Derivatives (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Commodity | Cost of Sales and Merchandising Revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives instruments	$ (41,873)	$ 34,800	$ (14,848)	$ 25,941
Foreign currency contract | Other Income | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives instruments	669	(87)	767	1,391
Interest rate contracts | Interest Expense | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives instruments	$ (17)	$ (694)	$ 372	$ (2,294)