Other Postretirement Benefits - Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefits - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Service cost - including administrative expenses	$ 4	$ 4	$ 7	$ 9
Interest cost on projected other postretirement benefit obligation	14	9	28	18
Expected return on plan assets	(18)	(18)	(35)	(36)
Recognition of net actuarial gain	(4)	(6)	(8)	(7)
Recognition of prior service credit	0	(1)	(1)	(1)
TOTAL PERIODIC OTHER POSTRETIREMENT CREDIT	(4)	(12)	(9)	(17)
Cost capitalized	(2)	(2)	(3)	(4)
Reconciliation to rate level	1	11	2	15
Total credit recognized	(5)	(3)	(10)	(6)
CECONY | Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Service cost - including administrative expenses	3	3	6	7
Interest cost on projected other postretirement benefit obligation	12	7	25	15
Expected return on plan assets	(14)	(15)	(28)	(29)
Recognition of net actuarial gain	(2)	(3)	(4)	(4)
Recognition of prior service credit	0	0	0	0
TOTAL PERIODIC OTHER POSTRETIREMENT CREDIT	(1)	(8)	(1)	(11)
Cost capitalized	(1)	(1)	(2)	(3)
Reconciliation to rate level	0	8	(2)	12
Total credit recognized	$ (2)	$ (1)	$ (5)	$ (2)