Segment Information Information By Segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Segment Reporting Information [Line Items]
Revenue, Net	$ 579,140	$ 612,401	$ 1,150,780	$ 1,176,092
Gross profit	196,745	191,951	379,850	376,929
Operating Income (Loss)	46,063	48,085	85,684	98,174
Total other income (expense)	(3,208)	(12,602)	(7,628)	(25,998)
Income Before Income Taxes	42,855	35,483	78,056	72,176
Depreciation and amortization	27,044	32,768	54,271	64,299
Energy Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue, Net	444,598	474,415	882,345	906,231
Gross profit	148,951	144,753	283,554	282,337
Operating Income (Loss)	47,069	45,463	85,233	88,631
Depreciation and amortization	20,488	24,368	41,144	47,923
Water Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue, Net	134,542	137,986	268,435	269,861
Gross profit	47,794	47,198	96,296	94,592
Operating Income (Loss)	11,666	13,755	27,603	30,609
Depreciation and amortization	6,539	8,399	13,095	16,374
Corporate Unallocated [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	(12,672)	(11,133)	(27,152)	(21,066)
Depreciation and amortization	$ 17	$ 1	$ 32	$ 2