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Intangible Assets (Details Textual) - USD ($)
6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Intangible Assets (Textual)    
Amortization expense $ 2,059,000 $ 1,970,000
Amortization expense, excluding amortization of landfill assets $ 136,000 $ 1,757,000
Minimum [Member]    
Intangible Assets (Textual)    
Useful life of intangible assets 5 years  
Maximum [Member]    
Intangible Assets (Textual)    
Useful life of intangible assets 20 years