Regulatory Matters - Summary of Utilities Rate Plans (CECONY-Steam) (Details) - CECONY - Steam	12 Months Ended										36 Months Ended		108 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Oct. 31, 2026 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2022 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory liabilities, amortization period								3 years				3 years
Amortizations to income of net regulatory (assets) and liabilities												$ 37,000,000
Negative revenue adjustments													$ 0
Cost reconciliation, deferred net regulatory liabilities	$ 18,000,000			$ 8,000,000		$ 14,000,000	$ 8,000,000		$ 42,000,000
Cost reconciliation, deferred net regulatory assets	11,000,000	$ 32,000,000	$ 35,000,000		$ 1,000,000			$ 17,000,000				$ 17,000,000	$ 32,000,000
Deferred regulatory asset (liability)	0		(1,000,000)	(2,000,000)
Increase (decrease) in regulatory liabilities	100,000		0	$ 0	0	0	0	0	0	$ 100,000
Authorized return on common equity (percent)												9.30%
Earnings sharing, positive adjustment						2,300,000	1,100,000	4,000,000
Earnings sharing, threshold limit	$ 0	0	$ 0		$ 5,000,000	$ 16,500,000	$ 8,500,000	7,800,000	$ 11,500,000	$ 0
Earnings sharing (percent)					9.90%
Earnings sharing, additional adjustment		$ 200,000						400,000
Common equity ratio (percent)												48.00%
Revenue from contracts with customer, late payment charges, annual cap, percent (in percent)	0.005
Difference in property taxes (percent)	90.00%											90.00%
Deferral, annual maximum (not more than) (percent)												0.10%
Recovery deferral (percent)	80.00%
Maximum deferral (percent)	30.00%
Other regulatory liabilities								$ 8,000,000				$ 8,000,000
Unprotected Portion
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA	$ 24,000,000
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%
Rate Plan for Year 1
Public Utilities, General Disclosures [Line Items]
Base rate changes												(22,400,000)
Weighted average cost of capital (after-tax)												$ 1,511,000,000
Weighted average cost of capital (after-tax) (percent)												7.10%
Actual return on common equity (percent)												9.82%
Cost of long-term debt rate							5.17%
Requested rate increase (decrease), amount	77,800,000
Late payment charges and fees	$ 2,500,000
Deferral, annual maximum (not more than) (percent)	0.10%
Rate Plan for Year 1 | Protected Portion
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA	$ 3,000,000
Tax cuts and jobs act of 2017, change in tax rate, regulatory asset, income tax benefit	11,000,000
Rate Plan for Year 1 | Scenario, Forecast | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Base rate changes											$ 110,000,000
Amortizations to income of net regulatory (assets) and liabilities											15,000,000
Potential Penalty Expense											3,700,000
Net utility plant reconciliations											2,025,000,000
Weighted average cost of capital (after-tax)											$ 1,799,000,000
Weighted average cost of capital (after-tax) (percent)											6.78%
Cost of long-term debt rate											4.51%
Rate Plan for Year 1 | Production
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations												$ 1,752,000,000
Rate Plan for Year 1 | Distribution
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations												6,000,000
Rate Plan for Year 2
Public Utilities, General Disclosures [Line Items]
Base rate changes												19,800,000
Weighted average cost of capital (after-tax)												$ 1,547,000,000
Weighted average cost of capital (after-tax) (percent)												7.13%
Actual return on common equity (percent)												10.88%
Cost of long-term debt rate							5.23%
Requested rate increase (decrease), amount	77,800,000
Late payment charges and fees	$ 3,000,000
Deferral, annual maximum (not more than) (percent)	0.075%
Rate Plan for Year 2 | Protected Portion
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA	$ 5,000,000
Rate Plan for Year 2 | Scenario, Forecast | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Base rate changes											$ 44,000,000
Amortizations to income of net regulatory (assets) and liabilities											3,000,000
Potential Penalty Expense											3,800,000
Net utility plant reconciliations											2,029,000,000
Weighted average cost of capital (after-tax)											$ 1,848,000,000
Weighted average cost of capital (after-tax) (percent)											6.81%
Cost of long-term debt rate											4.58%
Rate Plan for Year 2 | Production
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations												$ 1,732,000,000
Rate Plan for Year 2 | Distribution
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations												11,000,000
Rate Plan for Year 3
Public Utilities, General Disclosures [Line Items]
Base rate changes												20,300,000
Weighted average cost of capital (after-tax)												$ 1,604,000,000
Weighted average cost of capital (after-tax) (percent)												7.21%
Actual return on common equity (percent)												10.54%
Cost of long-term debt rate							5.39%
Requested rate increase (decrease), amount	77,800,000
Late payment charges and fees	$ 3,500,000
Deferral, annual maximum (not more than) (percent)	0.05%
Rate Plan for Year 3 | Protected Portion
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA	$ 6,000,000
Rate Plan for Year 3 | Scenario, Forecast | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Base rate changes											$ 45,000,000
Amortizations to income of net regulatory (assets) and liabilities											3,000,000
Potential Penalty Expense											3,800,000
Net utility plant reconciliations											2,015,000,000
Weighted average cost of capital (after-tax)											$ 1,882,000,000
Weighted average cost of capital (after-tax) (percent)											6.83%
Cost of long-term debt rate											4.62%
Rate Plan for Year 3 | Production
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations												$ 1,720,000,000
Rate Plan for Year 3 | Distribution
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations												25,000,000
Rate Plan for Year 3 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential Penalty Expense												1,000,000
Rate Plan for Year 4
Public Utilities, General Disclosures [Line Items]
Base rate changes												$ 0
Actual return on common equity (percent)												9.51%
Rate Plan for Year 5
Public Utilities, General Disclosures [Line Items]
Base rate changes												$ 0
Actual return on common equity (percent)												11.73%
Rate Plan For Year 6
Public Utilities, General Disclosures [Line Items]
Base rate changes												$ 0
Actual return on common equity (percent)												10.45%
Rate Plan For Year 7
Public Utilities, General Disclosures [Line Items]
Base rate changes												$ 0
Actual return on common equity (percent)												7.91%
Rate Plan For Year 8
Public Utilities, General Disclosures [Line Items]
Base rate changes												$ 0
Actual return on common equity (percent)												5.99%
Rate Plan For Year 9
Public Utilities, General Disclosures [Line Items]
Base rate changes												$ 0
Actual return on common equity (percent)												5.72%
Rate Plan For Year 10
Public Utilities, General Disclosures [Line Items]
Base rate changes												$ 0
Actual return on common equity (percent)												(0.10%)