Long-Term Debt Long-term Debt Schedule (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term debt	$ 340,990	$ 344,686
Less: Current portion	5,392	838
Total long-term debt, less current portion	335,598	343,848
Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt	265,000	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 2013 [Member]
Debt Instrument [Line Items]
Long-term debt	4,867	7,973
Mortgages [Member] | Mortgage loans due 2016 [Member]
Debt Instrument [Line Items]
Long-term debt	3,314	3,407
Mortgages [Member] | Mortgage loans due 2017 [Member]
Debt Instrument [Line Items]
Long-term debt	12,375	12,594
Mortgages [Member] | 444 West Santa Clara Street, L.P. [Member]
Debt Instrument [Line Items]
Long-term debt	3,153	3,248
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] | 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	2,281	2,464
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%
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%