Reconciliation of income and expenses (Details 5) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations	$ (5,400,000)	$ (223,112,000)	$ (299,538,000)	$ (816,517,000)
Loss from discontinued operations attributable to noncontrolling interest	0	(9,778,000)	(131,691,000)	(21,060,000)
Discontinued operations, held-for-sale or disposed of by sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	162,000	140,428,000	122,894,000	288,537,000
Operating expenses	230,000	478,798,000	513,756,000	1,565,579,000
Operating loss	(68,000)	(338,370,000)	(390,862,000)	(1,277,042,000)
Other income	375,000	298,000	762,000	2,758,000
Interest expense	0	703,000	1,753,000	1,221,000
Income (loss) from discontinued operations before income taxes	307,000	(338,775,000)	(391,853,000)	(1,275,505,000)
Income taxes	5,707,000	(115,663,000)	(92,315,000)	(458,988,000)
Loss from discontinued operations	(5,400,000)	(223,112,000)	(299,538,000)	(816,517,000)
Loss from discontinued operations attributable to noncontrolling interest	0	(9,778,000)	(131,691,000)	(21,060,000)
Loss from discontinued operations attributable to the Company	(5,400,000)	(213,334,000)	(167,847,000)	(795,457,000)
Discontinued operations, held-for-sale or disposed of by sale [Member] | Refining [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pretax income (loss) attributable to the Company	$ 935,000	$ (8,600,000)	$ (253,000,000)	$ (18,400,000)