Schedule I - Condensed Financial Information - Condensed Statement of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Cash Flow Statements, Captions [Line Items]
Net Income	$ 1,092	$ 1,062	$ 1,138
Common stock dividends	739us-gaap_PaymentsOfDividendsCommonStock	721us-gaap_PaymentsOfDividendsCommonStock	709us-gaap_PaymentsOfDividendsCommonStock
Change in Assets:
Special deposits	312us-gaap_IncreaseDecreaseInDeposits	(257)us-gaap_IncreaseDecreaseInDeposits	(13)us-gaap_IncreaseDecreaseInDeposits
Income taxes receivable	(224)
Other - net	4	34	40
Net Cash Flows from Operating Activities	2,831	2,552	2,599
INVESTING ACTIVITIES
Net Cash Flows Used in Investing Activities	(2,759)	(2,659)	(2,523)
FINANCING ACTIVITIES
Net proceeds of short-term debt	(651)	912	539
Retirement of long-term debt	(480)us-gaap_RepaymentsOfLongTermDebt	(709)us-gaap_RepaymentsOfLongTermDebt	(305)us-gaap_RepaymentsOfLongTermDebt
Common stock dividends	739us-gaap_PaymentsOfDividendsCommonStock	721us-gaap_PaymentsOfDividendsCommonStock	709us-gaap_PaymentsOfDividendsCommonStock
NET CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES	(47)	387	(330)
NET CHANGE FOR THE PERIOD	25	280	(254)
BALANCE AT BEGINNING OF PERIOD	674	394	648
BALANCE AT END OF PERIOD	699	674	394
Consolidated Edison Inc [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net Income	1,092	1,062	1,138
Common stock dividends	(739)	(721)	(709)
Equity in earnings of subsidiaries	(1,101)	(1,062)	(1,154)
Change in Assets:
Special deposits	314	(264)
Income taxes receivable	(224)
Other - net	(199)	166	(208)
Net Cash Flows from Operating Activities	642	680	503
INVESTING ACTIVITIES
Contributions to subsidiaries	(1)		(100)
Net Cash Flows Used in Investing Activities	(1)		(100)
FINANCING ACTIVITIES
Net proceeds of short-term debt	101	58	115
Retirement of long-term debt	(2)	(1)	(1)
Issuance of common shares for stock plans, net of repurchases	(10)	(8)	(9)
Common stock dividends	(739)	(721)	(709)
NET CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES	(650)	(672)	(604)
NET CHANGE FOR THE PERIOD	(9)	8	(201)
BALANCE AT BEGINNING OF PERIOD	12	4	205
BALANCE AT END OF PERIOD	3	12	4
CECONY [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net Income	1,058	1,020	1,014
Change in Assets:
Other - net	35	(88)	(40)
Net Cash Flows from Operating Activities	2,430	2,643	2,346
INVESTING ACTIVITIES
Net Cash Flows Used in Investing Activities	(2,304)	(2,417)	(1,958)
FINANCING ACTIVITIES
Net proceeds of short-term debt	(760)	789	421
Retirement of long-term debt	(475)	(700)	(300)
NET CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES	(114)	54	(407)
NET CHANGE FOR THE PERIOD	12	280	(19)
BALANCE AT BEGINNING OF PERIOD	633	353	372
BALANCE AT END OF PERIOD	645	633	353
CECONY [Member] \| Consolidated Edison Inc [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Common stock dividends	712	728	682
FINANCING ACTIVITIES
Common stock dividends	712	728	682
O&R [Member] \| Consolidated Edison Inc [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Common stock dividends	40	38	34
FINANCING ACTIVITIES
Common stock dividends	40	38	34
Competitive Energy Businesses [Member] \| Consolidated Edison Inc [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Common stock dividends	8	12	11
FINANCING ACTIVITIES
Common stock dividends	$ 8	$ 12	$ 11

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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The net cash inflow or outflow for the increase (decrease) in the beginning and end of period deposits balances.

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Amount of cash inflow (outflow) of investing activities, excluding discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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