Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 73	$ 62
Interest cost on projected benefit obligation	137	150
Expected return on plan assets	(258)	(247)
Recognition of net actuarial loss	175	130
Recognition of prior service cost/(credit)	(4)	(4)
TOTAL PERIODIC BENEFIT COST	123	91
Cost capitalized	(31)	(26)
Reconciliation to rate level	(64)	(5)
Total credit recognized	28	60
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	69	58
Interest cost on projected benefit obligation	129	141
Expected return on plan assets	(245)	(234)
Recognition of net actuarial loss	165	123
Recognition of prior service cost/(credit)	(5)	(5)
TOTAL PERIODIC BENEFIT COST	113	83
Cost capitalized	(29)	(24)
Reconciliation to rate level	(62)	(4)
Total credit recognized	$ 22	$ 55