Other Postretirement Benefits - Net Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 14	$ 18	$ 22
Interest cost on accumulated other postretirement benefit obligation	57	35	33
Expected return on plan assets	(70)	(72)	(68)
Recognition of net actuarial loss/(gain)	(16)	(14)	31
Recognition of prior service credit	(2)	(1)	(3)
TOTAL PERIODIC POSTRETIREMENT BENEFIT COST/(CREDIT)	(17)	(34)	15
Cost capitalized	(6)	(8)	(9)
Reconciliation to rate level	4	29	(7)
Total credit recognized	(19)	(13)	(1)
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost	12	15	16
Interest cost on accumulated other postretirement benefit obligation	49	30	28
Expected return on plan assets	(56)	(58)	(56)
Recognition of net actuarial loss/(gain)	(8)	(9)	27
Recognition of prior service credit	0	0	(1)
TOTAL PERIODIC POSTRETIREMENT BENEFIT COST/(CREDIT)	(3)	(22)	14
Cost capitalized	(5)	(7)	(7)
Reconciliation to rate level	(2)	24	(12)
Total credit recognized	$ (10)	$ (5)	$ (5)