Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 72	$ 86
Interest cost on projected benefit obligation	126	118
Expected return on plan assets	(292)	(276)
Recognition of net actuarial loss	94	199
Recognition of prior service credit	(4)	(4)
TOTAL PERIODIC BENEFIT COST/(CREDIT)	(4)	123
Cost capitalized	(33)	(39)
Reconciliation to rate level	64	(57)
Total credit recognized	27	27
CECONY | Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	67	81
Interest cost on projected benefit obligation	119	111
Expected return on plan assets	(277)	(262)
Recognition of net actuarial loss	89	189
Recognition of prior service credit	(5)	(5)
TOTAL PERIODIC BENEFIT COST/(CREDIT)	(7)	114
Cost capitalized	(32)	(37)
Reconciliation to rate level	61	(55)
Total credit recognized	$ 22	$ 22