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Derivative Instruments (Net Gain (Loss) On Derivative Instruments) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015
Derivative [Line Items] |  |  |  |
Net gain (loss) on derivative instruments | $ 35,281 | $ 91,756 | $ (44,376) | $ 131,778
Gas sales |  |  |  |
Derivative [Line Items] |  |  |  |
Net gain (loss) on derivative instruments | 33,167 | 79,684 | (43,454) | 118,137
Oil and condensate sales |  |  |  |
Derivative [Line Items] |  |  |  |
Net gain (loss) on derivative instruments | 1,708 | 12,072 | 362 | 13,641
Natural gas liquids sales |  |  |  |
Derivative [Line Items] |  |  |  |
Net gain (loss) on derivative instruments | $ 406 | $ 0 | $ (1,284) | $ 0

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- Definition The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.13(h)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 2: 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=56944662&loc=d3e3602-108585 + Details
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