Goodwill Schedule of Goodwill Allocated to Reporting Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	$ 1,191,808
Accumulated impairment losses, at beginning of period	(690,988)
Goodwill, net, at beginning of period	500,820
Goodwill impairment	0	(977)
Effect of change in exchange rates	(38,102)
Goodwill before impairment, at end of period	1,088,774
Accumulated impairment losses, at end of period	(626,056)
Goodwill, net, at end of period	462,718
Electricity Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	449,668
Accumulated impairment losses, at beginning of period	(393,981)
Goodwill, net, at beginning of period	55,687
Effect of change in exchange rates	(2,909)
Goodwill before impairment, at end of period	413,862
Accumulated impairment losses, at end of period	(361,084)
Goodwill, net, at end of period	52,778
Gas Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	359,485
Accumulated impairment losses, at beginning of period	0
Goodwill, net, at beginning of period	359,485
Effect of change in exchange rates	(28,826)
Goodwill before impairment, at end of period	330,659
Accumulated impairment losses, at end of period	0
Goodwill, net, at end of period	330,659
Water Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	382,655
Accumulated impairment losses, at beginning of period	(297,007)
Goodwill, net, at beginning of period	85,648
Effect of change in exchange rates	(6,367)
Goodwill before impairment, at end of period	344,253
Accumulated impairment losses, at end of period	(264,972)
Goodwill, net, at end of period	$ 79,281