Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 73	$ 62	$ 220	$ 187
Interest cost on projected benefit obligation	137	150	412	451
Expected return on plan assets	(258)	(247)	(775)	(741)
Recognition of net actuarial loss	175	130	524	389
Recognition of prior service credit	(4)	(4)	(12)	(13)
TOTAL PERIODIC BENEFIT COST	123	91	369	273
Cost capitalized	(34)	(26)	(98)	(80)
Reconciliation to rate level	(62)	(5)	(188)	(12)
Total credit recognized	27	60	83	181
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	69	58	206	175
Interest cost on projected benefit obligation	129	141	387	423
Expected return on plan assets	(245)	(234)	(735)	(702)
Recognition of net actuarial loss	165	123	496	369
Recognition of prior service credit	(5)	(5)	(15)	(15)
TOTAL PERIODIC BENEFIT COST	113	83	339	250
Cost capitalized	(32)	(24)	(93)	(76)
Reconciliation to rate level	(59)	(4)	(179)	(10)
Total credit recognized	$ 22	$ 55	$ 67	$ 164