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Reconciliation of income and expenses (Details 10) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Income (loss) from discontinued operations, net of tax | [1] |  |  |  |  |  |  |  |  | $ (3,783) | $ (300,354) | $ (834,080)
Loss from discontinued operations attributable to noncontrolling interest |  |  |  |  |  |  |  |  |  | 0 | (131,691) | (35,256)
Loss from discontinued operations attributable to the Company |  | $ (82) | $ (2,198) | $ (3,190) | $ 1,687 | $ (816) | $ (5,400) | $ (155,451) | $ (6,996) |  |  |
Discontinued operations, held-for-sale or disposed by sale [Member] |  |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Operating revenues |  |  |  |  |  |  |  |  |  | 465 | 123,024 | 363,115
Operating expenses |  |  |  |  |  |  |  |  |  | (4,607) | 513,813 | 1,666,941
Operating income (loss) |  |  |  |  |  |  |  |  |  | 5,072 | (390,789) | (1,303,826)
Other expense |  |  |  |  |  |  |  |  |  | (13) |  |
Other income |  |  |  |  |  |  |  |  |  |  | 306 | 3,149
Interest expense |  |  |  |  |  |  |  |  |  | 250 | 1,753 | 2,124
Income (loss) from discontinued operations before income taxes |  |  |  |  |  |  |  |  |  | 4,809 | (392,236) | (1,302,801)
Income taxes | [1] |  |  |  |  |  |  |  |  | 8,592 | (91,882) | (468,721)
Income (loss) from discontinued operations, net of tax |  |  |  |  |  |  |  |  |  | (3,783) | (300,354) | (834,080)
Loss from discontinued operations attributable to noncontrolling interest |  |  |  |  |  |  |  |  |  | 0 | (131,691) | (35,256)
Loss from discontinued operations attributable to the Company |  |  |  |  |  |  |  |  |  | (3,783) | (168,663) | (798,824)
Refining [Member] | Discontinued operations, held-for-sale or disposed by sale [Member] |  |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Pretax loss attributable to the company |  |  |  |  |  |  |  |  |  | $ 6,900 | $ (253,500) | $ (31,500)
[1] | Includes eliminations for the presentation of income tax adjustments between continuing and discontinued operations.

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