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Restructuring and Related Cost, Annualized Services

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Restructuring and Related Cost, Credit Applied

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Restructuring and Related Cost, Monthly Services Income

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of liability, recognized in statement of financial position, for defined benefit pension plan. Excludes other postretirement benefit plan.

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Amount of contributions received and expected to be received by defined benefit plan from employer in current fiscal year.

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Amount of projected benefit obligation for defined benefit pension plan with accumulated benefit obligation in excess of plan assets.

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For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.

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Amount of payable due to an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

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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, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of liability, recognized in statement of financial position, for defined benefit other postretirement plan. Excludes pension plan.

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The cash outflow from advancing money to an affiliate (an entity that is related but not strictly controlled by the entity).

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Reflects the sum of all other revenue and income realized from sales and other transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party during the period.

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Amount expected to be recognized in earnings for the specified restructuring cost.

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Discontinued Operations, Acquisitions and Dispositions - Discontinued Operations (Details) - USD ($) $ in Millions			1 Months Ended	7 Months Ended	12 Months Ended
	Jun. 14, 2017	Jun. 12, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other income - affiliate			$ 84.0		$ 87.0	$ 193.0	$ 193.0
Receivable from affiliate					125.0	0.0	$ 0.0
Long-term debt			$ 16,633.0	$ 16,633.0	$ 16,633.0	16,704.0
GenOn \| Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-term debt	$ 2,500.0
Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Aggregate principal percentage threshold			93.00%	93.00%	93.00%
Amount due from GenOn			$ 125.0	$ 125.0	$ 125.0
Amount of pension liability future contributions			13.0	13.0	13.0			$ 13.0
GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pension liability retained			92.0	92.0	92.0	$ 120.0
Liability retained other post-employment and retiree health and welfare benefits			25.0	25.0	25.0
GenOn \| Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Amount of pension liability future contributions								$ 13.0
Services Agreement \| Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Credit applied		$ 28.0	3.5		28.0
Receivable from affiliate			15.0
Shared services annualized rate		$ 84.0	84.0	84.0	84.0
Monthly cost of shared services	$ 5.0		7.0	5.0
GenOn \| Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Costs expected to be spent			261.3	261.3	261.3
Liability for estimated pension benefit obligations			92.0	92.0	92.0
GenOn \| Settlement Consideration \| Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Due to Affiliate			261.3	261.3	261.3
GenOn \| Services Agreement \| Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Due to Affiliate			$ 28.0	$ 28.0	$ 28.0
GenOn Senior Notes Due in 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage	7.875%
GenOn senior notes, due 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage	9.50%
GenOn senior notes, due 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage	9.875%
GenOn Americas Generation Senior Notes Due in 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage	8.50%
GenOn Americas Generation senior notes, due 2031
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage	9.125%