|**Recent Accounting Pronouncements**            | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|----------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|
|**Recent Accounting Pronouncements [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|Recent Accounting Pronouncements                | Note 16 –Recent Accounting Pronouncements
		﻿
		In March 2017, the FASB issued updated accounting guidance on the presentation of net periodic pension and postretirement benefit cost (net benefit cost).  Historically, net benefit cost is reported as an employee cost within operating income, net of amounts capitalized.  The guidance requires the bifurcation of net benefit cost.  The service cost component will be presented with other employee compensation costs in operating income and the other components of net benefit cost will be reported separately outside of operating income, and will not be eligible for capitalization.  The guidance is effective for annual reporting periods beginning after December 15, 2017, and interim periods within that reporting period, and is to be applied retrospectively for the presentation of the service cost component and the other components of net benefit cost, and on a prospective basis for the capitalization of only the service cost component of net benefit cost.  On January 1, 2018, the Company adopted the updated guidance, which did not have a material impact on its results of operations or financial position, and resulted in the reclassification, for the three and six months ended June 30, 2017, of$1,238and$2,478, respectively, for the other components of net benefit cost from operations and maintenance expense to other in the consolidated statements of net income.
		﻿
		In June 2016, the FASB issued updated accounting guidance on accounting for impairments of financial instruments, including trade receivables, which requires companies to estimate expected credit losses on trade receivables over their contractual life.  Historically, companies reserve for expected credit losses by applying historical loss percentages to respective aging categories.  Under the updated accounting guidance, companies will use a forward-looking methodology that incorporates lifetime expected credit losses, which will result in an allowance for expected credit losses for receivables that are either current or not yet due, which historically have not been reserved for.  The updated accounting guidance is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption available.  The Company is evaluating the requirements of the updated guidance to determine the impact of adoption.
		﻿
		In February 2016, the FASB issued updated accounting guidance on accounting for leases, which requires lessees to establish a right-of-use asset and a lease liability on the balance sheet for all leases with terms longer than 12 months.  For income statement purposes, leases will be classified as either operating or finance.  Operating leases will result in straight-line expense while finance leases will result in a front-loaded expense pattern.  The updated accounting guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption available.  The Company is in the process of evaluating the requirements of the updated guidance to determine the impact adoption will have on its consolidated financial statements; however, the Company expects that the adoption of the updated accounting guidance on accounting for leases should not have a material impact on the Company’s consolidated balance sheet due to the recognition of right-of-use assets and lease liabilities.
		﻿
		In January 2016, the FASB issued updated accounting guidance on the recognition and measurement of financial assets and financial liabilities, which amends certain aspects of recognition, measurement, presentation, and disclosure of financial instruments, including the requirement to measure certain equity investments at fair value with changes in fair value recognized in net income.  The updated guidance is effective for interim and annual periods beginning after December 31, 2017.  On January 1, 2018, the Company adopted the updated guidance, which did not have a material impact on its results of operations or financial position, and resulted in the recognition of$860of previous unrealized gains, which was recorded as an adjustment to beginning retained earnings (refer to the presentation of “cumulative effect of change in accounting principle – financial instruments” on the Company’s consolidated statement of equity).
		﻿
		In May 2014, the FASB issued updated accounting guidance on recognizing revenue from contracts with customers, which outlines a single comprehensive model that an entity will apply to determine the measurement of revenue and timing of recognition.  The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services.  In 2017, the American Institute of Certified Public Accountants (“AICPA”) power and utility entities revenue recognition task force determined that contributions in aid of construction are not in the scope of the new standard, which was approved by the AICPA’s revenue recognition working group.  The Company implemented the updated guidance using the modified retrospective approach on January 1, 2018, which did not result in a change in the Company’s measurement of revenue, and reached the following conclusions:
		﻿
		·The Company’s tariff sale contracts, including those with lower credit quality customers, are generally deemed to be probable of collection, and thus the timing of revenue recognition will continue to be concurrent with the delivery of water and wastewater services, consistent with our current practice.
		·Contributions in aid of construction are outside of the scope of the standard, and will continue to be accounted for as a noncurrent liability.
|                                                | ·                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|                                                | ·                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         

X- ReferencesNo definition available.
+ Details**Name:**
us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract**Namespace Prefix:**
us-gaap_**Data Type:**
xbrli:stringItemType**Balance Type:**
na**Period Type:**
duration X- DefinitionTabular disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.
+ ReferencesReference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 45 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=109236672&loc=d3e765-108305Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.10-01.(b)(6)) -URI http://asc.fasb.org/extlink&oid=27015980&loc=d3e46468-122699Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22580-107794Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=109236672&loc=d3e725-108305Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794
+ Details**Name:**
us-gaap_ScheduleOfNewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock**Namespace Prefix:**
us-gaap_**Data Type:**
nonnum:textBlockItemType**Balance Type:**
na**Period Type:**
duration