CONSOLIDATED STATEMENTS OF CAPITALIZATION (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Common Shareholders' Equity:
Common shares, no par value	$ 249,322	$ 233,306
Earnings reinvested in the business	205,257	175,360
Common shareholders' equity	454,579	408,666
Long-Term Debt
Long-Term Debt including Current maturities	335,791	340,686
Less: Current maturities	(3,328)	(291)
Long-Term Debt	332,463	340,395
Total capitalization	787,042	749,061
GOLDEN STATE WATER COMPANY
Common Shareholders' Equity:
Common shares, no par value	231,480	228,936
Earnings reinvested in the business	184,777	155,870
Common shareholders' equity	416,257	384,806
Long-Term Debt
Long-Term Debt including Current maturities	335,791	340,686
Less: Current maturities	(3,328)	(291)
Long-Term Debt	332,463	340,395
Total capitalization	748,720	725,201
6.64% notes due 2013
Long-Term Debt
Long-Term Debt including Current maturities	1,100	1,100
6.64% notes due 2013 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	1,100	1,100
6.80% notes due 2013
Long-Term Debt
Long-Term Debt including Current maturities	2,000	2,000
6.80% notes due 2013 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	2,000	2,000
6.87% notes due 2023
Long-Term Debt
Long-Term Debt including Current maturities	5,000	5,000
6.87% notes due 2023 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	5,000	5,000
7.00% notes due 2023
Long-Term Debt
Long-Term Debt including Current maturities	10,000	10,000
7.00% notes due 2023 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	10,000	10,000
7.55% notes due 2025
Long-Term Debt
Long-Term Debt including Current maturities		8,000
7.55% notes due 2025 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities		8,000
6.81% notes due 2028
Long-Term Debt
Long-Term Debt including Current maturities	15,000	15,000
6.81% notes due 2028 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	15,000	15,000
6.59% notes due 2029
Long-Term Debt
Long-Term Debt including Current maturities	40,000	40,000
6.59% notes due 2029 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	40,000	40,000
7.875% notes due 2030
Long-Term Debt
Long-Term Debt including Current maturities	20,000	20,000
7.875% notes due 2030 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	20,000	20,000
7.23% notes due 2031
Long-Term Debt
Long-Term Debt including Current maturities	50,000	50,000
7.23% notes due 2031 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	50,000	50,000
6.00% notes due 2041
Long-Term Debt
Long-Term Debt including Current maturities	62,000	62,000
6.00% notes due 2041 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	62,000	62,000
9.56% private placement notes due 2031
Long-Term Debt
Long-Term Debt including Current maturities	28,000	28,000
9.56% private placement notes due 2031 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	28,000	28,000
5.87% private placement notes due 2028
Long-Term Debt
Long-Term Debt including Current maturities	40,000	40,000
5.87% private placement notes due 2028 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	40,000	40,000
6.70% private placement notes due 2019
Long-Term Debt
Long-Term Debt including Current maturities	40,000	40,000
6.70% private placement notes due 2019 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	40,000	40,000
5.50% tax-exempt obligation due 2026
Long-Term Debt
Long-Term Debt including Current maturities	7,730	7,745
5.50% tax-exempt obligation due 2026 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	7,730	7,745
Tax-Exempt Variable Rate Obligation due 2014
Long-Term Debt
Long-Term Debt including Current maturities	6,000	6,000
Tax-Exempt Variable Rate Obligation due 2014 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	6,000	6,000
Tax-Exempt State Water Project due 2035
Long-Term Debt
Long-Term Debt including Current maturities	4,453	4,559
Tax-Exempt State Water Project due 2035 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	4,453	4,559
8.50% other fixed rate obligation due 2012
Long-Term Debt
Long-Term Debt including Current maturities		133
8.50% other fixed rate obligation due 2012 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities		133
Other Variable Rate Obligation due 2018
Long-Term Debt
Long-Term Debt including Current maturities	196	232
Other Variable Rate Obligation due 2018 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	196	232
American Recovery and Reinvestment Act Obligation due 2033
Long-Term Debt
Long-Term Debt including Current maturities	4,259	851
American Recovery and Reinvestment Act Obligation due 2033 | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	4,259	851
Capital lease obligations
Long-Term Debt
Long-Term Debt including Current maturities	53	66
Capital lease obligations | GOLDEN STATE WATER COMPANY
Long-Term Debt
Long-Term Debt including Current maturities	$ 53	$ 66