Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 62	$ 72	$ 187	$ 218
Interest cost on projected benefit obligation	150	140	451	420
Expected return on plan assets	(247)	(258)	(741)	(775)
Recognition of net actuarial loss	130	172	389	516
Recognition of prior service cost/(credit)	(4)	(4)	(13)	(13)
TOTAL PERIODIC BENEFIT COST	91	122	273	366
Cost capitalized	(26)	(32)	(80)	(94)
Reconciliation to rate level	(5)	(22)	(12)	(68)
Total expense/(credit) recognized	60	68	181	204
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	58	68	175	204
Interest cost on projected benefit obligation	141	131	423	394
Expected return on plan assets	(234)	(245)	(702)	(734)
Recognition of net actuarial loss	123	163	369	488
Recognition of prior service cost/(credit)	(5)	(5)	(15)	(15)
TOTAL PERIODIC BENEFIT COST	83	112	250	337
Cost capitalized	(24)	(30)	(76)	(89)
Reconciliation to rate level	(4)	(24)	(10)	(74)
Total expense/(credit) recognized	$ 55	$ 58	$ 164	$ 174