Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 41	$ 72
Interest cost on projected benefit obligation	162	126
Expected return on plan assets	(279)	(292)
Recognition of net actuarial loss/(gain)	(58)	94
Recognition of prior service credit	(4)	(4)
TOTAL PERIODIC BENEFIT CREDIT	(138)	(4)
Cost capitalized	(21)	(33)
Reconciliation to rate level	73	64
Total expense (credit) recognized	(86)	27
CECONY | Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	38	67
Interest cost on projected benefit obligation	153	119
Expected return on plan assets	(265)	(277)
Recognition of net actuarial loss/(gain)	(55)	89
Recognition of prior service credit	(5)	(5)
TOTAL PERIODIC BENEFIT CREDIT	(134)	(7)
Cost capitalized	(20)	(32)
Reconciliation to rate level	68	61
Total expense (credit) recognized	$ (86)	$ 22