SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT (Details 2) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed financial statements
Income from operations before income tax expense	$ 99,106,000	$ 98,469,000	$ 90,093,000
Net Income	61,058,000us-gaap_NetIncomeLoss	62,686,000us-gaap_NetIncomeLoss	54,148,000us-gaap_NetIncomeLoss
Weighted Average Number of Shares Outstanding (in shares)	38,658	38,639	37,998
Basic Earnings Per Common Share (in dollars per share)	$ 1.57us-gaap_EarningsPerShareBasic	$ 1.61us-gaap_EarningsPerShareBasic	$ 1.42us-gaap_EarningsPerShareBasic
Weighted Average Number of Diluted Common Shares Outstanding	38,880	38,869	38,262
Fully Diluted Earnings per Common Share (in dollars per share)	$ 1.57us-gaap_EarningsPerShareDiluted	$ 1.61us-gaap_EarningsPerShareDiluted	$ 1.41us-gaap_EarningsPerShareDiluted
AWR
Condensed financial statements
Maximum borrowing capacity on line of credit	100,000,000
Operating revenues and other income	81,000	227,000	64,000
Operating Expenses and Other Expenses	48,000	8,000	120,000
Operating income / (loss)	33,000	219,000	(56,000)
Equity in earnings of subsidiaries	60,029,000	60,205,000	54,212,000
Income from operations before income tax expense	60,062,000	60,424,000	54,156,000
Income tax expense (benefit)	(996,000)	(2,262,000)	8,000
Net Income	61,058,000	62,686,000	54,148,000
Promissory note \| AWR
Condensed financial statements
Maximum borrowing capacity on debt instrument	20,000,000
Notes Receivable \| Promissory note \| AWR
Condensed financial statements
Balance outstanding	$ 0

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