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, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 20,621	$ 20,623	$ 20,336	$ 20,053	$ 19,282	$ 19,065	$ 20,336	$ 19,065
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1	5		2	2	4	6	8
Ending balance	20,976	20,621	20,623	20,377	20,053	19,282	20,976	20,377
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance			20,037				20,037
Ending Balance	20,748						20,748
Subsidiaries
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES			1
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	16,568	16,618	16,312	15,924	15,192	14,849	16,312	14,849
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	0			0			1	0
Ending Balance	16,867	16,568	16,618	16,220	15,924	15,192	16,867	16,220
AOCI Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	10	5	5	(19)	(21)	(25)	5	(25)
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1	5		2	2	4
Ending balance	11	10	5	(17)	(19)	(21)	11	(17)
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
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	1	1	0	(7)	(7)	(7)	0	(7)
Ending Balance	1	$ 1	$ 1	(7)	$ (7)	$ (7)	1	(7)
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	2
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	1			2			2	6
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1			2			6	8
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, tax	0						(1)	(1)
Amounts reclassified from accumulated OCI related to pension plan liabilities, tax				(1)			(1)	(2)
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			0			1	0
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	$ 0			$ 0			1	0
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