Fair Value Measurements - Schedule of Reconciliation of Beginning and Ending Net Balances for Assets and Liabilities Measured at Level 3 Fair Value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance as of January 1,	$ (15)	$ (8)
Included in earnings	(3)	(9)
Included in regulatory assets and liabilities	10	(7)
Settlements	3	10
Transfer out of level 3	0	(1)
Ending balance as of December 31	(5)	(15)
CECONY
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance as of January 1,	(6)	(5)
Included in earnings	0	(4)
Included in regulatory assets and liabilities	3	0
Settlements	0	4
Transfer out of level 3	0	(1)
Ending balance as of December 31	$ (3)	$ (6)