Summary of Significant Accounting Policies and Other Matters - Changes in Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 20,889,000,000	$ 20,336,000,000
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	4,000,000	0
Ending balance	20,843,000,000	20,623,000,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	20,687,000,000
Ending Balance	20,843,000,000
Subsidiaries
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	(1,000,000)	1,000,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	16,878,000,000	16,312,000,000
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES	(1,000,000)	1,000,000
Ending Balance	18,892,000,000	16,618,000,000
AOCI Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	22,000,000	5,000,000
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	4,000,000
Ending balance	26,000,000	5,000,000
AOCI Attributable to Parent | Subsidiaries
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	(1,000,000)	1,000,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	4,000,000	0
Ending Balance	3,000,000	1,000,000
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	(1,000,000)
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	4,000,000	1,000,000
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	4,000,000	0
Accumulated Defined Benefit Plans Adjustment Attributable to Parent | Subsidiaries
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	0	1,000,000
TOTAL OTHER COMPREHENSIVE INCOME/(LOSS), NET OF TAXES	(1,000,000)	1,000,000
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 | Subsidiaries
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Ending Balance	18,892,000,000
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	$ (1,000,000)	$ 0