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Derivative Instruments (Details 3) - Not Designated as Hedging Instrument - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Revenues |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | $ 50 | $ 218 | $ 161
Purchase Power Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | (17) | (131) | (130)
Other Operating Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Unrealized Gain (Loss) Recognized | (81) | (9) | 73
Realized Gain (Loss) Reclassified | (14) | (35) | (49)
Fuel Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | 5 | (8) | (34)
Commodity contracts | Revenues |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | 54 | 210 | 111
Commodity contracts | Purchase Power Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | (17) | (131) | (130)
Commodity contracts | Other Operating Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Unrealized Gain (Loss) Recognized | (82) | (14) | 93
Realized Gain (Loss) Reclassified | 0 | 0 | 0
Commodity contracts | Fuel Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | 5 | (8) | (34)
FTRs | Revenues |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | (4) | 8 | 50
FTRs | Purchase Power Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | 0 | 0 | 0
FTRs | Other Operating Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Unrealized Gain (Loss) Recognized | 1 | 5 | (20)
Realized Gain (Loss) Reclassified | (14) | (35) | (49)
FTRs | Fuel Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | 0 | 0 | 0
FES | Revenues |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | 50 | 218 | 160
FES | Purchase Power Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | (17) | (131) | (130)
FES | Other Operating Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Unrealized Gain (Loss) Recognized | (78) | (9) | 74
Realized Gain (Loss) Reclassified | (14) | (35) | (49)
FES | Commodity contracts | Revenues |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | 54 | 210 | 111
FES | Commodity contracts | Purchase Power Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | (17) | (131) | (130)
FES | Commodity contracts | Other Operating Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Unrealized Gain (Loss) Recognized | (79) | (14) | 93
Realized Gain (Loss) Reclassified | 0 | 0 | 0
FES | FTRs | Revenues |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | (4) | 8 | 49
FES | FTRs | Purchase Power Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Realized Gain (Loss) Reclassified | 0 | 0 | 0
FES | FTRs | Other Operating Expense |  |  |
Effect of derivative instruments on the statements of income and comprehensive income for instruments not in hedging relationships |  |  |
Unrealized Gain (Loss) Recognized | 1 | 5 | (19)
Realized Gain (Loss) Reclassified | $ (14) | $ (35) | $ (49)

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- Definition Effect of derivative instruments on statements of income and comprehensive income for instruments designated in cash flow hedging relationships and not in hedging relationships. + References No definition available. + Details
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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a),(c),(d),(e) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 + Details
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- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
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