Segment Information Major Customers (Details)	3 Months Ended
	Mar. 31, 2012 customers	Mar. 31, 2011 customers
Revenue, Major Customer [Line Items]
Major Customers Percentage Revenue Threshold	10.00%	10.00%
Number Of Major Customers	1	0
Energy Operating Segment [Member]
Revenue, Major Customer [Line Items]
Major Customers Percentage Revenue Threshold	10.00%	10.00%
Number Of Major Customers	2	2
Water Operating Segment [Member]
Revenue, Major Customer [Line Items]
Major Customers Percentage Revenue Threshold	10.00%	10.00%
Number Of Major Customers	0	0