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Goodwill and Other Intangible Assets (Details Textual) - USD ($)
$ in Millions
12 Months Ended
Oct. 01, 2015
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Goodwill [Line Items]        
Total amortization expense   $ 5.1 $ 1.5 $ 0.8
Coal Logistics        
Goodwill [Line Items]        
Fair value of reporting unit in excess of carrying value, percent 15.00%      
Change in discount rate that would not impact goodwill impairment test 1.00%      
Goodwill | Coal Logistics        
Goodwill [Line Items]        
Discount rate on discounted cash flow analysis 18.00%      
Change in estimated discounted cash flows that would not impact goodwill impairment test 5.00%