Acquisitions, Investments and Dispositions - Con Edison Solutions' Retail Electric Supply Business (Details) - Retail Electric Supply Business - USD ($) $ in Millions	1 Months Ended
Sep. 30, 2016	Dec. 31, 2015
Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of business	$ 235
Gain on sale of business	104
Gain on sale of business, after tax	56
Gain on sale of derivatives	65
Gain on sale of derivatives, after tax	42
Tax effect of sale, state tax related to change in apportionment of state income taxes	16
Tax effect of sale, state tax related to change in apportionment of state income taxes, net of federal tax	$ 10
Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale		$ 134
Liabilities held for sale		$ 84

Gain (Loss) on Disposition of Business, Derivative

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Gain (Loss) on Disposition of Business, Derivative, Net of Tax

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Gain (Loss) on Disposition of Business, Net

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Gain (Loss) on Disposition of Business, State Tax Apportionment

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Gain (Loss) on Disposition of Business, State Tax Apportionment, Net of Federal Tax

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No definition available.

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Amount classified as assets attributable to disposal group held for sale or disposed of.

+ References

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Gain (loss) from sale or disposal of an organization or integrated set of activities (for example, but not limited to, a partnership or corporation) engaged in providing a product or service in a commercial, industrial, or professional environment.

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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.

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Amount classified as liabilities attributable to disposal group held for sale or disposed of.

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The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

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