Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] | 1. Basis of Preparation of Financials The condensed consolidated financial statements included herein have been prepared by Connecticut Water Service, Inc. (“CTWS” or the “Company”) and its wholly-owned subsidiaries, pursuant to the rules and regulations of the Securities and Exchange Commission and reflect all adjustments that are of a normal recurring nature which are, in the opinion of management, necessary to a fair statement of the results for interim periods. Certain information and footnote disclosures have been omitted pursuant to such rules and regulations, although the Company believes that the disclosures are adequate to make the information presented not misleading. The Company’s primary operating subsidiaries are: The Connecticut Water Company (“Connecticut Water”), The Heritage Village Water Company (“HVWC”) and The Avon Water Company (“Avon Water”) in the State of Connecticut and The Maine Water Company (“Maine Water”) in the State of Maine. The Condensed Consolidated Balance Sheet at December 31, 2017 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements. It is suggested that these condensed consolidated financial statements be read in conjunction with the financial statements and the notes thereto included in the Company’s latest Annual Report on Form 10-K for the fiscal year ended December 31, 2017 (the “10-K”) and as updated in the Company’s Quarterly Reports on Forms 10-Q for the periods ended March 31, 2018 and June 30, 2018. The results for interim periods are not necessarily indicative of results to be expected for the year since the consolidated earnings are subject to seasonal factors. Effective February 27, 2017 and July 1, 2017, the Company acquired HVWC and Avon Water, respectively, discussed further in Note 12 below. As a result, the Company’s Condensed Consolidated Statements of Net Income, Condensed Consolidated Statements of Comprehensive Income, Condensed Consolidated Statements of Retained Earnings and Condensed Consolidated Statements of Cash Flows for the three and nine months ended September 30, 2017 include only three months of activity related to Avon Water after its acquisition on July 1, 2017 and approximately seven months of activity related to HVWC after its acquisition on February 27, 2017. The Condensed Consolidated Statements of Net Income, Condensed Consolidated Statements of Comprehensive Income, Condensed Consolidated Statements Retained Earnings and the Condensed Consolidated Statements of Cash Flows for the three and nine months ended September 30, 2018 include HVWC’s and Avon Water’s results. HVWC’s and Avon Water’s assets and liabilities are included in the Condensed Consolidated Balance Sheet as of September 30, 2018 and December 31, 2017 . As noted in Note 12 below, HVWC serves approximately 4,700 water customers in the Towns of Southbury, Middlebury, and Oxford, Connecticut and approximately 3,000 wastewater customers in the Town of Southbury, Connecticut. The results of the wastewater line of business are included in the Company’s Water Operations segment. Additionally, as noted in Note 12, Avon Water serves approximately 4,800 water customers in the Towns of Avon, Farmington, and Simsbury, Connecticut. Proposed Merger with SJW Group On August 5, 2018, the Company entered into a Second Amended and Restated Agreement and Plan of Merger (the “Revised Merger Agreement”) with SJW Group, a Delaware corporation (“SJW”), and Hydro Sub, Inc., a Connecticut corporation and a direct wholly owned subsidiary of SJW (“Merger Sub”), pursuant to which Merger Sub will merge with and into the Company, with the Company surviving the merger as a wholly owned subsidiary of SJW (the “Merger”). Subject to the terms and conditions of the Revised Merger Agreement, at the effective time of the Merger, each outstanding share of our common stock (other than certain cancelled shares) will be automatically converted into the right to receive an amount in cash equal to $70.00 per share, payable without interest. The Revised Merger Agreement amends and restates in its entirety the Amended and Restated Agreement and Plan of Merger (the “First Amended and Restated Merger Agreement”), dated as of May 30, 2018, by and among the Company, SJW and Merger Sub, which amended and restated in its entirety the Agreement and Plan of Merger (the “Original Merger Agreement”), dated as of March 14, 2018, by and among the Company, SJW and Merger Sub. The Board of Directors approved, adopted and declared advisable and resolved to recommend to the Company’s shareholders the approval of the Revised Merger Agreement and the Merger following a comprehensive review of the transaction. The Merger is subject to certain customary closing conditions, including, among other things, approval of the Revised Merger Agreement by the Company’s shareholders and regulatory approvals (including the approval of the Connecticut Public Utilities Regulatory Authority (“PURA”) and the Maine Public Utilities Commission (“MPUC”)). The required waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the rules and regulations promulgated thereunder (the “HSR Act”), was terminated early on April 27, 2018. On October 15, 2018, the Federal Communications Commission (“FCC”) consented to the joint application for transfer of control filed by the Company and SJW on October 4, 2018 and amended on October 12, 2018, and no further clearance from the FCC is required. On May 4, 2018, Maine Water filed with the MPUC an application for approval of the Merger. On May 7, 2018, the Company and SJW filed with the PURA a joint application for approval of the Merger. Following the start on May 31, 2018 of a 45-day go-shop process permitted by the First Amended and Restated Merger Agreement, the Company and SJW withdrew their joint PURA application on June 19, 2018, and filed a new joint application on July 18, 2018, following the end of the go-shop process. On July 20, 2018, the California Public Utilities Commission (“CPUC”) formally issued an Order Instituting Investigation (“Order”) providing that the CPUC will investigate whether the Merger is subject to CPUC approval and the Merger’s anticipated impacts within California. The Order states that the CPUC plans to substantially complete its investigation in a manner sufficiently timely to allow the Merger to go forward by the end of 2018, if appropriate. The Company and SJW expect the closing of the Merger to occur during the first quarter of 2019. Regulatory Matters The rates we charge our water and waste water customers in Connecticut and Maine are established under the jurisdiction of and are approved by PURA and the MPUC, respectively. It is our policy to seek rate relief as necessary to enable us to achieve an adequate rate of return. The Regulated Companies’ allowed returns on equity and allowed returns on rate base are as follows: As of September 30, 2018 Allowed Return on Equity Allowed Return on Rate Base Connecticut Water 9.75 % 7.32 % HVWC (blended water and wastewater rates) 10.10 % 7.19 % Avon Water 10.00 % 7.79 % Maine Water 9.50 % 7.96 % The PURA establishes rates in Connecticut on a company-wide basis while the MPUC approves Maine Water’s rates on a division-by-division basis. Each of Connecticut Water, HVWC, Avon Water and Maine Water are allowed to add surcharges to customers’ bills in order to recover certain costs associated with approved capital projects in between full rate cases, as well as approved surcharges for Water Revenue Adjustments, in Connecticut, as discussed in more detail below. HVWC has not added surcharges to customers’ bills in order to recover certain approved capital projects as of September 30, 2018 , however, HVWC, as ordered by PURA, began to utilize Water Revenue Adjustments for water and wastewater as of March 31, 2017. On January 3, 2018, PURA filed a motion to reopen the most recent rate case decisions for the Company’s Connecticut Regulated Companies to determine what, if any, adjustments to rates are appropriate to account for revisions to tax laws, including corporate tax rates, contained in the Tax Cuts and Jobs Act (“Tax Act”). PURA held a hearing on July 30, 2018 for regulated water companies. As discussed below, Connecticut Water has entered into a settlement agreement with the Connecticut Office of Consumer Counsel (“OCC”), which was approved by PURA, that covers treatment of the Tax Act. On January 11, 2018, the MPUC issued a notice of investigation to determine the impact of the Tax Act on Maine Water. The investigation will allow the MPUC to determine the specific impact of the Tax Act and whether any rate adjustments are warranted. Following discovery, technical conferences were held on April 19, 2018 and July 17, 2018. In addition to determining the impact of the Tax Act on the justness and reasonableness of Maine Water’s rates, the MPUC will consider whether to issue an accounting order to establish a regulatory liability which defers for future return to ratepayers the impact of the tax changes. During the three months ended September 30, 2018, the Company reserved approximately $100,000 in revenues from Maine Water in anticipation of a rate order from the MPUC that will establish lower rates as a result of the Tax Act. Maine Water Land Sale On March 11, 2016, Maine Water entered into a purchase and sale agreement with the Coastal Mountains Land Trust, a Maine nonprofit corporation (the “Land Trust”) pursuant to which Maine Water agreed to sell two conservation easements to the Land Trust on approximately 1,300 acres of land located in the towns of Rockport, Camden and Hope, in Knox County, Maine valued in the aggregate at $3.1 million. The land had a book value of approximately $600,000 at September 30, 2018 and December 31, 2017 and is included in “Utility Plant” on the Company’s Consolidated Balance Sheets. The easements and purchase prices are as follows: 1. Ragged Mountain Mirror Lake Conservation Easement: $1,875,000; and 2. Grassy Pond conservation Easement: $600,000. On June 25, 2018, an amendment to the agreement was made to extend closing of the first transaction to September 30, 2018, from June 30, 2018. This amendment also will extend the second closing into 2020. Maine Water will make a $250,000 contribution to the Land Trust upon completion of the closing of the first easement sale. Maine Water also expects to claim a charitable deduction for the $600,000 in excess of the fair market value of the second easement over the $600,000 sale price. The first half of this easement sale, and Maine Water’s related contribution to the Land Trust, was completed in the third quarter of 2018. As a result of the transaction, the Company has recognized $435,000 in net income in the period and has recorded a regulatory liability of $435,000 that will be refunded to customers over a one-year period, beginning January 1, 2019. In addition to the net income recorded as part of the transaction, the Company recorded a $100,000 deferred income tax benefit due to the timing difference related to the cash refund to customers. The total net income benefit recorded by the Company for this transaction was $535,000 presented as $625,000 in gain on real estate transactions offset by $90,000 of donation deduction in the Other line item. Connecticut Rates Connecticut Water’s Water Infrastructure Conservation Adjustment (“WICA”) was 0.00% and 8.25% at September 30, 2018 and 2017 , respectively. Connecticut Water’s WICA was reset to zero as a result of a rate ruling on the Company’s limited reopener and settlement agreement issued by PURA, as discussed below. As of September 30, 2018 and 2017 , respectively, Avon Water’s WICA surcharge was 7.51% and 8.09%. As of September 30, 2018 , HVWC has not filed for a WICA surcharge. On February 6, 2018, Connecticut Water filed a petition with PURA to reopen Connecticut Water’s 2010 rate case proceeding (previously reopened in 2013) for the limited purpose of approving a Settlement Agreement entered into by Connecticut Water and the OCC (the “Agreement”). The Agreement proposes a change in Connecticut Water’s customer rates effective for bills rendered on and after April 1, 2018 made up of the following two components: (1) the revenue requirements associated with a $36.3 million addition to rate base to reflect necessary upgrades to Connecticut Water’s Rockville Water Treatment Plant; and (2) the folding in to base rates of the Company’s present WICA surcharges. In addition, the Agreement provides that: 1. Upon implementation of new rates under the Agreement, until such time as new rates are adopted in a general rate case, through a temporary modification of the earnings sharing mechanism, Connecticut Water customers will receive one hundred percent of any earnings in excess of levels allowed by law rather than limiting such customer credits to 50% as contemplated by applicable law; 2. Connecticut Water agrees it will not file for a general increase of Connecticut Water’s base rates to be effective before January 1, 2020; 3. The pending proceeding initiated by PURA in Docket No. 09-12-11RE03, Application of The Connecticut Water Company for Amended Rates – Federal Tax Cuts and Jobs Act shall be closed; and 4. Connecticut Water shall continue to make investments in infrastructure replacement consistent with its approved WICA plan. Connecticut Water shall be allowed to continue to pursue recovery of eligible projects through WICA and apply WRA charges as authorized. PURA issued a Proposed Final Decision on July 6, 2018 that rejected the Settlement Agreement, due to the proposed treatment of income tax expense resulting from the Tax Act. The Company and the Office of Consumer Council each filed written exceptions to the draft decision and a hearing was held on a revised settlement agreement submitted from both parties that would include an adjustment to reflect the impacts of the Tax Act but at a lower dollar amount than recommended in the PURA draft decision. On August 15, 2018, PURA issued a final decision that accepted the conditions of the revised settlement agreement. The primary facets of the revised settlement agreement were the revenue requirements associated with the Rockville Water Treatment Plant, discussed above, and the folding of previously approved WICA surcharges into base rates, which reset Connecticut Water’s WICA to zero and resolution of the Company’s obligations related to the Tax Act. Rates were effective retroactive to April 1, 2018. Since 2013, Connecticut law has authorized a Water Revenue Adjustment (“WRA”) to reconcile actual water revenues with the revenues projected in the last general rate case and allows companies to adjust rates as necessary to recover the revenues approved by PURA in the last general rate case. The WRA removes the financial disincentive for water utilities to develop and implement effective water conservation programs. The WRA allows water companies to defer on the balance sheet, as a regulatory asset or liability, for later collection from or crediting to customers the amount by which actual revenues deviate from the revenues allowed in the most recent general rate proceedings, including WICA proceedings. Additionally, projects eligible for WICA surcharges were expanded to include energy conservation projects, improvements required to comply with streamflow regulations, and improvements to certain acquired systems. Connecticut Water’s and HVWC’s allowed revenues for the nine months ended September 30, 2018 , as approved by PURA during each company’s most recent general rate case and including subsequently approved WICA surcharges, are approximately $64.9 million. Through normal billing for the nine months ended September 30, 2018 , revenue for Connecticut Water and HVWC would have been approximately $58.7 million had the WRA not been implemented. As a result of the implementation of the WRA, Connecticut Water and HVWC recorded $6.2 million in additional revenue for the nine months ended September 30, 2018 . Avon Water does not currently have PURA approval to apply the WRA surcharge to its customers’ bills and, therefore, does not currently use the WRA mechanism. Maine Rates In Maine, the overall, cumulative Water Infrastructure Charge (“WISC”) for all divisions was 6.80% and 6.47% as of September 30, 2018 and 2017 , respectively. The WISC rates for the Biddeford and Saco division were reset to zero with the approval of the general rate increase discussed below. On June 29, 2017, Maine Water filed for a rate increase in its Biddeford and Saco division. The rate request was for an approximate $1.6 million, or 25.1%, increase in revenues. The rate request was designed to recover higher operating expenses, depreciation and property taxes since Biddeford and Saco’s last rate increase in 2015. Maine Water and the Maine Office of the Public Advocate reached an agreement that increases annual revenue by $1.56 million. The agreement was approved by the MPUC on December 5, 2017, with new rates effective December 1, 2017. A water revenue adjustment mechanism law in Maine became available to regulated water utilities in Maine on October 15, 2015. Maine Water is currently precluded from seeking new rates in the Biddeford and Saco division due to provisions in the settlement agreement with the MPUC. As the stay-out periods for other divisions expire, Maine Water expects to request usage of this mechanism as Maine Water files rate cases for those divisions. |