Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 73	$ 62	$ 147	$ 125
Interest cost on projected benefit obligation	137	150	275	301
Expected return on plan assets	(258)	(247)	(517)	(494)
Recognition of net actuarial loss	175	130	349	259
Recognition of prior service credit	(4)	(4)	(8)	(9)
TOTAL PERIODIC BENEFIT COST	123	91	246	182
Cost capitalized	(33)	(29)	(64)	(55)
Reconciliation to rate level	(62)	(2)	(126)	(7)
Total credit recognized	28	60	56	120
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	69	58	137	117
Interest cost on projected benefit obligation	129	141	258	282
Expected return on plan assets	(245)	(234)	(490)	(468)
Recognition of net actuarial loss	165	123	331	246
Recognition of prior service credit	(5)	(5)	(10)	(10)
TOTAL PERIODIC BENEFIT COST	113	83	226	167
Cost capitalized	(32)	(27)	(61)	(52)
Reconciliation to rate level	(59)	(1)	(121)	(6)
Total credit recognized	$ 22	$ 55	$ 44	$ 109