Summary of Significant Accounting Policies (Details)	Jun. 30, 2012	Jun. 30, 2011
Revenue by segment
Percentage of revenue by segment	100.00%	100.00%
Minerals and materials [Member]
Revenue by segment
Percentage of revenue by segment	52.00%	51.00%
Environmental [Member]
Revenue by segment
Percentage of revenue by segment	23.00%	27.00%
Oilfield services [Member]
Revenue by segment
Percentage of revenue by segment	24.00%	20.00%
Transportation [Member]
Revenue by segment
Percentage of revenue by segment	5.00%	6.00%
Intersegment sales [Member]
Revenue by segment
Percentage of revenue by segment	(4.00%)	(4.00%)