Other Postretirement Benefits - Schedule of Net Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 11	$ 13	$ 14
Interest cost on accumulated other postretirement benefit obligation	48	47	57
Expected return on plan assets	(67)	(68)	(70)
Recognition of net actuarial (gain)	(27)	(20)	(16)
Recognition of prior service credit	(1)	(1)	(2)
TOTAL PERIODIC POSTRETIREMENT BENEFIT CREDIT	(36)	(29)	(17)
Cost capitalized	(5)	(6)	(6)
Reconciliation to rate level	12	16	4
Total benefit recognized	(29)	(19)	(19)
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost	9	10	12
Interest cost on accumulated other postretirement benefit obligation	41	40	49
Expected return on plan assets	(53)	(55)	(56)
Recognition of net actuarial (gain)	(18)	(13)	(8)
Recognition of prior service credit	0	0	0
TOTAL PERIODIC POSTRETIREMENT BENEFIT CREDIT	(21)	(18)	(3)
Cost capitalized	(4)	(5)	(5)
Reconciliation to rate level	10	13	(2)
Total benefit recognized	$ (15)	$ (10)	$ (10)