Information By Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	$ 537,110	$ 432,365
Sales Revenue, Services, Net	70,111	45,227
Revenues	607,221	477,592
Gross profit	179,855	157,637
Operating Income (Loss)	(140,448)	30,827
Total other income (expense)	(16,010)	(5,766)
Income Before Income Taxes	(156,458)	25,061
Electricity Operating Segment [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	213,877	205,903
Sales Revenue, Services, Net	38,528	32,848
Revenues	252,405	238,751
Gross profit	69,975	67,250
Operating Income (Loss)	(2,768)	17,084
Gas Operating Segment [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	130,243	117,127
Sales Revenue, Services, Net	7,496	7,084
Revenues	137,739	124,211
Gross profit	43,471	50,815
Operating Income (Loss)	(28,348)	21,731
Water Operating Segment [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	125,587	109,335
Sales Revenue, Services, Net	5,607	5,295
Revenues	131,194	114,630
Gross profit	37,805	39,572
Operating Income (Loss)	(11,710)	8,804
Networks Operating Segment [Member]
Segment Reporting Information [Line Items]
Sales Revenue, Goods, Net	67,403	0
Sales Revenue, Services, Net	18,480	0
Revenues	85,883	0
Gross profit	28,604	0
Operating Income (Loss)	(75,510)	0
Corporate Unallocated [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ (22,112)	$ (16,792)