Regulatory Matters - Summary of Utilities Rate Plans (CECONY-Gas) (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, 2022	Dec. 31, 2019	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
CECONY
Public Utilities, General Disclosures [Line Items]
Revenues		10,647,000,000	10,821,000,000	10,680,000,000
CECONY | Gas
Public Utilities, General Disclosures [Line Items]
Percentage of revenue reserve							15.00%
Other earnings incentives		3,000,000	7,000,000	6,000,000	7,000,000
Deferred revenues		27,000,000	10,000,000	12,000,000	3,000,000		$ 10,000,000
Negative revenue adjustments		0	0	4,000,000	5,000,000
Cost reconciliation, deferred net regulatory liabilities		91,000,000	18,000,000	44,000,000	2,000,000		18,000,000
Deferred regulatory asset (liability)		$ (24,700,000)	(1,700,000)	(2,200,000)	(2,200,000)		$ (1,700,000)
Earnings sharing (percent)		9.50%
Earnings sharing, threshold limit		$ 0	0	0	$ 0
Common Equity Ratio, Percentage							4800.00%
Increase in gas base rate due to expiration of temporary credit under the prior rate plan	$ 41,000,000
CECONY | Gas | Maximum
Public Utilities, General Disclosures [Line Items]
Amount of revenues retained			65,000,000				$ 65,000,000
CECONY | Gas | Gas Leak Backlog, Leak Prone Pipe and Service Terminations
Public Utilities, General Disclosures [Line Items]
Revenues		$ 13,000,000	$ 9,000,000	$ 5,000,000
CECONY | Gas | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Percentage of revenue reserve						15.00%
Earnings sharing (percent)								9.30%
Common Equity Ratio, Percentage						4800.00%
Income tax benefit to be credited to customers resulting from TCJA						$ 63,000,000
CECONY | Gas | Scenario, Forecast | Maximum
Public Utilities, General Disclosures [Line Items]
Amount of revenues retained						65,000,000
CECONY | Gas | Year 1
Public Utilities, General Disclosures [Line Items]
Base rate changes							(5,000,000)
Utilities operating expense, depreciation and amortization							39,000,000
Potential incentives if performance targets are met							7,000,000
Potential penalties (annually)							68,000,000
Average rate base							$ 4,841,000,000
Weighted average cost of capital (after-tax) (percent)							6.82%
Authorized return on common equity (percent)							900.00%
Actual return on common equity (percent)							9.22%
Cost of long-term debt rate		4.93%
CECONY | Gas | Year 1 | Gas average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							$ 5,844,000,000
CECONY | Gas | Year 1 | AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							27,000,000
CECONY | Gas | Year 1 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Base rate changes						84,000,000
Utilities operating expense, depreciation and amortization						45,000,000
Potential incentives if performance targets are met						20,000,000
Potential penalties (annually)						81,000,000
Average rate base						$ 7,171,000,000
Weighted average cost of capital (after-tax) (percent)						661.00%
Authorized return on common equity (percent)						880.00%
Actual return on common equity (percent)						8.40%
Cost of long-term debt rate								463.00%
CECONY | Gas | Year 1 | Scenario, Forecast | Gas average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						$ 8,108,000,000
CECONY | Gas | Year 1 | Scenario, Forecast | AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						142,000,000
CECONY | Gas | Year 2
Public Utilities, General Disclosures [Line Items]
Base rate changes							92,000,000
Utilities operating expense, depreciation and amortization							37,000,000
Potential incentives if performance targets are met							8,000,000
Potential penalties (annually)							63,000,000
Average rate base							$ 5,395,000,000
Weighted average cost of capital (after-tax) (percent)							6.80%
Actual return on common equity (percent)							9.04%
Cost of long-term debt rate		4.88%
CECONY | Gas | Year 2 | Gas average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							$ 6,512,000,000
CECONY | Gas | Year 2 | AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							57,000,000
CECONY | Gas | Year 2 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Base rate changes						122,000,000
Utilities operating expense, depreciation and amortization						43,000,000
Potential incentives if performance targets are met						22,000,000
Potential penalties (annually)						88,000,000
Average rate base						7,911,000,000
CECONY | Gas | Year 2 | Scenario, Forecast | Gas average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						8,808,000,000
CECONY | Gas | Year 2 | Scenario, Forecast | AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						183,000,000
CECONY | Gas | Year 3
Public Utilities, General Disclosures [Line Items]
Base rate changes							90,000,000
Utilities operating expense, depreciation and amortization							36,000,000
Potential incentives if performance targets are met							8,000,000
Potential penalties (annually)							70,000,000
Average rate base							$ 6,005,000,000
Weighted average cost of capital (after-tax) (percent)							6.73%
Actual return on common equity (percent)							8.72%
Cost of long-term debt rate		4.74%
CECONY | Gas | Year 3 | Gas average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							$ 7,177,000,000
CECONY | Gas | Year 3 | AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations							$ 100,000,000
CECONY | Gas | Year 3 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Base rate changes						167,000,000
Utilities operating expense, depreciation and amortization						10,000,000
Potential incentives if performance targets are met						25,000,000
Potential penalties (annually)						96,000,000
Average rate base						8,622,000,000
CECONY | Gas | Year 3 | Scenario, Forecast | Gas average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						9,510,000,000
CECONY | Gas | Year 3 | Scenario, Forecast | AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						211,000,000
NYSPSC
Public Utilities, General Disclosures [Line Items]
Percentage of total consolidated revenues		15.00%
NYSPSC | Maximum
Public Utilities, General Disclosures [Line Items]
Percentage of total consolidated revenues		15.00%
Percentage of debt to total consolidated debt		20.00%
Annually | CECONY | Gas | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA						32,000,000
Over Ten Years | CECONY | Gas | Year 1 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount						47,000,000
Amount of cost recovery						30,000,000
Over Ten Years | CECONY | Gas | Year 2 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount						176,000,000
Amount of cost recovery						37,000,000
Over Ten Years | CECONY | Gas | Year 3 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount						170,000,000
Amount of cost recovery						40,000,000
Over Two Years | CECONY | Gas | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA						63,000,000
Protected Portion | CECONY | Gas | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						725,000,000
Protected Portion | CECONY | Gas | Year 1 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						14,000,000
Protected Portion | CECONY | Gas | Year 2 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						14,000,000
Protected Portion | CECONY | Gas | Year 3 | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						12,000,000
Unprotected Portion | CECONY | Gas | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						107,000,000
Unprotected Portion | Annually | CECONY | Gas | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						21,000,000
Unprotected Portion | Over Five Years | CECONY | Gas | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						$ 107,000,000