Business Segments (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Business Segments
Total utility plant	$ 917,791,000	$ 896,500,000	$ 854,956,000
Other assets	363,152,000	341,862,000	337,079,000
Total Assets	1,280,943,000	1,238,362,000	1,192,035,000
GSWC
Business Segments
Total utility plant	913,137,000	891,945,000
Total Assets	1,214,052,000	1,173,383,000
Segment Reporting Information [Line Items]
Depreciation on transportation equipment	1,800,000	2,500,000	2,200,000
AWR Parent
Business Segments
Total Assets	455,166,000	411,145,000
CCWC
Segment Reporting Information [Line Items]
Direct transaction costs, before tax		449,000	708,000
Direct transaction costs, net of tax		217,000	426,000
CCWC | AWR Parent
Segment Reporting Information [Line Items]
Direct transaction costs, before tax		449,000	708,000
Direct transaction costs, net of tax		$ 217,000	$ 426,000