Consolidated Statement of Capitalization - Long-term Debt - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Schedule of Capitalization, Long-term Debt [Line Items]
Other long-term debt		$ 971	$ 974
Unamortized debt expense		(168)	(141)
Unamortized debt discount		(47)	(37)
TOTAL		22,349	19,973
Less: Long-term debt due within one year			1,446
TOTAL LONG-TERM DEBT		20,382	18,527
TOTAL CAPITALIZATION		39,229	36,549
CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Unamortized debt expense		(130)	(115)
Unamortized debt discount		(46)	(36)
TOTAL		16,789	14,964
Less: Long-term debt due within one year			350
TOTAL LONG-TERM DEBT		16,149	14,614
TOTAL CAPITALIZATION		$ 30,998	28,761
Copper Mountain Solar 2
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.04%
TOTAL PROJECT DEBT	[1]	$ 204	224
Coram
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT	[1]	$ 141	150
Coram | Minimum
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.78%
Coram | Maximum
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.52%
Copper Mountain Solar 3
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.10%
TOTAL PROJECT DEBT	[1]	$ 264	289
CED Southwest
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.72%
TOTAL PROJECT DEBT	[1]	$ 437	456
Wind Holdings
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.41%
TOTAL PROJECT DEBT		$ 109	123
Copper Mountain Solar 1
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.41%
TOTAL PROJECT DEBT	[1]	$ 56	67
Mesquite Solar 1
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		$ 180	193
Mesquite Solar 1 | Minimum
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		2.24%
Mesquite Solar 1 | Maximum
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.03%
Texas Solar 4
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		$ 54	56
Texas Solar 4 | Minimum
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.25%
Texas Solar 4 | Maximum
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.95%
California Solar 2
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.94%
TOTAL PROJECT DEBT		$ 93	98
California Solar 3
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.07%
TOTAL PROJECT DEBT		$ 82	86
California Solar
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.78%
TOTAL PROJECT DEBT		$ 178	184
California Solar 4
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.82%
TOTAL PROJECT DEBT		$ 284	297
Broken Bow II
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.82%
TOTAL PROJECT DEBT		$ 67	68
Texas Solar 5
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.53%
TOTAL PROJECT DEBT		$ 140	145
Texas Solar 7
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.21%
TOTAL PROJECT DEBT		$ 192	199
Upton County Solar
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL PROJECT DEBT		$ 87	90
Other project debt
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		10	12
Project Debt
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		2,578	2,737
Debentures
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		18,565	15,990
Debentures | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		$ 16,515	14,665
Debentures | Debenture Series 2010A, 4.45% Due 2020
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL		$ 0	350
Debentures | Debenture Series 2010A, 4.45% Due 2020 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL		$ 0	350
Debentures | Debenture Series 2016A, 2.00% Due 2021
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		2.00%
TOTAL		$ 500	500
Debentures | Debenture 2018C, 0.65 Percent, Due 2021
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		0.65%
TOTAL		$ 640	640
Debentures | Debenture 2020A, 0.65 Percent, Due 2023
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		0.65%
TOTAL	[2]	$ 650	0
Debentures | Debenture 2014B, 3.30 Percent, Due 2024
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.30%
TOTAL		$ 250	250
Debentures | Debenture 2014B, 3.30 Percent, Due 2024 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.30%
TOTAL		$ 250	250
Debentures | Debenture Series 2016B, 2.90% Due 2026
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		2.90%
TOTAL		$ 250	250
Debentures | Debenture Series 2016B, 2.90% Due 2026 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		2.90%
TOTAL		$ 250	250
Debentures | Debenture Series 1997F, 6.50% Due 2027
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.50%
TOTAL		$ 80	80
Debentures | Debenture Series 2017B, 3.125% Due 2027
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.125%
TOTAL		$ 350	350
Debentures | Debenture Series 2017B, 3.125% Due 2027 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.125%
TOTAL		$ 350	350
Debentures | Debenture Series 2018A, 3.80% Due 2028
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.80%
TOTAL		$ 300	300
Debentures | Debenture Series 2018A, 3.80% Due 2028 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.80%
TOTAL		$ 300	300
Debentures | Debenture Series 2018D, 4.00% Due 2028
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.00%
TOTAL		$ 500	500
Debentures | Debenture Series 2018D, 4.00% Due 2028 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.00%
TOTAL		$ 500	500
Debentures | Debenture 2019B, 2.94 Percent, Due 2029
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		2.94%
TOTAL		$ 44	44
Debentures | Debenture 2020A, 3.35 Percent, Due 2030
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.35%
TOTAL		$ 600	0
Debentures | Debenture 2020A, 3.35 Percent, Due 2030 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.35%
TOTAL		$ 600	0
Debentures | Debenture 2020A, 2.02 Percent, Due 2030
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		2.02%
TOTAL		$ 35	0
Debentures | Debenture Series 2003A, 5.875% Due 2033
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.875%
TOTAL		$ 175	175
Debentures | Debenture Series 2003A, 5.875% Due 2033 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.875%
TOTAL		$ 175	175
Debentures | Debenture Series 2003C, 5.10% Due 2033
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.10%
TOTAL		$ 200	200
Debentures | Debenture Series 2003C, 5.10% Due 2033 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.10%
TOTAL		$ 200	200
Debentures | Debenture Series 2004B, 5.70% Due 2034
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
TOTAL		$ 200	200
Debentures | Debenture Series 2004B, 5.70% Due 2034 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
TOTAL		$ 200	200
Debentures | Debenture Series 2005A, 5.30% Due 2035
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.30%
TOTAL		$ 350	350
Debentures | Debenture Series 2005A, 5.30% Due 2035 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.30%
TOTAL		$ 350	350
Debentures | Debenture Series 2005B, 5.25% Due 2035
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.25%
TOTAL		$ 125	125
Debentures | Debenture Series 2005B, 5.25% Due 2035 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.25%
TOTAL		$ 125	125
Debentures | Debenture Series 2006A, 5.85% Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.85%
TOTAL		$ 400	400
Debentures | Debenture Series 2006A, 5.85% Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.85%
TOTAL		$ 400	400
Debentures | Debenture Series 2006B, 6.20% Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.20%
TOTAL		$ 400	400
Debentures | Debenture Series 2006B, 6.20% Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.20%
TOTAL		$ 400	400
Debentures | Debenture Series 2006E, 5.70% Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
TOTAL		$ 250	250
Debentures | Debenture Series 2006E, 5.70% Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
TOTAL		$ 250	250
Debentures | Debenture Series 2007A, 6.30% Due 2037
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.30%
TOTAL		$ 525	525
Debentures | Debenture Series 2007A, 6.30% Due 2037 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.30%
TOTAL		$ 525	525
Debentures | Debenture 2008B, 6.75 Percent, Due 2038
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.75%
TOTAL		$ 600	600
Debentures | Debenture 2008B, 6.75 Percent, Due 2038 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.75%
TOTAL		$ 600	600
Debentures | Debenture 2009B, 6.00 Percent, Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.00%
TOTAL		$ 60	60
Debentures | Debenture 2009C, 5.50 Percent, Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
TOTAL		$ 600	600
Debentures | Debenture 2009C, 5.50 Percent, Due 2039 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
TOTAL		$ 600	600
Debentures | Debenture 2019C, 3.46 Percent, Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.46%
TOTAL		$ 38	38
Debentures | Debenture 2010B, 5.70 Percent, Due 2040
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
TOTAL		$ 350	350
Debentures | Debenture 2010B, 5.70 Percent, Due 2040 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
TOTAL		$ 350	350
Debentures | Debenture 2010B, 5.50 Percent, Due 2040
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
TOTAL		$ 115	115
Debentures | Debenture 2012A, 4.20 Percent, Due 2042
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.20%
TOTAL		$ 400	400
Debentures | Debenture 2012A, 4.20 Percent, Due 2042 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.20%
TOTAL		$ 400	400
Debentures | Debenture 2013A, 3.95 Percent, Due 2043
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.95%
TOTAL		$ 700	700
Debentures | Debenture 2013A, 3.95 Percent, Due 2043 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.95%
TOTAL		$ 700	700
Debentures | Debenture 2014A, 4.45 Percent, Due 2044
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL		$ 850	850
Debentures | Debenture 2014A, 4.45 Percent, Due 2044 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL		$ 850	850
Debentures | Debenture 2015A, 4.50 Percent, Due 2045
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.50%
TOTAL		$ 650	650
Debentures | Debenture 2015A, 4.50 Percent, Due 2045 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.50%
TOTAL		$ 650	650
Debentures | Debenture 2015A, 4.95 Percent, Due 2045
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.95%
TOTAL		$ 120	120
Debentures | Debenture Series 2015B, 4.69% due 2045
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.69%
TOTAL		$ 100	100
Debentures | Debenture 2016A, 3.85 Percent, Due 2046
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.85%
TOTAL		$ 550	550
Debentures | Debenture 2016A, 3.85 Percent, Due 2046 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.85%
TOTAL		$ 550	550
Debentures | Debenture Series 2016A. 3.88% Due 2046
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.88%
TOTAL		$ 75	75
Debentures | Debenture Series 2017A, 3.875% Due 2047
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.875%
TOTAL		$ 500	500
Debentures | Debenture Series 2017A, 3.875% Due 2047 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.875%
TOTAL		$ 500	500
Debentures | Debenture Series 2018E, 4.65% Due 2048
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.65%
TOTAL		$ 600	600
Debentures | Debenture Series 2018E, 4.65% Due 2048 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.65%
TOTAL		$ 600	600
Debentures | Debenture Series 2018A, 4.35% Due 2048
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.35%
TOTAL		$ 125	125
Debentures | Debenture Series 2018B, 4.35% Due 2048
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.35%
TOTAL		$ 25	25
Debentures | Debenture 2019A, 4.125 Percent, Due 2049
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.125%
TOTAL		$ 700	700
Debentures | Debenture 2019A, 4.125 Percent, Due 2049 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.125%
TOTAL		$ 700	700
Debentures | Debenture 2019A, 3.73 Percent, Due 2049
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.73%
TOTAL		$ 43	43
Debentures | Debenture 2020B, 3.95 Percent, Due 2050
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.95%
TOTAL		$ 1,000	0
Debentures | Debenture 2020B, 3.95 Percent, Due 2050 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.95%
TOTAL		$ 1,000	0
Debentures | Debenture 2020B, 3.24 Percent, Due 2050
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.24%
TOTAL		$ 40	0
Debentures | Debenture Series 2014C, 4.625% Due 2054
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.625%
TOTAL		$ 750	750
Debentures | Debenture Series 2014C, 4.625% Due 2054 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.625%
TOTAL		$ 750	750
Debentures | Debenture Series 2016C, 4.30% Due 2056
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.30%
TOTAL		$ 500	500
Debentures | Debenture Series 2016C, 4.30% Due 2056 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.30%
TOTAL		$ 500	500
Debentures | Debenture Series 2017C, 4.00% Due 2057
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.00%
TOTAL		$ 350	350
Debentures | Debenture Series 2017C, 4.00% Due 2057 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.00%
TOTAL		$ 350	350
Debentures | Debenture Series 2018B, 4.50% Due 2058
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.50%
TOTAL		$ 700	700
Debentures | Debenture Series 2018B, 4.50% Due 2058 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.50%
TOTAL		$ 700	700
Debentures | Debenture 2019B, 3.70 Percent, Due 2059
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.70%
TOTAL		$ 600	600
Debentures | Debenture 2019B, 3.70 Percent, Due 2059 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.70%
TOTAL		$ 600	600
Debentures | Debenture 2020C, 3.00 Percent, Due 2060
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.00%
TOTAL		$ 600	0
Debentures | Debenture 2020C, 3.00 Percent, Due 2060 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.00%
TOTAL		$ 600	0
Debentures | Debenture 2018C, 2.75 Percent, Due 2021 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		0.65%
TOTAL		$ 640	640
Tax-Exempt Debt
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		450	450
Tax-Exempt Debt | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		$ 450	450
Tax-Exempt Debt | Tax Exempt Debt Series 2010A Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		0.11%
TOTAL PROJECT DEBT	[2]	$ 225	225
Tax-Exempt Debt | Tax Exempt Debt Series 2010A Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		0.11%
TOTAL	[3]	$ 225	225
Tax-Exempt Debt | Tax Exempt Debt Series 2004C, 1.663% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		0.11%
TOTAL PROJECT DEBT	[2]	$ 99	99
Tax-Exempt Debt | Tax Exempt Debt Series 2004C, 1.663% Due 2039 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		0.11%
TOTAL	[3]	$ 99	99
Tax-Exempt Debt | Tax-Exempt Debt Series 2005A, 1.627% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		0.09%
TOTAL PROJECT DEBT	[2]	$ 126	126
Tax-Exempt Debt | Tax-Exempt Debt Series 2005A, 1.627% Due 2039 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		0.09%
TOTAL	[3]	$ 126	$ 126

[1] December 31, 2020 effective rates shown, reflecting variable interest rates on the debt that are reset quarterly or semi-annually and the effect of applicable interest rate swaps, if any

[2] Rates reset weekly or quarterly; December 31, 2020 rates shown.

[3] Rates reset weekly or quarterly; December 31, 2020 rates shown.