Other Postretirement Benefits - Schedule of Actuarial Assumptions (Details) - Other Postretirement Benefits	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Expected Return on Plan Assets	7.50%	7.00%	7.75%
CECONY
Defined Benefit Plan Disclosure [Line Items]
Discount Rate, Benefit Obligations	3.55%	4.00%	4.05%
Discount rate, net periodic benefit cost	4.00%	4.05%	3.75%
O&R
Defined Benefit Plan Disclosure [Line Items]
Discount Rate, Benefit Obligations	3.70%	4.20%	4.20%
Discount rate, net periodic benefit cost	4.20%	4.20%	3.85%