Fair Value Measurements - Reconciliation of Assets and Liabilities Measured at Level 3 Fair Value (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 0	$ (11)	$ (8)	$ 15
Included in earnings	(2)	(2)	(5)	(4)
Included in regulatory assets and liabilities	(12)	6	(3)	15
Settlements	3	(1)	5	2
Decrease due to the sale of the Clean Energy Businesses			0	(29)
Transfer out of level 3	0	1	0	(6)
Ending balance	(11)	(7)	(11)	(7)
CECONY | Subsidiaries
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	(5)	(5)	(6)
Included in earnings	(1)	(1)	(2)	(2)
Included in regulatory assets and liabilities	(6)	2	(1)	9
Settlements	1	(1)	2	1
Decrease due to the sale of the Clean Energy Businesses			0	0
Transfer out of level 3	0	1	0	(6)
Ending balance	$ (6)	$ (4)	$ (6)	$ (4)