Regulatory Matters - Other Regulatory Matters (Details) customer in Thousands, $ in Thousands			1 Months Ended		9 Months Ended	12 Months Ended		36 Months Ended
	Aug. 05, 2020 customer	Jul. 13, 2019 USD ($) customer	Apr. 30, 2020 USD ($)	Mar. 31, 2018 customer	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018	Dec. 31, 2022 USD ($)	Jun. 30, 2020 USD ($)
CECONY | NYSPSC | Manhattan Steam Main Rupture
Public Utilities, General Disclosures [Line Items]
Property damage, clean up and response expense						$ 17,000
Capital and retirement costs						9,000
Loss contingency accrual									$ 3,000
CECONY | NYSPSC | Steam
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA					$ 15,000	185,000
TCJA, net benefit amortization, allocation period					3 years
Tax credit, amortization period							3 years
CECONY | Electric | West Side of Manhattan
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer		72
Revenues, negative adjustment		$ 5,000
CECONY | Electric | Brooklyn
Public Utilities, General Disclosures [Line Items]
Revenues, negative adjustment		$ 10,000
CECONY | Electric | Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer				209
Restoration costs						134,000
Operation and maintenance expenses						15,000
Operation and maintenance expenses charged against a storm reserve						84,000
Capital expenditures						29,000
Removal costs						6,000
CECONY | Electric | Tropical Storm | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer	300
CECONY | Electric | NYSPSC | Hurricane
Public Utilities, General Disclosures [Line Items]
Loss contingency accrual									5,600
CECONY | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA								$ 377,000
TCJA, net benefit amortization, allocation period								3 years
CECONY | Electric | Scenario, Forecast | Protected Portion
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA								$ 1,663,000
CECONY | Electric | Scenario, Forecast | Unprotected Portion
Public Utilities, General Disclosures [Line Items]
TCJA, net benefit amortization, allocation period								5 years
Impact in regulatory liability resulting from TCJA								$ 784,000
CECONY | Gas | NYSPSC | Violations of Gas Operator Qualification, Performance and Inspection Requirements
Public Utilities, General Disclosures [Line Items]
Loss contingency accrual						10,000			5,000
Settlement agreement, amount			$ 15,000
CECONY | Gas | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA								$ 63,000
TCJA, net benefit amortization, allocation period								2 years
CECONY | Gas | Scenario, Forecast | Protected Portion
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA								$ 725,000
CECONY | Gas | Scenario, Forecast | Unprotected Portion
Public Utilities, General Disclosures [Line Items]
TCJA, net benefit amortization, allocation period								5 years
Impact in regulatory liability resulting from TCJA								$ 107,000
O&R | Electric | Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer				93
Restoration costs						43,000
O&R | Electric | Tropical Storm | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer	225
O&R | Electric | NYSPSC | Hurricane
Public Utilities, General Disclosures [Line Items]
Loss contingency accrual									$ 850
O&R | Electric and Gas Transmission Projects | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA								$ 22,000
TCJA, net benefit amortization, allocation period								3 years
O&R | Electric and Gas Transmission Projects | Scenario, Forecast | Protected Portion
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA								$ 123,000
O&R | Electric and Gas Transmission Projects | Scenario, Forecast | Unprotected Portion
Public Utilities, General Disclosures [Line Items]
TCJA, net benefit amortization, allocation period								15 years
Impact in regulatory liability resulting from TCJA								$ 30,000
RECO | Electric | Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer				44
Restoration costs						$ 17,000