Summary of Significant Accounting Policies and Other Matters - Changes in Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 21,158	$ 20,889
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES	(4)	4
Ending balance	21,615	20,843
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	21,158
TOTAL OTHER COMPREHENSIVE LOSS, NET OF TAXES	(4)	4
Ending Balance	21,615
AOCI Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	22	22
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES	(4)	4
Ending balance	18	26
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI before reclassifications, net of tax	(4)	0
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	0	4
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES	(4)	4
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, tax	2
CECONY
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES		(1)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	19,146	16,878
TOTAL OTHER COMPREHENSIVE LOSS, NET OF TAXES	0	(1)
Ending Balance	19,597	18,892
CECONY | AOCI Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES		(1)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	2	4
Ending Balance	2	3
CECONY | AOCI Attributable to Parent | Subsidiaries
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	2	4
Ending Balance	2	3
CECONY | Accumulated Defined Benefit Plans Adjustment Attributable to Parent | Subsidiaries
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, net of tax	0	(1)
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	0	0
TOTAL OTHER COMPREHENSIVE LOSS, NET OF TAXES	$ 0	$ (1)