New Accounting Pronouncements	6 Months Ended
Jun. 30, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS Recently Adopted Pronouncements In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330), Simplifying the Measurement of Inventory. The ASU replaces the current lower of cost or market test with a lower of cost or net realizable value test when cost is determined on a first-in, first-out or average cost basis. The standard is effective for public entities for annual reporting periods beginning after December 15, 2016, and interim periods therein. It was applied prospectively. The Registrants adopted this ASU at January 1, 2017. The adoption of the ASU did not have a significant impact on the Registrants' Consolidated Financial Statements. Recently Issued Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), as amended. The objectives of this ASU are to improve upon revenue recognition requirements by providing a single comprehensive model to determine the measurement of revenue and timing of recognition. The core 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. This ASU also requires expanded qualitative and quantitative disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows arising from contracts with customers. The standard is to be applied retrospectively. The Registrants will adopt the standard effective January 1, 2018. The Registrants are currently assessing the impact of the ASU, as amended, on their Consolidated Financial Statements as well as the transition method the Registrants will use to adopt the guidance. The Registrants have completed the preliminary evaluations of the impact of this guidance and do not expect the ASU to significantly affect results of operations for tariff-based sales, which represent a majority of the Registrants' revenues, and the remaining non-tariff revenues. The Registrants will continue to evaluate the impact of the ASU on existing revenue recognition policies and procedures and monitor the unresolved industry-related issues. The previously disclosed issue regarding contributions in aid of construction (CIAC) has been resolved, subject to finalization of implementation guidance. The Registrants do not expect CIAC to be in the scope of the ASU, therefore, the accounting will not change as a result of ASC 606. Based on recent developments in the industry-related issue resolution process, accounting for certain contracts where collectibility is in question is not expected to result in a significant change. The Registrants are evaluating information that would be useful for users of the Consolidated Financial Statements and have determined the ASU will result in additional disclosures for revenue compared to the current guidance. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), a replacement of Leases (Topic 840). This guidance requires a lessee to account for leases as finance or operating leases. Both leases will result in the lessee recognizing a right-of-use asset and a corresponding lease liability on its balance sheet, with differing methodology for income statement recognition. For lessors, the standard modifies the classification criteria and the accounting for sales-type and direct financing leases. Entities will classify leases to determine how to recognize lease-related revenue and expense. This standard is effective for public entities for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. The Registrants do not plan to early adopt the standard. A modified retrospective approach is required for leases existing or entered into after the beginning of the earliest comparative period in the Consolidated Financial Statements. The Registrants expect an increase in assets and liabilities, however, they are currently assessing the impact of this ASU on their Consolidated Financial Statements. This assessment includes monitoring unresolved utility industry implementation guidance. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments in this update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Entities will apply the new guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The ASU is effective for the Registrants beginning after December 15, 2019, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements. In March 2017, the FASB issued ASU No. 2017-07, Compensation — Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendments in this update require that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside income from operations. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. The standard will be applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement and prospectively for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. The ASU is effective for the Registrants beginning after December 15, 2017, including interim periods therein. Early adoption is permitted. The components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits are disclosed in Note 12 to the Consolidated Financial Statements, "Retirement Benefits and Trusteed Assets." The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements.

NEW ACCOUNTING PRONOUNCEMENTS

Recently Adopted Pronouncements

In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330), Simplifying the Measurement of Inventory. The ASU replaces the current lower of cost or market test with a lower of cost or net realizable value test when cost is determined on a first-in, first-out or average cost basis. The standard is effective for public entities for annual reporting periods beginning after December 15, 2016, and interim periods therein. It was applied prospectively. The Registrants adopted this ASU at January 1, 2017. The adoption of the ASU did not have a significant impact on the Registrants' Consolidated Financial Statements.

Recently Issued Pronouncements

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), as amended. The objectives of this ASU are to improve upon revenue recognition requirements by providing a single comprehensive model to determine the measurement of revenue and timing of recognition. The core 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. This ASU also requires expanded qualitative and quantitative disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows arising from contracts with customers. The standard is to be applied retrospectively. The Registrants will adopt the standard effective January 1, 2018. The Registrants are currently assessing the impact of the ASU, as amended, on their Consolidated Financial Statements as well as the transition method the Registrants will use to adopt the guidance. The Registrants have completed the preliminary evaluations of the impact of this guidance and do not expect the ASU to significantly affect results of operations for tariff-based sales, which represent a majority of the Registrants' revenues, and the remaining non-tariff revenues. The Registrants will continue to evaluate the impact of the ASU on existing revenue recognition policies and procedures and monitor the unresolved industry-related issues. The previously disclosed issue regarding contributions in aid of construction (CIAC) has been resolved, subject to finalization of implementation guidance. The Registrants do not expect CIAC to be in the scope of the ASU, therefore, the accounting will not change as a result of ASC 606. Based on recent developments in the industry-related issue resolution process, accounting for certain contracts where collectibility is in question is not expected to result in a significant change. The Registrants are evaluating information that would be useful for users of the Consolidated Financial Statements and have determined the ASU will result in additional disclosures for revenue compared to the current guidance.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), a replacement of Leases (Topic 840). This guidance requires a lessee to account for leases as finance or operating leases. Both leases will result in the lessee recognizing a right-of-use asset and a corresponding lease liability on its balance sheet, with differing methodology for income statement recognition. For lessors, the standard modifies the classification criteria and the accounting for sales-type and direct financing leases. Entities will classify leases to determine how to recognize lease-related revenue and expense. This standard is effective for public entities for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. The Registrants do not plan to early adopt the standard. A modified retrospective approach is required for leases existing or entered into after the beginning of the earliest comparative period in the Consolidated Financial Statements. The Registrants expect an increase in assets and liabilities, however, they are currently assessing the impact of this ASU on their Consolidated Financial Statements. This assessment includes monitoring unresolved utility industry implementation guidance.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments in this update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Entities will apply the new guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The ASU is effective for the Registrants beginning after December 15, 2019, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements.

In March 2017, the FASB issued ASU No. 2017-07, Compensation — Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendments in this update require that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside income from operations. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. The standard will be applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement and prospectively for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. The ASU is effective for the Registrants beginning after December 15, 2017, including interim periods therein. Early adoption is permitted. The components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits are disclosed in Note 12 to the Consolidated Financial Statements, "Retirement Benefits and Trusteed Assets." The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements.