CONSOLIDATED STATEMENTS OF CAPITALIZATION (Parenthetical)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 6.64% notes due 2013	Dec. 31, 2011 6.64% notes due 2013	Dec. 31, 2012 6.64% notes due 2013 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 6.64% notes due 2013 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 6.80% notes due 2013	Dec. 31, 2011 6.80% notes due 2013	Dec. 31, 2012 6.80% notes due 2013 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 6.80% notes due 2013 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 6.87% notes due 2023	Dec. 31, 2011 6.87% notes due 2023	Dec. 31, 2012 6.87% notes due 2023 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 6.87% notes due 2023 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 7.00% notes due 2023	Dec. 31, 2011 7.00% notes due 2023	Dec. 31, 2012 7.00% notes due 2023 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 7.00% notes due 2023 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 6.81% notes due 2028	Dec. 31, 2011 6.81% notes due 2028	Dec. 31, 2012 6.81% notes due 2028 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 6.81% notes due 2028 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 6.59% notes due 2029	Dec. 31, 2011 6.59% notes due 2029	Dec. 31, 2012 6.59% notes due 2029 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 6.59% notes due 2029 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 7.875% notes due 2030	Dec. 31, 2011 7.875% notes due 2030	Dec. 31, 2012 7.875% notes due 2030 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 7.875% notes due 2030 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 7.23% notes due 2031	Dec. 31, 2011 7.23% notes due 2031	Dec. 31, 2012 7.23% notes due 2031 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 7.23% notes due 2031 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 5.87% private placement notes due 2028	Dec. 31, 2011 5.87% private placement notes due 2028	Dec. 31, 2012 5.87% private placement notes due 2028 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 5.87% private placement notes due 2028 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 6.70% private placement notes due 2019	Dec. 31, 2011 6.70% private placement notes due 2019	Dec. 31, 2012 6.70% private placement notes due 2019 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 6.70% private placement notes due 2019 GOLDEN STATE WATER COMPANY	Dec. 31, 2012 5.50% tax-exempt obligation due 2026	Dec. 31, 2011 5.50% tax-exempt obligation due 2026	Dec. 31, 2012 5.50% tax-exempt obligation due 2026 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 5.50% tax-exempt obligation due 2026 GOLDEN STATE WATER COMPANY	Dec. 31, 2011 8.50% other fixed rate obligation due 2012	Dec. 31, 2011 8.50% other fixed rate obligation due 2012 GOLDEN STATE WATER COMPANY
Interest rate per annum (as a percent)					6.64%	6.64%	6.64%	6.64%	6.80%	6.80%	6.80%	6.80%	6.87%	6.87%	6.87%	6.87%	7.00%	7.00%	7.00%	7.00%	6.81%	6.81%	6.81%	6.81%	6.59%	6.59%	6.59%	6.59%	7.875%	7.875%	7.875%	7.875%	7.23%	7.23%	7.23%	7.23%	5.87%	5.87%	5.87%	5.87%	6.70%	6.70%	6.70%	6.70%	5.50%	5.50%	5.50%	5.50%	8.50%	8.50%
Common stock, shares authorized	30,000,000	30,000,000
Common stock, shares outstanding	19,237,212	18,788,993	146	146