Annual report pursuant to Section 13 and 15(d)

Commitments And Contingencies (Funding Commitments By Third Parties Or Contingent Events) (Details)

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Commitments And Contingencies (Funding Commitments By Third Parties Or Contingent Events) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2011
Recorded Unconditional Purchase Obligation [Line Items]  
Amount of Commitments Expiration Per Period, Total Amounts Committed $ 213,952
Amount of Commitments Expiration Per Period, Less Than 1 Year 119,788
Amount of Commitments Expiration Per Period, 1 - 3 Years 93,244
Amount of Commitments Expiration Per Period, 3 - 5 Years 920
Amount of Commitments Expiration Per Period, More Than 5 Years   
Letters Of Credit And Surety Bonds [Member]
 
Recorded Unconditional Purchase Obligation [Line Items]  
Amount of Commitments Expiration Per Period, Total Amounts Committed 34,687
Amount of Commitments Expiration Per Period, Less Than 1 Year 34,637
Amount of Commitments Expiration Per Period, 1 - 3 Years 50
Amount of Commitments Expiration Per Period, 3 - 5 Years   
Amount of Commitments Expiration Per Period, More Than 5 Years   
Purchase Obligations [Member]
 
Recorded Unconditional Purchase Obligation [Line Items]  
Amount of Commitments Expiration Per Period, Total Amounts Committed 179,265
Amount of Commitments Expiration Per Period, Less Than 1 Year 85,151
Amount of Commitments Expiration Per Period, 1 - 3 Years 93,194
Amount of Commitments Expiration Per Period, 3 - 5 Years 920
Amount of Commitments Expiration Per Period, More Than 5 Years