	35,000,000			10,000,000
Deferred regulatory asset (liability)		4,100,000	(11,800,000)	(400,000)	400,000			$ (11,800,000)
Earnings sharing, threshold limit		$ 0	0	0	$ 0
Earnings sharing, positive adjustment						$ 5,700,000
Common Equity Ratio, Percentage								4800.00%
Increase in gas base rate due to expiration of temporary credit under the prior rate plan	$ 48,000,000
Recovery or refund of energy costs, deferral period								10 years
Deferrals for property taxes limitation from rates (percent)									90.00%
Recovery deferral (percent)		80.00%
Maximum deferral (percent)		30.00%
CECONY | Electric | NYSPSC
Public Utilities, General Disclosures [Line Items]
Base rate changes		$ 199,000,000
CECONY | Electric | Service Termination
Public Utilities, General Disclosures [Line Items]
Revenues			$ 7,000,000	$ 3,000,000
CECONY | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Retention of annual transmission congestion revenues							$ 75,000,000
Weighted average cost of capital (after-tax) (percent)							661.00%
Authorized return on common equity (percent)							880.00%
Earnings sharing (percent)										9.30%
Common Equity Ratio, Percentage							4800.00%
Maximum deferral (percent)										15.00%
Income tax benefit to be credited to customers resulting from TCJA							$ 377,000,000
CECONY | Electric | Year 1
Public Utilities, General Disclosures [Line Items]
Base rate changes		$ 195,000,000
Utilities operating expense, depreciation and amortization								$ 84,000,000
Potential earnings adjustment mechanism incentives								28,000,000
Average rate base								$ 18,902,000,000
Weighted average cost of capital (after-tax) (percent)								6.82%
Authorized return on common equity (percent)								900.00%
Actual return on common equity (percent)								9.30%
Earnings sharing (percent)		9.50%
Cost of long-term debt rate		4.93%
Recovery of energy efficiency and savings program costs								$ 20,500,000
Deferral, annual maximum (not more than) (percent)									10.00%
CECONY | Electric | Year 1 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations								21,689,000,000
CECONY | Electric | Year 1 | Advanced metering infrastructure (AMI)
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations								126,000,000
CECONY | Electric | Year 1 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)								376,000,000
CECONY | Electric | Year 1 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Base rate changes										$ 113,000,000
Utilities operating expense, depreciation and amortization							267,000,000
Potential earnings adjustment mechanism incentives							69,000,000
Potential penalties (annually)							450,000,000
Average rate base							$ 21,660,000,000
Actual return on common equity (percent)							8.50%
Cost of long-term debt rate										463.00%
Amount of cost recovery							$ 206,000,000
CECONY | Electric | Year 1 | Scenario, Forecast | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							24,491,000,000
CECONY | Electric | Year 1 | Scenario, Forecast | Advanced metering infrastructure (AMI)
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							572,000,000
CECONY | Electric | Year 2
Public Utilities, General Disclosures [Line Items]
Base rate changes		$ 155,000,000
Utilities operating expense, depreciation and amortization								83,000,000
Potential earnings adjustment mechanism incentives								47,000,000
Average rate base								$ 19,530,000,000
Weighted average cost of capital (after-tax) (percent)								6.80%
Actual return on common equity (percent)								9.36%
Cost of long-term debt rate		4.88%
Recovery of energy efficiency and savings program costs								$ 49,000,000
Deferral, annual maximum (not more than) (percent)									7.50%
CECONY | Electric | Year 2 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations								22,338,000,000
CECONY | Electric | Year 2 | Advanced metering infrastructure (AMI)
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations								257,000,000
CECONY | Electric | Year 2 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)								341,000,000
CECONY | Electric | Year 2 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Base rate changes										$ 370,000,000
Utilities operating expense, depreciation and amortization							269,000,000
Potential earnings adjustment mechanism incentives							74,000,000
Potential penalties (annually)							461,000,000
Average rate base							22,783,000,000
Amount of cost recovery							245,000,000
CECONY | Electric | Year 2 | Scenario, Forecast | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							25,092,000,000
CECONY | Electric | Year 2 | Scenario, Forecast | Advanced metering infrastructure (AMI)
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							740,000,000
CECONY | Electric | Year 3
Public Utilities, General Disclosures [Line Items]
Base rate changes		$ 155,000,000
Utilities operating expense, depreciation and amortization								69,000,000
Potential earnings adjustment mechanism incentives								64,000,000
Average rate base								$ 20,277,000,000
Weighted average cost of capital (after-tax) (percent)								6.73%
Actual return on common equity (percent)								8.82%
Cost of long-term debt rate		4.74%
Recovery of energy efficiency and savings program costs								$ 107,500,000
Deferral, annual maximum (not more than) (percent)									5.00%
CECONY | Electric | Year 3 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations								23,002,000,000
CECONY | Electric | Year 3 | Advanced metering infrastructure (AMI)
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations								415,000,000
CECONY | Electric | Year 3 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)								$ 352,000,000
CECONY | Electric | Year 3 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Base rate changes										$ 326,000,000
Utilities operating expense, depreciation and amortization							272,000,000
Potential earnings adjustment mechanism incentives							79,000,000
Potential penalties (annually)							476,000,000
Average rate base							23,926,000,000
Amount of cost recovery							251,000,000
CECONY | Electric | Year 3 | Scenario, Forecast | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							25,708,000,000
CECONY | Electric | Year 3 | Scenario, Forecast | Advanced metering infrastructure (AMI)
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							806,000,000
Annually | CECONY | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA							126,000,000
Annually | CECONY | Electric | Scenario, Forecast | Deferred Project Costs
Public Utilities, General Disclosures [Line Items]
Utilities operating expense, depreciation and amortization							48,000,000
Over Five Years | CECONY | Electric | Scenario, Forecast | Deferred Project Costs
Public Utilities, General Disclosures [Line Items]
Utilities operating expense, depreciation and amortization							238,000,000
Over Three Years | CECONY | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA							377,000,000
Protected Portion | CECONY | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA							1,663,000,000
Protected Portion | CECONY | Electric | Year 1 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA							49,000,000
Protected Portion | CECONY | Electric | Year 2 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA							50,000,000
Protected Portion | CECONY | Electric | Year 3 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA							53,000,000
Unprotected Portion | CECONY | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA							$ 784,000,000
TCJA of 2017 regulatory liabilities, income tax benefit, amortization period							5 years
Unprotected Portion | Annually | CECONY | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA							$ 157,000,000