Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value
Derivative Assets	$ 1,678	$ 303
Derivative Liabilities	3,273	2,585
Forward Contracts \| Commodity Contracts
Derivatives, Fair Value
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	1,678	303
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	2,395	281
Forward Contracts \| Fair Value Hedges
Derivatives, Fair Value
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	878	2,304
Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	1,678	303
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	2,395	281
Not Designated as Hedging Instrument \| Accounts Receivable \| Forward Contracts \| Commodity Contracts
Derivatives, Fair Value
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	1,678	303
Not Designated as Hedging Instrument \| Accrued Liabilities \| Forward Contracts \| Commodity Contracts
Derivatives, Fair Value
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	2,395	281
Designated as Hedging Instrument
Derivatives, Fair Value
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	878	2,304
Designated as Hedging Instrument \| Other Noncurrent Liabilities \| Forward Contracts \| Fair Value Hedges
Derivatives, Fair Value
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ 878	$ 2,304

Fair value, after offset of derivative liability, of 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, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets 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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