Financial Information by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 2,719	$ 2,744	$ 5,953	$ 6,258
Depreciation and amortization	476	418	946	831
Operating income/(loss)	479	458	1,287	1,244
Clean Energy Businesses
Segment Reporting Information [Line Items]
Depreciation and amortization	57	58	115	116
Operating income/(loss)	82	72	96	83
Con Edison Transmission
Segment Reporting Information [Line Items]
Depreciation and amortization	0	0	0	0
Operating income/(loss)	(1)	(2)	(3)	(3)
Electric
Segment Reporting Information [Line Items]
Depreciation and amortization			946	831
Operating income/(loss)			1,287	1,244
CECONY
Segment Reporting Information [Line Items]
Total revenues	2,345	2,331	5,200	5,371
Depreciation and amortization	396	339	786	673
Operating income/(loss)	389	376	1,132	1,101
CECONY | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	301	261	598	518
Operating income/(loss)	318	314	600	571
CECONY | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	72	56	143	111
Operating income/(loss)	105	94	474	438
CECONY | Steam
Segment Reporting Information [Line Items]
Depreciation and amortization	23	22	45	44
Operating income/(loss)	(34)	(32)	58	92
O&R
Segment Reporting Information [Line Items]
Depreciation and amortization	23	21	45	42
Operating income/(loss)	10	13	65	67
O&R | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	16	15	32	30
Operating income/(loss)	13	16	27	31
O&R | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	7	6	13	12
Operating income/(loss)	(3)	(3)	38	36
Operating segment
Segment Reporting Information [Line Items]
Total revenues	2,719	2,744
Operating segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Total revenues	198	233	344	450
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			5,953	6,258
Operating segment | CECONY
Segment Reporting Information [Line Items]
Total revenues	2,345	2,331	5,200	5,371
Operating segment | CECONY | Electric
Segment Reporting Information [Line Items]
Total revenues	1,845	1,833	3,616	3,630
Operating segment | CECONY | Gas
Segment Reporting Information [Line Items]
Total revenues	416	408	1,250	1,330
Operating segment | CECONY | Steam
Segment Reporting Information [Line Items]
Total revenues	84	90	334	411
Operating segment | O&R
Segment Reporting Information [Line Items]
Total revenues	175	179	408	437
Operating segment | O&R | Electric
Segment Reporting Information [Line Items]
Total revenues	138	138	274	283
Operating segment | O&R | Gas
Segment Reporting Information [Line Items]
Total revenues	37	41	134	154
Other
Segment Reporting Information [Line Items]
Total revenues	0	0	(1)	(2)
Depreciation and amortization	0	0	0	0
Operating income/(loss)	(1)	(1)	(3)	(4)
Inter-segment | Electric
Segment Reporting Information [Line Items]
Total revenues			0	0
Inter-segment | CECONY
Segment Reporting Information [Line Items]
Total revenues	(25)	(23)	(50)	(47)
Inter-segment | CECONY | Electric
Segment Reporting Information [Line Items]
Total revenues	4	5	9	9
Inter-segment | CECONY | Gas
Segment Reporting Information [Line Items]
Total revenues	2	2	3	3
Inter-segment | CECONY | Steam
Segment Reporting Information [Line Items]
Total revenues	$ 19	$ 16	$ 38	$ 35