Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 3,953	$ 3,602
Total revenues	4,060	3,677
Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	3,517	3,205
Other
Disaggregation of Revenue [Line Items]
Total revenues	107	75
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	4,060	3,677
Operating Segments | Clean Energy Businesses
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	159	176
Total revenues	260	224
Operating Segments | Clean Energy Businesses | Other
Disaggregation of Revenue [Line Items]
Total revenues	101	48
Operating Segments | Clean Energy Businesses | Renewables
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	140	154
Total revenues	140	154
Operating Segments | Clean Energy Businesses | Renewables | Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Operating Segments | Clean Energy Businesses | Energy services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	19	22
Total revenues	19	22
Operating Segments | Clean Energy Businesses | Energy services | Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Operating Segments | Clean Energy Businesses | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Total revenues	101	48
Operating Segments | Clean Energy Businesses | Other | Other
Disaggregation of Revenue [Line Items]
Total revenues	101	48
Operating Segments | Con Edison Transmission
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1	1
Total revenues	1	1
Operating Segments | Con Edison Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Operating Segments | CECONY | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,510	3,173
Total revenues	3,517	3,205
Operating Segments | CECONY | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	7	32
Operating Segments | CECONY | Electric | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,107	1,966
Total revenues	2,084	1,968
Operating Segments | CECONY | Electric | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	(23)	2
Operating Segments | CECONY | Gas | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,104	946
Total revenues	1,131	973
Operating Segments | CECONY | Gas | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	27	27
Operating Segments | CECONY | Steam | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	299	261
Total revenues	302	264
Operating Segments | CECONY | Steam | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	3	3
Operating Segments | O&R | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	283	252
Total revenues	285	248
Operating Segments | O&R | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	2	(4)
Operating Segments | O&R | Electric | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	163	144
Total revenues	166	145
Operating Segments | O&R | Electric | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	3	1
Operating Segments | O&R | Gas | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	120	108
Total revenues	119	103
Operating Segments | O&R | Gas | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	(1)	(5)
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Total revenues	(3)	(1)
Other | Other
Disaggregation of Revenue [Line Items]
Total revenues	$ (3)	$ (1)