Long-Term Debt Long-term Debt Schedule (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term debt	$ 384,949us-gaap_LongTermDebt	$ 335,551us-gaap_LongTermDebt
Less: Current portion	584us-gaap_LongTermDebtCurrent	554us-gaap_LongTermDebtCurrent
Total long-term debt, less current portion	384,365us-gaap_LongTermDebtNoncurrent	334,997us-gaap_LongTermDebtNoncurrent
Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt	315,000	265,000
Mortgages [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Stated interest rates	5.61%
Mortgages [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Stated interest rates	6.09%
Mortgages [Member] \| Mortgage loans due 2016 [Member]
Debt Instrument [Line Items]
Long-term debt	3,109	3,215
Mortgages [Member] \| Mortgage loans due 2017 [Member]
Debt Instrument [Line Items]
Long-term debt	11,896	12,142
Mortgages [Member] \| 444 West Santa Clara Street, L.P. [Member]
Debt Instrument [Line Items]
Long-term debt	2,947	3,053
Stated interest rates	5.68%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series A [Member]
Debt Instrument [Line Items]
Long-term debt	20,000	20,000
Stated interest rates	8.58%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series B [Member]
Debt Instrument [Line Items]
Long-term debt	30,000	30,000
Stated interest rates	7.37%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series C [Member]
Debt Instrument [Line Items]
Long-term debt	10,000	10,000
Stated interest rates	9.45%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series D [Member]
Debt Instrument [Line Items]
Long-term debt	15,000	15,000
Stated interest rates	7.15%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series E [Member]
Debt Instrument [Line Items]
Long-term debt	15,000	15,000
Stated interest rates	6.81%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series F [Member]
Debt Instrument [Line Items]
Long-term debt	20,000	20,000
Stated interest rates	7.20%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series G [Member]
Debt Instrument [Line Items]
Long-term debt	20,000	20,000
Stated interest rates	5.93%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series H [Member]
Debt Instrument [Line Items]
Long-term debt	20,000	20,000
Stated interest rates	5.71%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series I [Member]
Debt Instrument [Line Items]
Long-term debt	20,000	20,000
Stated interest rates	5.93%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series J [Member]
Debt Instrument [Line Items]
Long-term debt	10,000	10,000
Stated interest rates	6.54%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series K [Member]
Debt Instrument [Line Items]
Long-term debt	20,000	20,000
Stated interest rates	6.75%
San Jose Water Company [Member] \| Senior Notes [Member] \| Series L [Member]
Debt Instrument [Line Items]
Long-term debt	50,000	0
Stated interest rates	5.14%
San Jose Water Company [Member] \| Bonds [Member] \| California Pollution Control Financing Authority Revenue Bonds [Member]
Debt Instrument [Line Items]
Long-term debt	50,000	50,000
Stated interest rates	5.10%
San Jose Water Company [Member] \| SDWSRF loans [Member]
Debt Instrument [Line Items]
Long-term debt	1,997	2,141
San Jose Water Company [Member] \| SDWSRF loans [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Stated interest rates	2.39%
San Jose Water Company [Member] \| SDWSRF loans [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Stated interest rates	2.60%	2.60%
SJWTX,Inc. dba Canyon Lake Water Supply Corporation [Member] \| Senior Notes [Member] \| Series A [Member]
Debt Instrument [Line Items]
Long-term debt	15,000	15,000
Stated interest rates	6.27%
SJW Corp. [Member] \| Senior Notes [Member] \| Series A [Member]
Debt Instrument [Line Items]
Long-term debt	$ 50,000	$ 50,000
Stated interest rates	4.35%

Contractual interest rate for funds borrowed, under the debt agreement.

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