Derivatives (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Commodity | Cost of Sales and Merchandising Revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives instruments	$ (690)	$ (48,620)	$ (15,538)	$ (22,679)
Not Designated as Hedging Instrument | Interest rate contracts | Interest Income (Expense)
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives instruments	229	652	601	(1,642)
Not Designated as Hedging Instrument | Foreign currency contract | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives instruments	$ 950	$ (261)	$ 1,717	$ (1,130)