Financial Information by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 3,514	$ 3,364
Depreciation and amortization	413	348
Operating income/(loss)	786	755
Clean Energy Businesses
Segment Reporting Information [Line Items]
Depreciation and amortization	58	19
Operating income/(loss)	11	9
Con Edison Transmission
Segment Reporting Information [Line Items]
Operating income/(loss)	(2)	(1)
CECONY
Segment Reporting Information [Line Items]
Total revenues	3,039	2,884
Depreciation and amortization	334	310
Operating income/(loss)	726	705
CECONY | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	257	240
Operating income/(loss)	257	254
CECONY | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	55	49
Operating income/(loss)	344	321
CECONY | Steam
Segment Reporting Information [Line Items]
Depreciation and amortization	22	21
Operating income/(loss)	125	130
O&R
Segment Reporting Information [Line Items]
Depreciation and amortization	21	19
Operating income/(loss)	54	44
O&R | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	15	14
Operating income/(loss)	16	8
O&R | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	6	5
Operating income/(loss)	38	36
Operating segment
Segment Reporting Information [Line Items]
Total revenues	3,514	3,364
Operating segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Total revenues	217	233
Operating segment | Con Edison Transmission
Segment Reporting Information [Line Items]
Total revenues	1	1
Operating segment | CECONY
Segment Reporting Information [Line Items]
Total revenues	3,039	2,884
Operating segment | CECONY | Electric
Segment Reporting Information [Line Items]
Total revenues	1,797	1,729
Operating segment | CECONY | Gas
Segment Reporting Information [Line Items]
Total revenues	921	841
Operating segment | CECONY | Steam
Segment Reporting Information [Line Items]
Total revenues	321	314
Operating segment | O&R
Segment Reporting Information [Line Items]
Total revenues	258	246
Operating segment | O&R | Electric
Segment Reporting Information [Line Items]
Total revenues	145	149
Operating segment | O&R | Gas
Segment Reporting Information [Line Items]
Total revenues	113	97
Other
Segment Reporting Information [Line Items]
Total revenues	(1)	0
Depreciation and amortization	0	0
Operating income/(loss)	(3)	(2)
Inter-segment | CECONY
Segment Reporting Information [Line Items]
Total revenues	(24)	(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	1
Inter-segment | CECONY | Steam
Segment Reporting Information [Line Items]
Total revenues	$ 18	$ 19