Schedule of Goodwill Allocated to Reporting Segments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 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	59,137
Effect of change in exchange rates	39,101
Goodwill before impairment, at end of period	1,219,302
Accumulated impairment losses, at end of period	(668,570)
Goodwill, net, at end of period	452,494	$ 550,732
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	59,137
Effect of change in exchange rates	2,900
Goodwill before impairment, at end of period	495,848
Accumulated impairment losses, at end of period	(382,438)
Goodwill, net, at end of period	51,373	113,410
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	29,390
Goodwill before impairment, at end of period	349,303
Accumulated impairment losses, at end of period	0
Goodwill, net, at end of period	319,913	349,303
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	6,811
Goodwill before impairment, at end of period	374,151
Accumulated impairment losses, at end of period	(286,132)
Goodwill, net, at end of period	$ 81,208	$ 88,019