Schedule of Goodwill Allocated to Reporting Segments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	$ 1,232,229
Accumulated impairment losses, at beginning of period	(676,467)
Goodwill, net, at beginning of period	555,762
Goodwill acquired	570,790
Effect of change in exchange rates	(4,657)
Goodwill before impairment, at end of period	1,791,125
Accumulated impairment losses, at end of period	(669,230)
Goodwill, net, at end of period	555,762	$ 1,121,895
Electricity Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	500,625
Accumulated impairment losses, at beginning of period	(386,384)
Goodwill, net, at beginning of period	114,241
Goodwill acquired	0
Effect of change in exchange rates	(370)
Goodwill before impairment, at end of period	496,565
Accumulated impairment losses, at end of period	(382,694)
Goodwill, net, at end of period	114,241	113,871
Gas Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	352,703
Accumulated impairment losses, at beginning of period	0
Goodwill, net, at beginning of period	352,703
Goodwill acquired	0
Effect of change in exchange rates	(3,259)
Goodwill before impairment, at end of period	349,444
Accumulated impairment losses, at end of period	0
Goodwill, net, at end of period	352,703	349,444
Water Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	378,901
Accumulated impairment losses, at beginning of period	(290,083)
Goodwill, net, at beginning of period	88,818
Goodwill acquired	0
Effect of change in exchange rates	(785)
Goodwill before impairment, at end of period	374,569
Accumulated impairment losses, at end of period	(286,536)
Goodwill, net, at end of period	88,818	88,033
Networks Operating Segment [Member]
Goodwill [Roll Forward]
Goodwill before impairment, at beginning of period	0
Accumulated impairment losses, at beginning of period	0
Goodwill, net, at beginning of period	0
Goodwill acquired	570,790
Effect of change in exchange rates	(243)
Goodwill before impairment, at end of period	570,547
Accumulated impairment losses, at end of period	0
Goodwill, net, at end of period	$ 0	$ 570,547