Other Postretirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012
Schedule Of Other Postretirement Benefits [Line Items]
Contributions	$ 887	$ 821
Other Postretirement Benefits [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Contributions	9
CECONY [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Contributions	830	761
CECONY [Member] \| Other Postretirement Benefits [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Contributions	$ 9

The amount of cash or cash equivalents contributed during the reporting period by the entity to fund its pension plans and its non-pension postretirement benefit plans.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

Name:	us-gaap_PensionAndOtherPostretirementBenefitContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration