Pension Benefits - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 759,000,000	$ 185,000,000
Investments value	465,000,000	397,000,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets and liabilities for future income taxes, net	734,000,000
Charge to OCI	8,000,000
Investments value	17,022,000,000	15,608,000,000	$ 13,450,000,000	$ 14,274,000,000
Accumulated benefit obligation	16,768,000,000	15,015,000,000	13,030,000,000
Defined benefit plan, bond amount (excess of)	50,000,000
Estimated future employer contributions	480,000,000
Other Nonqualified Supplemental Defined Benefit Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	414,000,000	395,000,000
CECONY
Defined Benefit Plan Disclosure [Line Items]
Pension liability	714,000,000	162,000,000
Investments value	439,000,000	371,000,000
CECONY | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets and liabilities for future income taxes, net	696,000,000
Charge to OCI	2,000,000
Investments value	16,147,000,000	14,790,000,000	12,744,000,000	$ 13,519,000,000
Accumulated benefit obligation	15,676,000,000	14,010,000,000	$ 12,161,000,000
Estimated future employer contributions	441,000,000
CECONY | Other Nonqualified Supplemental Defined Benefit Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 377,000,000	$ 360,000,000