Other Postretirement Benefits - Additional Information (Details) - Other Postretirement Benefits $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Increase in liability for other postretirement benefits	$ 49
Increase (decrease) in regulatory liabilities	70
Net losses unrecognized to be amortized	(7)
Prior service cost estimated to be amortized	$ (2)
Health care cost trend rate for net periodic benefit cost, current	5.60%
Health care cost trend rate for net periodic benefit cost	4.50%
Health care cost trend rate for benefit obligations, current	5.40%
Health care cost trend rate for benefit obligations	4.50%
Expected contributions	$ 10
Clean Energy Businesses, Con Edison Transmission and RECO
Defined Benefit Plan Disclosure [Line Items]
Credit to OCI (net of taxes) for unrecognized net losses	4
Debit to OCI (net of taxes) for unrecognized prior service costs	1
CECONY
Defined Benefit Plan Disclosure [Line Items]
Increase in liability for other postretirement benefits	62
Increase (decrease) in regulatory liabilities	(85)
Credit to OCI (net of taxes) for unrecognized net losses	1
Net losses unrecognized to be amortized	(10)
Prior service cost estimated to be amortized	(2)
Expected contributions	$ 8