Pension Benefits - Schedule of Employer Contribution to Defined Savings Plan (Detail) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Employer contribution to the defined savings plan	$ 34	$ 32	$ 30
CECONY
Defined Benefit Plan Disclosure [Line Items]
Employer contribution to the defined savings plan	$ 29	$ 27	$ 26

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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