Financial Information by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Total revenues	$ 2,971	$ 2,719	$ 6,648	$ 5,953
Depreciation and amortization	502	476	1,000	946
Operating income/(loss)	418	479	1,279	1,287
Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	2,486	2,345	5,692	5,200
Depreciation and amortization	423	396	838	786
Operating income/(loss)	321	389	1,108	1,132
Clean Energy Businesses
Segment Reporting Information [Line Items]
Depreciation and amortization	55	57	114	115
Operating income/(loss)	89	82	117	96
Con Edison Transmission
Segment Reporting Information [Line Items]
Depreciation and amortization	0	0	1	0
Operating income/(loss)	(1)	(1)	(4)	(3)
Electric
Segment Reporting Information [Line Items]
Depreciation and amortization			1,000	946
Operating income/(loss)			1,279	1,287
CECONY | Subsidiaries
Segment Reporting Information [Line Items]
Depreciation and amortization	423	396	838	786
Operating income/(loss)	321	389	1,108	1,132
CECONY | Electric | Subsidiaries
Segment Reporting Information [Line Items]
Depreciation and amortization	320	301	635	598
Operating income/(loss)	255	318	501	600
CECONY | Gas | Subsidiaries
Segment Reporting Information [Line Items]
Depreciation and amortization	80	72	157	143
Operating income/(loss)	99	105	538	474
CECONY | Steam | Subsidiaries
Segment Reporting Information [Line Items]
Depreciation and amortization	23	23	46	45
Operating income/(loss)	(33)	(34)	69	58
O&R | Subsidiaries
Segment Reporting Information [Line Items]
Depreciation and amortization	24	23	47	45
Operating income/(loss)	11	10	61	65
O&R | Electric | Subsidiaries
Segment Reporting Information [Line Items]
Depreciation and amortization	17	16	34	32
Operating income/(loss)	14	13	22	27
O&R | Gas | Subsidiaries
Segment Reporting Information [Line Items]
Depreciation and amortization	7	7	13	13
Operating income/(loss)	(3)	(3)	39	38
Operating segment
Segment Reporting Information [Line Items]
Total revenues	2,971	2,719
Operating segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Total revenues	291	198	515	344
Operating segment | Con Edison Transmission
Segment Reporting Information [Line Items]
Total revenues	1	1	2	2
Operating segment | Electric
Segment Reporting Information [Line Items]
Total revenues			6,648	5,953
Operating segment | CECONY | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	2,486	2,345	5,692	5,200
Operating segment | CECONY | Electric | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	1,963	1,845	3,931	3,616
Operating segment | CECONY | Gas | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	449	416	1,423	1,250
Operating segment | CECONY | Steam | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	74	84	338	334
Operating segment | O&R | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	194	175	442	408
Operating segment | O&R | Electric | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	153	138	299	274
Operating segment | O&R | Gas | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	41	37	143	134
Other
Segment Reporting Information [Line Items]
Total revenues	(1)	0	(3)	(1)
Depreciation and amortization	0	0	0	0
Operating income/(loss)	(2)	(1)	(3)	(3)
Other | Con Edison Transmission
Segment Reporting Information [Line Items]
Total revenues			2
Inter-segment | Electric
Segment Reporting Information [Line Items]
Total revenues			0	0
Inter-segment | CECONY | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	(25)	(25)	(50)	(50)
Inter-segment | CECONY | Electric | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	5	4	9	9
Inter-segment | CECONY | Gas | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	2	2	4	3
Inter-segment | CECONY | Steam | Subsidiaries
Segment Reporting Information [Line Items]
Total revenues	$ 18	$ 19	$ 37	$ 38