Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 62	$ 72	$ 125	$ 145
Interest cost on projected benefit obligation	150	140	301	280
Expected return on plan assets	(247)	(258)	(494)	(516)
Recognition of net actuarial loss	130	172	259	344
Recognition of prior service cost/(credit)	(4)	(4)	(9)	(9)
TOTAL PERIODIC BENEFIT COST	91	122	182	244
Cost capitalized	(29)	(31)	(55)	(62)
Reconciliation to rate level	(2)	(23)	(7)	(46)
Total expense/(credit) recognized	60	68	120	136
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	58	68	117	136
Interest cost on projected benefit obligation	141	131	282	263
Expected return on plan assets	(234)	(245)	(468)	(490)
Recognition of net actuarial loss	123	163	246	326
Recognition of prior service cost/(credit)	(5)	(5)	(10)	(10)
TOTAL PERIODIC BENEFIT COST	83	112	167	225
Cost capitalized	(27)	(29)	(52)	(59)
Reconciliation to rate level	(1)	(25)	(6)	(50)
Total expense/(credit) recognized	$ 55	$ 58	$ 109	$ 116