| Summary of Significant Accounting and Reporting Policies | Summary of Significant Accounting and Reporting Policies Basis of Presentation - NEP’s consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S., or GAAP. The consolidated financial statements include NEP’s accounts and operations and those of its subsidiaries in which NEP has a controlling interest. The acquisitions from NEER described in Note 3 (the common control acquisitions) were a transfer of assets between entities under common control, which require them to be accounted for as if the transfers occurred since the inception of common control, with prior periods retrospectively adjusted to furnish comparative information. Accordingly, the consolidated financial statements have been retrospectively adjusted to include the historical results of the common control acquisitions prior to their respective acquisition dates. Adjustments related to the historical results of the common control acquisitions are attributable to noncontrolling interest for all periods prior to the date the project was acquired by NEP. All intercompany transactions have been eliminated in consolidation. Certain amounts included in prior years' consolidated financial statements have been reclassified to conform to the current year's presentation. The preparation of financial statements requires the use of estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates. NEP presents as cash in its consolidated statements of cash flows certain financing transactions with related parties where it does not directly receive the cash. Revenue Recognition - Revenue is generated primarily from various non-affiliated parties under long-term power purchase agreements, Feed-in-Tariff (FIT) agreements and Renewable Energy Standard Offer Program (RESOP) agreements (collectively, PPAs) and natural gas transportation agreements. Certain PPAs are accounted for as operating leases. GAAP requires minimum lease payments to be recognized over the term of the lease and contingent rents to be recorded when the achievement of the contingency becomes probable. None of the operating leases have minimum lease payments, so revenue from these contracts is recognized as energy and any related renewable energy attributes are delivered. Contingent rental revenues from these contracts were approximately $476 million , $457 million and $396 million in 2017 , 2016 and 2015 , respectively. Revenue is recognized as energy and any related renewable energy attributes are delivered, which is when revenue is earned based on energy delivered at rates stipulated in the respective PPAs, or natural gas transportation services are performed. In 2017 , 2016 and 2015 approximately $275 million , $265 million and $154 million , respectively, of NEP's consolidated revenues were attributable to foreign countries, primarily related to its Canadian operations and its contract with a Mexican counterparty. Effective January 1, 2018, NEP adopted an accounting standards update that provides guidance on the recognition of revenue from contracts with customers and requires additional disclosures regarding such contracts (new revenue standard). NEP adopted the new revenue standard using the modified retrospective approach. NEP's operating revenues are derived primarily from the sale of energy and performance of natural gas transportation services. Revenue is recognized as energy and any related renewable energy attributes are delivered, based on rates stipulated in the respective PPAs, or as natural gas transportation services are performed. NEP believes that the obligation to deliver energy and provide the natural gas transportation services is satisfied over time as the customer simultaneously receives and consumes benefits provided by NEP. In addition, NEP believes that the obligation to deliver renewable energy attributes is satisfied at multiple points in time, with the control of the renewable energy attribute being transferred at the same time the related energy is delivered. Revenue recognition under the new revenue standard for NEP is substantially consistent with prior practice and as a result, NEP did not record any cumulative effect of adopting the new revenue standard on January 1, 2018. Income Taxes - For periods prior to the date a project is acquired by NEP (NEP acquisition date), income taxes are calculated on the predecessor method using the separate return method applied to the group of renewable energy projects acquired. As a result of the governance changes discussed in Note 3, beginning in January 2018, acquisitions from NEER will no longer be treated as common control acquisitions, which will result in NEP no longer including predecessor method taxes in NEP's financial statements. For periods after the NEP acquisition date, taxes are calculated on the successor method where taxes are calculated for NEP as a single taxpaying corporation for U.S. federal and state income taxes (based on its election to be taxed as a corporation). Because NEP OpCo is a limited partnership, NEP only recognizes in income its applicable ownership share of U.S. income taxes related to both the U.S. and Canadian projects, allocated by NEP OpCo. The Canadian subsidiaries are all Canadian taxpayers, and therefore, NEP recognizes in income all of the Canadian taxes. For periods after the NEP acquisition date, income taxes include NEP's applicable ownership share of U.S. taxes and 100% of Canadian taxes. Net income or loss attributable to noncontrolling interest includes no U.S. taxes and NEER's applicable ownership share of Canadian taxes. Net income attributable to NEP includes NEP's applicable ownership share of U.S. and Canadian taxes. Foreign Operations and Currency Translation - NEP’s reporting currency is the U.S. dollar. The functional currency for its Canadian project companies is the Canadian dollar because Canada is the primary economic environment in which they conduct their Canadian operations. The assets and liabilities of the Canadian project companies are translated to U.S. dollars at exchange rates at the balance sheet date. The income and expenses of the Canadian project companies are translated to U.S. dollars at exchange rates in effect during each respective period. The translation adjustment is recorded in accumulated other comprehensive income (loss) (AOCI). Noncontrolling Interest - At December 31, 2017 and 2016 , NEP's limited partner interest in NEP OpCo's common units was approximately 34.9% and 34.8% , respectively. Distributions to the noncontrolling interest are reflected as Partners/Members' distributions in the consolidated statements of cash flows. In addition, as part of the acquisition of the Texas pipelines, a subsidiary of NEP acquired a 90% controlling interest in one of the pipelines and a non-affiliated party owns the remaining 10% interest. See Note 3. Equity - Equity reflects the financial position of the parties with an ownership interest in the consolidated financial statements. NextEra Energy Partners GP, Inc. has a total equity interest in NEP of $10,000 at December 31, 2017 and 2016 . Limited partners' equity at December 31, 2017 and 2016 reflects the investment of NEP unitholders, changes to net income attributable to NEP, distributions of available cash to unitholders and other contributions from or distributions to NEP unitholders. Accumulated other comprehensive income (loss) at December 31, 2017 and 2016 reflects comprehensive income attributable to NEP. Noncontrolling interest at December 31, 2017 and 2016 reflects the equity attributable to NEE based on the initial contribution as part of the IPO, the net income and other comprehensive income attributable to noncontrolling interest subsequent to the IPO and contributions to or distributions from noncontrolling interest. Property, Plant and Equipment - net - Property, plant and equipment consists primarily of development, engineering and construction costs for the renewable energy assets, equipment, land, substations, transmission lines and pipeline facilities. Property, plant and equipment, excluding land and perpetual rights-of-way, is recorded at cost and depreciated on a straight-line basis over the estimated useful lives ranging from three to 50 years , commencing on the date the assets are placed in service or acquired. See Note 7. Maintenance and repairs of property, plant and equipment are charged to O&M expense as incurred. Property, plant and equipment - net on the consolidated balance sheets includes construction work in progress which reflects construction materials, other equipment, third-party engineering costs, capitalized interest and other costs directly associated with the development and construction of the various projects. There was no interest capitalized in 2017. Interest capitalized for the years ended 2016 and 2015 was approximately $7 million and $9 million , respectively. Upon commencement of plant or pipeline operations, costs associated with construction work in progress are transferred to the appropriate category in property, plant and equipment - net. Convertible investment tax credits (CITCs) of approximately $707 million and $709 million at December 31, 2017 and 2016 , respectively, are recorded as a reduction in property, plant and equipment - net on the consolidated balance sheets and are amortized as a corresponding reduction to depreciation expense over the estimated life of the related asset. Total net long-lived assets, including construction work in progress, held by operations located in Canada amounted to approximately $912 million and $881 million at December 31, 2017 and 2016 , respectively. Cash and Cash Equivalents - Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less. NEP primarily holds such investments in money market funds. Accounts Receivable and Allowance for Doubtful Accounts - Accounts receivable are reported at the invoiced or estimated amount adjusted for any write-offs and any estimated allowance for doubtful accounts on the consolidated balance sheets. The allowance for doubtful accounts is reviewed periodically based on amounts past due and significance. There was no allowance for doubtful accounts recorded at December 31, 2017 and 2016 . Restricted Cash - In the fourth quarter of 2017, NEP early adopted an accounting standards update which requires that restricted cash be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the consolidated statements of cash flows. NEP adopted the standards update retrospectively, which adoption did not have a material impact to the consolidated statements of cash flows. Current restricted cash on NEP's consolidated balance sheets and approximately $19 million and $8 million of other non-current assets on NEP's consolidated balance sheets at December 31, 2017 and 2016 , respectively, are held by certain subsidiaries to pay for certain capital or operating expenditures, as well as to fund required equity contributions pursuant to restrictions contained in the subsidiaries' debt agreements. Restricted cash reported as current assets are recorded as such based on the anticipated use of these funds. Concentration of Credit Risk - Financial instruments which potentially subject NEP to concentrations of credit risk consist primarily of accounts receivable and derivative instruments. Accounts receivable are comprised primarily of amounts due from various non-affiliated parties who are counterparties to the PPAs or natural gas transportation agreements. NEP has a limited number of counterparties, the majority of which are in the energy industry, and this concentration may impact the overall exposure to credit risk, either positively or negatively, in that the counterparties may be similarly affected by changes in economic, industry or other conditions. If any of these customers’ receivable balances should be deemed uncollectible, it could have a material adverse effect on NEP’s consolidated results of operations and financial condition. However, management does not believe significant credit risk exists at December 31, 2017 , because of the creditworthiness of the counterparties. Substantially all amounts due from such counterparties at December 31, 2017 have been collected. During 2017 , NEP derived approximately 17% , 16% and 14% of its consolidated revenue from its contracts with Pacific Gas and Electric Company, Mex Gas Supply S.L. and the Independent Electricity System Operator (IESO), respectively. Inventories - Spare parts inventories are carried at the lower of weighted-average cost and net realizable value and are included in other current assets on NEP’s consolidated balance sheets. Spare parts inventories were approximately $21 million and $18 million at December 31, 2017 and 2016 , respectively. Impairment of Long-Lived Assets and Finite-Lived Intangible Assets - Long-lived assets that are held and used and finite-lived intangible assets are reviewed for impairment when events or changes in circumstances indicate that the carrying amount may not be recoverable. An impairment loss is required to be recognized if the carrying value of the asset exceeds the undiscounted future net cash flows associated with that asset. The impairment loss to be recognized is the amount by which the carrying value of the asset exceeds the asset's fair value. In most instances, the fair value is determined by discounting estimated future cash flows using an appropriate interest rate. During the years ended December 31, 2017 and 2016 , no impairment adjustments were necessary. Business Combinations - For projects acquired in a business combination, NEP allocates the cost of the acquisition to assets acquired and liabilities assumed based on fair values as of the acquisition date. Goodwill acquired in connection with business combinations represents the excess of consideration over the fair value of net assets acquired. Certain assumptions and estimates are employed in determining the fair value of assets acquired and evaluating the fair value of liabilities assumed. See Note 3. Effective January 1, 2018, NEP adopted an accounting standards update that clarified the definition of a business. The revised guidance affects the evaluation of whether a transaction should be accounted for as an acquisition or disposition of an asset or a business. NEP adopted this guidance on a prospective basis effective January 1, 2018. Goodwill and Indefinite-Lived Intangible Assets - During 2015 , NEP recorded goodwill related to the acquisition of NET Holdings Management, LLC discussed in Note 3. Goodwill and indefinite-lived intangible assets are assessed for impairment at least annually by applying a fair value-based analysis. NEP completed the annual impairment test for goodwill and indefinite-lived intangibles using an assessment date of October 1 and determined, based on the results, that no goodwill impairment charge was required. Intangible Asset - Customer Relationships - At December 31, 2017 and 2016 , NEP's consolidated balance sheets reflect intangible asset - customer relationships related to the acquisition of NET Holdings Management, LLC discussed in Note 3. Intangible asset - customer relationships are amortized on a straight-line basis over the estimated useful life of approximately 40 years . For the years ended December 31, 2017 and 2016 , amortization expense was approximately $17 million and $18 million , respectively, and is expected to be approximately $17 million in each of the next five years. Derivative Instruments and Hedging Activities - Derivative instruments, when required to be marked to market, are recorded on NEP’s consolidated balance sheets as either an asset or a liability measured at fair value. In January 2016, NEP discontinued hedge accounting for its cash flow hedges related to interest rate contracts. Prior to 2016, NEP generally assessed the effectiveness of its designated cash flow hedging instruments by using non-statistical methods including dollar value comparisons of the change in the fair value of the derivative to the change in the fair value or cash flows of the hedged item. See Note 6. Fair Value Measurements - NEP uses several different valuation techniques to measure the fair value of assets and liabilities relying primarily on the market approach of using prices and other market information for identical or comparable assets and liabilities for those assets and liabilities that are measured on a recurring basis. Certain financial instruments may be valued using multiple inputs including discount rates, counterparty credit ratings and credit enhancements. NEP’s assessment of the significance of any particular input to the fair value measurement requires judgment and may affect the fair value measurement of its assets and liabilities and the placement of those assets and liabilities within the fair value hierarchy levels. See Note 5. Long-term Debt Costs - NEP recognizes interest expense using the effective interest method over the life of the related debt. Certain of NEP’s debt obligations include escalating interest rates that are incorporated into the effective interest rate for the related debt. Deferred interest includes interest expense recognized in excess of the interest payments accrued for the related debt’s stated interest payments and is recorded in other non-current liabilities on NEP’s consolidated balance sheets. Debt issuance costs include fees and costs incurred to obtain long-term debt and are amortized over the life of the related debt using the effective interest rate established at debt issuance. NEP incurred approximately $24 million and $11 million of debt issuance costs during the years ended December 31, 2017 and 2016 , respectively. The amortization of debt issuance costs totaled approximately $11 million , $9 million and $7 million for the years ended December 31, 2017 , 2016 and 2015 , respectively, and is included in interest expense in NEP’s consolidated statements of income. See Note 9 - Debt. Asset Retirement Obligations - Asset retirement obligations are those for which a legal obligation exists under laws, statutes, and written or oral contracts, including obligations arising under the doctrine of promissory estoppel, and for which the timing or method of settlement may be conditioned on a future event. NEP accounts for asset retirement obligations and conditional asset retirement obligations (collectively, AROs) under accounting guidance that requires a liability for the fair value of an ARO to be recognized in the period in which it is incurred if it can be reasonably estimated, with the offsetting associated asset retirement costs capitalized as part of the carrying amount of the long-lived asset. The asset retirement cost is subsequently allocated to expense using a systematic and rational method over the asset’s estimated useful life. Changes in the ARO resulting from the passage of time are recognized as an increase in the carrying amount of the liability and as accretion expense, which is included in depreciation and amortization expense in NEP’s consolidated statements of income. Changes resulting from revisions to the timing or amount of the original estimate of cash flows are recognized as an increase or a decrease in the asset retirement cost, or income when the asset retirement cost is depleted. NEP recorded accretion expense of approximately $4 million , $4 million and $2 million in 2017 , 2016 and 2015 , respectively. Additional AROs were established amounting to approximately $20 million in 2016 primarily reflecting the effect of revised cost estimates for decommissioning certain of NEP's renewable energy sites. Investments in Unconsolidated Entities - NEP accounts for the investments in its unconsolidated entities under the equity method. NEP’s share of earnings (losses) in the unconsolidated entities is included in equity in earnings (losses) of non-economic ownership interests and equity in earnings of equity method investee in the consolidated statements of income. NEP records losses of the unconsolidated entities only to the extent of its investment. All equity in earnings (losses) of the non-economic ownership interests is allocated to net income attributable to noncontrolling interest. See Note 3 and Note 8. Sale of Differential Membership Interests - Certain subsidiaries of NEER sold differential membership interests in ten wind projects to third-party tax equity investors. The holders of the differential membership interests will receive a portion of the economic attributes of the facilities, including income tax attributes, for ten years . The tax equity investors will also make ongoing deferred contingent capital contributions based on the production and sale of electricity that generates production tax credits under Section 45 of the Internal Revenue Code of 1986, as amended. The proceeds received were deferred and recorded as a liability in deferral related to differential membership interests on NEP's consolidated balance sheets. At December 31, 2017 and 2016 , this liability includes approximately $8 million and $12 million of deferred financing costs, net of accumulated amortization, respectively. The deferred amount was being recognized in benefits associated with differential membership interests - net in NEP's consolidated statements of income as the tax equity investors received their portion of the economic attributes. NEP operates and manages the ten wind projects, and consolidates the entities that directly and indirectly own the ten wind projects. Effective January 1, 2018, NEP adopted an accounting standards update regarding the accounting for partial sales of nonfinancial assets using the modified retrospective approach. This standards update affects the accounting and related financial statement presentation for the sales of differential membership interests to third-party investors. The cumulative effect of adopting the standards update is not expected to be material. The liability reflected as deferral related to differential membership interests on NEP's consolidated balance sheets at December 31, 2017 will be reflected as noncontrolling interest. In future periods, as the tax equity investors receive their portion of the economic attributes, NEP will record a reduction to net income attributable to noncontrolling interest. Variable Interest Entities (VIEs) - An entity is considered to be a VIE when its total equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support, or its equity investors, as a group, lack the characteristics of having a controlling financial interest. A reporting company is required to consolidate a VIE as its primary beneficiary when it has both the power to direct the activities of the VIE that most significantly impact the VIE's economic performance, and the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. NEP evaluates whether an entity is a VIE whenever reconsideration events as defined by the accounting guidance occur. See Note 8. Leases - In February 2016, the Financial Accounting Standards Board (FASB) issued an accounting standards update which requires, among other things, that lessees recognize a lease liability, initially measured at the present value of the future lease payments, and a right-of-use asset for all leases (with the exception of short-term leases).This standards update also requires new qualitative and quantitative disclosures for both lessees and lessors. This standards update will be effective for NEP beginning January 1, 2019. Early adoption is permitted. NEP is currently reviewing its portfolio of contracts and evaluating the proper application of the standards update to these contracts in order to determine the impact the adoption will have on its consolidated financial statements. Additionally, NEP is implementing a number of system enhancements to facilitate the identification, tracking and reporting of leases based upon the requirements of this standards update. NEP anticipates adopting this standards update on January 1, 2019. |
