Concentrations (Details)	12 Months Ended
	Dec. 31, 2017 union Vessel Service_Center
POLAND
Concentration [Abstract]
Number Of Unions	3
Canadian
Concentration [Abstract]
Number of service centers | Service_Center	3
GERMANY
Concentration [Abstract]
Number Of Unions	1
Petroleum Industry [Member]
Concentration [Abstract]
Approximate percentage of revenue	26.00%
Chemical Industry [Member]
Concentration [Abstract]
Approximate percentage of revenue	19.00%
Transportation Industry [Member]
Concentration [Abstract]
Approximate percentage of revenue	16.00%
Steel Industry [Member]
Concentration [Abstract]
Approximate percentage of revenue	8.00%
Food/Agriculture [Member]
Concentration [Abstract]
Approximate percentage of revenue	9.00%
Customer Concentration Risk [Member]
Concentration [Abstract]
Approximate percentage of revenue	10.00%
Workforce Subject to Collective Bargaining Arrangements [Member] | Unionized Employees Concentration Risk [Member]
Concentration [Abstract]
Approximate percentage of revenue	45.00%
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] | Unionized Employees Concentration Risk [Member]
Concentration [Abstract]
Approximate percentage of revenue	7.00%
ASC [Member]
Concentration [Abstract]
Concentration Risk, Labor Subject to Collective Bargaining Arrangements | Vessel	9