Information By Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 506,859	$ 469,528	$ 1,517,473	$ 1,387,085
Gross profit	170,749	147,290	503,657	404,266
Operating Income (Loss)	6,410	26,940	65,457	36,468
Total other income (expense)	(1,882)	(3,738)	(8,824)	(11,899)
Income Before Income Taxes	4,528	23,202	56,633	24,569
Electricity Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	242,667	206,810	692,785	602,999
Gross profit	75,362	56,385	210,840	163,330
Operating Income (Loss)	20,452	9,819	51,092	14,958
Gas Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	144,185	136,726	433,707	401,099
Gross profit	56,096	46,790	158,156	134,854
Operating Income (Loss)	7,136	15,836	48,811	44,986
Water Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	120,007	125,992	390,981	382,987
Gross profit	39,291	44,115	134,661	106,082
Operating Income (Loss)	(3,546)	14,265	28,707	11,415
Corporate Unallocated [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ (17,632)	$ (12,980)	$ (63,153)	$ (34,891)