Regulatory Matters: (Details 4) (GSWC, La Serena Plant Improvement Project, CPUC Rehearing Matter, USD $)	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 31, 2008	Dec. 31, 2012	Dec. 31, 2010
GSWC | La Serena Plant Improvement Project | CPUC Rehearing Matter
Regulatory matters:
Costs included in rehearing matter	$ 3,500,000
Disallowed costs and related refunds		$ 416,000	$ 2,200,000