Other Postretirement Benefits - Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Service cost - including administrative expenses	$ 3	$ 4	$ 9	$ 11
Interest cost on projected other postretirement benefit obligation	12	14	35	43
Expected return on plan assets	(17)	(18)	(51)	(53)
Recognition of net actuarial gain	(5)	(4)	(14)	(12)
Recognition of prior service credit			(1)	(1)
TOTAL PERIODIC OTHER POSTRETIREMENT CREDIT	(7)	(4)	(22)	(12)
Cost capitalized	(2)	(2)	(4)	(5)
Reconciliation to rate level	4	1	12	2
Total credit recognized	(5)	(5)	(14)	(15)
CECONY
Defined Benefit Plan Disclosure [Line Items]
Recognition of prior service credit			0	0
CECONY | Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Service cost - including administrative expenses	3	3	8	9
Interest cost on projected other postretirement benefit obligation	10	12	30	37
Expected return on plan assets	(14)	(14)	(41)	(42)
Recognition of net actuarial gain	(4)	(2)	(11)	(6)
TOTAL PERIODIC OTHER POSTRETIREMENT CREDIT	(5)	(1)	(14)	(2)
Cost capitalized	(1)	(2)	(4)	(4)
Reconciliation to rate level	3	0	10	(2)
Total credit recognized	$ (3)	$ (3)	$ (8)	$ (8)