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DERIVATIVE INSTRUMENTS - GAINS (LOSSES) AND NOTIONAL VOLUMES (Details) gal in Millions, MWh in Millions, MMBTU in Millions, $ in Millions | 3 Months Ended | 9 Months Ended
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Sep. 30, 2018 USD ($) MWh MMBTU gal | Sep. 30, 2017 USD ($) MWh MMBTU gal | Sep. 30, 2018 USD ($) MWh MMBTU gal | Sep. 30, 2017 USD ($) MWh MMBTU gal
Realized Gain (Loss) on Derivatives, Net |  |  |  |
Gains (Losses) | $ 8.0 | $ 1.6 | $ 8.9 | $ 6.9
Natural gas contracts |  |  |  |
Realized Gain (Loss) on Derivatives, Net |  |  |  |
Gains (Losses) | $ 0.4 | $ (2.1) | $ (7.1) | $ (1.1)
Notional Sales Volumes |  |  |  |
Notional sales volumes | MMBTU | 36.7 | 24.9 | 124.7 | 84.2
Petroleum products contracts |  |  |  |
Realized Gain (Loss) on Derivatives, Net |  |  |  |
Gains (Losses) | $ 0.5 | $ (0.5) | $ 1.3 | $ (1.4)
Notional Sales Volumes |  |  |  |
Notional sales volumes (gallons) | gal | 1.3 | 4.4 | 5.1 | 14.2
FTRs |  |  |  |
Realized Gain (Loss) on Derivatives, Net |  |  |  |
Gains (Losses) | $ 7.1 | $ 4.2 | $ 14.7 | $ 9.4
Notional Sales Volumes |  |  |  |
Notional sales volumes | MWh | 7.9 | 9.4 | 22.9 | 28.0

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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/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
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