Derivative Instruments and Hedging Activities - Realized and Unrealized Gains or Losses on Commodity Derivatives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	$ (90)	$ (332)
Total deferred or recognized gains (losses)		(780)
Net deferred gains/(losses)	(185)	(1,112)
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income	$ 0	$ 26
Gas purchased for resale (b)
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating costs	Operating costs
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income	$ 0	$ 4
Non-utility
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	TOTAL OPERATING REVENUES	TOTAL OPERATING REVENUES
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income	$ 0	$ 17
Other interest expense (b)
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other interest expense (income)	Other interest expense (income)
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income		$ 5
Interest Expense
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income	$ 0
Regulatory Liabilities Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	(49)	(236)
Total deferred or recognized gains (losses)	(95)
Regulatory Liabilities Non Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	(41)	(96)
Regulatory Assets Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	166	(85)
Recoverable energy costs
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	(318)	(563)
Deferred Derivative Losses, Noncurrent
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	57	(132)
CECONY
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)		(297)
Net deferred gains/(losses)	(171)	(1,028)
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income	$ 0	$ 0
CECONY | Gas purchased for resale (b)
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating costs	Operating costs
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income		$ 0
CECONY | Non-utility
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	TOTAL OPERATING REVENUES	TOTAL OPERATING REVENUES
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income		$ 0
CECONY | Other interest expense (b)
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other interest expense (income)	Other interest expense (income)
CECONY | Interest Expense
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income		$ 0
CECONY | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	$ (92)
CECONY | Subsidiaries | Gas purchased for resale (b)
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income	0
CECONY | Subsidiaries | Non-utility
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income	0
CECONY | Subsidiaries | Interest Expense
Pre-tax gains (losses) recognized in income
Total pre-tax gains (losses) recognized in income	0
CECONY | Regulatory Liabilities Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)		(216)
Total deferred or recognized gains (losses)		(731)
CECONY | Regulatory Liabilities Current | Subsidiaries
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 Non Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)		(81)
CECONY | Regulatory Liabilities Non Current | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains (losses)	(43)
CECONY | Regulatory Assets Current
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)		(76)
CECONY | Regulatory Assets Current | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	161
CECONY | Recoverable energy costs
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)		(533)
CECONY | Recoverable energy costs | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	(294)
CECONY | Deferred Derivative Losses, Noncurrent
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)		$ (122)
CECONY | Deferred Derivative Losses, Noncurrent | Subsidiaries
Pre-tax gains (losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains (losses)	$ 54