Short-Term Borrowing - Additional Information (Detail) (USD $)	12 Months Ended									12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 October 2016 [Member]	Dec. 31, 2013 Minimum [Member]	Oct. 31, 2011 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Oct. 31, 2011 Maximum [Member]	Dec. 31, 2013 Letters of Credit [Member] October 2016 [Member]	Dec. 31, 2013 Letters of Credit [Member] October 2017 [Member]	Dec. 31, 2013 CECONY [Member]	Dec. 31, 2012 CECONY [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]
Short-term Debt [Line Items]
Credit facility expiry date	Oct. 31, 2017
Maximum borrowing capacity								$ 2,250,000,000	$ 2,100,000,000
Current amount available			1,000,000,000					1,200,000,000
Commercial paper, outstanding	1,451,000,000	539,000,000								1,210,000,000	421,000,000
Weighted average interest rate	0.20%	0.30%								0.20%	0.30%
Letters of credit outstanding under the Credit Agreement	$ 26,000,000	$ 131,000,000								$ 11,000,000	$ 121,000,000
Line of credit facility, covenant terms	Ratio of consolidated debt to consolidated total capital of 0.65 to 1 (at December 31, 2013 this ratio was 0.50 to 1 for Con Edison and CECONY); having liens on its assets in an aggregate amount exceeding 5 percent of its consolidated total capital, subject to certain exceptions; and the failure, following any applicable notice period, to meet certain other customary covenants.
Ratio of consolidated debt to consolidated total capital				0.500	0.650	1.000	1.000					0.500	0.650	1.000	1.000
Minimum percentage of liens on assets				5.00%