Short-Term Borrowing (Details) - USD ($)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Commercial paper, outstanding	$ 577,000,000	$ 1,054,000,000
Weighted average interest rate	1.80%	1.00%
Loans outstanding under credit agreement	$ 0	$ 0
Letters of credit outstanding under the Credit Agreement	$ 0	2,000,000
Ratio of consolidated debt to consolidated total capital	0.51
Minimum percentage of liens on assets	5.00%
Maximum
Short-term Debt [Line Items]
Ratio of consolidated debt to consolidated total capital	0.65
Revolving Credit
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 1,500,000,000
Current amount available	1,000,000,000
Letters of Credit
Short-term Debt [Line Items]
Maximum borrowing capacity	1,200,000,000
CECONY
Short-term Debt [Line Items]
Commercial paper, outstanding	$ 150,000,000	$ 600,000,000
Weighted average interest rate	1.80%	1.00%
Letters of credit outstanding under the Credit Agreement		$ 2,000,000
Ratio of consolidated debt to consolidated total capital	0.52
CECONY \| Maximum
Short-term Debt [Line Items]
Ratio of consolidated debt to consolidated total capital	0.65
CECONY \| Revolving Credit
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 2,250,000,000

Percentage Of Liens Of Companies Consolidated Asset

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- Definition

Weighted Average Interest Rate Of Commercial Paper

+ References

No definition available.

+ Details

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- Definition

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13)(2))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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- Definition

Carrying value as of the balance sheet date of portion of long-term loans payable due within one year or the operating cycle if longer.

+ References

+ Details

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- Definition

Indebtedness divided by net capital.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

+ Details

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