Goodwill Schedule of Goodwill Allocated to Reporting Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010
Goodwill [Line Items]
Goodwill before impairment	$ 1,226,165		$ 1,221,757
Accumulated impairment losses	575,169		584,847
Goodwill, net	650,996	1,294,452	636,910	1,209,376
Goodwill, Acquired During Period		10,083
Effect of change in exchange rates	14,086	74,993
Energy Operating Segment [Member]
Goodwill [Line Items]
Goodwill before impairment	811,447		808,601
Accumulated impairment losses	250,520		254,735
Goodwill, net	560,927		553,866
Effect of change in exchange rates	7,061
Water Operating Segment [Member]
Goodwill [Line Items]
Goodwill before impairment	414,718		413,156
Accumulated impairment losses	324,649		330,112
Goodwill, net	90,069		83,044
Effect of change in exchange rates	$ 7,025