Condensed Consolidating Financial Statements (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Operating activities:
Net income	$ 33,650	$ 29,151	$ 45,344	$ 41,588
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization			48,481	45,067
Changes in value of life insurance contracts			(501)	(1,147)
Other changes in noncurrent assets and liabilities			13,340	13,501
Changes in operating assets and liabilities			(6,497)	2,890
Net cash provided by operating activities			100,167	101,899
Investing activities:
Utility plant expenditures			(86,258)	(94,782)
Purchase of life insurance contracts			(3,207)	(3,204)
Changes in restricted cash and other changes, net			354	1,148
Net cash used in investing activities			(89,111)	(96,838)
Financing Activities:
Short-term borrowings			99,900	35,315
Repayment of short-term borrowings			(85,000)	(113,275)
Proceeds from long-term debt				48
Repayment of long-term debt			(4,604)	(3,058)
Advances and contributions in aid for construction			8,780	7,577
Refunds of advances for construction			(4,858)	(5,230)
Dividends paid to non-affiliates			(23,295)	(21,981)
Issuance of common stock, net				105,600
Net cash (used in) provided by financing activities			(9,077)	4,996
Change in cash and cash equivalents			1,979	10,057
Cash and cash equivalents at beginning of period			27,506	38,790
Cash and cash equivalents at end of period	29,485	48,847	29,485	48,847
Consolidating Adjustments
Operating activities:
Net income	(33,484)	(28,821)	(44,756)	(40,866)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity earnings of subsidiaries	33,499	28,838	44,803	40,916
Dividends received from affiliates			(23,295)	(21,981)
Depreciation and amortization			(80)	(84)
Other changes in noncurrent assets and liabilities			33	(49)
Changes in operating assets and liabilities				83
Net cash provided by operating activities			(23,295)	(21,981)
Investing activities:
Investment in affiliates			46,850	35,000
Net changes in affiliate advances			877	10,801
Repayment of affiliates long-term debt				(8,710)
Proceeds from affiliates long-term debt			(699)
Net cash used in investing activities			47,028	37,091
Financing Activities:
Net changes in affiliate advances			(877)	(10,801)
Repayment of affiliates long-term borrowings			699	8,710
Dividends paid to affiliates			23,295	21,981
Investment from affiliates			(46,850)	(35,000)
Net cash (used in) provided by financing activities			(23,733)	(15,110)
Parent Company
Operating activities:
Net income	33,650	29,151	45,344	41,588
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity earnings of subsidiaries	(33,499)	(28,838)	(44,803)	(40,916)
Dividends received from affiliates			23,295	21,981
Depreciation and amortization			157	42
Other changes in noncurrent assets and liabilities			2,160	1,164
Changes in operating assets and liabilities			(68)	390
Net cash provided by operating activities			26,085	24,249
Investing activities:
Utility plant expenditures				(640)
Investment in affiliates			(46,850)	(35,000)
Net changes in affiliate advances			(5,455)	(9,583)
Repayment of affiliates long-term debt				913
Proceeds from affiliates long-term debt			699
Net cash used in investing activities			(51,606)	(44,310)
Financing Activities:
Short-term borrowings			64,900	15,315
Repayment of short-term borrowings			(20,000)	(68,275)
Net changes in affiliate advances			(48)
Repayment of affiliates long-term borrowings				(7,796)
Dividends paid to non-affiliates			(23,295)	(21,981)
Issuance of common stock, net				105,600
Net cash (used in) provided by financing activities			21,557	22,863
Change in cash and cash equivalents			(3,964)	2,802
Cash and cash equivalents at beginning of period			5,280	1,470
Cash and cash equivalents at end of period	1,316	4,272	1,316	4,272
Cal Water
Operating activities:
Net income	32,558	28,386	45,560	42,177
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization			45,059	42,509
Changes in value of life insurance contracts			(501)	(1,147)
Other changes in noncurrent assets and liabilities			11,539	12,415
Changes in operating assets and liabilities			(7,969)	4,220
Net cash provided by operating activities			93,688	100,174
Investing activities:
Utility plant expenditures			(81,505)	(84,688)
Net changes in affiliate advances			4,778	(2,359)
Repayment of affiliates long-term debt				7,797
Purchase of life insurance contracts			(3,207)	(3,204)
Changes in restricted cash and other changes, net			354	1,148
Net cash used in investing activities			(79,580)	(81,306)
Financing Activities:
Short-term borrowings			35,000	20,000
Repayment of short-term borrowings			(65,000)	(45,000)
Net changes in affiliate advances			1,814	(972)
Repayment of long-term debt			(2,919)	(2,531)
Advances and contributions in aid for construction			8,239	7,545
Refunds of advances for construction			(4,809)	(5,184)
Dividends paid to affiliates			(23,005)	(19,790)
Investment from affiliates			42,000	35,000
Net cash (used in) provided by financing activities			(8,680)	(10,932)
Change in cash and cash equivalents			5,428	7,936
Cash and cash equivalents at beginning of period			20,790	34,609
Cash and cash equivalents at end of period	26,218	42,545	26,218	42,545
All Other Subsidiaries
Operating activities:
Net income	926	435	(804)	(1,311)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization			3,345	2,600
Other changes in noncurrent assets and liabilities			(392)	(29)
Changes in operating assets and liabilities			1,540	(1,803)
Net cash provided by operating activities			3,689	(543)
Investing activities:
Utility plant expenditures			(4,753)	(9,454)
Net changes in affiliate advances			(200)	1,141
Net cash used in investing activities			(4,953)	(8,313)
Financing Activities:
Proceeds from long-term debt				48
Net changes in affiliate advances			(889)	11,773
Repayment of affiliates long-term borrowings			(699)	(914)
Repayment of long-term debt			(1,685)	(527)
Advances and contributions in aid for construction			541	32
Refunds of advances for construction			(49)	(46)
Dividends paid to affiliates			(290)	(2,191)
Investment from affiliates			4,850
Net cash (used in) provided by financing activities			1,779	8,175
Change in cash and cash equivalents			515	(681)
Cash and cash equivalents at beginning of period			1,436	2,711
Cash and cash equivalents at end of period	$ 1,951	$ 2,030	$ 1,951	$ 2,030