Segment Information Major Customers (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2012 customers	Jun. 30, 2011 customers	Jun. 30, 2012 customers	Jun. 30, 2011 customers
Revenue, Major Customer [Line Items]
Major Customers Percentage Revenue Threshold	10.00%	10.00%	10.00%	10.00%
Entity-Wide Revenue, Major Customer, Percentage	11.00%		11.00%
Number Of Major Customers	1	0	1	0
Energy Operating Segment [Member]
Revenue, Major Customer [Line Items]
Major Customers Percentage Revenue Threshold	10.00%	10.00%	10.00%	10.00%
Number Of Major Customers	1	1	1	1
Segment Revenue, Percentage, by Each Major Customer	15.00%	12.00%	15.00%	11.00%
Water Operating Segment [Member]
Revenue, Major Customer [Line Items]
Major Customers Percentage Revenue Threshold	10.00%	10.00%	10.00%	10.00%
Number Of Major Customers	0	0	0	0