Schedule of Goodwill Allocated to Reporting Segments (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	$ 1,054,717
Accumulated impairment losses, at beginning of period	(602,223)
Goodwill, net, at beginning of period	452,494
Goodwill acquired	60,286
Effect of change in exchange rates	28,291
Goodwill before impairment, at end of period	1,191,090
Accumulated impairment losses, at end of period	(650,019)
Goodwill, net, at end of period	452,494	$ 541,071
Electricity Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	400,299
Accumulated impairment losses, at beginning of period	(348,926)
Goodwill, net, at beginning of period	51,373
Goodwill acquired	60,286
Effect of change in exchange rates	2,065
Goodwill before impairment, at end of period	486,834
Accumulated impairment losses, at end of period	(373,110)
Goodwill, net, at end of period	51,373	113,724
Gas Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	319,913
Accumulated impairment losses, at beginning of period	0
Goodwill, net, at beginning of period	319,913
Goodwill acquired	0
Effect of change in exchange rates	21,158
Goodwill before impairment, at end of period	341,071
Accumulated impairment losses, at end of period	0
Goodwill, net, at end of period	319,913	341,071
Water Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	334,505
Accumulated impairment losses, at beginning of period	(253,297)
Goodwill, net, at beginning of period	81,208
Goodwill acquired	0
Effect of change in exchange rates	5,068
Goodwill before impairment, at end of period	363,185
Accumulated impairment losses, at end of period	(276,909)
Goodwill, net, at end of period	$ 81,208	$ 86,276