Financial Information by Business Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 12,337	$ 12,033	$ 12,075
Depreciation and amortization	1,438	1,341	1,216
Operating income	2,664	2,774	2,780
Other Income (deductions)	(62)	(48)	(141)
Interest charges	819	729	696
Income taxes on operating income	406	459	714
Total assets	53,920	48,111	48,255
Capital expenditures	5,249	3,606	5,235
Income taxes on non-operating income	(5)	13	(16)
Federal income tax expense		259
Parent Company
Segment Reporting Information [Line Items]
Interest charges	59	50	41
Total assets	19,542	17,231
Federal income tax expense		(21)
Clean Energy Businesses
Segment Reporting Information [Line Items]
Federal income tax expense		269
Con Edison Transmission
Segment Reporting Information [Line Items]
Federal income tax expense		11
CECONY
Segment Reporting Information [Line Items]
Revenues	10,680	10,468	10,165
Depreciation and amortization	1,276	1,195	1,106
Operating income	2,354	2,549	2,451
Other Income (deductions)	(143)	(137)	(189)
Interest charges	689	623	603
Total assets	43,108	40,451
Income taxes on non-operating income	(2)	(3)	(14)
Operating segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Revenues	763	694	1,091
Depreciation and amortization	85	74	42
Operating income	194	69	183
Other Income (deductions)	33	33	21
Interest charges	63	43	34
Income taxes on operating income	19	(273)	53
Total assets	5,821	2,735	2,551
Capital expenditures	1,791	447	1,235
Operating segment | Con Edison Transmission
Segment Reporting Information [Line Items]
Revenues	4	2	0
Depreciation and amortization	1	1	0
Operating income	(7)	(8)	(3)
Other Income (deductions)	91	80	43
Interest charges	20	16	6
Income taxes on operating income	(1)	(11)	0
Total assets	1,425	1,222	1,150
Capital expenditures	248	66	1,078
Operating segment | CECONY
Segment Reporting Information [Line Items]
Revenues	10,680	10,468	10,165
Depreciation and amortization	1,276	1,195	1,106
Operating income	2,354	2,549	2,451
Other Income (deductions)	(143)	(137)	(189)
Interest charges	689	623	603
Income taxes on operating income	328	688	617
Total assets	43,108	40,451	40,856
Capital expenditures	3,005	2,904	2,756
Operating segment | CECONY | Electric
Segment Reporting Information [Line Items]
Revenues	7,971	7,972	8,106
Depreciation and amortization	984	925	865
Operating income	1,799	1,974	1,996
Other Income (deductions)	(110)	(105)	(147)
Interest charges	519	472	459
Income taxes on operating income	233	511	495
Total assets	31,012	29,661	30,708
Capital expenditures	1,861	1,905	1,819
Operating segment | CECONY | Gas
Segment Reporting Information [Line Items]
Revenues	2,078	1,901	1,508
Depreciation and amortization	205	185	159
Operating income	478	495	387
Other Income (deductions)	(23)	(23)	(31)
Interest charges	131	113	105
Income taxes on operating income	87	152	92
Total assets	9,710	8,387	7,553
Capital expenditures	1,050	909	811
Operating segment | CECONY | Steam
Segment Reporting Information [Line Items]
Revenues	631	595	551
Depreciation and amortization	87	85	82
Operating income	77	80	68
Other Income (deductions)	(10)	(9)	(11)
Interest charges	39	38	39
Income taxes on operating income	8	25	30
Total assets	2,386	2,403	2,595
Capital expenditures	94	90	126
Operating segment | O&R
Segment Reporting Information [Line Items]
Revenues	891	874	821
Depreciation and amortization	77	71	67
Operating income	132	161	146
Other Income (deductions)	(19)	(19)	(15)
Interest charges	39	36	36
Income taxes on operating income	21	42	40
Total assets	2,892	2,773	2,758
Capital expenditures	205	189	166
Operating segment | O&R | Electric
Segment Reporting Information [Line Items]
Revenues	642	642	637
Depreciation and amortization	56	51	49
Operating income	93	115	107
Other Income (deductions)	(14)	(14)	(11)
Interest charges	25	24	24
Income taxes on operating income	14	30	30
Total assets	2,036	1,949	1,949
Capital expenditures	138	128	114
Operating segment | O&R | Gas
Segment Reporting Information [Line Items]
Revenues	249	232	184
Depreciation and amortization	21	20	18
Operating income	39	46	39
Other Income (deductions)	(5)	(5)	(4)
Interest charges	14	12	12
Income taxes on operating income	7	12	10
Total assets	856	824	809
Capital expenditures	67	61	52
Other
Segment Reporting Information [Line Items]
Revenues	(1)	(5)	(2)
Depreciation and amortization	(1)	0	1
Operating income	(9)	3	3
Other Income (deductions)	(24)	(5)	(1)
Interest charges	8	11	17
Income taxes on operating income	39	13	4
Total assets	674	930	940
Capital expenditures	0	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	0
Income taxes on operating income	0	0	0
Total assets	0	0	0
Capital expenditures	0	0	0
Inter-segment
Segment Reporting Information [Line Items]
Revenues	0	0	(7)
Inter-segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Revenues	0	0	7
Inter-segment | CECONY
Segment Reporting Information [Line Items]
Revenues	(98)	(97)	(111)
Inter-segment | CECONY | Electric
Segment Reporting Information [Line Items]
Revenues	16	16	17
Inter-segment | CECONY | Gas
Segment Reporting Information [Line Items]
Revenues	7	6	6
Inter-segment | CECONY | Steam
Segment Reporting Information [Line Items]
Revenues	$ 75	$ 75	$ 88