Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	$ 671,000,000	$ 874,000,000
Derivative liabilities:	155,000,000	90,000,000
Assets transferred out of level 3	10,000,000
Liabilities transferred out of Level 3		0
CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities transferred out of Level 3		0
CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	645,000,000	663,000,000
Derivative liabilities:	139,000,000	44,000,000
Assets transferred out of level 3	10,000,000
Netting Adjustment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	(75,000,000)	(418,000,000)
Derivative liabilities:	(72,000,000)	(182,000,000)
Netting Adjustment | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	(73,000,000)	(388,000,000)
Derivative liabilities:	(73,000,000)	(180,000,000)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	483,000,000	527,000,000
Derivative liabilities:	16,000,000	26,000,000
Level 1 | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	471,000,000	505,000,000
Derivative liabilities:	15,000,000	18,000,000
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	258,000,000	732,000,000
Derivative liabilities:	196,000,000	228,000,000
Level 2 | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	244,000,000	544,000,000
Derivative liabilities:	187,000,000	198,000,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	5,000,000	33,000,000
Derivative liabilities:	15,000,000	18,000,000
Level 3 | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	3,000,000	2,000,000
Derivative liabilities:	10,000,000	8,000,000
Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	88,000,000	142,000,000
Derivative liabilities:	155,000,000	54,000,000
Assets transferred out of level 3		10,000,000
Commodity | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	81,000,000	131,000,000
Derivative liabilities:	139,000,000	44,000,000
Assets transferred out of level 3		9,000,000
Commodity | Netting Adjustment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	(75,000,000)	(420,000,000)
Derivative liabilities:	(72,000,000)	(184,000,000)
Commodity | Netting Adjustment | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	(73,000,000)	(388,000,000)
Derivative liabilities:	(73,000,000)	(180,000,000)
Commodity | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	21,000,000	84,000,000
Derivative liabilities:	16,000,000	18,000,000
Commodity | Level 1 | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	21,000,000	83,000,000
Derivative liabilities:	15,000,000	18,000,000
Commodity | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	137,000,000	476,000,000
Derivative liabilities:	196,000,000	204,000,000
Commodity | Level 2 | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	130,000,000	434,000,000
Derivative liabilities:	187,000,000	198,000,000
Commodity | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	5,000,000	2,000,000
Derivative liabilities:	15,000,000	16,000,000
Commodity | Level 3 | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	3,000,000	2,000,000
Derivative liabilities:	10,000,000	8,000,000
Commodity held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	73,000,000
Derivative liabilities:	0	36,000,000
Commodity held for sale | Netting Adjustment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	2,000,000
Derivative liabilities:	0	2,000,000
Commodity held for sale | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	6,000,000
Derivative liabilities:	0	8,000,000
Commodity held for sale | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	34,000,000
Derivative liabilities:	0	24,000,000
Commodity held for sale | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	31,000,000
Derivative liabilities:	0	2,000,000
Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	106,000,000
Interest rate swap | Netting Adjustment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	0
Interest rate swap | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	0
Interest rate swap | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	106,000,000
Interest rate swap | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	0
Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	583,000,000	553,000,000
Other | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	564,000,000	532,000,000
Other | Netting Adjustment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	0
Other | Netting Adjustment | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	0
Other | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	462,000,000	437,000,000
Other | Level 1 | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	450,000,000	422,000,000
Other | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	121,000,000	116,000,000
Other | Level 2 | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	114,000,000	110,000,000
Other | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	0	0
Other | Level 3 | CECONY | Subsidiaries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	$ 0	$ 0