Stock-Based Compensation - Summary of Stock Options Outstanding (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining Contractual Life	1 year
Options Outstanding / Exercisable	481,310	606,475
Weighted Average Exercise Price	$ 43.383	$ 43.008
2006 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining Contractual Life	2 years
Options Outstanding / Exercisable	201,700
Weighted Average Exercise Price	$ 43.768
2005 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining Contractual Life	1 year
Options Outstanding / Exercisable	150,410
Weighted Average Exercise Price	$ 42.252
2004 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding / Exercisable	129,200
Weighted Average Exercise Price	$ 44.100
2004 [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining Contractual Life	1 year
CECONY [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding / Exercisable	381,010	481,175
Weighted Average Exercise Price	$ 43.338	$ 42.973
CECONY [Member] | 2006 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding / Exercisable	165,100
Weighted Average Exercise Price	$ 43.705
CECONY [Member] | 2005 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding / Exercisable	122,810
Weighted Average Exercise Price	$ 42.268
CECONY [Member] | 2004 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding / Exercisable	93,100
Weighted Average Exercise Price	$ 44.100