Summary of Significant Accounting Policies and Other Matters - Changes in Accumulated Other Comprehensive Income/(Loss) by Component (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
BALANCE AS OF BEGINNING OF PERIOD	$ 20,889	$ 20,336	$ 19,065
BALANCE AS OF BEGINNING OF PERIOD	20,687
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES		17	30
BALANCE AS OF END OF PERIOD	21,158	20,889	20,336
BALANCE AS OF END OF PERIOD	21,158	20,687
Accumulated OCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
BALANCE AS OF BEGINNING OF PERIOD	22	5	(25)
BALANCE AS OF END OF PERIOD	22	22	5
Pension Plan Liabilities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, net of tax	0	13	22
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	0	4	8
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	0	17	30
OCI before reclassifications, tax		(5)	(8)
Amounts reclassified from accumulated OCI related to pension plan liabilities, tax		(1)	(3)
Accumulated OCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
BALANCE AS OF BEGINNING OF PERIOD	22	5	(25)
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES		17	30
BALANCE AS OF END OF PERIOD	22	22	5
CECONY
AOCI Attributable to Parent, Net of Tax [Roll Forward]
BALANCE AS OF BEGINNING OF PERIOD	16,878	16,312	14,849
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	(2)	4	7
BALANCE AS OF END OF PERIOD	19,146	16,878	16,312
CECONY | Pension Plan Liabilities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated OCI related to pension plan liabilities, tax			(1)
CECONY | Accumulated OCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
BALANCE AS OF BEGINNING OF PERIOD	4	0	(7)
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	(2)	4	7
BALANCE AS OF END OF PERIOD	2	4	0
CECONY | Pension Plan Liabilities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, net of tax	(2)	3	5
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	0	1	2
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	$ (2)	4	7
OCI before reclassifications, tax		$ (1)	$ 2