Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 40	$ 72	$ 122	$ 215
Interest cost on projected benefit obligation	162	126	486	379
Expected return on plan assets	(279)	(292)	(837)	(876)
Recognition of net actuarial loss/(gain)	(58)	94	(174)	283
Recognition of prior service credit	(4)	(4)	(12)	(12)
TOTAL PERIODIC BENEFIT CREDIT	(139)	(4)	(415)	(11)
Cost capitalized	(19)	(32)	(61)	(100)
Reconciliation to rate level	72	63	218	192
Total credit recognized	(86)	27	(258)	81
CECONY | Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	38	67	113	202
Interest cost on projected benefit obligation	153	119	458	357
Expected return on plan assets	(265)	(277)	(795)	(832)
Recognition of net actuarial loss/(gain)	(55)	89	(164)	268
Recognition of prior service credit	(5)	(5)	(15)	(15)
TOTAL PERIODIC BENEFIT CREDIT	(134)	(7)	(403)	(20)
Cost capitalized	(18)	(30)	(58)	(95)
Reconciliation to rate level	66	59	202	182
Total credit recognized	$ (86)	$ 22	$ (259)	$ 67