Segment and Nonregulated Business Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014 subsidiaries		Jun. 30, 2013		Dec. 31, 2013
Segment Reporting Information [Line Items]
Number of Subsidiaries					4
Operating revenue	$ 70,356		$ 74,230		$ 124,952		$ 124,369
Operating expense	58,235		57,293		106,777		101,659
Operating income (loss)	12,121		16,937		18,175		22,710
Net income (loss)	6,846		7,440		7,752		8,757
Depreciation and amortization	9,495		8,743		18,980		17,559
Senior note, mortgage and other interest expense	4,954		4,956		9,824		9,978
Income tax expense (benefit) in net income	3,092		5,191		3,653		6,121
Assets	1,147,022		1,130,465		1,147,022		1,130,465		1,109,986
Water Utility Services [Member] | Regulated [Member]
Segment Reporting Information [Line Items]
Operating revenue	66,967		71,457		118,593		119,255
Operating expense	55,642		54,960		102,105		96,585
Operating income (loss)	11,325		16,497		16,488		22,670
Net income (loss)	5,591		7,686		6,494		9,286
Depreciation and amortization	8,989		8,264		17,966		16,586
Senior note, mortgage and other interest expense	4,139		4,146		8,220		8,298
Income tax expense (benefit) in net income	2,208		5,379		2,760		6,301
Assets	1,053,145		1,034,842		1,053,145		1,034,842
Water Utility Services [Member] | Nonregulated [Member]
Segment Reporting Information [Line Items]
Operating revenue	1,553		1,579		2,781		2,665
Operating expense	1,216		1,353		2,088		3,035
Operating income (loss)	337		226		693		(370)
Net income (loss)	132		108		283		(400)
Depreciation and amortization	90		92		180		180
Senior note, mortgage and other interest expense	0		0		0		0
Income tax expense (benefit) in net income	117		57		241		(87)
Assets	17,487		16,596		17,487		16,596
Real Estate Services [Member] | Nonregulated [Member]
Segment Reporting Information [Line Items]
Operating revenue	1,836		1,194		3,578		2,449
Operating expense	1,055		748		2,077		1,558
Operating income (loss)	781		446		1,501		891
Net income (loss)	380		33		584		669
Depreciation and amortization	416		387		834		793
Senior note, mortgage and other interest expense	262		265		499		585
Income tax expense (benefit) in net income	273		47		426		507
Assets	66,300		71,300		66,300		71,300
All Other [Member] | Nonregulated [Member]
Segment Reporting Information [Line Items]
Operating revenue	0	[1]	0	[1]	0	[1]	0	[1]
Operating expense	322	[1]	232	[1]	507	[1]	481	[1]
Operating income (loss)	(322)	[1]	(232)	[1]	(507)	[1]	(481)	[1]
Net income (loss)	743	[1]	(387)	[1]	391	[1]	(798)	[1]
Depreciation and amortization	0	[1]	0	[1]	0	[1]	0	[1]
Senior note, mortgage and other interest expense	553	[1]	545	[1]	1,105	[1]	1,095	[1]
Income tax expense (benefit) in net income	494	[1]	(292)	[1]	226	[1]	(600)	[1]
Assets	10,090	[1]	7,727	[1]	10,090	[1]	7,727	[1]
SJW Corp. [Member] | Regulated [Member]
Segment Reporting Information [Line Items]
Operating revenue	66,967		71,457		118,593		119,255
Operating expense	55,642		54,960		102,105		96,585
Operating income (loss)	11,325		16,497		16,488		22,670
Net income (loss)	5,591		7,686		6,494		9,286
Depreciation and amortization	8,989		8,264		17,966		16,586
Senior note, mortgage and other interest expense	4,139		4,146		8,220		8,298
Income tax expense (benefit) in net income	2,208		5,379		2,760		6,301
Assets	1,053,145		1,034,842		1,053,145		1,034,842
SJW Corp. [Member] | Nonregulated [Member]
Segment Reporting Information [Line Items]
Operating revenue	3,389		2,773		6,359		5,114
Operating expense	2,593		2,333		4,672		5,074
Operating income (loss)	796		440		1,687		40
Net income (loss)	1,255		(246)		1,258		(529)
Depreciation and amortization	506		479		1,014		973
Senior note, mortgage and other interest expense	815		810		1,604		1,680
Income tax expense (benefit) in net income	884		(188)		893		(180)
Assets	$ 93,877		$ 95,623		$ 93,877		$ 95,623

[1] The “All Other” category includes the accounts of SJW Corp. on a stand-alone basis.