Pension Benefits - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 995,000,000
Investments value	273,000,000	$ 243,000,000
Other Nonqualified Supplemental Defined Benefit Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	303,000,000	285,000,000
CECONY
Defined Benefit Plan Disclosure [Line Items]
Pension liability	953,000,000
Investments value	246,000,000	221,000,000
CECONY | Other Nonqualified Supplemental Defined Benefit Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	268,000,000	249,000,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Decrease to regulatory assets	1,002,000,000
Charge to OCI	5,000,000
Net loss estimated to be amortized	579,000,000
Prior service cost estimated to be amortized	(16,000,000)
Accumulated benefit obligation	12,655,000,000	12,909,000,000	$ 13,454,000,000
Defined benefit plan, bond amount (excess of)	50,000,000
Estimated future employer contributions	$ 423,000,000
Increase in pension benefit obligation			800,000,000
Pension Benefits | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, percent of bond original price	50.00%
Defined benefit plan, bond yield (percent)	1.00%
Pension Benefits | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, percent of bond original price	200.00%
Defined benefit plan, bond yield (percent)	20.00%
Pension Benefits | CECONY
Defined Benefit Plan Disclosure [Line Items]
Decrease to regulatory assets	$ 967,000,000
Charge to OCI	1,000,000
Net loss estimated to be amortized	548,000,000
Prior service cost estimated to be amortized	(18,000,000)
Accumulated benefit obligation	11,806,000,000	$ 12,055,000,000	$ 12,553,000,000
Estimated future employer contributions	$ 388,000,000