Condensed Consolidating Financial Statements (Details 4) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating activities:
Net (loss) income	$ (798)	$ 1,575
Adjustments to reconcile net loss to net cash provided by operating activities:
Equity earnings of subsidiaries	0	0
Dividends received from affiliates	0	0
Depreciation and amortization	16,454	15,736
Change in value of life insurance contracts	43	(161)
Changes in operating assets and liabilities	10,723	3,204
Other changes in noncurrent assets and liabilities	4,604	6,535
Net cash provided by operating activities	31,026	26,889
Investing activities:
Utility plant expenditures	(56,463)	(35,047)
Investment in affiliates		0
Changes in affiliate advances	0	0
Reduction of affiliate long-term debt	0	0
Life insurance proceeds	495	0
Reduction of affiliate short-term borrowings	0
Issuance of affiliate short-term borrowings	0
Purchase of life insurance contracts	(960)	0
Change in restricted cash	(465)	(26)
Net cash used in investing activities	(57,393)	(35,073)
Financing activities:
Short-term borrowings	54,500	30,000
Repayment of short-term borrowings	(53,615)	0
Changes in affiliate advances	$ 0
Investment from affiliates		0
Repayment of affiliate short-term borrowings
Proceeds from affiliate short-term borrowings
Changes in affiliate advances		0
Repayment of affiliate long-term borrowings	$ 0	0
Proceeds from long-term debt, net of expenses	50,039	50
Repayment of long-term debt	(254)	(338)
Advances and contributions in aid of construction	7,608	1,777
Refunds of advances for construction	(1,612)	(1,574)
Dividends paid	(8,258)	(8,007)
Dividends paid to affiliates	0	0
Net cash provided by financing activities	48,408	21,908
Change in cash and cash equivalents	22,041	13,724
Cash and cash equivalents at beginning of period	8,837	19,587
Cash and cash equivalents at end of period	30,878	33,311
Consolidating Adjustments
Operating activities:
Net (loss) income	951	(1,390)
Adjustments to reconcile net loss to net cash provided by operating activities:
Equity earnings of subsidiaries	(937)	1,405
Dividends received from affiliates	(8,258)	(8,007)
Depreciation and amortization	(24)	(25)
Change in value of life insurance contracts	0	0
Changes in operating assets and liabilities	0	(84)
Other changes in noncurrent assets and liabilities	10	94
Net cash provided by operating activities	(8,258)	(8,007)
Investing activities:
Utility plant expenditures	0	0
Investment in affiliates		1,000
Changes in affiliate advances	(1,368)	667
Reduction of affiliate long-term debt	(279)	(243)
Life insurance proceeds	0
Reduction of affiliate short-term borrowings	(21,500)
Issuance of affiliate short-term borrowings	20,850
Purchase of life insurance contracts	0
Change in restricted cash	0	0
Net cash used in investing activities	(2,297)	1,424
Financing activities:
Short-term borrowings	0	0
Repayment of short-term borrowings	0
Changes in affiliate advances	1,368
Investment from affiliates		(1,000)
Repayment of affiliate short-term borrowings	21,500
Proceeds from affiliate short-term borrowings	(20,850)
Changes in affiliate advances		(667)
Repayment of affiliate long-term borrowings	279	243
Proceeds from long-term debt, net of expenses	0	0
Repayment of long-term debt	0	0
Advances and contributions in aid of construction	0	0
Refunds of advances for construction	0	0
Dividends paid	0	0
Dividends paid to affiliates	8,258	8,007
Net cash provided by financing activities	10,555	6,583
Change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Parent Company
Operating activities:
Net (loss) income	(798)	1,575
Adjustments to reconcile net loss to net cash provided by operating activities:
Equity earnings of subsidiaries	937	(1,405)
Dividends received from affiliates	8,258	8,007
Depreciation and amortization	57	57
Change in value of life insurance contracts	0	0
Changes in operating assets and liabilities	(280)	(1,151)
Other changes in noncurrent assets and liabilities	155	1,109
Net cash provided by operating activities	8,329	8,192
Investing activities:
Utility plant expenditures	0	0
Investment in affiliates		(1,000)
Changes in affiliate advances	40	(3,220)
Reduction of affiliate long-term debt	279	243
Life insurance proceeds	0
Reduction of affiliate short-term borrowings	0
Issuance of affiliate short-term borrowings	(250)
Purchase of life insurance contracts	0
Change in restricted cash	0	0
Net cash used in investing activities	69	(3,977)
Financing activities:
Short-term borrowings	21,500	0
Repayment of short-term borrowings	(20,615)
Changes in affiliate advances	0
Investment from affiliates		0
Repayment of affiliate short-term borrowings	(21,500)
Proceeds from affiliate short-term borrowings	20,600
Changes in affiliate advances		0
Repayment of affiliate long-term borrowings	0	0
Proceeds from long-term debt, net of expenses	0	0
Repayment of long-term debt	0	0
Advances and contributions in aid of construction	0	0
Refunds of advances for construction	0	0
Dividends paid	(8,258)	(8,007)
Dividends paid to affiliates	0	0
Net cash provided by financing activities	(8,273)	(8,007)
Change in cash and cash equivalents	125	(3,792)
Cash and cash equivalents at beginning of period	582	4,108
Cash and cash equivalents at end of period	707	316
Cal Water
Operating activities:
Net (loss) income	(889)	2,030
Adjustments to reconcile net loss to net cash provided by operating activities:
Equity earnings of subsidiaries	0	0
Dividends received from affiliates	0	0
Depreciation and amortization	15,277	14,575
Change in value of life insurance contracts	43	(161)
Changes in operating assets and liabilities	9,414	(2,185)
Other changes in noncurrent assets and liabilities	4,432	10,717
Net cash provided by operating activities	28,277	24,976
Investing activities:
Utility plant expenditures	(54,944)	(33,793)
Investment in affiliates		0
Changes in affiliate advances	1,468	2,725
Reduction of affiliate long-term debt	0	0
Life insurance proceeds	495
Reduction of affiliate short-term borrowings	21,500
Issuance of affiliate short-term borrowings	(20,600)
Purchase of life insurance contracts	(960)
Change in restricted cash	(465)	(26)
Net cash used in investing activities	(53,506)	(31,094)
Financing activities:
Short-term borrowings	33,000	30,000
Repayment of short-term borrowings	(33,000)
Changes in affiliate advances	(98)
Investment from affiliates		0
Repayment of affiliate short-term borrowings	0
Proceeds from affiliate short-term borrowings	0
Changes in affiliate advances		1,309
Repayment of affiliate long-term borrowings	0	0
Proceeds from long-term debt, net of expenses	49,823	0
Repayment of long-term debt	(175)	(197)
Advances and contributions in aid of construction	7,590	1,759
Refunds of advances for construction	(1,611)	(1,573)
Dividends paid	0	0
Dividends paid to affiliates	(8,058)	(7,909)
Net cash provided by financing activities	47,471	23,389
Change in cash and cash equivalents	22,242	17,271
Cash and cash equivalents at beginning of period	4,270	13,929
Cash and cash equivalents at end of period	26,512	31,200
All Other Subsidiaries
Operating activities:
Net (loss) income	(62)	(640)
Adjustments to reconcile net loss to net cash provided by operating activities:
Equity earnings of subsidiaries	0	0
Dividends received from affiliates	0	0
Depreciation and amortization	1,144	1,129
Change in value of life insurance contracts	0	0
Changes in operating assets and liabilities	1,589	6,624
Other changes in noncurrent assets and liabilities	7	(5,385)
Net cash provided by operating activities	2,678	1,728
Investing activities:
Utility plant expenditures	(1,519)	(1,254)
Investment in affiliates		0
Changes in affiliate advances	(140)	(172)
Reduction of affiliate long-term debt	0	0
Life insurance proceeds	0
Reduction of affiliate short-term borrowings	0
Issuance of affiliate short-term borrowings	0
Purchase of life insurance contracts	0
Change in restricted cash	0	0
Net cash used in investing activities	(1,659)	(1,426)
Financing activities:
Short-term borrowings	0	0
Repayment of short-term borrowings	0
Changes in affiliate advances	(1,270)
Investment from affiliates		1,000
Repayment of affiliate short-term borrowings	0
Proceeds from affiliate short-term borrowings	250
Changes in affiliate advances		(642)
Repayment of affiliate long-term borrowings	(279)	(243)
Proceeds from long-term debt, net of expenses	216	50
Repayment of long-term debt	(79)	(141)
Advances and contributions in aid of construction	18	18
Refunds of advances for construction	(1)	(1)
Dividends paid	0	0
Dividends paid to affiliates	(200)	(98)
Net cash provided by financing activities	(1,345)	(57)
Change in cash and cash equivalents	(326)	245
Cash and cash equivalents at beginning of period	3,985	1,550
Cash and cash equivalents at end of period	$ 3,659	$ 1,795