Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net income	$ 37,882	$ 51,806	$ 22,384
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	42,330	39,491	36,595
Deferred income taxes	15,925	26,067	11,567
Share-based compensation	1,603	1,031	912
Gain on sale of real estate investment	(1,886)	(554)	(1,063)
Gain on sale of California Water Service Group stock	0	(2,017)	0
Changes in operating assets and liabilities:
Accounts receivable and accrued unbilled utility revenue	735	(1,276)	(3,073)
Accounts payable and other current liabilities	1,550	(403)	(369)
Accrued groundwater extraction charges, purchased water and power	1,133	(1,751)	2,709
Tax receivable and accrued taxes	(3,297)	(5,546)	(1,112)
Postretirement benefits	(117)	(325)	127
Regulatory asset related to balancing and memorandum accounts	1,429	(39,727)	(3,257)
Other noncurrent assets and noncurrent liabilities	1,950	(2,001)	(884)
Other changes, net	(1,980)	1,116	(1,111)
Net cash provided by operating activities	97,257	65,911	63,425
Investing activities:
Company-funded	(96,012)	(91,846)	(82,720)
Contributions in aid of construction	(10,762)	(10,090)	(11,605)
Additions to real estate investment	(1,097)	(13)	(4,232)
Payments for business/asset acquisition and water rights	(991)	(1,768)	(3,349)
Cost to retire utility plant, net of salvage	(3,673)	(1,551)	(2,695)
Proceeds from sale of real estate investment	1,925	4,572	8,831
Proceeds from sale of California Water Service Group stock	0	3,056	0
Net cash used in investing activities	(110,610)	(97,640)	(95,770)
Financing activities:
Borrowings from line of credit	97,000	57,200	48,600
Repayments of line of credit	(75,600)	(66,400)	(41,500)
Long-term borrowings	0	50,000	0
Repayments of long-term borrowings	(633)	(602)	(5,439)
Debt issuance costs	0	(528)	(19)
Dividends paid	(15,885)	(15,177)	(14,443)
Issuance of common stock, net of issuance costs	0	0	35,894
Exercise of stock options and similar instruments	895	1,917	1,004
Tax benefits realized from share options exercised	634	462	28
Receipts of advances and contributions in aid of construction	12,266	7,569	10,293
Refunds of advances for construction	(2,484)	(2,612)	(2,296)
Net cash provided by financing activities	16,193	31,829	32,122
Net change in cash and cash equivalents	2,840	100	(223)
Cash and cash equivalents, beginning of year	5,239	2,399	2,299
Cash and cash equivalents, end of year	2,399	2,299	2,522
Cash paid during the year for:
Interest	23,634	21,046	20,886
Income Taxes Paid, Net	9,723	6,324	4,186
Supplemental disclosure of non-cash activities:
Increase (Decrease) in accrued payables for construction costs capitalized	7,540	(4,981)	4,588
Utility property installed by developers	$ 1,011	$ 6,549	$ 2,162