Other Postretirement Benefits - Additional Information (Details) - Other Postretirement Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Increase in liability for other postretirement benefits	$ 102
Increase (decrease) in regulatory liabilities	134
Net losses unrecognized to be amortized	27
Prior service cost estimated to be amortized	$ (3)
Health care cost trend rate for net periodic benefit cost, current	5.40%	5.60%	5.80%
Health care cost trend rate for net periodic benefit cost	4.50%
Health care cost trend rate for benefit obligations, current	5.20%	5.40%	5.60%
Health care cost trend rate for benefit obligations	4.50%
Expected contributions	$ 6
Clean Energy Businesses, Con Edison Transmission and RECO
Defined Benefit Plan Disclosure [Line Items]
Credit to OCI (net of taxes) for unrecognized net losses	6
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	128
Increase (decrease) in regulatory liabilities	153
Net losses unrecognized to be amortized	22
Prior service cost estimated to be amortized	$ (2)