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Consolidated Statement of Comprehensive Income (Parenthetical) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Deferred taxes on unrealized gain (loss), other, tax effect | $ 5 | $ 5 | $ 0
Deferred taxes on postretirement | 2 | (13) | (7)
Fuel derivatives |  |  |
Deferred taxes on unrealized gain (loss) on derivatives, tax effect | 185 | 432 | (181)
Interest rate derivatives |  |  |
Deferred taxes on unrealized gain (loss) on derivatives, tax effect | $ 4 | $ 5 | $ 6

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