Segment Information Information By Segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Revenues	$ 489,353	$ 482,175	$ 964,148	$ 929,711
Gross profit	163,041	159,588	317,576	299,711
Operating Income (Loss)	31,927	17,976	36,466	20,323
Total other income (expense)	(4,235)	(3,884)	(9,545)	(5,978)
Income Before Income Taxes	27,692	14,092	26,921	14,345
Electricity Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	183,755	213,612	363,973	389,375
Gross profit	52,976	62,545	95,716	107,457
Operating Income (Loss)	(1,247)	(4,117)	(24,216)	(23,167)
Gas Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	154,322	136,011	300,431	272,926
Gross profit	56,711	50,128	115,117	100,770
Operating Income (Loss)	24,329	18,881	50,053	38,411
Water Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues	151,276	132,552	299,744	267,410
Gross profit	53,354	46,915	106,743	91,484
Operating Income (Loss)	20,519	15,389	41,162	27,964
Corporate Unallocated [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ (11,674)	$ (12,177)	$ (30,533)	$ (22,885)