Derivative Financial Instruments (Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Commodity futures, asset derivatives	$ 19,976	$ 6,797
Commodity futures, liability derivatives	5,505	7,442
Designated as hedging instrument \| Commodity contract \| Futures \| Other current assets
Commodity futures, asset derivatives	17,009	5,092
Commodity futures, liability derivatives	3,825	4,635
Not designated as hedging instrument \| Commodity contract \| Futures \| Other current assets
Commodity futures, asset derivatives	2,967	1,705
Commodity futures, liability derivatives	$ 1,680	$ 2,807

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
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-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

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