Derivative Financial Instruments (Schedule of Derivatives Instruments Statements of Financial Position) (Details) - Commodity contract - Futures - Cost of goods sold - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Designated as hedging instrument
Amount of gain (loss) recognized in income on derivatives	$ (3,287)	$ 591	$ (2,449)	$ (862)
Amount of gain (loss) recognized in income on related hedged items	2,095	1,121	2,595	343
Designated as hedging instrument | Firm commitments
Amount of gain (loss) recognized in income on related hedged items	(484)	1,415	1,255	(84)
Designated as hedging instrument | Inventory
Amount of gain (loss) recognized in income on related hedged items	2,579	(294)	1,340	427
Not designated as hedging instrument
Amount of gain (loss) recognized in income on derivatives	$ (1,289)	$ 5,487	$ 9,650	$ 1,410