Pension Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended				12 Months Ended					12 Months Ended			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Other Nonqualified Supplemental Defined Benefit Pension [Member]	Dec. 31, 2012 Other Nonqualified Supplemental Defined Benefit Pension [Member]	Dec. 31, 2013 CECONY [Member]	Dec. 31, 2012 CECONY [Member]	Dec. 31, 2013 CECONY [Member] Other Nonqualified Supplemental Defined Benefit Pension [Member]	Dec. 31, 2012 CECONY [Member] Other Nonqualified Supplemental Defined Benefit Pension [Member]	Dec. 31, 2013 Con Edison [Member]	Dec. 31, 2013 Pension Benefits [Member]	Dec. 31, 2012 Pension Benefits [Member]	Dec. 31, 2011 Pension Benefits [Member]	Dec. 31, 2013 Pension Benefits [Member] CECONY [Member]	Dec. 31, 2012 Pension Benefits [Member] CECONY [Member]	Dec. 31, 2011 Pension Benefits [Member] CECONY [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension liability					$ 2,672				$ 2,829
Decrease to regulatory assets	2,799												(2,677)
Credit to OCI	24												3
Net loss estimated to be amortized					586					619
Prior service cost estimated to be amortized					2					4
Investments value	201	164			183	148
Accumulated benefit obligation			234	231			199	193		11,004	11,911	10,595	10,268	11,116	9,876
Assumptions used in calculating net periodic benefit cost										To determine the assumed discount rate, the Companies use a model that produces a yield curve based on yields on selected highly rated (Aa or higher by either Moody’s Investors Service (Moody’s) or Standard & Poor’s) corporate bonds. Bonds with insufficient liquidity, bonds with questionable pricing information and bonds that are not representative of the overall market are excluded from consideration. For example, the bonds used in the model cannot be callable, they must have a price between 50 percent and 200 percent of the original price, the yield must lie between 1 percent and 20 percent, and the amount of the bond issue outstanding must be in excess of $50 million. The spot rates defined by the yield curve and the plan’s projected benefit payments are used to develop a weighted average discount rate.
Estimated future employer contributions										$ 575			$ 536