Capitalization - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended																	12 Months Ended		12 Months Ended
	Dec. 31, 2013 Y	Dec. 31, 2012	Dec. 31, 2013 Level 2 [Member]	Dec. 31, 2013 Level 3 [Member]	Dec. 31, 2013 Minimum [Member]	Oct. 31, 2011 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Oct. 31, 2011 Maximum [Member]	Dec. 31, 2013 Transition Bonds, Issued in 2004 [Member]	Dec. 31, 2012 Transition Bonds, Issued in 2004 [Member]	Dec. 31, 2013 CECONY [Member]		Dec. 31, 2012 CECONY [Member]		May 31, 2012 CECONY [Member]	Dec. 31, 2013 CECONY [Member] Level 2 [Member]	Dec. 31, 2013 CECONY [Member] Level 3 [Member]	Dec. 31, 2013 CECONY [Member] Minimum [Member]	Dec. 31, 2011 CECONY [Member] Minimum [Member]	Dec. 31, 2013 CECONY [Member] Maximum [Member]	Dec. 31, 2011 CECONY [Member] Maximum [Member]	Dec. 31, 2013 Con Edison [Member] Minimum [Member]	Dec. 31, 2013 Con Edison [Member] Maximum [Member]
Schedule of Capitalization [Line Items]
Common stock shares, outstanding	21,976,200	21,976,200
Outstanding shares of Cumulative Preferred Stock															5
Cumulative Preferred Stock, par value															$ 100
Percentage limitation for income available for dividends	100.00%
Rolling average calculation of income available for dividends, years	2
Tax-exempt debt issued, value	$ 494
Long-term debt, fair value	12,082	12,935	11,446	636							10,797		11,751			10,161	636
Long-term debt	10,974	10,768							22	25	9,841	[1]	9,845	[1]
Debt instrument, covenant description	Con Edison's ratio of consolidated debt to consolidated capital to exceed 0.675 to 1
Covenant principal balance amount limit	$ 100																	$ 150		$ 100
Ratio of consolidated debt to consolidated capital					0.500	0.650	1.000	1.000										0.500	0.650	1.000	1.000	0.675	1.000

[1] Rates are to be reset weekly or by auction held every 35 days; December 31, 2013 rates shown.