Consolidated Statement of Capitalization - Long-term Debt - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL DEBENTURES		$ 11,110	$ 10,685
TOTAL TRANSITION BONDS		14	18
TOTAL TAX-EXEMPT DEBT		1,086	1,130
Other long-term debt		648	380
Unamortized debt expense		(91)	(85)
Unamortized debt discount		(22)	(22)
TOTAL		12,745	12,106
Less: Long-term debt due within one year		739	560
TOTAL LONG-TERM DEBT		12,006	11,546
TOTAL CAPITALIZATION		25,058	24,122
CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
TOTAL DEBENTURES		10,450	10,150
TOTAL TAX-EXEMPT DEBT		1,086	1,086
Unamortized debt expense		(78)	(76)
Unamortized debt discount		(21)	(22)
TOTAL		11,437	11,138
Less: Long-term debt due within one year		650	350
TOTAL LONG-TERM DEBT		10,787	10,788
TOTAL CAPITALIZATION		$ 22,202	21,976
Debenture Series 2005C, 5.375% due 2015
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.375%
Debt instrument, fair value		$ 0	350
Debenture Series 2005C, 5.375% due 2015 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.375%
Debt instrument, fair value		$ 0	350
Debenture Series 2005A, 5.30% due 2015
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.30%
Debt instrument, fair value		$ 0	40
Debenture Series 2010A, 2.50% Due 2015
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		2.50%
Debt instrument, fair value		$ 0	55
Debenture Series 2006A, 5.45% Due 2016
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.45%
Debt instrument, fair value		$ 75	75
Debenture Series 2006C, 5.50% Due 2016
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
Debt instrument, fair value		$ 400	400
Debenture Series 2006C, 5.50% Due 2016 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
Debt instrument, fair value		$ 400	400
Debenture Series 2006D, 5.30% Due 2016
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.30%
Debt instrument, fair value		$ 250	250
Debenture Series 2006D, 5.30% Due 2016 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.30%
Debt instrument, fair value		$ 250	250
Debenture Series 2008A, 5.85% Due 2018
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.85%
Debt instrument, fair value		$ 600	600
Debenture Series 2008A, 5.85% Due 2018 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.85%
Debt instrument, fair value		$ 600	600
Debenture Series 2008A, 6.15% Due 2018
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.15%
Debt instrument, fair value		$ 50	50
Debenture Series 2008C, 7.125% Due 2018
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		7.125%
Debt instrument, fair value		$ 600	600
Debenture Series 2008C, 7.125% Due 2018 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		7.125%
Debt instrument, fair value		$ 600	600
Debenture Series 2009A, 4.96% Due 2019
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.96%
Debt instrument, fair value		$ 60	60
Debenture Series 2009B, 6.65% Due 2019
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.65%
Debt instrument, fair value		$ 475	475
Debenture Series 2009B, 6.65% Due 2019 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.65%
Debt instrument, fair value		$ 475	475
Debenture Series 2010A, 4.45% Due 2020
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
Debt instrument, fair value		$ 350	350
Debenture Series 2010A, 4.45% Due 2020 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
Debt instrument, fair value		$ 350	350
Debenture Series 2014B, 3.30% Due 2024
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.30%
Debt instrument, fair value		$ 250	250
Debenture Series 2014B, 3.30% Due 2024 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.30%
Debt instrument, fair value		$ 250	250
Debenture Series 1997F, 6.50% Due 2027
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.50%
Debt instrument, fair value		$ 80	80
Debenture Series 2003A, 5.875% Due 2033
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.875%
Debt instrument, fair value		$ 175	175
Debenture Series 2003A, 5.875% Due 2033 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.875%
Debt instrument, fair value		$ 175	175
Debenture Series 2003C, 5.10% Due 2033
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.10%
Debt instrument, fair value		$ 200	200
Debenture Series 2003C, 5.10% Due 2033 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.10%
Debt instrument, fair value		$ 200	200
Debenture Series 2004B, 5.70% Due 2034
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
Debt instrument, fair value		$ 200	200
Debenture Series 2004B, 5.70% Due 2034 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
Debt instrument, fair value		$ 200	200
Debenture Series 2005A, 5.30% Due 2035
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.30%
Debt instrument, fair value		$ 350	350
Debenture Series 2005A, 5.30% Due 2035 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.30%
Debt instrument, fair value		$ 350	350
Debenture Series 2005B, 5.25% Due 2035
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.25%
Debt instrument, fair value		$ 125	125
Debenture Series 2005B, 5.25% Due 2035 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.25%
Debt instrument, fair value		$ 125	125
Debenture Series 2006A, 5.85% Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.85%
Debt instrument, fair value		$ 400	400
Debenture Series 2006A, 5.85% Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.85%
Debt instrument, fair value		$ 400	400
Debenture Series 2006B, 6.20% Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.20%
Debt instrument, fair value		$ 400	400
Debenture Series 2006B, 6.20% Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.20%
Debt instrument, fair value		$ 400	400
Debenture Series 2006E, 5.70% Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
Debt instrument, fair value		$ 250	250
Debenture Series 2006E, 5.70% Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
Debt instrument, fair value		$ 250	250
Debenture Series 2007A, 6.30% Due 2037
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.30%
Debt instrument, fair value		$ 525	525
Debenture Series 2007A, 6.30% Due 2037 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.30%
Debt instrument, fair value		$ 525	525
Debenture Series 2008B, 6.75% Due 2038
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.75%
Debt instrument, fair value		$ 600	600
Debenture Series 2008B, 6.75% Due 2038 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.75%
Debt instrument, fair value		$ 600	600
Debenture Series 2009B, 6.00% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		6.00%
Debt instrument, fair value		$ 60	60
Debenture Series 2009C, 5.50% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
Debt instrument, fair value		$ 600	600
Debenture Series 2009C, 5.50% Due 2039 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
Debt instrument, fair value		$ 600	600
Debenture Series 2010B, 5.70% Due 2040
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
Debt instrument, fair value		$ 350	350
Debenture Series 2010B, 5.70% Due 2040 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.70%
Debt instrument, fair value		$ 350	350
Debenture Series 2010B, 5.50% Due 2040
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		5.50%
Debt instrument, fair value		$ 115	115
Debenture Series 2012A, 4.20% Due 2042
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.20%
Debt instrument, fair value		$ 400	400
Debenture Series 2012A, 4.20% Due 2042 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.20%
Debt instrument, fair value		$ 400	400
Debenture Series 2013A, 3.95% Due 2043
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.95%
Debt instrument, fair value		$ 700	700
Debenture Series 2013A, 3.95% Due 2043 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		3.95%
Debt instrument, fair value		$ 700	700
Debenture Series 2014A, 4.45% Due 2044
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
Debt instrument, fair value		$ 850	850
Debenture Series 2014A, 4.45% Due 2044 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.45%
Debt instrument, fair value		$ 850	850
Debenture Series 2015A, 4.50% due 2045
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.50%
Debt instrument, fair value		$ 650
Debenture Series 2015A, 4.50% due 2045 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.50%
Debt instrument, fair value		$ 650	0
Debenture Series 2015A, 4.95% due 2045
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.95%
Debt instrument, fair value		$ 120
Debenture Series 2015B, 4.69% due 2045
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.69%
Debt instrument, fair value		$ 100
Debenture Series 2014C, 4.625% Due 2054
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.625%
Debt instrument, fair value		$ 750	750
Debenture Series 2014C, 4.625% Due 2054 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate		4.625%
Debt instrument, fair value		$ 750	750
Debenture Series 2004-1, 5.22% Due 2019
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	5.22%
Debt instrument, fair value	[1]	$ 14	18
Debenture Series 1995, 0.00% Due 2015
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[2],[3]	0.00%
Debt instrument, fair value	[2],[3]	$ 0	44
Tax Exempt Debt Series 2004B-1, 0.42% Due 2032
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[3]	0.42%
Debt instrument, fair value	[3]	$ 127	127
Tax Exempt Debt Series 2004B-1, 0.42% Due 2032 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	0.42%
Debt instrument, fair value	[1]	$ 127	127
Tax Exempt Debt Series 1999A, .34% Due 2034
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[3]	0.34%
Debt instrument, fair value	[3]	$ 293	293
Tax Exempt Debt Series 1999A, .34% Due 2034 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	0.34%
Debt instrument, fair value	[1]	$ 293	293
Tax Exempt Debt Series 2004B Series 2, .44% Due 2035
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[3]	0.44%
Debt instrument, fair value	[3]	$ 20	20
Tax Exempt Debt Series 2004B Series 2, .44% Due 2035 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	0.44%
Debt instrument, fair value	[1]	$ 20	20
Tax-Exempt Debt Series 2001B, 0.27% Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[3]	0.27%
Debt instrument, fair value	[3]	$ 98	98
Tax-Exempt Debt Series 2001B, 0.27% Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	0.27%
Debt instrument, fair value	[1]	$ 98	98
Tax-Exempt Debt Series 2010A, 0.01% Due 2036
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[3]	0.01%
Debt instrument, fair value	[3]	$ 225	225
Tax-Exempt Debt Series 2010A, 0.01% Due 2036 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	0.01%
Debt instrument, fair value	[1]	$ 225	225
Tax-Exempt Debt Series 2004A, 0.36% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[3]	0.36%
Debt instrument, fair value	[3]	$ 98	98
Tax-Exempt Debt Series 2004A, 0.36% Due 2039 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	0.36%
Debt instrument, fair value	[1]	$ 98	98
Tax-Exempt Debt Series 2004C, 0.01% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[3]	0.01%
Debt instrument, fair value	[3]	$ 99	99
Tax-Exempt Debt Series 2004C, 0.01% Due 2039 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	0.01%
Debt instrument, fair value	[1]	$ 99	99
Tax-Exempt Debt Series 2005A, 0.01% Due 2039
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[3]	0.01%
Debt instrument, fair value	[3]	$ 126	126
Tax-Exempt Debt Series 2005A, 0.01% Due 2039 | CECONY
Schedule of Capitalization, Long-term Debt [Line Items]
Interest Rate	[1]	0.01%
Debt instrument, fair value	[1]	$ 126	$ 126

[1] The final date to pay the entire remaining unpaid principal balance, if any, of all outstanding bonds is May 17, 2021.

[2] Issued for O&R pollution control financing.

[3] Rates are to be reset weekly or by auction held every 35 days; December 31, 2015 rates shown.