v2.4.0.8
Commitments and Contingencies (Details) (Manufactured Gas Plant Sites [Member], USD $)
In Millions, unless otherwise specified
9 Months Ended
Sep. 30, 2013
Manufactured Gas Plant Sites [Member]
 
Commitments and Contingencies [Line Items]  
Loss Contingency, Range of Possible Loss, Minimum $ 16
Loss Contingency, Range of Possible Loss, Maximum 62
Period for future costs of detailed site investigation and remediation costs over the next ten years
Accrual for Environmental Loss Contingencies, Provision for New Losses $ 38.2