Consolidated Statement of Capitalization - Long-term Debt - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Schedule of Capitalization, Long-term Debt [Line Items]
Other long-term debt		$ 304	$ 310
Unamortized debt expense		(152)	(113)
Unamortized debt discount		(33)	(29)
TOTAL		18,145	16,029
Less: Long-term debt due within one year		650	1,298
TOTAL LONG-TERM DEBT		17,495	14,731
TOTAL CAPITALIZATION		34,221	30,149
CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Unamortized debt expense		(107)	(94)
Unamortized debt discount		(32)	(27)
TOTAL		14,151	13,265
Less: Long-term debt due within one year		475	1,200
TOTAL LONG-TERM DEBT		13,676	12,065
TOTAL CAPITALIZATION		26,586	24,504
Copper Mountain Solar 2
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		230	0
Coram
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		$ 160	170
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]
TOTAL PROJECT DEBT		$ 298	0
Wind Holdings
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.41%
TOTAL PROJECT DEBT		$ 137	0
Copper Mountain Solar 1
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		70	0
Mesquite Solar 1
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		$ 208	0
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%
Broken Bow II
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.82%
TOTAL PROJECT DEBT		$ 69	0
Texas Solar 4
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		$ 58	61
Texas Solar 4 | Minimum
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.95%
Texas Solar 4 | Maximum
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.25%
California Solar 2
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.94%
TOTAL PROJECT DEBT		$ 103	110
California Solar 3
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.07%
TOTAL PROJECT DEBT		$ 89	93
California Solar
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.78%
TOTAL PROJECT DEBT		$ 190	0
Texas Solar 5
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.53%
TOTAL PROJECT DEBT		$ 150	155
Texas Solar 7
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.21%
TOTAL PROJECT DEBT		$ 206	214
Upton County Solar
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL PROJECT DEBT		$ 94	97
Other project debt
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		14	15
Project Debt
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT		2,076	915
Debentures
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		15,500	13,860
Debentures | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		$ 13,840	12,300
Debentures | Debenture Series 2008A, 5.85% Due 2018
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.85%
TOTAL		$ 0	600
Debentures | Debenture Series 2008A, 5.85% Due 2018 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.85%
TOTAL		$ 0	600
Debentures | Debenture Series 2008A, 6.15% Due 2018
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.15%
TOTAL		$ 0	50
Debentures | Debenture Series 2008C, 7.125% Due 2018
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		7.125%
TOTAL		$ 0	600
Debentures | Debenture Series 2008C, 7.125% Due 2018 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		7.125%
TOTAL		$ 0	600
Debentures | Debenture Series 2009A, 4.96% Due 2019
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.96%
TOTAL		$ 60	60
Debentures | Debenture Series 2009B, 6.65% Due 2019
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.65%
TOTAL		$ 475	475
Debentures | Debenture Series 2009B, 6.65% Due 2019 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.65%
TOTAL		$ 475	475
Debentures | Debenture Series 2010A, 4.45% Due 2020
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL		$ 350	350
Debentures | Debenture Series 2010A, 4.45% Due 2020 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL		$ 350	350
Debentures | Debenture Series 2017A, 2.00% Due 2020
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		2.00%
TOTAL		$ 400	400
Debentures | Debenture Series 2018C, Variable Rate, Due 2021
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		640	0
Debentures | Debenture Series 2018C, Variable Rate, Due 2021 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		$ 640	0
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 Series 2014B, 3.30% Due 2024
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.30%
TOTAL		$ 250	250
Debentures | Debenture Series 2014B, 3.30% 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	0
Debentures | Debenture Series 2018A, 3.80% Due 2028 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.80%
TOTAL		$ 300	0
Debentures | Debenture Series 2018D, 4.00% Due 2028
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.00%
TOTAL		$ 500	0
Debentures | Debenture Series 2018D, 4.00% Due 2028 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.00%
TOTAL		$ 500	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 Series 2008B, 6.75% Due 2038
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.75%
TOTAL		$ 600	600
Debentures | Debenture Series 2008B, 6.75% Due 2038 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.75%
TOTAL		$ 600	600
Debentures | Debenture Series 2009B, 6.00% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.00%
TOTAL		$ 60	60
Debentures | Debenture Series 2009C, 5.50% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
TOTAL		$ 600	600
Debentures | Debenture Series 2009C, 5.50% Due 2039 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
TOTAL		$ 600	600
Debentures | Debenture Series 2010B, 5.70% Due 2040
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
TOTAL		$ 350	350
Debentures | Debenture Series 2010B, 5.70% Due 2040 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
TOTAL		$ 350	350
Debentures | Debenture Series 2010B, 5.50% Due 2040
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
TOTAL		$ 115	115
Debentures | Debenture Series 2012A, 4.20% Due 2042
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.20%
TOTAL		$ 400	400
Debentures | Debenture Series 2012A, 4.20% Due 2042 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.20%
TOTAL		$ 400	400
Debentures | Debenture Series 2013A, 3.95% Due 2043
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.95%
TOTAL		$ 700	700
Debentures | Debenture Series 2013A, 3.95% Due 2043 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.95%
TOTAL		$ 700	700
Debentures | Debenture Series 2014A, 4.45% Due 2044
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL		$ 850	850
Debentures | Debenture Series 2014A, 4.45% Due 2044 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
TOTAL		$ 850	850
Debentures | Debenture Series 2015A, 4.50% due 2045
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.50%
TOTAL		$ 650	650
Debentures | Debenture Series 2015A, 4.50% due 2045 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.50%
TOTAL		$ 650	650
Debentures | Debenture Series 2015A, 4.95% 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 Series 2016A, 3.85% Due 2046
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.85%
TOTAL		$ 550	550
Debentures | Debenture Series 2016A, 3.85% 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	0
Debentures | Debenture Series 2018E, 4.65% Due 2048 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.65%
TOTAL		$ 600	0
Debentures | Debenture Series 2018A, 4.35% Due 2048
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.35%
TOTAL		$ 125	0
Debentures | Debenture Series 2018B, 4.35% Due 2048
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.35%
TOTAL		$ 25	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		400.00%
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	0
Debentures | Debenture Series 2018B, 4.50% Due 2058 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.50%
TOTAL		$ 700	0
Tax-Exempt Debt
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT	[1]	450	1,086
Tax-Exempt Debt | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		450	1,086
Tax-Exempt Debt | Tax Exempt Debt Series 2004B Series 1, 2.45% Due 2032
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT	[1]	0	127
Tax-Exempt Debt | Tax Exempt Debt Series 2004B Series 1, 2.45% Due 2032 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		0	127
Tax-Exempt Debt | Tax Exempt Debt Series 1999A, 1.834% Due 2034
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT	[1]	0	293
Tax-Exempt Debt | Tax Exempt Debt Series 1999A, 1.834% Due 2034 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		0	293
Tax-Exempt Debt | Tax Exempt Debt Series 2004B Series 2, 1.68% Due 2035
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT	[1]	0	20
Tax-Exempt Debt | Tax Exempt Debt Series 2004B Series 2, 1.68% Due 2035 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		0	20
Tax-Exempt Debt | Tax Exempt Debt Series 2001B, 1.796% Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT	[1]	0	98
Tax-Exempt Debt | Tax Exempt Debt Series 2001B, 1.796% Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		$ 0	98
Tax-Exempt Debt | Tax Exempt Debt Series 2010A Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	1.74%
TOTAL PROJECT DEBT	[1]	$ 225	225
Tax-Exempt Debt | Tax Exempt Debt Series 2010A Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		1.74%
TOTAL		$ 225	225
Tax-Exempt Debt | Tax Exempt Debt Series 2004A, 1.943% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL PROJECT DEBT	[1]	0	98
Tax-Exempt Debt | Tax Exempt Debt Series 2004A, 1.943% Due 2039 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL		$ 0	98
Tax-Exempt Debt | Tax Exempt Debt Series 2004C, 1.663% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	1.75%
TOTAL PROJECT DEBT	[1]	$ 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		1.75%
TOTAL		$ 99	99
Tax-Exempt Debt | Tax-Exempt Debt Series 2005A, 1.627% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	1.71%
TOTAL PROJECT DEBT	[1]	$ 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		1.71%
TOTAL		$ 126	$ 126

[1] Rates are to be reset weekly; December 31, 2018 rates shown.