Other Postretirement Benefits - Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefits - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Service cost - including administrative expenses	$ 4	$ 7	$ 9	$ 13
Interest cost on projected other postretirement benefit obligation	9	8	18	16
Expected return on plan assets	(18)	(17)	(36)	(34)
Recognition of net actuarial loss/(gain)	(6)	6	(7)	12
Recognition of prior service credit	(1)	(1)	(1)	(1)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	(12)	3	(17)	6
Cost capitalized	(2)	(3)	(4)	(6)
Reconciliation to rate level	11	0	15	0
Total credit recognized	(3)	0	(6)	0
CECONY | Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Service cost - including administrative expenses	3	5	7	10
Interest cost on projected other postretirement benefit obligation	7	7	15	13
Expected return on plan assets	(15)	(14)	(29)	(27)
Recognition of net actuarial loss/(gain)	(3)	5	(4)	10
Recognition of prior service credit	0	0	0	(1)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	(8)	3	(11)	5
Cost capitalized	(1)	(3)	(3)	(5)
Reconciliation to rate level	8	(1)	12	(3)
Total credit recognized	$ (1)	$ (1)	$ (2)	$ (3)