Pension Benefits - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 185,000,000
Investments value	397,000,000	$ 326,000,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets and liabilities for future income taxes, net	167,000,000
Charge to OCI	10,000,000
Net loss estimated to be amortized	701,000,000
Prior service cost estimated to be amortized	(16,000,000)
Investments value	15,608,000,000	13,450,000,000	$ 14,274,000,000	$ 12,472,000,000
Accumulated benefit obligation	15,015,000,000	13,030,000,000	13,897,000,000
Defined benefit plan, bond amount (excess of)	50,000,000
Estimated future employer contributions	472,000,000
Other Nonqualified Supplemental Defined Benefit Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	395,000,000	316,000,000
CECONY
Defined Benefit Plan Disclosure [Line Items]
Pension liability	162,000,000
Investments value	371,000,000	301,000,000
CECONY | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets and liabilities for future income taxes, net	147,000,000
Charge to OCI	2,000,000
Net loss estimated to be amortized	663,000,000
Prior service cost estimated to be amortized	(20,000,000)
Investments value	14,790,000,000	12,744,000,000	13,519,000,000	$ 11,815,000,000
Accumulated benefit obligation	14,010,000,000	12,161,000,000	$ 12,972,000,000
Estimated future employer contributions	433,000,000
CECONY | Other Nonqualified Supplemental Defined Benefit Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 360,000,000	$ 285,000,000