Goodwill Schedule of Goodwill Allocated to Reporting Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Beginning of the Period [Roll Forward]
Goodwill before impairment	$ 1,318,271
Accumulated impairment losses	(769,693)
Goodwill, net	548,578
Goodwill, Impairment Loss	(977)	0	(173,200)
Effect of change in exchange rates	(1,164)
End of the Period [Roll Forward]
Goodwill before impairment	1,315,480		1,318,271
Accumulated impairment losses	(769,043)		(769,693)
Goodwill, net	546,437		548,578
Electricity Operating Segment [Member]
Beginning of the Period [Roll Forward]
Goodwill before impairment	493,610
Accumulated impairment losses	(433,378)
Goodwill, net	60,232
Goodwill, Impairment Loss	(977)
Effect of change in exchange rates	(105)
End of the Period [Roll Forward]
Goodwill before impairment	492,619
Accumulated impairment losses	(433,469)
Goodwill, net	59,150
Gas Operating Segment [Member]
Beginning of the Period [Roll Forward]
Goodwill before impairment	394,878
Accumulated impairment losses	0
Goodwill, net	394,878
Goodwill, Impairment Loss	0
Effect of change in exchange rates	(852)
End of the Period [Roll Forward]
Goodwill before impairment	394,026
Accumulated impairment losses	0
Goodwill, net	394,026
Water Operating Segment [Member]
Beginning of the Period [Roll Forward]
Goodwill before impairment	429,783
Accumulated impairment losses	(336,315)
Goodwill, net	93,468
Goodwill, Impairment Loss	0
Effect of change in exchange rates	(207)
End of the Period [Roll Forward]
Goodwill before impairment	428,835
Accumulated impairment losses	(335,574)
Goodwill, net	$ 93,261