Other Postretirement Benefits - Additional Information (Details) - Other Postretirement Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Increase (decrease) in liability for other postretirement benefits	$ (62)	$ 21
Noncurrent liabilities	79
Increase (decrease) in regulatory liabilities	67
Expected contributions	8
CECONY
Defined Benefit Plan Disclosure [Line Items]
Increase (decrease) in liability for other postretirement benefits	(35)	$ 13
Noncurrent liabilities	55
Increase (decrease) in regulatory liabilities	$ 46