Long-Term Debt (Details 3) (USD $)	0 Months Ended	12 Months Ended
	Oct. 31, 2009 item	Dec. 31, 2012	Dec. 31, 2011
Long-term debt
Loan proceeds received for reimbursement of costs of conversion		$ 3,408,000	$ 61,912,000
GSWC
Long-term debt
Number of water meters to be installed	6,200
Loan proceeds received for reimbursement of costs of conversion		3,408,000	61,912,000
GSWC | American Recovery and Reinvestment Act Obligation due 2033
Long-term debt
Maximum amount of loan that can be borrowed	9,000,000
Interest rate (as a percent)		2.50%
Maturity term		20 years
Loan proceeds received for reimbursement of costs of conversion		8,500,000
GSWC | American Recovery and Reinvestment Act Obligation due 2033 | Letters of credit to CDHP
Long-term debt
Letters of credit issued, percentage of maximum available under facility		80.00%
Amount of debt issued		$ 7,200,000