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Accounting for Derivative Instruments and Hedging Activities - Pre-tax effects of economic hedges not designated a cash flow hedges (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Unrealized mark-to-market results |  |  |  |
Reversal of previously recognized unrealized (gains)/losses on settled positions related to economic hedges | $ (3) | $ 22 | $ (1) | $ 25
Reversal of acquired (gain)/loss positions related to economic hedges | (1) | 1 | (1) | 1
Net unrealized (losses)/gains on open positions related to economic hedges | (67) | 36 | 127 | 15
Total unrealized mark-to-market (losses)/gains for economic hedging activities | (71) | 59 | 125 | 41
Reversal of previously recognized unrealized gains on settled positions related to trading activity | (3) | (4) | (6) | (19)
Net unrealized gains on open positions related to trading activity | 8 | 16 | 19 | 17
Total unrealized mark-to-market gains/(losses) for trading activity | 5 | 12 | 13 | (2)
Total unrealized (losses)/gains | (66) | 71 | 138 | 39
Credit Risk Related Contingent Features |  |  |  |
Unrealized gain from open economic hedge positions |  |  | 127 | 15
Collateral due on net liability position that has not been called by a certain marginable agreement counterparty | 4 |  | 4 |
Adequate Assurance Clauses |  |  |  |
Credit Risk Related Contingent Features |  |  |  |
Derivative net liability position, collateral required Contracts with Credit Rating Contingent Feature | 31 |  | 31 |
Credit Rating Contingent Features |  |  |  |
Credit Risk Related Contingent Features |  |  |  |
Derivative net liability position, collateral required Contracts with Credit Rating Contingent Feature | 3 |  | 3 |
Commodity contracts |  |  |  |
Unrealized mark-to-market results |  |  |  |
Total unrealized (losses)/gains | (66) | 71 | 138 | 39
Commodity contracts | Sales |  |  |  |
Unrealized mark-to-market results |  |  |  |
Total unrealized (losses)/gains | 20 | 53 | (78) | 157
Commodity contracts | Cost of Sales |  |  |  |
Unrealized mark-to-market results |  |  |  |
Total unrealized (losses)/gains | (86) | 18 | 216 | (118)
Interest rate contracts |  |  |  |
Unrealized mark-to-market results |  |  |  |
Total unrealized (losses)/gains | $ 13 | $ (24) | $ 61 | $ (19)

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- Definition Amount reversed into entity's statement of operations for previously recognized unrealized (gains) losses on settled positions related to acquired economic hedges. + References No definition available. + Details
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- Definition Amount reversed into entity's statement of operations for previously recognized unrealized (gains) losses on settled positions related to economic hedges. + References No definition available. + Details
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- Definition Amount reversed into entity's statement of operations for previously recognized unrealized (gains) losses on settled positions related to trading activities. + References No definition available. + Details
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- Definition Unrealized Gain (Loss) on Derivatives, Mark To Market, Economic Hedging Activities + References No definition available. + Details
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- Definition The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4H -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624258-113959 + Details
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- Definition Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 + Details
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- Definition The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4H -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624258-113959 + Details
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- Definition Amount of unrealized gain (loss) related to derivatives designated as cash flow hedging instruments, recorded in results of operations to the extent that the cash flow hedge is determined to be ineffective. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (d)(1) -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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