Financial Information by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 3,333	$ 3,365	$ 9,286	$ 9,623
Depreciation and amortization	482	421	1,428	1,253
Operating income/(loss)	860	867	2,147	2,111
Clean Energy Businesses
Segment Reporting Information [Line Items]
Depreciation and amortization	58	53	173	169
Operating income/(loss)	92	100	188	183
Con Edison Transmission
Segment Reporting Information [Line Items]
Depreciation and amortization	0	0	1	1
Operating income/(loss)	(2)	(1)	(6)	(5)
Electric
Segment Reporting Information [Line Items]
Depreciation and amortization			1,428	1,253
Operating income/(loss)			2,147	2,111
CECONY
Segment Reporting Information [Line Items]
Total revenues	2,872	2,877	8,072	8,248
Depreciation and amortization	401	346	1,187	1,020
Operating income/(loss)	722	723	1,854	1,825
CECONY | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	305	266	904	785
Operating income/(loss)	813	803	1,413	1,374
CECONY | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	74	58	216	168
Operating income/(loss)	(34)	(24)	440	414
CECONY | Steam
Segment Reporting Information [Line Items]
Depreciation and amortization	22	22	67	67
Operating income/(loss)	(57)	(56)	1	37
O&R
Segment Reporting Information [Line Items]
Depreciation and amortization	23	22	67	63
Operating income/(loss)	49	46	114	113
O&R | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	17	16	48	46
Operating income/(loss)	58	56	86	88
O&R | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	6	6	19	17
Operating income/(loss)	(9)	(10)	28	25
Operating segment
Segment Reporting Information [Line Items]
Total revenues	3,333	3,365
Operating segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Total revenues	222	247	566	696
Operating segment | Con Edison Transmission
Segment Reporting Information [Line Items]
Total revenues	1	1	3	3
Operating segment | Electric
Segment Reporting Information [Line Items]
Total revenues			9,286	9,623
Operating segment | CECONY
Segment Reporting Information [Line Items]
Total revenues	2,872	2,877	8,072	8,248
Operating segment | CECONY | Electric
Segment Reporting Information [Line Items]
Total revenues	2,562	2,544	6,178	6,174
Operating segment | CECONY | Gas
Segment Reporting Information [Line Items]
Total revenues	259	275	1,509	1,605
Operating segment | CECONY | Steam
Segment Reporting Information [Line Items]
Total revenues	51	58	385	469
Operating segment | O&R
Segment Reporting Information [Line Items]
Total revenues	238	241	647	678
Operating segment | O&R | Electric
Segment Reporting Information [Line Items]
Total revenues	208	210	483	493
Operating segment | O&R | Gas
Segment Reporting Information [Line Items]
Total revenues	30	31	164	185
Other
Segment Reporting Information [Line Items]
Total revenues	0	(1)	(2)	(2)
Depreciation and amortization	0	0	0	0
Operating income/(loss)	(1)	(1)	(3)	(5)
Inter-segment | Electric
Segment Reporting Information [Line Items]
Total revenues			0	0
Inter-segment | CECONY
Segment Reporting Information [Line Items]
Total revenues	(24)	(24)	(74)	(71)
Inter-segment | CECONY | Electric
Segment Reporting Information [Line Items]
Total revenues	4	4	13	13
Inter-segment | CECONY | Gas
Segment Reporting Information [Line Items]
Total revenues	2	2	5	6
Inter-segment | CECONY | Steam
Segment Reporting Information [Line Items]
Total revenues	$ 18	$ 18	$ 56	$ 52