Reconciliation of income and expenses (Details 9) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations, net of tax	[1]									$ (300,354)	$ (834,080)	$ 109,311
Loss from discontinued operations attributable to noncontrolling interest										(131,691)	(35,256)	(3,895)
Income (loss) from discontinued operations attributable to the Company		$ (816)	$ (5,400)	$ (155,451)	$ (6,996)	$ (3,368)	$ (213,334)	$ (255,665)	$ (326,457)
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										123,024	363,115	547,571
Operating expenses										513,813	1,666,941	386,651
Operating income (loss)										(390,789)	(1,303,826)	160,920
Other income										306	3,149	1,898
Interest expense										1,753	2,124	145
Income (loss) from discontinued operations before income taxes										(392,236)	(1,302,801)	162,673
Income taxes										(91,882)	(468,721)	53,362
Income (loss) from discontinued operations, net of tax										(300,354)	(834,080)	109,311
Loss from discontinued operations attributable to noncontrolling interest										(131,691)	(35,256)	(3,895)
Income (loss) from discontinued operations attributable to the Company										(168,663)	(798,824)	113,206
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										$ (253,500)	$ (31,500)	$ (3,200)

[1] Includes eliminations for the presentation of income tax adjustments between continuing and discontinued operations.