Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

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The amount recognized in earnings related to the change in fair value during the period of derivative or nonderivative instruments designated as fair value hedging instruments.

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The amount recognized in earnings related to the change in fair value during the period of the hedged item in a fair value hedge.

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Fair value of liability associated with derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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The number of derivative instruments of a particular group held by the entity.

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Net gain (loss) relating to components of the gain (loss) on the fair value hedging instrument excluded from the assessment of fair value hedge effectiveness. Recognized in earnings.

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Net gain (loss) recognized in earnings during the reporting period representing the amount of the fair value of the hedges' ineffectiveness.

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The aggregate net gain (loss) on price risk derivatives included in earnings in the period.

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Derivative Financial Instruments (Details) (USD $)	3 Months Ended
Derivative Financial Instruments (Details) (USD $)	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Fair values of derivative instruments, balance sheet
Commodity futures (in dollars)	$ 5,713,000		$ 4,024,000
Commodity futures (in dollars)	(848,000)		(1,854,000)
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on related hedged items	221,000
Gain excluded from hedge effectiveness testing	2,300,000
Interest rate swap
Commodity contract commitments
Number of derivative instruments	0
Forward exchange contracts on foreign currency
Commodity contract commitments
Number of derivative instruments	0
Designated
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on related hedged items	(5,463,000)
Designated \| Commodity Futures
Fair values of derivative instruments, balance sheet
Commodity futures (in dollars)	3,417,000
Commodity futures (in dollars)	(521,000)
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on related hedged items	5,684,000
Designated \| Firm commitments
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on related hedged items	1,316,000
Designated \| Inventory
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on related hedged items	(6,779,000)
Not designated \| Commodity Futures
Fair values of derivative instruments, balance sheet
Commodity futures (in dollars)	2,296,000		4,024,000
Commodity futures (in dollars)	(327,000)		(1,854,000)
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on derivatives	$ 2,401,000	$ (3,618,000)
Aluminum \| Long \| Commodity futures net
Commodity contract commitments
Commodity contract (in MT/Lbs)	2,950
Aluminum \| Short \| Commodity futures net
Commodity contract commitments
Commodity contract (in MT/Lbs)	3,050
Copper \| Long \| Commodity futures net
Commodity contract commitments
Commodity contract (in MT/Lbs)	2,813
Copper \| Short \| Commodity futures net
Commodity contract commitments
Commodity contract (in MT/Lbs)	11,884
Nickel \| Short \| Commodity futures net
Commodity contract commitments
Commodity contract (in MT/Lbs)	78
Silver \| Short \| Commodity futures net
Commodity contract commitments
Commodity contract (in MT/Lbs)	686