Pension Benefits - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 263,000,000
Investments value	326,000,000	$ 330,000,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets and liabilities for future income taxes, net	273,000,000
Charge to OCI	7,000,000
Net loss estimated to be amortized	512,000,000
Prior service cost estimated to be amortized	(17,000,000)
Investments value	13,450,000,000	14,274,000,000	$ 12,472,000,000	$ 11,759,000,000
Accumulated benefit obligation	13,030,000,000	13,897,000,000	12,655,000,000
Defined benefit plan, bond amount (excess of)	50,000,000
Estimated future employer contributions	332,000,000
Other Nonqualified Supplemental Defined Benefit Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	316,000,000	331,000,000
CECONY
Defined Benefit Plan Disclosure [Line Items]
Pension liability	250,000,000
Investments value	301,000,000	301,000,000
CECONY | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets and liabilities for future income taxes, net	265,000,000
Charge to OCI	1,000,000
Net loss estimated to be amortized	486,000,000
Prior service cost estimated to be amortized	(19,000,000)
Investments value	12,744,000,000	13,519,000,000	11,815,000,000	$ 11,141,000,000
Accumulated benefit obligation	12,161,000,000	12,972,000,000	$ 11,806,000,000
Estimated future employer contributions	301,000,000
CECONY | Other Nonqualified Supplemental Defined Benefit Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 285,000,000	$ 297,000,000