Schedule II - Valuation and Qualifying Accounts (Details) - Allowance For Uncollectible Accounts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 70	$ 83	$ 96
Charged To Costs And Expenses	62	64	63
Charged To Other Accounts	0	0	0
Deductions	64	77	76
Balance At End of Period	68	70	83
CECONY
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	65	78	91
Charged To Costs And Expenses	56	60	57
Charged To Other Accounts	0	0	0
Deductions	60	73	70
Balance At End of Period	$ 61	$ 65	$ 78