Derivative Financial Instruments (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Gains or losses on derivative instruments, statement of income
Ineffectiveness - amount of gain (loss) recognized in income on related hedged items	$ (101,000)	$ 68,000	$ (28,000)
Gain (loss) excluded from hedge effectiveness testing	3,100,000	(2,600,000)	(1,600,000)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	40,900,000	2,800,000	137,000
Net gains (loss) reclassified	46,100,000	265,000	$ 541,000
Price Risk Cash Flow Hedge Unrealized Gain (Loss) to be Reclassified During Next 12 Months	(2,700,000)
Futures | Commodity contract | Other current assets
Commodity contract commitments
Fair value of derivatives including required margin deposits	$ 24,900,000	$ 13,200,000