Tax Cuts And Jobs Act Of 2017, Change In Tax Rate, Deferred Income Tax Liabilities, Net, Income Tax (Expense) Benefit

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Tax Cuts And Jobs Act Of 2017, Change In Tax Rate, Regulatory Assets, Income Tax Expense (Benefit)

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Amount of regulatory costs not yet approved by the regulatory authority.

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Percentage of public utility's requested equity to capital, including debt and equity.

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Amount of public utility's requested rate increase (decrease) with regulatory agency.

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Percentage of public utility's requested return on equity.

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 50
-Paragraph 1
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section S99
-Paragraph 1
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Regulatory Matters - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended			3 Months Ended	9 Months Ended	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Apr. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2016
Public Utilities, General Disclosures [Line Items]
Regulatory assets					$ 4,333.0	$ 4,333.0		$ 7,124.0
Decrease in net deferred tax liabilities resulting from TCJA						5,312.0
Regulatory liabilities					4,577.0	4,577.0		1,905.0
Future Income Tax
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						3,713.0
Regulatory liabilities					2,545.0	2,545.0		0.0
Net Unbilled Revenue Deferrals
Public Utilities, General Disclosures [Line Items]
Regulatory liabilities					$ 183.0	183.0		145.0
Future Income Tax
Public Utilities, General Disclosures [Line Items]
Decrease in regulatory asset resulting from TCJA						1,250.0
Revenue Taxes
Public Utilities, General Disclosures [Line Items]
Decrease in regulatory asset resulting from TCJA						90.0
O&R
Public Utilities, General Disclosures [Line Items]
Decrease in net deferred tax liabilities resulting from TCJA						216.0
O&R \| Future Income Tax
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						161.0
O&R \| Future Income Tax
Public Utilities, General Disclosures [Line Items]
Decrease in regulatory asset resulting from TCJA						51.0
O&R \| Revenue Taxes
Public Utilities, General Disclosures [Line Items]
Decrease in regulatory asset resulting from TCJA						4.0
O&R \| NYSPSC \| Subsequent Event
Public Utilities, General Disclosures [Line Items]
Requested rate increase, amount		$ 4.5
Requested return on equity (percent)		9.75%
Requested equity capital structure (percent)		48.00%
O&R \| NYSPSC \| Electric \| Subsequent Event
Public Utilities, General Disclosures [Line Items]
Requested rate increase, amount	$ 20.3
Requested return on equity (percent)	9.75%
Requested equity capital structure (percent)	48.00%
RECO
Public Utilities, General Disclosures [Line Items]
Decrease in net deferred tax liabilities resulting from TCJA						45.0
RECO \| Future Income Tax
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						28.0
RECO \| Future Income Tax
Public Utilities, General Disclosures [Line Items]
Decrease in regulatory asset resulting from TCJA						17.0
RECO \| Revenue Taxes
Public Utilities, General Disclosures [Line Items]
Decrease in regulatory asset resulting from TCJA						0.0
RECO \| FERC
Public Utilities, General Disclosures [Line Items]
Requested rate increase, amount			$ 17.7	$ 11.8
Requested return on equity (percent)					10.00%
CECONY
Public Utilities, General Disclosures [Line Items]
Regulatory assets					$ 3,925.0	3,925.0		6,563.0
Decrease in net deferred tax liabilities resulting from TCJA						4,781.0
Regulatory liabilities					4,219.0	4,219.0		1,712.0
CECONY \| Future Income Tax
Public Utilities, General Disclosures [Line Items]
Increase in regulatory liability resulting from TCJA						3,513.0
Regulatory liabilities					2,390.0	2,390.0		0.0
CECONY \| Net Unbilled Revenue Deferrals
Public Utilities, General Disclosures [Line Items]
Regulatory liabilities					183.0	183.0		$ 145.0
CECONY \| Future Income Tax
Public Utilities, General Disclosures [Line Items]
Decrease in regulatory asset resulting from TCJA						1,182.0
CECONY \| Revenue Taxes
Public Utilities, General Disclosures [Line Items]
Decrease in regulatory asset resulting from TCJA						86.0
CECONY \| NYSPSC \| Issued by NYSPSC on MTA Subway Power Outage
Public Utilities, General Disclosures [Line Items]
Regulatory costs					65.0	65.0
Regulatory assets					50.0	50.0
CECONY \| NYSPSC \| Scenario, Forecast \| Issued by NYSPSC on MTA Subway Power Outage
Public Utilities, General Disclosures [Line Items]
Regulatory costs							$ 137.0
Regulatory assets							127.0
CECONY \| NYSPSC \| Electric \| Issued by NYSPSC on MTA Subway Power Outage
Public Utilities, General Disclosures [Line Items]
Regulatory costs					$ 15.0	$ 15.0
CECONY \| NYSPSC \| Electric \| Scenario, Forecast \| Issued by NYSPSC on MTA Subway Power Outage
Public Utilities, General Disclosures [Line Items]
Regulatory costs							$ 10.0