Derivative Financial Instruments (Schedule of Derivative Offset Amounts) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Commodity derivatives deposits	$ 14,031	$ 27,415
Exchange Traded [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability	(4,386)	(11,033)
Derivative Asset, Fair Value, Gross Asset	2,740	811
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(1,646)	(10,222)
Commodity derivatives deposits	14,031	27,415
Amount After Offset	$ 12,385	$ 17,193

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Fair value, before effects of master netting arrangements, of a financial asset or other 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 assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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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.

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Fair value, after offset of derivative asset, of 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, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of right to receive cash and securities on deposit with broker-dealers to demonstrate an intention to complete a purchase (good faith deposit) and collateral deposited by counterparty to cover the credit risk assumed (margin deposit).

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