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Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Restricted stock and deferred restricted stock Restricted Stock and Deferred Restricted Stock [Member] Restricted Stock and Deferred Restricted Stock [Member] Schedule of Compensation Costs Charged to Income and Proceeds from the Exercise of Any Restricted Stock and Similar Instruments that are Recorded to Additional Paid-In Capital and Common Stock, by Award Type Share-based Payment Arrangement, Cost by Plan [Table Text Block] Stock-based compensation Share-based Payment Arrangement, Noncash Expense Entity [Domain] Entity [Domain] Other changes, net Proceeds from (Payments for) Other Financing Activities 2012 General Rate Case true-up 2012 General Rate Case True-up [Member] 2012 General Rate Case True-up [Member] Cover [Abstract] Regulatory Asset [Domain] Regulatory Asset [Domain] Cost of capital memorandum account Cost of capital [Member] Cost of capital [Member] Long-term debt, book value Long-term Debt Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Regulatory Asset Increase (Decrease) Balancing and Memorandum Cost Recovery Account, Increase (Decrease) Balancing and Memorandum Cost Recovery Account, Increase (Decrease) Investments Investments Service cost Defined Benefit Plan, Service Cost LESS RESTRICTED CASH, END OF PERIOD Restricted Cash and Cash Equivalents Tax receivable and payable, and other accrued taxes Increase (Decrease) in Accrued Taxes Payable Equity Components [Axis] Equity Components [Axis] Construction in progress Public Utilities, Property, Plant and Equipment, Construction Work in Progress Regulatory assets, net not earning a return Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Minimum Minimum [Member] Other balancing and memorandum accounts revenue, net Regulatory Balancing and Memorandum Accounts Revenue, Net Regulatory Balancing and Memorandum Accounts Revenue, Net Consolidated Entities [Domain] Consolidated Entities [Domain] 3.89% Note Due March 2041 3.89% Note Due March 2041 [Member] 3.89% Note Due March 2041 Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Water Rate Adjustment (“WRA”) WRA [Member] WRA [Member] SJW Corp. and SJWTX, Inc. SJW Corp. and SJWTX, Inc. [Member] SJW Corp. and SJWTX, Inc. 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income Operating Lease, Lease Income Contributions in aid of construction Payments to Acquire Water Systems using Contributions In Aid of Construction Payments to Acquire Water Systems using Contributions In Aid of Construction Sale of Stock [Axis] Sale of Stock [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Purchase price of common stock under ESPP (percent) Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent Refunds (Collections) Adjustments Balancing and Memorandum Account, Refunds (Collections) Balancing and Memorandum Account, Refunds (Collections) Cash Cash Goodwill Goodwill CTWS Plan CTWS Plan [Member] CTWS Plan [Member] Document Transition Report Document Transition Report Power Utilities Operating Expense, Purchased Power Purchased water Cost of Purchased Water Title of Individual [Axis] Title of Individual [Axis] Regulatory Rate Filings Regulatory Rate Filings [Text Block] Regulatory Rate Filings [Text Block] Connecticut Water Company Connecticut Water Company [Member] Connecticut Water Company [Member] Schedule of Regulatory Assets [Table] Schedule of Regulatory Assets [Table] Restricted cash Restricted Cash and Cash Equivalents, Current Aggregate principal amount Debt Instrument, Face Amount Significant Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Building and Building Improvements Building and Building Improvements [Member] Other current assets Other Assets, Current Regulatory rate filings, requested rate increase, year one Regulatory Rate Filings, Requested Rate Increase, Year One Regulatory Rate Filings, Requested Rate Increase, Year One Document Quarterly Report Document Quarterly Report Equity [Abstract] General and Administrative Expense General and Administrative Expense [Member] Accounts receivable and accrued unbilled utility revenue Increase (Decrease) in Receivables Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Real Estate Services Reportable Segment Two [Member] Reportable Segment Two [Member] Supplemental disclosure of non-cash activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Other production expenses Utilities Operating Expense, Other Subsequent Event [Line Items] Subsequent Event [Line Items] Credit Facility [Domain] Credit Facility [Domain] Beginning Balance Ending Balance Balancing and Memorandum Cost Recovery Account, Net Balancing and Memorandum Cost Recovery Account, Net Diluted (shares) Weighted Average Number of Shares Outstanding, Diluted Mutual funds Mutual Fund [Member] Basic (usd per share) Earnings Per Share, Basic Maintenance Utilities Operating Expense, Maintenance Public Utilities General Disclosures [Table] Public Utilities General Disclosures [Table] Unrealized gain (loss) on investment, tax benefit OCI, Debt Securities, 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Authorized Regulatory Surcharge, Per Thousand Gallons Authorized Regulatory Surcharge, Per Thousand Gallons Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Other current liabilities Other Liabilities, Current Other comprehensive income (loss), net Other Comprehensive Income (Loss), Net of Tax Regulatory Asset [Axis] Regulatory Asset [Axis] WICA WICA [Member] WICA Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Total current assets Assets, Current Current Fiscal Year End Date Current Fiscal Year End Date EARNINGS PER SHARE Earnings Per Share [Abstract] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Payments to retire utility plant, net of salvage Payments for (Proceeds from) Removal Costs Allowance for equity funds used during construction Public Utilities, Allowance for Funds Used During Construction, Additions Refunds (Collections) Adjustments Balancing and Memorandum Cost Recovery Account, Refunds (Collections) Balancing and Memorandum Cost Recovery Account, Refunds (Collections) Document Fiscal Period Focus Document Fiscal Period Focus Regulatory Assets, Net Schedule of Regulatory Assets and Liabilities [Text Block] Subsidiary, Sale of Stock [Line Items] Subsidiary, Sale of Stock [Line Items] ADVANCES FOR CONSTRUCTION Contract with Customer, Liability, Noncurrent Accrued additional common stock issuance costs Stock Issuance Costs Incurred But Not Yet Paid Stock Issuance Costs Incurred But Not Yet Paid Cash paid during the period for: Supplemental Cash Flow Information [Abstract] Employee stock purchase plan (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Entity Filer Category Entity Filer Category Common Stock Common Stock [Member] SJWC Credit Agreement SJWC Credit Agreement [Member] SJWC Credit Agreement Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset [Domain] Schedule of Regulatory Assets, Net Schedule of Regulatory Assets [Table Text Block] SJWTX, Inc. SJWTX, Inc. [Member] SJWTX, Inc. [Member] Regulatory assets and liabilities related to balancing and memorandum accounts Increase (Decrease) to Regulatory Asset Related to Balancing and Memorandum Accounts Increase (Decrease) to Regulatory Asset Related to Balancing and Memorandum Accounts Beginning Balance Ending Balance Balancing and Memorandum Account, Net Balancing and Memorandum Account, Net Common stock issuance, net of costs (in shares) Stock Issued During Period, Shares, New Issues Regulated Regulated Operation [Member] Intangible assets Finite-Lived Intangible Assets, Gross Requested WISC surcharge increase (decrease), percentage Requested WISC Surcharge Increase (Decrease), Percentage Requested WISC Surcharge Increase (Decrease), Percentage Stockholders’ equity: Stockholders' Equity, Number of Shares, Par Value and Other Disclosures [Abstract] Estimated employer contributions for the current fiscal year Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year Interest Rate Debt Instrument, Interest Rate, Stated Percentage Money market funds Money Market Funds [Member] Tax memorandum account Tax memorandum [Member] Tax memorandum account [Member] NET CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Alternative revenue programs, net Alternative Revenue Programs, Net Alternative Revenue Programs, Net Basis of Accounting Basis of Accounting, Policy [Policy Text Block] Maine Water Company Maine Water Company [Member] Maine Water Company [Member] Basic (shares) Weighted Average Number of Shares Outstanding, Basic Accrued unbilled utility revenue Receivables, Long-term Contracts or Programs OPERATING EXPENSE: Costs and Expenses [Abstract] Sale of Stock [Domain] Sale of Stock [Domain] Plan Name [Domain] Plan Name [Domain] Interest Interest Paid, Excluding Capitalized Interest, Operating Activities Total operating expense Operating expense Utilities Operating Expense Unrecognized actuarial loss Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Long-term debt, fair value Long-term Debt, Fair Value Equity Plans Shareholders' Equity and Share-based Payments [Text Block] REVENUE Total revenues Revenues Class of Stock [Axis] Class of Stock [Axis] (Benefit) provision for income taxes (Benefit) provision for income taxes Income Tax Expense (Benefit) Income taxes Income Taxes Paid, Net Total production expenses Water Production Costs CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF PERIOD CASH, CASH EQUIVALENTS AND RESTRICTED CASH , END OF PERIOD Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Employer plan contributions Defined Contribution Plan, Employer Discretionary Contribution Amount Regulatory rate filings, requested deferment period Regulatory Rate Filings, Requested Deferment Period Regulatory Rate Filings, Requested Deferment Period Title of Individual [Domain] Title of Individual [Domain] Production Expenses: Water Production Costs [Abstract] Water Production Costs [Abstract] Public utilities, requested rate increase (decrease), amount Public Utilities, Requested Rate Increase (Decrease), Amount Diluted (usd per share) Earnings Per Share, Diluted Local Phone Number Local Phone Number Accounts receivable: Accounts Receivable, after Allowance for Credit Loss, Current [Abstract] Beginning Balance Ending Balance Balancing and Memorandum Revenue Account, Net Balancing and Memorandum Revenue Accounting, Net Depreciation Depreciation Entity Address, Address Line One Entity Address, Address Line One Entity Emerging Growth Company Entity Emerging Growth Company Deferred income taxes Deferred Income Tax Expense (Benefit) Regulatory Asset Increase (Decrease) Balancing and Memorandum Account, Increase (Decrease) Balancing and Memorandum Account, Increase (Decrease) Regulatory rate filings, requested authorization for capital budget, amount Regulatory Rate Filings, Requested Authorization For Capital Budget, Amount Regulatory Rate Filings, Requested Authorization For Capital Budget, Amount 2014-2017 WCMA 2014-2017 WCMA [Member] 2014-2017 WCMA [Member] Line of credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Award Type [Axis] Award Type [Axis] Requested WICA surcharge, percentage Requested WICA Surcharge, Percentage Requested WICA Surcharge, Percentage Maximum Maximum [Member] Retained Earnings Retained Earnings [Member] Public Utility, Property, Plant and Equipment [Line Items] Public Utility, Property, Plant and Equipment [Line Items] Effective consolidated income tax rate Effective Income Tax Rate Reconciliation, Percent Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] General Significant Accounting Policies [Text Block] NET CASH USED IN INVESTING ACTIVITIES Net Cash Provided by (Used in) Investing Activities Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Long-Term Liabilities and Bank Borrowings [Abstract] Long-Term Liabilities and Bank Borrowings [Abstract] Long-Term Liabilities and Bank Borrowings [Abstract] Revenue accounts: Balancing and Memorandum Revenue Account [Roll Forward] Balancing and Memorandum Revenue Account [Roll Forward] Award Type [Domain] Award Type [Domain] Trading Symbol Trading Symbol Postretirement pensions and other medical benefits Postretirement Pensions and Other Medical Benefits [Member] Postretirement Pensions and Other Medical Benefits [Member] ESPP proceeds Proceeds, Issuance of Shares, Share-based Payment Arrangement, Including Option Exercised Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Less accumulated depreciation and amortization Real Estate Investment Property, Accumulated Depreciation Regulation Status [Axis] Regulation Status [Axis] Cost-recovery accounts: Balancing and Memorandum Cost Recovery Account [Roll Forward] Balancing and Memorandum Cost Recovery Account [Roll Forward] CURRENT LIABILITIES: Liabilities, Current [Abstract] Entity Shell Company Entity Shell Company Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Real estate investments, net Real Estate Investment Property, Net Recently Adopted Accounting Principles New Accounting Pronouncements, Policy [Policy Text Block] Borrowings on line of credit Proceeds from Lines of Credit Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Utility Plant Depreciation Regulatory Depreciation and Amortization, Policy [Policy Text Block]