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