New Financial Accounting Standards	12 Months Ended
Dec. 31, 2016
Accounting Changes and Error Corrections [Abstract]
New Financial Accounting Standards	New Financial Accounting Standards In May 2014, the Financial Accounting Standards Board (FASB) and the International Accounting Standards Board jointly issued a revenue recognition standard that will supersede the revenue recognition requirements within Accounting Standards Codification Topic 605, “Revenue Recognition,” and most industry-specific guidance under the Codification through Accounting Standards Update (ASU) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” The purpose of the new guidance is to create a consistent framework for revenue recognition. The guidance clarifies how to measure and recognize revenue arising from customer contracts to depict the transfer of goods or services in an amount that reflects the consideration the entity expects to receive. Amendments were issued subsequently to clarify key areas including principal/agent considerations, performance obligations, licensing, sales taxes, noncash consideration, and contracts. The new standard is effective for reporting periods beginning after December 15, 2017. Early adoption is permitted for reporting periods beginning after December 15, 2016, however, the Companies plan to adopt the new standard for reporting periods beginning after December 15, 2017. Under the new standard, companies may use either of the following transition methods: (i) a full retrospective approach reflecting the application of the standard in each prior reporting period with the option to elect certain practical expedients, or (ii) a modified retrospective approach with the cumulative effect of initially adopting ASU 2014-09 recognized at the date of adoption (which includes additional footnote disclosures). The Companies anticipate using the modified retrospective approach. The Companies are currently in the process of evaluating the impact of the new standard on their various revenue streams. The majority of the Companies’ sales are derived from tariffs to provide electric, gas, and steam service to customers. For such tariffs, the Companies expect that the revenue from contracts with the customer under ASU 2014-09 will be equivalent to the electricity, gas, or steam supplied in that period which is consistent with current practice. Consequently, the Companies do not anticipate that the new standard will significantly impact the amount and/or timing of such revenues. The Companies continue to review the potential impacts of other revenue at the Utilities and the Clean Energy Businesses on the Companies' financial position, results of operations and liquidity as well as the additional disclosures required under the new standard. In January 2016, the FASB issued amendments on certain aspects of recognition, measurement, presentation, and disclosure of financial instruments through ASU No. 2016-01, “Financial Instruments (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities.” The amendments require changes to the accounting for equity investments, the presentation and disclosure requirements for financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, clarification was provided related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted for portions of the standard. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ financial position, results of operations and liquidity. In February 2016, the FASB issued amendments on financial reporting of leasing transactions through ASU No. 2016-02, “Leases (Topic 842)." The amendments require lessees to recognize assets and liabilities on the balance sheet and disclose key information about leasing arrangements. Lessees will need to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). Lessor accounting is similar to the current model, but updated to align with certain changes to the lessee model. For income statement purposes, the pattern of expense recognition will be dependent on whether transactions are designated as operating leases or finance leases. The amendments are effective for reporting periods beginning after December 15, 2018. Early adoption is permitted. The amendments must be adopted using a modified retrospective transition and provide for certain practical expedients. Based on the existing portfolio of leases at implementation, for leases currently classified as operating leases, the Companies expect to recognize on the statements of financial position right-of-use assets and lease liabilities. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ results of operations and liquidity. In March 2016, the FASB issued amendments to the guidance for Derivatives and Hedging accounting through ASU 2016-05, “Derivatives and Hedging (Topic 815): Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships." The amendments clarify that a change in the counterparty to a derivative instrument that has been designated as a hedging instrument under Topic 815 does not, in and of itself, require discontinuation of the application of hedge accounting. The amendments in this update are effective for financial statements issued for reporting periods beginning after December 15, 2016. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In March 2016, the FASB issued amendments to clarify the guidance for assessing whether contingent call (put) options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts through ASU No. 2016-06, “Derivatives & Hedging (Topic 815): Contingent Put and Call Options in Debt Instruments.” An entity performing the assessment under the amendments is required to assess the embedded call (put) options solely in accordance with the four-step decision sequence. The amendments are effective for financial statements issued for reporting periods beginning after December 15, 2016. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In March 2016, the FASB issued amendments to eliminate the requirement to retroactively adopt the equity method of accounting when a company increases its level of ownership or degree of influence over an investment through ASU No. 2016-07, “Investments-Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting.” The amendments require that an entity that has an available-for-sale equity security that becomes qualified for the equity method of accounting recognize through earnings the unrealized holding gain or loss in Accumulated Other Comprehensive Income at the date the investment qualifies for the equity method. The amendments are effective for reporting periods beginning after December 15, 2016. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In March 2016, the FASB issued amendments to simplify several aspects of the accounting for share-based payment transactions through ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.” The amendments simplify areas such as income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amendments are effective for reporting periods beginning after December 15, 2016. The company elected to early adopt this standard as permitted, and it did not have a material impact on the Companies’ financial position, results of operations and liquidity. In May 2016, the FASB issued amendments to the guidance on revenue recognition and derivatives and hedging through ASU 2016-11, “Revenue Recognition (Topic 605) and Derivatives and Hedging (Topic 815): Rescission of SEC Guidance Because of Accounting Standards Updates 2014-09 and 2014-16 Pursuant to Staff Announcements at the March 3, 2016 EITF Meeting (SEC Update).” The amendment rescinds certain SEC guidance superseded by the newly issued revenue recognition and hedging guidance (ASU 2014-09 and 2014-16 respectively). The amendments will be effective upon adoption of ASU 2014-09 and 2014-16. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In June 2016, the FASB issued amendments to the guidance for recognition of credit losses for financial instruments through ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The amendment replaces the incurred loss impairment methodology which involved delayed recognition of credit losses. As the updated guidance now requires credit losses to be recognized when expected rather than when incurred, a broader range of reasonable and supportable information must be considered in developing the credit loss estimates. This includes financial instruments that are valued at amortized cost and available for sale. For public entities, the amendments are effective for reporting periods beginning after December 15, 2019. Early adoption is permitted for reporting periods beginning after December 15, 2018. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In August 2016, the FASB issued amendments to the guidance for the Statement of Cash Flows through ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force).” The amendment specifies the classification and presentation of certain cash flow items to reduce diversity in practice. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In October 2016, the FASB issued amendments to the guidance for Income Taxes through ASU 2016-16, “Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory).” The amendment clarifies the tax treatment of intra-entity transfers of assets other than inventory. The updated guidance requires entities to recognize the income tax consequences of an intra-entity transfer of assets other than inventory when the transfer occurs. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In October 2016, the FASB issued amendments to the guidance for Consolidation through ASU 2016-17, “Consolidation (Topic 810): Interests Held through Related Parties That Are under Common Control.” The amendments in this update change how a single decision maker of a VIE will consider its indirect interests in a VIE held by related parties under common control when performing the primary beneficiary analysis. If a single decision maker and its related parties are under common control, the single decision maker must evaluate indirect interests on a proportionate basis when evaluating whether it is a primary beneficiary of the VIE. The guidance does not change the characteristics of a primary beneficiary under GAAP but has amended the considerations in the evaluation of determining the primary beneficiary of a VIE under common control. For public entities, the amendments are effective for reporting periods beginning after December 15, 2016. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In November 2016, the FASB issued amendments to the guidance for the Statement of Cash Flows through ASU 2016-18, “Update 2016-18-Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force).” The amendments in this update clarify the presentation of changes in restricted cash and restricted cash equivalents in the statement of cash flows. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In January 2017, the FASB issued amendments to the guidance for Business Combinations through ASU 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business.” The amendments in this update clarify the definition of a business and provide guidance on evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In January 2017, the FASB issued amendments to the guidance for the subsequent measurement of goodwill through ASU 2017-04, “Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” The amendments in this update simplify goodwill impairment testing by eliminating Step 2 of the goodwill impairment test wherein an entity has to compute the implied fair value of goodwill by performing procedures to determine the fair value of its assets and liabilities. Under the new guidance, an entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value up to the total amount of goodwill allocated to that reporting unit. For public entities, the amendments are effective for reporting periods beginning after December 15, 2019. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

New Financial Accounting Standards

In May 2014, the Financial Accounting Standards Board (FASB) and the International Accounting Standards Board jointly issued a revenue recognition standard that will supersede the revenue recognition requirements within Accounting Standards Codification Topic 605, “Revenue Recognition,” and most industry-specific guidance under the Codification through Accounting Standards Update (ASU) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” The purpose of the new guidance is to create a consistent framework for revenue recognition. The guidance clarifies how to measure and recognize revenue arising from customer contracts to depict the transfer of goods or services in an amount that reflects the consideration the entity expects to receive. Amendments were issued subsequently to clarify key areas including principal/agent considerations, performance obligations, licensing, sales taxes, noncash consideration, and contracts. The new standard is effective for reporting periods beginning after December 15, 2017. Early adoption is permitted for reporting periods beginning after December 15, 2016, however, the Companies plan to adopt the new standard for reporting periods beginning after December 15, 2017.

Under the new standard, companies may use either of the following transition methods: (i) a full retrospective approach reflecting the application of the standard in each prior reporting period with the option to elect certain practical expedients, or (ii) a modified retrospective approach with the cumulative effect of initially adopting ASU 2014-09 recognized at the date of adoption (which includes additional footnote disclosures). The Companies anticipate using the modified retrospective approach.

The Companies are currently in the process of evaluating the impact of the new standard on their various revenue streams. The majority of the Companies’ sales are derived from tariffs to provide electric, gas, and steam service to customers. For such tariffs, the Companies expect that the revenue from contracts with the customer under ASU 2014-09 will be equivalent to the electricity, gas, or steam supplied in that period which is consistent with current practice. Consequently, the Companies do not anticipate that the new standard will significantly impact the amount and/or timing of such revenues. The Companies continue to review the potential impacts of other revenue at the Utilities and the Clean Energy Businesses on the Companies' financial position, results of operations and liquidity as well as the additional disclosures required under the new standard.

In January 2016, the FASB issued amendments on certain aspects of recognition, measurement, presentation, and disclosure of financial instruments through ASU No. 2016-01, “Financial Instruments (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities.” The amendments require changes to the accounting for equity investments, the presentation and disclosure requirements for financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, clarification was provided related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted for portions of the standard. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ financial position, results of operations and liquidity.

In February 2016, the FASB issued amendments on financial reporting of leasing transactions through ASU No. 2016-02, “Leases (Topic 842)." The amendments require lessees to recognize assets and liabilities on the balance sheet and disclose key information about leasing arrangements. Lessees will need to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). Lessor accounting is similar to the current model, but updated to align with certain changes to the lessee model. For income statement purposes, the pattern of expense recognition will be dependent on whether transactions are designated as operating leases or finance leases. The amendments are effective for reporting periods beginning after December 15, 2018. Early adoption is permitted. The amendments must be adopted using a modified retrospective transition and provide for certain practical expedients. Based on the existing portfolio of leases at implementation, for leases currently classified as operating leases, the Companies expect to recognize on the statements of financial position right-of-use assets and lease liabilities. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ results of operations and liquidity.

In March 2016, the FASB issued amendments to the guidance for Derivatives and Hedging accounting through ASU 2016-05, “Derivatives and Hedging (Topic 815): Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships." The amendments clarify that a change in the counterparty to a derivative instrument that has been designated as a hedging instrument under Topic 815 does not, in and of itself, require discontinuation of the application of hedge accounting. The amendments in this update are effective for financial statements issued for reporting periods beginning after December 15, 2016. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In March 2016, the FASB issued amendments to clarify the guidance for assessing whether contingent call (put) options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts through ASU No. 2016-06, “Derivatives & Hedging (Topic 815): Contingent Put and Call Options in Debt Instruments.” An entity performing the assessment under the amendments is required to assess the embedded call (put) options solely in accordance with the four-step decision sequence. The amendments are effective for financial statements issued for reporting periods beginning after December 15, 2016. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In March 2016, the FASB issued amendments to eliminate the requirement to retroactively adopt the equity method of accounting when a company increases its level of ownership or degree of influence over an investment through ASU No. 2016-07, “Investments-Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting.” The amendments require that an entity that has an available-for-sale equity security that becomes qualified for the equity method of accounting recognize through earnings the unrealized holding gain or loss in Accumulated Other Comprehensive Income at the date the investment qualifies for the equity method. The amendments are effective for reporting periods beginning after December 15, 2016. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In March 2016, the FASB issued amendments to simplify several aspects of the accounting for share-based payment transactions through ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.” The amendments simplify areas such as income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amendments are effective for reporting periods beginning after December 15, 2016. The company elected to early adopt this standard as permitted, and it did not have a material impact on the Companies’ financial position, results of operations and liquidity.

In May 2016, the FASB issued amendments to the guidance on revenue recognition and derivatives and hedging through ASU 2016-11, “Revenue Recognition (Topic 605) and Derivatives and Hedging (Topic 815): Rescission of SEC Guidance Because of Accounting Standards Updates 2014-09 and 2014-16 Pursuant to Staff Announcements at the March 3, 2016 EITF Meeting (SEC Update).” The amendment rescinds certain SEC guidance superseded by the newly issued revenue recognition and hedging guidance (ASU 2014-09 and 2014-16 respectively). The amendments will be effective upon adoption of ASU 2014-09 and 2014-16. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In June 2016, the FASB issued amendments to the guidance for recognition of credit losses for financial instruments through ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The amendment replaces the incurred loss impairment methodology which involved delayed recognition of credit losses. As the updated guidance now requires credit losses to be recognized when expected rather than when incurred, a broader range of reasonable and supportable information must be considered in developing the credit loss estimates. This includes financial instruments that are valued at amortized cost and available for sale. For public entities, the amendments are effective for reporting periods beginning after December 15, 2019. Early adoption is permitted for reporting periods beginning after December 15, 2018. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In August 2016, the FASB issued amendments to the guidance for the Statement of Cash Flows through ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force).” The amendment specifies the classification and presentation of certain cash flow items to reduce diversity in practice. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In October 2016, the FASB issued amendments to the guidance for Income Taxes through ASU 2016-16, “Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory).” The amendment clarifies the tax treatment of intra-entity transfers of assets other than inventory. The updated guidance requires entities to recognize the income tax consequences of an intra-entity transfer of assets other than inventory when the transfer occurs. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In October 2016, the FASB issued amendments to the guidance for Consolidation through ASU 2016-17, “Consolidation (Topic 810): Interests Held through Related Parties That Are under Common Control.” The amendments in this update change how a single decision maker of a VIE will consider its indirect interests in a VIE held by related parties under common control when performing the primary beneficiary analysis. If a single decision maker and its related parties are under common control, the single decision maker must evaluate indirect interests on a proportionate basis when evaluating whether it is a primary beneficiary of the VIE. The guidance does not change the characteristics of a primary beneficiary under GAAP but has amended the considerations in the evaluation of determining the primary beneficiary of a VIE under common control. For public entities, the amendments are effective for reporting periods beginning after December 15, 2016. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In November 2016, the FASB issued amendments to the guidance for the Statement of Cash Flows through ASU 2016-18, “Update 2016-18-Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force).” The amendments in this update clarify the presentation of changes in restricted cash and restricted cash equivalents in the statement of cash flows. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In January 2017, the FASB issued amendments to the guidance for Business Combinations through ASU 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business.” The amendments in this update clarify the definition of a business and provide guidance on evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.

In January 2017, the FASB issued amendments to the guidance for the subsequent measurement of goodwill through ASU 2017-04, “Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” The amendments in this update simplify goodwill impairment testing by eliminating Step 2 of the goodwill impairment test wherein an entity has to compute the implied fair value of goodwill by performing procedures to determine the fair value of its assets and liabilities. Under the new guidance, an entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value up to the total amount of goodwill allocated to that reporting unit. For public entities, the amendments are effective for reporting periods beginning after December 15, 2019. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity.