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Commitments and Contingencies (Details Textual 1) - USD ($)
$ in Millions
 9 Months Ended
Sep. 30, 2015
Dec. 31, 2014
Loss Contingencies [Abstract]    
Letters of Credit Outstanding, Amount $ 19.3 $ 19.3
Letters Of Credit Outstanding Amount Related To Payment Obligation Under Insurance Programs 17.5 17.5
Letters Of Credit Outstanding Amount Related To Contract Performance Obligations 1.8 $ 1.8
Future minimum lease payments for operating leases    
2015 0.4  
2016 1.2  
2017 0.7  
2018 0.6  
2019 0.4  
Thereafter $ 0.2  
Purchase Commitments    
Significant Purchase Commitment Scheduled Period of Time for Cash Outlay 3 months  
Outstanding purchase orders for certain construction equipment $ 1.2  
Maximum [Member]    
Operating Leases [Abstract]    
Operating Lease Term 6 years  
Minimum [Member]    
Operating Leases [Abstract]    
Operating Lease Term 1 year