Derivative Instruments and Hedging Activities - Realized and Unrealized Gains or Losses on Commodity Derivatives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	$ (332)	$ 251
Total deferred or recognized gains/(losses)	(780)	384
Net deferred gains/(losses)	(1,112)	635
Pre-tax gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 26	$ 168
Gas purchased for resale
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 gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 4	$ 5
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 gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 17	$ 0
Other operations and maintenance expense
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 gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 0	$ 4
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 gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 5	$ 159
Regulatory Liabilities Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(236)	168
Regulatory Liabilities Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(96)	83
Regulatory Assets Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains/(losses)	(85)	(43)
Recoverable Energy Costs, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains/(losses)	(563)	408
Regulatory Assets Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains/(losses)	(132)	19
CECONY
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(297)	230
Total deferred or recognized gains/(losses)	(731)	347
Net deferred gains/(losses)	(1,028)	577
Pre-tax gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 0	$ 4
CECONY | Gas purchased for resale
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 gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 0	$ 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 gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 0	$ 0
CECONY | Other operations and maintenance expense
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 gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 0	$ 4
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)
Pre-tax gain/(loss) recognized in income
Total pre-tax gain/(loss) recognized in income	$ 0	$ 0
CECONY | Regulatory Liabilities Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(216)	155
CECONY | Regulatory Liabilities Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(81)	75
CECONY | Regulatory Assets Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains/(losses)	(76)	(44)
CECONY | Recoverable Energy Costs, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains/(losses)	(533)	372
CECONY | Regulatory Assets Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred or recognized gains/(losses)	$ (122)	$ 19