Derivative Instruments and Hedging Activities - Schedule of Realized and Unrealized Gains or Losses on Commodity Derivatives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	$ 251	$ (90)
Total deferred or recognized gains (losses)		(95)
Net deferred or recognized gains (losses)	398	(185)
Regulatory Liabilities Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	140	(49)
Total deferred or recognized gains (losses)	147
Regulatory Liabilities Non Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	111	(41)
Regulatory Assets Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	5	166
Recoverable energy costs
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	54	(318)
Regulatory Assets Non Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	88	57
CECONY
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)		(92)
Net deferred or recognized gains (losses)	364	(171)
CECONY | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	233
CECONY | Regulatory Liabilities Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)		(49)
Total deferred or recognized gains (losses)		(79)
CECONY | Regulatory Liabilities Current | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	130
Total deferred or recognized gains (losses)	131
CECONY | Regulatory Liabilities Non Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)		(43)
CECONY | Regulatory Liabilities Non Current | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	103
CECONY | Regulatory Assets Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)		161
CECONY | Regulatory Assets Current | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	2
CECONY | Recoverable energy costs
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)		(294)
CECONY | Recoverable energy costs | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	50
CECONY | Regulatory Assets Non Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)		$ 54
CECONY | Regulatory Assets Non Current | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	$ 79