Segment Information Information By Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Revenues	$ 469,092	$ 496,454	$ 1,387,442	$ 1,460,602
Gross profit	146,966	150,762	403,736	468,338
Operating Income (Loss)	27,208	16,458	36,796	52,924
Total other income (expense)	(3,739)	(4,421)	(11,899)	(13,966)
Income Before Income Taxes	23,469	12,037	24,897	38,958
Electricity Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	206,389	203,441	603,651	567,414
Gross profit	56,859	45,959	164,601	141,675
Operating Income (Loss)	10,575	(11,196)	16,875	(35,412)
Gas Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	136,588	149,276	401,063	449,707
Gross profit	45,916	53,492	133,541	168,609
Operating Income (Loss)	15,741	23,836	44,075	73,889
Water Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	126,115	143,737	382,728	443,481
Gross profit	44,191	51,311	105,594	158,054
Operating Income (Loss)	14,290	19,157	10,876	60,319
Corporate Unallocated [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ (13,398)	$ (15,339)	$ (35,030)	$ (45,872)