Financial Information by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 3,234	$ 3,514
Depreciation and amortization	470	413
Operating income/(loss)	808	786
Clean Energy Businesses
Segment Reporting Information [Line Items]
Depreciation and amortization	57	58
Operating income/(loss)	14	11
Con Edison Transmission
Segment Reporting Information [Line Items]
Depreciation and amortization	1	0
Operating income/(loss)	(2)	(2)
CECONY
Segment Reporting Information [Line Items]
Total revenues	2,854	3,039
Depreciation and amortization	390	334
Operating income/(loss)	742	726
CECONY | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	297	257
Operating income/(loss)	282	257
CECONY | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	71	55
Operating income/(loss)	369	344
CECONY | Steam
Segment Reporting Information [Line Items]
Depreciation and amortization	22	22
Operating income/(loss)	91	125
O&R
Segment Reporting Information [Line Items]
Depreciation and amortization	22	21
Operating income/(loss)	55	54
O&R | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	16	15
Operating income/(loss)	14	16
O&R | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	6	6
Operating income/(loss)	41	38
Operating segment
Segment Reporting Information [Line Items]
Total revenues	3,234	3,514
Operating segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Total revenues	146	217
Operating segment | Con Edison Transmission
Segment Reporting Information [Line Items]
Total revenues	1	1
Operating segment | CECONY
Segment Reporting Information [Line Items]
Total revenues	2,854	3,039
Operating segment | CECONY | Electric
Segment Reporting Information [Line Items]
Total revenues	1,770	1,797
Operating segment | CECONY | Gas
Segment Reporting Information [Line Items]
Total revenues	834	921
Operating segment | CECONY | Steam
Segment Reporting Information [Line Items]
Total revenues	250	321
Operating segment | O&R
Segment Reporting Information [Line Items]
Total revenues	233	258
Operating segment | O&R | Electric
Segment Reporting Information [Line Items]
Total revenues	136	145
Operating segment | O&R | Gas
Segment Reporting Information [Line Items]
Total revenues	97	113
Other
Segment Reporting Information [Line Items]
Total revenues	0	(1)
Depreciation and amortization	0	0
Operating income/(loss)	(1)	(3)
Inter-segment | CECONY
Segment Reporting Information [Line Items]
Total revenues	(25)	(24)
Inter-segment | CECONY | Electric
Segment Reporting Information [Line Items]
Total revenues	4	4
Inter-segment | CECONY | Gas
Segment Reporting Information [Line Items]
Total revenues	2	2
Inter-segment | CECONY | Steam
Segment Reporting Information [Line Items]
Total revenues	$ 19	$ 18