Schedule of Goodwill Allocated to Reporting Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 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	572,499
Effect of change in exchange rates	14,496
Goodwill before impairment, at end of period	1,843,857
Accumulated impairment losses, at end of period	(701,100)
Goodwill, net, at end of period	555,762	$ 1,142,757
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	1,031
Goodwill before impairment, at end of period	514,057
Accumulated impairment losses, at end of period	(398,785)
Goodwill, net, at end of period	114,241	115,272
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	10,788
Goodwill before impairment, at end of period	363,491
Accumulated impairment losses, at end of period	0
Goodwill, net, at end of period	352,703	363,491
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	2,560
Goodwill before impairment, at end of period	393,693
Accumulated impairment losses, at end of period	(302,315)
Goodwill, net, at end of period	88,818	91,378
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	572,499
Effect of change in exchange rates	117
Goodwill before impairment, at end of period	572,616
Accumulated impairment losses, at end of period	0
Goodwill, net, at end of period	$ 0	$ 572,616