Regulatory Matters - Other Regulatory Matters (Details) customer in Thousands, $ in Millions		1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended		15 Months Ended	36 Months Ended
	Jul. 13, 2019 customer	Mar. 31, 2018 customer	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2022 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory assets			$ 4,242	$ 4,242			$ 4,370
CECONY
Public Utilities, General Disclosures [Line Items]
Regulatory assets			3,900	3,900			$ 3,987
CECONY | Electric | West Side of Manhattan
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer	72
Revenues			5
Accrued liabilities, power outages			5	5
CECONY | Electric | Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer		209
Restoration costs								$ 134
Operation and maintenance expenses								15
Operation and maintenance expenses charged against a storm reserve								84
Capital expenditures			$ 29	29
Removal costs								6
CECONY | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA									$ 377
Tax credit, amortization period									3 years
O&R | Electric | Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer		93
Restoration costs								43
RECO | Electric | Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service | customer		44
Restoration costs								$ 17
NYSPSC | CECONY | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA						$ 259
NYSPSC | CECONY | Gas | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA						113
NYSPSC | CECONY | Steam
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA					$ 15
Tax credit, amortization period							3 years
Impact in regulatory liability resulting from TCJA				$ 185
NYSPSC | CECONY | Steam | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA						$ 25