CONDENSED CONSOLIDATING FINANCIAL STATEMENTS (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net income (loss)	$ 45,017	$ 56,738	$ 47,254
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity earnings of subsidiaries	0	0	0
Dividends received from affiliates	0	0	0
Depreciation and amortization	63,182	63,322	60,250
Change in value of life insurance contracts	218	(994)	(1,878)
Stock-based compensation	2,578	2,195	1,832
(Gain) on sale of non-utility property	(315)	(51)	0
Changes in deferred income taxes	24,393	34,125	9,800
Changes in operating assets and liabilities	(1,877)	(12,681)	(4,410)
Other changes in noncurrent assets and liabilities	11,435	(14,521)	11,325
Net cash provided by operating activities	144,631	128,133	124,173
Investing activities:
Utility plant expenditures	(176,833)	(132,015)	(122,988)
Proceeds from sale of non-utility assets	319	57	0
Investment in affiliates	0	0	0
Change in affiliate advances	0	0	0
Reduction of affiliate short-term borrowings	0
Issuance of affiliate short-term borrowings	0
Reduction of affiliate long-term debt	0	0
Proceeds from affiliates long term debt			0
Purchase of life insurance	(2,032)	(3,207)	(3,281)
Change in restricted cash	288	396	1,073
Net cash used in investing activities	(178,258)	(134,769)	(125,196)
Financing Activities:
Short-term borrowings	94,303	117,300	70,615
Repayment of short-term borrowings	(141,000)	(85,000)	(113,275)
Investment from affiliates	0	0	0
Change in affiliate advances	0	0	0
Proceeds from affiliate short-term borrowings	0
Reduction of affiliate short-term borrowings	0
Repayment of affiliate long-term debt	0
Repayment of affiliate long-term debt		0	0
Proceeds from long-term debt	99,343	497	48
Repayment of long-term debt	(7,003)	(8,705)	(47,248)
Advances and contributions in aid of construction	16,026	12,329	10,563
Refunds of advances for construction	(6,726)	(6,641)	(6,922)
Dividends paid	(32,066)	(31,063)	(29,619)
Dividends paid to affiliates	0	0	0
Issuance of common stock			105,577
Net cash provided by (used in) financing activities	22,877	(1,283)	(10,261)
Change in cash and cash equivalents	(10,750)	(7,919)	(11,284)
Cash and cash equivalents at beginning of year	19,587	27,506	38,790
Cash and cash equivalents at end of year	8,837	19,587	27,506
Consolidating Adjustments
Operating activities:
Net income (loss)	(44,456)	(56,000)	(46,453)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity earnings of subsidiaries	44,516	56,064	46,519
Dividends received from affiliates	(32,066)	(31,063)	(29,619)
Depreciation and amortization	(101)	(107)	(112)
Change in value of life insurance contracts	0	0	0
Stock-based compensation	0	0	0
(Gain) on sale of non-utility property	0	0
Changes in deferred income taxes	0	0	0
Changes in operating assets and liabilities	(94)	0	95
Other changes in noncurrent assets and liabilities	135	43	(49)
Net cash provided by operating activities	(32,066)	(31,063)	(29,619)
Investing activities:
Utility plant expenditures	0	0	0
Proceeds from sale of non-utility assets	0	0
Investment in affiliates	1,000	47,650	35,000
Change in affiliate advances	1,235	1,133	16,268
Reduction of affiliate short-term borrowings	(3,000)
Issuance of affiliate short-term borrowings	24,780
Reduction of affiliate long-term debt	(1,007)	(938)
Proceeds from affiliates long term debt			(9,023)
Purchase of life insurance	0	0	0
Change in restricted cash	0	0	0
Net cash used in investing activities	23,008	47,845	42,245
Financing Activities:
Short-term borrowings	0	0	0
Repayment of short-term borrowings	0	0	0
Investment from affiliates	(1,000)	(47,650)	(35,000)
Change in affiliate advances	(1,235)	(1,133)	(16,268)
Proceeds from affiliate short-term borrowings	(24,780)
Reduction of affiliate short-term borrowings	3,000
Repayment of affiliate long-term debt	1,007
Repayment of affiliate long-term debt		938	9,023
Proceeds from long-term debt	0	0	0
Repayment of long-term debt	0	0	0
Advances and contributions in aid of construction	0	0	0
Refunds of advances for construction	0	0	0
Dividends paid	0	0	0
Dividends paid to affiliates	32,066	31,063	29,619
Issuance of common stock			0
Net cash provided by (used in) financing activities	9,058	(16,782)	(12,626)
Change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of year	0	0	0
Parent Company
Operating activities:
Net income (loss)	45,017	56,738	47,254
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity earnings of subsidiaries	(44,516)	(56,064)	(46,519)
Dividends received from affiliates	32,066	31,063	29,619
Depreciation and amortization	228	214	56
Change in value of life insurance contracts	0	0	0
Stock-based compensation	2,578	2,195	1,832
(Gain) on sale of non-utility property	0	0
Changes in deferred income taxes	0	0	0
Changes in operating assets and liabilities	(758)	16	544
Other changes in noncurrent assets and liabilities	1,436	789	(76)
Net cash provided by operating activities	36,051	34,951	32,710
Investing activities:
Utility plant expenditures	0	0	(712)
Proceeds from sale of non-utility assets	0	0
Investment in affiliates	(1,000)	(47,650)	(35,000)
Change in affiliate advances	(239)	(3,200)	(14,903)
Reduction of affiliate short-term borrowings	3,000
Issuance of affiliate short-term borrowings	(3,280)
Reduction of affiliate long-term debt	1,007	938
Proceeds from affiliates long term debt			1,227
Purchase of life insurance	0	0	0
Change in restricted cash	0	0	0
Net cash used in investing activities	(512)	(49,912)	(49,388)
Financing Activities:
Short-term borrowings	15,101	64,900	20,615
Repayment of short-term borrowings	(43,600)	(20,000)	(68,275)
Investment from affiliates	0	0	0
Change in affiliate advances	0	(48)	(14)
Proceeds from affiliate short-term borrowings	21,500
Reduction of affiliate short-term borrowings	0
Repayment of affiliate long-term debt	0
Repayment of affiliate long-term debt		0	(7,796)
Proceeds from long-term debt	0	0	0
Repayment of long-term debt	0	0	0
Advances and contributions in aid of construction	0	0	0
Refunds of advances for construction	0	0	0
Dividends paid	(32,066)	(31,063)	(29,619)
Dividends paid to affiliates	0	0	0
Issuance of common stock			105,577
Net cash provided by (used in) financing activities	(39,065)	13,789	20,488
Change in cash and cash equivalents	(3,526)	(1,172)	3,810
Cash and cash equivalents at beginning of year	4,108	5,280	1,470
Cash and cash equivalents at end of year	582	4,108	5,280
Cal Water
Operating activities:
Net income (loss)	44,056	57,680	49,009
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity earnings of subsidiaries	0	0	0
Dividends received from affiliates	0	0	0
Depreciation and amortization	58,385	58,657	56,670
Change in value of life insurance contracts	218	(994)	(1,878)
Stock-based compensation	0	0	0
(Gain) on sale of non-utility property	(315)	(51)
Changes in deferred income taxes	24,393	34,125	9,800
Changes in operating assets and liabilities	(6,417)	(11,803)	226
Other changes in noncurrent assets and liabilities	14,807	(15,596)	11,899
Net cash provided by operating activities	135,127	122,018	125,726
Investing activities:
Utility plant expenditures	(171,645)	(125,048)	(111,819)
Proceeds from sale of non-utility assets	319	57
Investment in affiliates	0	0	0
Change in affiliate advances	(1,111)	2,147	(2,575)
Reduction of affiliate short-term borrowings	0
Issuance of affiliate short-term borrowings	(21,500)
Reduction of affiliate long-term debt	0	0
Proceeds from affiliates long term debt			7,796
Purchase of life insurance	(2,032)	(3,207)	(3,281)
Change in restricted cash	288	396	1,073
Net cash used in investing activities	(195,681)	(125,655)	(108,806)
Financing Activities:
Short-term borrowings	79,202	52,400	50,000
Repayment of short-term borrowings	(97,400)	(65,000)	(45,000)
Investment from affiliates	0	42,000	35,000
Change in affiliate advances	397	270	(1,152)
Proceeds from affiliate short-term borrowings	0
Reduction of affiliate short-term borrowings	0
Repayment of affiliate long-term debt	0
Repayment of affiliate long-term debt		0	0
Proceeds from long-term debt	99,293	0	0
Repayment of long-term debt	(6,528)	(6,934)	(46,547)
Advances and contributions in aid of construction	14,195	11,219	10,465
Refunds of advances for construction	(6,681)	(6,529)	(6,814)
Dividends paid	0	0	0
Dividends paid to affiliates	(31,583)	(30,650)	(26,691)
Issuance of common stock			0
Net cash provided by (used in) financing activities	50,895	(3,224)	(30,739)
Change in cash and cash equivalents	(9,659)	(6,861)	(13,819)
Cash and cash equivalents at beginning of year	13,929	20,790	34,609
Cash and cash equivalents at end of year	4,270	13,929	20,790
All Other Subsidiaries
Operating activities:
Net income (loss)	400	(1,680)	(2,556)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity earnings of subsidiaries	0	0	0
Dividends received from affiliates	0	0	0
Depreciation and amortization	4,670	4,558	3,636
Change in value of life insurance contracts	0	0	0
Stock-based compensation	0	0	0
(Gain) on sale of non-utility property	0	0
Changes in deferred income taxes	0	0	0
Changes in operating assets and liabilities	5,392	(894)	(5,275)
Other changes in noncurrent assets and liabilities	(4,943)	243	(449)
Net cash provided by operating activities	5,519	2,227	(4,644)
Investing activities:
Utility plant expenditures	(5,188)	(6,967)	(10,457)
Proceeds from sale of non-utility assets	0	0
Investment in affiliates	0	0	0
Change in affiliate advances	115	(80)	1,210
Reduction of affiliate short-term borrowings	0
Issuance of affiliate short-term borrowings	0
Reduction of affiliate long-term debt	0	0
Proceeds from affiliates long term debt			0
Purchase of life insurance	0	0	0
Change in restricted cash	0	0	0
Net cash used in investing activities	(5,073)	(7,047)	(9,247)
Financing Activities:
Short-term borrowings	0	0	0
Repayment of short-term borrowings	0	0	0
Investment from affiliates	1,000	5,650	0
Change in affiliate advances	838	911	17,434
Proceeds from affiliate short-term borrowings	3,280
Reduction of affiliate short-term borrowings	(3,000)
Repayment of affiliate long-term debt	(1,007)
Repayment of affiliate long-term debt		(938)	(1,227)
Proceeds from long-term debt	50	497	48
Repayment of long-term debt	(475)	(1,771)	(701)
Advances and contributions in aid of construction	1,831	1,110	98
Refunds of advances for construction	(45)	(112)	(108)
Dividends paid	0	0	0
Dividends paid to affiliates	(483)	(413)	(2,928)
Issuance of common stock			0
Net cash provided by (used in) financing activities	1,989	4,934	12,616
Change in cash and cash equivalents	2,435	114	(1,275)
Cash and cash equivalents at beginning of year	1,550	1,436	2,711
Cash and cash equivalents at end of year	$ 3,985	$ 1,550	$ 1,436