Financial Information by Business Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 12,574	$ 12,337	$ 12,033
Depreciation and amortization	1,684	1,438	1,341
Operating income	2,676	2,664	2,774
Other Income (deductions)	51	(62)	(48)
Interest charges	991	819	729
Income taxes on operating income	300	406	459
Total assets	58,079	53,920	48,111
Capital expenditures	3,676	5,249	3,606
Income tax expense (benefit) on non-operating income	(4)	(5)	13
Federal income tax expense			259
Parent Company
Segment Reporting Information [Line Items]
Total assets	20,638	19,542
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	10,821	10,680	10,468
Depreciation and amortization	1,373	1,276	1,195
Operating income	2,348	2,354	2,549
Other Income (deductions)	(35)	(143)	(137)
Total assets	46,557	43,108
Income tax expense (benefit) on non-operating income	(7)	(2)	(3)
Operating segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Revenues	857	763	694
Depreciation and amortization	226	85	74
Operating income	202	194	69
Other Income (deductions)	5	33	33
Interest charges	186	63	43
Income taxes on operating income	(58)	19	(273)
Total assets	6,528	5,821	2,735
Capital expenditures	248	1,791	447
Operating segment | Con Edison Transmission
Segment Reporting Information [Line Items]
Revenues	4	4	2
Depreciation and amortization	1	1	1
Operating income	(6)	(7)	(8)
Other Income (deductions)	104	91	80
Interest charges	25	20	16
Income taxes on operating income	1	(1)	(11)
Total assets	1,618	1,425	1,222
Capital expenditures	205	248	66
Operating segment | CECONY
Segment Reporting Information [Line Items]
Revenues	10,821	10,680	10,468
Depreciation and amortization	1,373	1,276	1,195
Operating income	2,348	2,354	2,549
Other Income (deductions)	(35)	(143)	(137)
Interest charges	728	689	623
Income taxes on operating income	342	328	688
Total assets	46,557	43,108	40,451
Capital expenditures	3,020	3,005	2,904
Operating segment | CECONY | Electric
Segment Reporting Information [Line Items]
Revenues	8,062	7,971	7,972
Depreciation and amortization	1,053	984	925
Operating income	1,758	1,799	1,974
Other Income (deductions)	(28)	(110)	(105)
Interest charges	539	519	472
Income taxes on operating income	239	233	511
Total assets	32,988	31,012	29,661
Capital expenditures	1,851	1,861	1,905
Operating segment | CECONY | Gas
Segment Reporting Information [Line Items]
Revenues	2,132	2,078	1,901
Depreciation and amortization	231	205	185
Operating income	528	478	495
Other Income (deductions)	(4)	(23)	(23)
Interest charges	147	131	113
Income taxes on operating income	99	87	152
Total assets	11,090	9,710	8,387
Capital expenditures	1,078	1,050	909
Operating segment | CECONY | Steam
Segment Reporting Information [Line Items]
Revenues	627	631	595
Depreciation and amortization	89	87	85
Operating income	62	77	80
Other Income (deductions)	(3)	(10)	(9)
Interest charges	42	39	38
Income taxes on operating income	4	8	25
Total assets	2,479	2,386	2,403
Capital expenditures	91	94	90
Operating segment | O&R
Segment Reporting Information [Line Items]
Revenues	893	891	874
Depreciation and amortization	84	77	71
Operating income	139	132	161
Other Income (deductions)	(11)	(19)	(19)
Interest charges	41	39	36
Income taxes on operating income	21	21	42
Total assets	3,006	2,892	2,773
Capital expenditures	203	205	189
Operating segment | O&R | Electric
Segment Reporting Information [Line Items]
Revenues	634	642	642
Depreciation and amortization	60	56	51
Operating income	98	93	115
Other Income (deductions)	(7)	(14)	(14)
Interest charges	27	25	24
Income taxes on operating income	15	14	30
Total assets	2,130	2,036	1,949
Capital expenditures	142	138	128
Operating segment | O&R | Gas
Segment Reporting Information [Line Items]
Revenues	259	249	232
Depreciation and amortization	24	21	20
Operating income	41	39	46
Other Income (deductions)	(4)	(5)	(5)
Interest charges	14	14	12
Income taxes on operating income	6	7	12
Total assets	876	856	824
Capital expenditures	61	67	61
Other
Segment Reporting Information [Line Items]
Revenues	(1)	(1)	(5)
Depreciation and amortization	0	(1)	0
Operating income	(7)	(9)	3
Other Income (deductions)	(12)	(24)	(5)
Interest charges	11	8	11
Income taxes on operating income	(6)	39	13
Total assets	370	674	930
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	0
Inter-segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Revenues	0	0	0
Inter-segment | CECONY
Segment Reporting Information [Line Items]
Revenues	(94)	(98)	(97)
Inter-segment | CECONY | Electric
Segment Reporting Information [Line Items]
Revenues	17	16	16
Inter-segment | CECONY | Gas
Segment Reporting Information [Line Items]
Revenues	7	7	6
Inter-segment | CECONY | Steam
Segment Reporting Information [Line Items]
Revenues	$ 70	$ 75	$ 75