Summary of Significant Accounting Policies and Other Matters - Capitalized Cost of Utility Plant (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Public Utility, Property, Plant and Equipment [Line Items]
General	$ 4,170	$ 3,880
Held for future use	80	92
Construction work in progress	2,152	2,474
NET UTILITY PLANT	44,214	42,024
Electric Generation
Public Utility, Property, Plant and Equipment [Line Items]
Generation	559	572
Electric Transmission
Public Utility, Property, Plant and Equipment [Line Items]
Transmission	3,955	3,786
Electric Distribution
Public Utility, Property, Plant and Equipment [Line Items]
Distribution	22,418	21,481
General
Public Utility, Property, Plant and Equipment [Line Items]
General	87	52
Gas
Public Utility, Property, Plant and Equipment [Line Items]
Gas	10,473	9,206
Steam
Public Utility, Property, Plant and Equipment [Line Items]
Steam	1,924	1,854
General
Public Utility, Property, Plant and Equipment [Line Items]
General	2,566	2,507
CECONY
Public Utility, Property, Plant and Equipment [Line Items]
General	3,854	3,585
Held for future use	72	84
Construction work in progress	1,985	2,320
NET UTILITY PLANT	41,611	39,552
CECONY | Electric Generation
Public Utility, Property, Plant and Equipment [Line Items]
Generation	559	572
CECONY | Electric Transmission
Public Utility, Property, Plant and Equipment [Line Items]
Transmission	3,658	3,496
CECONY | Electric Distribution
Public Utility, Property, Plant and Equipment [Line Items]
Distribution	21,240	20,366
CECONY | General
Public Utility, Property, Plant and Equipment [Line Items]
General	87	52
CECONY | Gas
Public Utility, Property, Plant and Equipment [Line Items]
Gas	9,748	8,522
CECONY | Steam
Public Utility, Property, Plant and Equipment [Line Items]
Steam	1,924	1,854
CECONY | General
Public Utility, Property, Plant and Equipment [Line Items]
General	$ 2,338	$ 2,286