Dividend Limitations (Details)	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Dividend limitations
Common shareholder’s equity	$ 494,297,000	$ 465,945,000	$ 506,801,000	$ 492,404,000
Retained Earnings (Accumulated Deficit)	247,065,000	220,923,000
GSWC
Dividend limitations
Fixed amount in computing maximum ability to pay dividends	$ 21,000,000.0
Percentage of consolidated net income plus the aggregate net cash proceeds received from capital stock offerings or other instruments convertible into capital stock	100.00%
Amount available to pay dividends under the most restrictive of the Note Agreements	$ 374,800,000
Dividends paid	25,450,000	62,000,000	52,000,000
Common shareholder’s equity	$ 446,770,000	423,730,000	435,190,000	437,613,000
Ratio of Indebtedness to Net Capital	0.4680
Retained Earnings (Accumulated Deficit)		184,935,000
GSWC | Maximum [Member]
Dividend limitations
Ratio of Indebtedness to Net Capital	0.6667
AWR
Dividend limitations
Common shareholder’s equity	$ 494,297,000	465,945,000
Subsidiaries [Member]
Dividend limitations
Dividends paid	33,800,000		52,000,000
Earnings Reinvested in the Business
Dividend limitations
Common shareholder’s equity	247,065,000	220,923,000	253,602,000	238,443,000
Earnings Reinvested in the Business | GSWC
Dividend limitations
Common shareholder’s equity	206,288,000	$ 184,935,000	$ 199,583,000	$ 203,892,000
Retained Earnings (Accumulated Deficit)	206,288,000
Earnings Reinvested in the Business | American States Utility Services [Member]
Dividend limitations
Retained Earnings (Accumulated Deficit)	$ 57,200,000