Concentrations (Details)	Dec. 31, 2011
Petroleum Industry [Member]
Concentration [Abstract]
Approximate percentage of revenue	23.00%
Chemical Industry [Member]
Concentration [Abstract]
Approximate percentage of revenue	22.00%
Food/Agriculture [Member]
Concentration [Abstract]
Approximate percentage of revenue	11.00%
Steel Industry [Member]
Concentration [Abstract]
Approximate percentage of revenue	11.00%
Transportation Industry [Member]
Concentration [Abstract]
Approximate percentage of revenue	13.00%
Percentage of employees covered by union contracts [Member]
Concentration [Abstract]
Approximate percentage of revenue	44.00%
Percentage of employees covered by union contracts, expiring within an year [Member]
Concentration [Abstract]
Approximate percentage of revenue	0.00%