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Commitments And Contingencies (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2012
Site Contingency [Line Items]  
Estimated minimum liability for environmental remediation $ 15.5
Estimated maximum liability for environmental remediation 19.7
Former Manufactured Gas Plant Site [Member]
 
Site Contingency [Line Items]  
Estimated minimum liability for environmental remediation $ 14.0