CONDENSED CONSOLIDATING FINANCIAL STATEMENTS (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Utility plant:
Utility plant	$ 2,342,471	$ 2,213,328
Less accumulated depreciation and amortization	(752,040)	(697,497)
Net utility plant	1,590,431	1,515,831
Current assets:
Cash and cash equivalents	19,587	27,506	38,790	27,203
Receivables	116,878	98,089
Other current assets	17,659	13,895
Total current assets	154,124	139,490
Other assets:
Regulatory assets	390,331	251,681
Other assets	52,465	52,853
Total other assets	442,796	304,534
Total assets	2,187,351	1,959,855
Capitalization:
Common stockholders' equity	626,626	598,756	473,712	449,829
Long-term debt, less current maturities	419,233	426,142
Total capitalization	1,045,859	1,024,898
Current liabilities:
Current maturities of long-term debt	6,607	7,908
Short-term borrowings	79,115	46,815
Accounts payable	59,395	55,087
Accrued expenses and other liabilities	72,589	56,774
Total current liabilities	217,706	166,584
Unamortized investment tax credits	2,032	2,106
Deferred income taxes, net	214,842	183,245
Pension and postretirement benefits other than pensions	270,865	145,451
Regulatory and other liabilities	83,279	86,455
Advances for construction	182,284	183,393
Contributions in aid of construction	170,484	167,723
Total capitalization and liabilities	2,187,351	1,959,855
Consolidating Adjustments
Utility plant:
Utility plant	(7,197)	(7,197)
Less accumulated depreciation and amortization	1,722	1,615
Net utility plant	(5,475)	(5,582)
Current assets:
Receivables	(1,051)	(94)
Receivables from affiliates	(23,609)	(22,502)
Total current assets	(24,660)	(22,596)
Other assets:
Investments in affiliates	(637,998)	(565,347)
Long-term affiliate notes receivable	(25,263)	(26,255)
Other assets	(321)	(205)
Total other assets	(663,582)	(591,807)
Total assets	(693,717)	(619,985)
Capitalization:
Common stockholders' equity	(643,426)	(570,838)
Affiliate long-term debt	(25,263)	(26,255)
Total capitalization	(668,689)	(597,093)
Current liabilities:
Payables to affiliates	(23,609)	(22,502)
Accounts payable	(201)
Accrued expenses and other liabilities	(756)
Total current liabilities	(24,566)	(22,502)
Deferred income taxes, net	(462)	(390)
Total capitalization and liabilities	(693,717)	(619,985)
Parent Company
Utility plant:
Utility plant	1,318	1,318
Less accumulated depreciation and amortization	(377)	(164)
Net utility plant	941	1,154
Current assets:
Cash and cash equivalents	4,108	5,280	1,470	89
Receivables		(756)
Receivables from affiliates	20,001	16,747
Total current assets	24,109	21,271
Other assets:
Investments in affiliates	637,998	565,347
Long-term affiliate notes receivable	25,263	26,255
Other assets	891	1,120
Total other assets	664,152	592,722
Total assets	689,202	615,147
Capitalization:
Common stockholders' equity	626,626	598,756
Total capitalization	626,626	598,756
Current liabilities:
Short-term borrowings	61,715	16,815
Payables to affiliates		48
Accrued expenses and other liabilities	861	107
Total current liabilities	62,576	16,970
Deferred income taxes, net		(579)
Total capitalization and liabilities	689,202	615,147
Cal Water
Utility plant:
Utility plant	2,154,146	2,034,935
Less accumulated depreciation and amortization	(710,840)	(661,780)
Net utility plant	1,443,306	1,373,155
Current assets:
Cash and cash equivalents	13,929	20,790	34,609	18,475
Receivables	108,815	90,008
Receivables from affiliates	3,608	5,755
Other current assets	16,443	13,011
Total current assets	142,795	129,564
Other assets:
Regulatory assets	387,387	248,938
Other assets	47,617	44,827
Total other assets	435,004	293,765
Total assets	2,021,105	1,796,484
Capitalization:
Common stockholders' equity	569,319	500,290
Long-term debt, less current maturities	417,884	424,854
Total capitalization	987,203	925,144
Current liabilities:
Current maturities of long-term debt	6,173	6,137
Short-term borrowings	17,400	30,000
Payables to affiliates	270
Accounts payable	56,666	51,764
Accrued expenses and other liabilities	71,203	55,346
Total current liabilities	151,712	143,247
Unamortized investment tax credits	2,032	2,106
Deferred income taxes, net	210,789	179,870
Pension and postretirement benefits other than pensions	270,865	145,451
Regulatory and other liabilities	74,282	77,627
Advances for construction	181,763	182,776
Contributions in aid of construction	142,459	140,263
Total capitalization and liabilities	2,021,105	1,796,484
All Other Subsidiaries
Utility plant:
Utility plant	194,204	184,272
Less accumulated depreciation and amortization	(42,545)	(37,168)
Net utility plant	151,659	147,104
Current assets:
Cash and cash equivalents	1,550	1,436	2,711	8,639
Receivables	9,114	8,931
Other current assets	1,216	884
Total current assets	11,880	11,251
Other assets:
Regulatory assets	2,944	2,743
Other assets	4,278	7,111
Total other assets	7,222	9,854
Total assets	170,761	168,209
Capitalization:
Common stockholders' equity	74,107	70,548
Affiliate long-term debt	25,263	26,255
Long-term debt, less current maturities	1,349	1,288
Total capitalization	100,719	98,091
Current liabilities:
Current maturities of long-term debt	434	1,771
Payables to affiliates	23,339	22,454
Accounts payable	2,930	3,323
Accrued expenses and other liabilities	1,281	1,321
Total current liabilities	27,984	28,869
Deferred income taxes, net	4,515	4,344
Regulatory and other liabilities	8,997	8,828
Advances for construction	521	617
Contributions in aid of construction	28,025	27,460
Total capitalization and liabilities	$ 170,761	$ 168,209