Goodwill Schedule of Goodwill Allocated to Reporting Segments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Goodwill beginning balance	$ 701,016	$ 636,910
Goodwill acquired		46,101
Goodwill, Other Changes		4,767
Goodwill impairment	(173,249)	0	(584,847)
Goodwill, Purchase Accounting Adjustments	3,958
Effect of change in exchange rates	16,853	13,238
Goodwill before impairment	1,318,271	1,273,848	1,221,757
Accumulated impairment losses	(769,693)	(572,832)	(584,847)
Goodwill ending balance	548,578	701,016	636,910
Electricity Operating Segment [Member]
Goodwill [Line Items]
Goodwill beginning balance	226,209	181,841
Goodwill acquired		36,540
Goodwill, Other Changes		2,269
Goodwill impairment	(173,249)
Goodwill, Purchase Accounting Adjustments	3,958
Effect of change in exchange rates	3,314	5,559
Goodwill before impairment	493,610	475,711	436,576
Accumulated impairment losses	(433,378)	(249,502)	(254,735)
Goodwill ending balance	60,232	226,209
Gas Operating Segment [Member]
Goodwill [Line Items]
Goodwill beginning balance	383,743	372,025
Goodwill acquired		9,561
Goodwill, Other Changes		1,725
Goodwill impairment	0
Goodwill, Purchase Accounting Adjustments	0
Effect of change in exchange rates	11,135	432
Goodwill before impairment	394,878	383,743	372,025
Accumulated impairment losses	0	0	0
Goodwill ending balance	394,878	383,743
Water Operating Segment [Member]
Goodwill [Line Items]
Goodwill beginning balance	91,064	83,044
Goodwill acquired		0
Goodwill, Other Changes		773
Goodwill impairment	0
Goodwill, Purchase Accounting Adjustments	0
Effect of change in exchange rates	2,404	7,247
Goodwill before impairment	429,783	414,394	413,156
Accumulated impairment losses	(336,315)	(323,330)	(330,112)
Goodwill ending balance	$ 93,468	$ 91,064