Annual report pursuant to Section 13 and 15(d)

Financial Instruments And Risk Management (Narrative) (Details)

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Financial Instruments And Risk Management (Narrative) (Details) (USD $)
Dec. 31, 2011
Derivative [Line Items]  
Deferred net losses on derivatives accumulated in other comprehensive income expected reclassification to net income in next twelve months $ 6,074,000
Maximum [Member]
 
Derivative [Line Items]  
Remaining maturity of derivative contracts two years or less
Aggregate unrealized gain of derivative contracts with single counterparty $ 3,000,000