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           Financial Instruments - Changes in Fair Value of De-Designated Interest Rate Derivatives (Details) (Not Designated as Hedging Instrument [Member], Interest Rate Contract [Member], USD $) 
        In Thousands, unless otherwise specified  | 
        12 Months Ended | ||
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           Dec. 31, 2012 
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           Dec. 31, 2011 
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           Dec. 31, 2010 
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           Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] 
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| Derivative [Line Items] | |||
| Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net | $ 679 | $ 0 | $ 0 | 
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- Definition 
          Net gain (loss) from the increase (decrease) in fair value of derivative instrument not designated as hedging instrument. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
          
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