Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 3,381	$ 2,950	$ 7,341	$ 6,552
Total revenues	3,415	2,971	7,475	6,648
Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	2,906	2,486	6,423	5,692
Other
Disaggregation of Revenue [Line Items]
Total revenues	34	21	134	96
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	3,415	2,971	7,475	6,648
Operating Segments | Clean Energy Businesses
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	232	273	390	449
Total revenues	272	291	532	515
Operating Segments | Clean Energy Businesses | Other
Disaggregation of Revenue [Line Items]
Total revenues	40	18	142	66
Operating Segments | Clean Energy Businesses | Renewables
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	199	183	327	334
Total revenues	199	183	327	334
Operating Segments | Clean Energy Businesses | Renewables | Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Clean Energy Businesses | Energy services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	25	81	44	103
Total revenues	25	81	44	103
Operating Segments | Clean Energy Businesses | Energy services | Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Clean Energy Businesses | Develop/Transfer Projects
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8	9	19	12
Total revenues	8	9	19	12
Operating Segments | Clean Energy Businesses | Develop/Transfer Projects | Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Clean Energy Businesses | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Total revenues	40	18	142	66
Operating Segments | Clean Energy Businesses | Other | Other
Disaggregation of Revenue [Line Items]
Total revenues	40	18	142	66
Operating Segments | Con Edison Transmission
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1	1	2	2
Total revenues	1	1	2	2
Operating Segments | Con Edison Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | CECONY | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,908	2,471	6,422	5,644
Total revenues	2,906	2,486	6,423	5,692
Operating Segments | CECONY | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	(2)	15	1	48
Operating Segments | CECONY | Electric | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,255	1,953	4,360	3,919
Total revenues	2,240	1,963	4,324	3,931
Operating Segments | CECONY | Electric | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	(15)	10	(36)	12
Operating Segments | CECONY | Gas | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	571	447	1,681	1,394
Total revenues	582	449	1,713	1,423
Operating Segments | CECONY | Gas | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	11	2	32	29
Operating Segments | CECONY | Steam | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	82	71	381	331
Total revenues	84	74	386	338
Operating Segments | CECONY | Steam | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	2	3	5	7
Operating Segments | O&R | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	240	205	527	457
Total revenues	238	194	522	442
Operating Segments | O&R | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	(2)	(11)	(5)	(15)
Operating Segments | O&R | Electric | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	175	161	339	305
Total revenues	177	153	342	299
Operating Segments | O&R | Electric | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	2	(8)	3	(6)
Operating Segments | O&R | Gas | Subsidiaries
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	65	44	188	152
Total revenues	61	41	180	143
Operating Segments | O&R | Gas | Other | Subsidiaries
Disaggregation of Revenue [Line Items]
Total revenues	(4)	(3)	(8)	(9)
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Total revenues	(2)	(1)	(4)	(3)
Other | Other
Disaggregation of Revenue [Line Items]
Total revenues	$ (2)	$ (1)	$ (4)	$ (3)