Summary of Significant Accounting Policies and Other Matters - Changes in Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 20,805	$ 20,843	$ 20,889	$ 20,621	$ 20,623	$ 20,336	$ 20,889	$ 20,336
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES		(1)	4	1	5
Ending balance	21,078	20,805	20,843	20,976	20,621	20,623	21,078	20,976
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance			20,687				20,687
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES	0			1			3	6
Ending Balance	21,078						21,078
Reclassification from AOCI, tax								(1)
AOCI Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	25	26	22	10	5	5	22	5
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES		(1)	4	1	5
Ending balance	25	25	26	11	10	5	25	11
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							1	4
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	0			1			2	2
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	0			1			3	6
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, tax								(1)
CECONY
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES			(1)			1
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	18,843	18,892	16,878	16,568	16,618	16,312	16,878	16,312
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES	0			0			(1)	1
Ending Balance	19,113	18,843	18,892	16,867	16,568	16,618	19,113	16,867
CECONY | AOCI Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES			(1)			1
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	3	3	4	1	1	0	4	0
Ending Balance	3	3	3	1	1	1	3	1
CECONY | AOCI Attributable to Parent | Subsidiaries
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	3		$ 4	1		$ 0	4	0
Ending Balance	3	$ 3		1	$ 1		3	1
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							(1)	0
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	0			0			0	1
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES	$ 0			$ 0			$ (1)	$ 1