v2.4.0.6

Derivative Commodity Instruments (Narrative) (Details) (Commodity Forward Contracts [Member], Designated As Fair Value Hedges [Member]) | Dec. 31, 2011
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Commodity Forward Contracts [Member] | Designated As Fair Value Hedges [Member] |
Derivative [Line Items] |
Number of derivative instruments, in gallons | 57,960,000

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- Definition Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 + Details
Name: | invest_DerivativeNonmonetaryNotionalAmount
Namespace Prefix: | invest_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

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- Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration