Other Postretirement Benefits - Net Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 22	$ 21	$ 18
Interest cost on accumulated other postretirement benefit obligation	33	37	44
Expected return on plan assets	(68)	(66)	(66)
Recognition of net actuarial loss/(gain)	31	37	(9)
Recognition of prior service credit	(3)	(3)	(2)
TOTAL PERIODIC POSTRETIREMENT BENEFIT COST/(CREDIT)	15	26	(15)
Cost capitalized	(9)	(9)	(7)
Reconciliation to rate level	(7)	(17)	12
Total credit recognized	(1)	0	(10)
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost	16	16	13
Interest cost on accumulated other postretirement benefit obligation	28	31	36
Expected return on plan assets	(56)	(54)	(54)
Recognition of net actuarial loss/(gain)	27	36	(10)
Recognition of prior service credit	(1)	(2)	(2)
TOTAL PERIODIC POSTRETIREMENT BENEFIT COST/(CREDIT)	14	27	(17)
Cost capitalized	(7)	(7)	(5)
Reconciliation to rate level	(12)	(25)	7
Total credit recognized	$ (5)	$ (5)	$ (15)