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
	Mar. 31, 2020	Mar. 31, 2019
Designated as hedging instrument
Amount of gain (loss) recognized in income on derivatives	$ 838	$ (1,453)
Amount of gain (loss) recognized in income on related hedged items	500	(778)
Designated as hedging instrument | Firm commitments
Amount of gain (loss) recognized in income on related hedged items	1,739	(1,499)
Designated as hedging instrument | Inventory
Amount of gain (loss) recognized in income on related hedged items	(1,239)	721
Not designated as hedging instrument
Amount of gain (loss) recognized in income on derivatives	$ 10,939	$ (4,077)