Derivative Instruments and Hedging Activities - Fair Values of Commodity Derivatives Including Offsetting (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Fair value of derivative assets
Net Amounts of Assets/ (Liabilities)	$ 691	$ 874
Fair value of derivative liabilities
Net Amounts of Assets/ (Liabilities)	(115)	(90)
Net fair value derivative assets/(liabilities)
Gross Amounts of Recognized Assets/(Liabilities)	(24)	466
Gross Amounts Offset	4	(237)
Net Amounts of Assets/ (Liabilities)	(20)	229
Interest Rate Swap
Fair value of derivative assets
Net Amounts of Assets/ (Liabilities)	0	106
CECONY | Subsidiaries
Fair value of derivative assets
Net Amounts of Assets/ (Liabilities)	665	663
Fair value of derivative liabilities
Net Amounts of Assets/ (Liabilities)	(104)	(44)
Net fair value derivative assets/(liabilities)
Gross Amounts of Recognized Assets/(Liabilities)	(25)	294
Gross Amounts Offset	4	(214)
Net Amounts of Assets/ (Liabilities)	(21)	80
Clean Energy Businesses | Interest Rate Swap
Net fair value derivative assets/(liabilities)
Notional amount		982
Current
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(153)	(198)
Gross Amounts Offset	76	166
Net Amounts of Assets/ (Liabilities)	(77)	(32)
Current | Interest Rate Swap
Fair value of derivative liabilities
Net Amounts of Assets/ (Liabilities)		31
Current | CECONY | Subsidiaries
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(147)	(189)
Gross Amounts Offset	73	160
Net Amounts of Assets/ (Liabilities)	(74)	(29)
Noncurrent
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(79)	(49)
Gross Amounts Offset	49	36
Net Amounts of Assets/ (Liabilities)	(30)	(13)
Noncurrent | CECONY | Subsidiaries
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(74)	(43)
Gross Amounts Offset	47	34
Net Amounts of Assets/ (Liabilities)	(27)	(9)
Total fair value of derivative liabilities held and used
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(232)	(247)
Gross Amounts Offset	125	202
Net Amounts of Assets/ (Liabilities)	(107)	(45)
Current - liabilities held for sale
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	0	(31)
Gross Amounts Offset	0	6
Net Amounts of Assets/ (Liabilities)	0	(25)
Noncurrent - liabilities held for sale
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	0	(3)
Gross Amounts Offset	0	(8)
Net Amounts of Assets/ (Liabilities)	0	(11)
Total fair value of derivative liabilities
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(232)	(281)
Gross Amounts Offset	125	200
Net Amounts of Assets/ (Liabilities)	(107)	(81)
Net fair value derivative assets/(liabilities)
Margin deposit liability	(7)	(10)
Total fair value of derivative liabilities | CECONY
Net fair value derivative assets/(liabilities)
Margin deposit liability		(6)
Total fair value of derivative liabilities | CECONY | Subsidiaries
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(221)	(232)
Gross Amounts Offset	120	194
Net Amounts of Assets/ (Liabilities)	(101)	(38)
Net fair value derivative assets/(liabilities)
Margin deposit liability	(2)
Noncurrent | Interest Rate Swap
Fair value of derivative assets
Net Amounts of Assets/ (Liabilities)		75
Current
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	133	378
Gross Amounts Offset	(76)	(332)
Net Amounts of Assets/ (Liabilities)	57	46
Current | CECONY | Subsidiaries
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	124	350
Gross Amounts Offset	(72)	(312)
Net Amounts of Assets/ (Liabilities)	52	38
Noncurrent
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	75	193
Gross Amounts Offset	(45)	(108)
Net Amounts of Assets/ (Liabilities)	30	85
Noncurrent | CECONY | Subsidiaries
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	72	176
Gross Amounts Offset	(44)	(96)
Net Amounts of Assets/ (Liabilities)	28	80
Total fair value of derivative assets held and used
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	208	571
Gross Amounts Offset	(121)	(440)
Net Amounts of Assets/ (Liabilities)	87	131
Current - assets held for sale
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	0	93
Gross Amounts Offset	0	(8)
Net Amounts of Assets/ (Liabilities)	0	85
Noncurrent - assets held for sale
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	0	83
Gross Amounts Offset	0	11
Net Amounts of Assets/ (Liabilities)	0	94
Total fair value of derivative assets
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	208	747
Gross Amounts Offset	(121)	(437)
Net Amounts of Assets/ (Liabilities)	87	310
Net fair value derivative assets/(liabilities)
Margin deposits assets	12	13
Total fair value of derivative assets | CECONY
Net fair value derivative assets/(liabilities)
Margin deposits assets		13
Total fair value of derivative assets | CECONY | Subsidiaries
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	196	526
Gross Amounts Offset	(116)	(408)
Net Amounts of Assets/ (Liabilities)	80	$ 118
Net fair value derivative assets/(liabilities)
Margin deposits assets	$ 11