Summary of Significant Accounting Policies (Regulatory Rate Filings) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Jan. 03, 2012	Oct. 27, 2010	Dec. 31, 2013 Cost of capital memorandum account [Member]	Dec. 31, 2012 Cost of capital memorandum account [Member]	Dec. 31, 2013 Water supply balancing accounts [Member]	Dec. 31, 2012 Water supply balancing accounts [Member]	Dec. 31, 2013 Income tax temporary differences [Member]	Dec. 31, 2012 Income tax temporary differences [Member]	Dec. 31, 2013 Postretirement pensions and other medical benefits [Member]	Dec. 31, 2012 Postretirement pensions and other medical benefits [Member]	Dec. 31, 2013 Pension balancing account [Member]	Dec. 31, 2012 Pension balancing account [Member]	Dec. 31, 2013 Water rate assistance program balancing account [Member]	Dec. 31, 2012 Water rate assistance program balancing account [Member]	Dec. 31, 2013 Other [Member]	Dec. 31, 2012 Other [Member]	Oct. 03, 2013 SJWTX,Inc. dba Canyon Lake Water Supply Corporation [Member]
Regulatory Assets and Liabilities [Abstract]
Regulatory assets	$ 88,218	$ 134,377							$ 8,220	$ 8,146	$ 62,949	$ 113,633	$ 9,734	$ 6,671	$ 2,590	$ 776	$ 4,725	$ 5,151
Regulatory liabilities	4,675	3,889			2,297	2,295	2,378	1,594
Net Regulatory Assets	83,543	130,488
Requested rate increase for 2013			47,400
Requested rate increase for 2013 as percentage of total revenue at time of request			21.51%
Requested rate increase for 2014			13,000
Requested rate increase for 2014 as percentage of total revenue at time of request			4.87%
Requested rate increase for 2015			34,800
Requested rate increase for 2015 as percentage of total revenue at time of request			12.59%
Regulatory Rate Filings, Requested Recovery of Under-Collected Balance Accounts			2,599
Amount of net over-collection requested to be refunded to customers			$ 650
Immediate increase requested, percentage				38.00%
Total increase requested, percentage				71.00%															23.10%