Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 62	$ 72
Interest cost on projected benefit obligation	150	140
Expected return on plan assets	(247)	(258)
Recognition of net actuarial loss	130	172
Recognition of prior service cost/(credit)	(4)	(4)
TOTAL PERIODIC BENEFIT COST	91	122
Cost capitalized	(26)	(31)
Reconciliation to rate level	(5)	(23)
Total expense/(credit) recognized	60	68
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	58	68
Interest cost on projected benefit obligation	141	131
Expected return on plan assets	(234)	(245)
Recognition of net actuarial loss	123	163
Recognition of prior service cost/(credit)	(5)	(5)
TOTAL PERIODIC BENEFIT COST	83	112
Cost capitalized	(24)	(29)
Reconciliation to rate level	(4)	(25)
Total expense/(credit) recognized	$ 55	$ 58