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Related Party Transactions - Service Agreement and Transition Service Agreement with GeOn (Details) - USD ($) $ in Millions |  | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jul. 16, 2018 | Dec. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Jun. 12, 2017
Related Party Transaction [Line Items] |  |  |  |  |  |
Service fees |  |  | $ 32 | $ 8 | $ 7 |
Other income - affiliate |  | $ 84 | 0 | 87 | $ 193 |
Services Agreement | GenOn |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Credit applied |  | $ 28 |  |  |  |
Services Agreement | Restructuring Support Agreement |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Shared services annualized rate |  |  |  |  |  | $ 84
Services Agreement | Restructuring Support Agreement | GenOn |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Credit applied | $ 28 |  |  |  |  |
Transition Services Agreement | Restructuring Support Agreement | GenOn |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Other income - affiliate |  |  |  | 87 |  |
Shared service, selling, general and administrative |  |  | 53 | $ 42 |  |
Management Service | Services Agreement | GenOn |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Service fees |  |  | $ 193 |  |  |

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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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- Definition 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. + References No definition available. + Details
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- Definition Amount of selling, general and administrative expenses resulting from transactions, excluding transactions that are eliminated in consolidated or combined financial statements, with related party. + References No definition available. + Details
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- Definition Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07.1(c)) -URI http://asc.fasb.org/extlink&oid=114873854&loc=SL114874292-224272 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1(e)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
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