Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 290	$ 263	$ 275
Interest cost on projected benefit obligation	561	591	596
Expected return on plan assets	(1,033)	(968)	(947)
Recognition of net actuarial loss	688	595	596
Recognition of prior service cost/(credit)	(17)	(17)	4
TOTAL PERIODIC BENEFIT COST	489	464	524
Cost capitalized	(127)	(181)	(214)
Reconciliation to rate level	(92)	(34)	54
Total expense/(credit) recognized	270	249	364
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	272	246	258
Interest cost on projected benefit obligation	525	554	559
Expected return on plan assets	(979)	(917)	(898)
Recognition of net actuarial loss	651	563	565
Recognition of prior service cost/(credit)	(19)	(19)	2
TOTAL PERIODIC BENEFIT COST	450	427	486
Cost capitalized	(119)	(169)	(203)
Reconciliation to rate level	(100)	(41)	58
Total expense/(credit) recognized	$ 231	$ 217	$ 341