Segment Information Depreciation and Amortization, by Segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 24,274	$ 27,044	$ 49,031	$ 54,271
Energy Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	18,348	20,488	36,819	41,144
Water Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	5,909	6,539	12,178	13,095
Corporate Unallocated [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 17	$ 17	$ 34	$ 32