Financial Information by Business Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$ 12,075	$ 12,554	$ 12,919
Depreciation and amortization	1,216	1,130	1,071
Operating income	2,575	2,427	2,209
Other Income (deductions)	64	24	42
Interest charges	696	653	591
Income taxes on operating income	714	644	589
Total assets	48,255	45,642	44,071
Capital expenditures	5,235	3,418	2,721
Income taxes on non-operating income	16	40	21
New Accounting Pronouncement, Early Adoption, Effect
Segment Reporting Information [Line Items]
Total assets			237
CECONY
Segment Reporting Information [Line Items]
Revenues	10,165	10,328	10,786
Depreciation and amortization	1,106	1,040	991
Operating income	2,262	2,247	2,139
Other Income (deductions)	0	(5)	11
Interest charges	603	584	537
Total assets	40,856	40,230
Income taxes on non-operating income	14	14	7
Operating segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Revenues	1,091	1,383	1,244
Depreciation and amortization	42	22	19
Operating income	183	58	(60)
Other Income (deductions)	21	35	28
Interest charges	34	11	(8)
Income taxes on operating income	53	22	(8)
Total assets	2,551	1,680	1,013
Capital expenditures	1,235	823	447
Operating segment | Con Edison Transmission
Segment Reporting Information [Line Items]
Revenues	0	0	0
Depreciation and amortization	0	0	0
Operating income	(3)	0	0
Other Income (deductions)	43	0	0
Interest charges	6	0	0
Income taxes on operating income	0	0	0
Total assets	1,150	3	1
Capital expenditures	1,078	0	0
Operating segment | CECONY
Segment Reporting Information [Line Items]
Revenues	10,165	10,328	10,786
Depreciation and amortization	1,106	1,040	991
Operating income	2,262	2,247	2,139
Other Income (deductions)	0	(5)	11
Interest charges	603	584	537
Income taxes on operating income	617	588	562
Total assets	40,856	40,230	39,443
Capital expenditures	2,756	2,435	2,132
Operating segment | CECONY | Electric
Segment Reporting Information [Line Items]
Revenues	8,106	8,172	8,437
Depreciation and amortization	865	820	781
Operating income	1,847	1,798	1,712
Other Income (deductions)	2	(2)	8
Interest charges	459	447	412
Income taxes on operating income	495	447	425
Total assets	30,708	30,603	30,295
Capital expenditures	1,819	1,658	1,500
Operating segment | CECONY | Gas
Segment Reporting Information [Line Items]
Revenues	1,508	1,527	1,721
Depreciation and amortization	159	142	132
Operating income	357	356	314
Other Income (deductions)	(1)	(2)	2
Interest charges	105	96	89
Income taxes on operating income	92	100	88
Total assets	7,553	6,974	6,478
Capital expenditures	811	671	549
Operating segment | CECONY | Steam
Segment Reporting Information [Line Items]
Revenues	551	629	628
Depreciation and amortization	82	78	78
Operating income	58	93	113
Other Income (deductions)	(1)	(1)	1
Interest charges	39	41	36
Income taxes on operating income	30	41	49
Total assets	2,595	2,653	2,670
Capital expenditures	126	106	83
Operating segment | O&R
Segment Reporting Information [Line Items]
Revenues	821	845	892
Depreciation and amortization	67	68	61
Operating income	130	121	128
Other Income (deductions)	1	(4)	3
Interest charges	36	35	35
Income taxes on operating income	40	33	35
Total assets	2,758	2,719	2,810
Capital expenditures	166	160	142
Operating segment | O&R | Electric
Segment Reporting Information [Line Items]
Revenues	637	663	680
Depreciation and amortization	49	50	46
Operating income	95	103	103
Other Income (deductions)	1	(2)	3
Interest charges	24	23	24
Income taxes on operating income	30	31	29
Total assets	1,949	2,140	2,023
Capital expenditures	114	114	105
Operating segment | O&R | Gas
Segment Reporting Information [Line Items]
Revenues	184	182	212
Depreciation and amortization	18	18	15
Operating income	35	18	25
Other Income (deductions)	0	(2)	0
Interest charges	12	12	10
Income taxes on operating income	10	2	6
Total assets	809	579	786
Capital expenditures	52	46	37
Other
Segment Reporting Information [Line Items]
Revenues	(2)	(2)	(3)
Depreciation and amortization	1	0	0
Operating income	3	1	2
Other Income (deductions)	(1)	(2)	0
Interest charges	17	23	27
Income taxes on operating income	4	1	0
Total assets	940	1,010	804
Capital expenditures	0	0
Other | O&R
Segment Reporting Information [Line Items]
Revenues	0	0	0
Depreciation and amortization	0	0	0
Operating income	0	0	0
Other Income (deductions)	0	0	0
Interest charges	0	0	1
Income taxes on operating income	0	0	0
Total assets	0	0	1
Capital expenditures	0	0	0
Inter-segment
Segment Reporting Information [Line Items]
Revenues	(7)	2	10
Inter-segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Revenues	7	(2)	(10)
Inter-segment | CECONY
Segment Reporting Information [Line Items]
Revenues	(111)	(110)	(106)
Inter-segment | CECONY | Electric
Segment Reporting Information [Line Items]
Revenues	17	18	16
Inter-segment | CECONY | Gas
Segment Reporting Information [Line Items]
Revenues	6	6	6
Inter-segment | CECONY | Steam
Segment Reporting Information [Line Items]
Revenues	$ 88	$ 86	$ 84