Schedule II - Valuation and Qualifying Accounts (Details) - Allowance For Uncollectible Accounts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 68	$ 70	$ 83
Charged To Costs And Expenses	77	62	64
Charged To Other Accounts	0	0	0
Deductions	(71)	(64)	(77)
Balance At End of Period	74	68	70
CECONY
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	61	65	78
Charged To Costs And Expenses	72	56	60
Charged To Other Accounts	0	0	0
Deductions	(65)	(60)	(73)
Balance At End of Period	$ 68	$ 61	$ 65