Other Postretirement Benefits - Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Service cost - including administrative expenses	$ 5	$ 2	$ 14	$ 15
Interest cost on projected other postretirement benefit obligation	8	7	26	23
Expected return on plan assets	(18)	(17)	(54)	(51)
Recognition of net actuarial loss/(gain)	(4)	4	(11)	17
Recognition of prior service credit			(1)	(2)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	(9)	(4)	(26)	2
Cost capitalized	(2)	(3)	(6)	(9)
Reconciliation to rate level	7	7	22	7
Total credit recognized	(4)	0	(10)	0
CECONY | Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Service cost - including administrative expenses	4	1	11	11
Interest cost on projected other postretirement benefit obligation	8	6	23	19
Expected return on plan assets	(14)	(14)	(43)	(41)
Recognition of net actuarial loss/(gain)	(3)	3	(7)	13
Recognition of prior service credit			0	(1)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	(5)	(4)	(16)	1
Cost capitalized	(2)	(3)	(5)	(7)
Reconciliation to rate level	6	6	18	2
Total credit recognized	$ (1)	$ (1)	$ (3)	$ (4)