Derivative Instruments and Hedging Activities - Fair Values of Commodity Derivatives Including Offsetting (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Fair value of derivative assets
Net Amounts of Assets/ (Liabilities)	$ 1,037,000,000	$ 832,000,000
Fair value of derivative liabilities
Net Amounts of Assets/ (Liabilities)	(101,000,000)	(236,000,000)
Net fair value derivative assets/(liabilities)
Gross Amounts of Recognized Assets/(Liabilities)	690,000,000	(8,000,000)
Gross Amounts Offset	(289,000,000)	(24,000,000)
Net Amounts of Assets/ (Liabilities)	401,000,000	(32,000,000)
Interest Rate Swap
Fair value of derivative assets
Net Amounts of Assets/ (Liabilities)	105,000,000	4,000,000
Fair value of derivative liabilities
Net Amounts of Assets/ (Liabilities)	0	(57,000,000)
CECONY | Subsidiaries
Fair value of derivative assets
Net Amounts of Assets/ (Liabilities)	836,000,000	728,000,000
Fair value of derivative liabilities
Net Amounts of Assets/ (Liabilities)	(65,000,000)	(128,000,000)
Net fair value derivative assets/(liabilities)
Gross Amounts of Recognized Assets/(Liabilities)	518,000,000	25,000,000
Gross Amounts Offset	(261,000,000)	(26,000,000)
Net Amounts of Assets/ (Liabilities)	257,000,000	(1,000,000)
Clean Energy Businesses | Interest Rate Swap
Net fair value derivative assets/(liabilities)
Notional amount	996,000,000	1,031,000,000
Total fair value of derivative assets, Noncurrent | Interest Rate Swap
Fair value of derivative assets
Net Amounts of Assets/ (Liabilities)	84,000,000	4,000,000
Total fair value of derivative liabilities
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(280,000,000)	(383,000,000)
Gross Amounts Offset	179,000,000	147,000,000
Net Amounts of Assets/ (Liabilities)	(101,000,000)	(236,000,000)
Total fair value of derivative liabilities | CECONY | Subsidiaries
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(184,000,000)	(181,000,000)
Gross Amounts Offset	119,000,000	53,000,000
Net Amounts of Assets/ (Liabilities)	(65,000,000)	(128,000,000)
Fair value of derivative liabilities, Current
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(212,000,000)	(289,000,000)
Gross Amounts Offset	142,000,000	137,000,000
Net Amounts of Assets/ (Liabilities)	(70,000,000)	(152,000,000)
Fair value of derivative liabilities, Current | Interest Rate Swap
Fair value of derivative liabilities
Net Amounts of Assets/ (Liabilities)		(20,000,000)
Fair value of derivative liabilities, Current | CECONY | Subsidiaries
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(134,000,000)	(131,000,000)
Gross Amounts Offset	84,000,000	43,000,000
Net Amounts of Assets/ (Liabilities)	(50,000,000)	(88,000,000)
Fair value of derivative liabilities, Noncurrent
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(68,000,000)	(94,000,000)
Gross Amounts Offset	37,000,000	10,000,000
Net Amounts of Assets/ (Liabilities)	(31,000,000)	(84,000,000)
Fair value of derivative liabilities, Noncurrent | Interest Rate Swap
Fair value of derivative liabilities
Net Amounts of Assets/ (Liabilities)		(38,000,000)
Fair value of derivative liabilities, Noncurrent | CECONY | Subsidiaries
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(50,000,000)	(50,000,000)
Gross Amounts Offset	35,000,000	10,000,000
Net Amounts of Assets/ (Liabilities)	(15,000,000)	(40,000,000)
Fair value of derivative assets, Current | Interest Rate Swap
Fair value of derivative assets
Net Amounts of Assets/ (Liabilities)	21,000,000
Fair value of derivative assets, Current
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	667,000,000	285,000,000
Gross Amounts Offset	(415,000,000)	(158,000,000)
Net Amounts of Assets/ (Liabilities)	252,000,000	127,000,000
Fair value of derivative assets, Current | CECONY | Subsidiaries
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	521,000,000	135,000,000
Gross Amounts Offset	(335,000,000)	(64,000,000)
Net Amounts of Assets/ (Liabilities)	186,000,000	71,000,000
Total fair value of derivative assets, Noncurrent
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	303,000,000	90,000,000
Gross Amounts Offset	(53,000,000)	(13,000,000)
Net Amounts of Assets/ (Liabilities)	250,000,000	77,000,000
Total fair value of derivative assets, Noncurrent | CECONY | Subsidiaries
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	181,000,000	71,000,000
Gross Amounts Offset	(45,000,000)	(15,000,000)
Net Amounts of Assets/ (Liabilities)	136,000,000	56,000,000
Total fair value of derivative assets
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	970,000,000	375,000,000
Gross Amounts Offset	(468,000,000)	(171,000,000)
Net Amounts of Assets/ (Liabilities)	502,000,000	204,000,000
Net fair value derivative assets/(liabilities)
Margin deposits	4,000,000	1,000,000
Total fair value of derivative assets | CECONY | Subsidiaries
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	702,000,000	206,000,000
Gross Amounts Offset	(380,000,000)	(79,000,000)
Net Amounts of Assets/ (Liabilities)	322,000,000	127,000,000
Net fair value derivative assets/(liabilities)
Margin deposits	$ 4,000,000	$ 0