Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The consolidated financial statements include the results of wholly-owned and partially-owned subsidiaries in which the Company has a controlling interest with all significant intercompany accounts and transactions eliminated in consolidation.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) for interim financial information and Article 10 of Regulation S-X issued by the U.S. Securities and Exchange Commission (SEC). Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, the interim financial information reflects all adjustments of a normal recurring nature, necessary for a fair presentation of the Company’s financial position at June 30, 2017, the results of operations and comprehensive income (loss) for the three and six months ended June 30, 2017 and 2016, respectively, and the cash flows for the six months ended June 30, 2017 and 2016, respectively. The consolidated balance sheet at December 31, 2016 has been derived from the audited financial statements at that date, but does not include all of the information and footnotes required by U.S. GAAP for complete financial statements. This Form 10-Q should be read in conjunction with the consolidated financial statements and accompanying notes contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.
Use of Estimates	Use of Estimates The preparation of the financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates, and such differences may be material to the financial statements.
Reclassification	Reclassification Certain prior period balances have been reclassified to conform to the current period presentation in the Company’s consolidated financial statements and the accompanying notes. The Company adopted the provisions of Accounting Standards Update (ASU) 2016-18 Statement of Cash Flows (Topic 230): Restricted Cash as of December 31, 2016 and has revised its consolidated statements of cash flows for the six months ended June 30, 2016 to reflect amounts described as restricted cash and restricted cash equivalents included with cash and cash equivalents in the reconciliation of beginning of period and end of period total amounts shown on the consolidated statements of cash flows.
Recently Issued Accounting Standards	Recently Issued Accounting Standards Except for the evaluation of recently issued accounting standards set forth below, there have been no changes to the Company's evaluation of other recently issued accounting standards disclosed in Note 2, Summary of Significant Accounting Policies, in the Notes to Consolidated Financial Statements, contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016. In January 2017, the Financial Accounting Standards Board (FASB) issued ASU 2017-01, Clarifying the Definition of a Business (ASU 2017-01), which provides a screen to determine when a set of assets and activities is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. ASU 2017-01 is effective for annual periods beginning after December 15, 2017, including interim periods within those periods. Early application is allowed for transactions for which the acquisition date occurs before the issuance date or effective date of this amendment, only if the transaction has not been reported in previously issued financial statements. Early application is also permitted for transactions in which a subsidiary is deconsolidated or a group of assets is derecognized that occur before the issuance date or effective date of the amendments, only if the transaction has not been reported in previously issued financial statements. The amendments should be applied prospectively on or after the effective date and no disclosures are required at transition. The Company will adopt ASU 2017-01 during the third quarter of 2017 and does not expect the adoption to have a material impact on the Company’s consolidated financial statements and related disclosures. In February 2016, the FASB issued ASU 2016-02, Leases (ASU 2016-02), which requires lessees to recognize right-of-use assets and lease liabilities, for all leases, with the exception of short-term leases, at the commencement date of each lease. Under the new guidance, lessor accounting is largely unchanged. ASU 2016-02 simplifies the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and liabilities. ASU 2016-02 is effective for annual periods beginning after December 15, 2018, and interim periods within those annual periods. Early adoption is permitted. The Company does not plan to early adopt, and accordingly, will adopt the new standard effective January 1, 2019. The amendments of this update should be applied using a modified retrospective approach, which requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented. The Company is in the initial stages of evaluating the impact of the new standard on its accounting policies, processes and system requirements. The Company has assigned internal resources in addition to the engagement of a third party service provider to assist in evaluation. The Company is also assessing the accounting impact of the ASU 2016-02 as it applies to its PPAs, land leases, office leases and equipment leases. As the Company progresses further in its analysis, the scope of this assessment could be expanded to review other types of contracts. In May 2014, the FASB issued a new standard, ASU 2014-09, which creates Accounting Standards Codification (ASC) Topic 606, Revenue from Contracts with Customers and supersedes ASC Topic 605, Revenue Recognition (ASU 2014-09). The new standard replaces industry-specific guidance and establishes a single five-step model to identify and recognize revenue. The core principle of the new standard is that an entity should recognize revenue upon transfer of control of promised goods or services to customers in an amount that reflects the consideration to which an entity expects to be entitled in exchange for those goods or services. Additionally, the new standard requires the entity to disclose further quantitative and qualitative information regarding the nature and amount of revenues arising from contracts with customers, as well as other information about the significant judgments and estimates used in recognizing revenues from contracts with customers. In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers (Topic 606) Principal versus Agent Considerations (Reporting Revenue Gross versus Net), which clarifies how to apply the implementation guidance on principal versus agent considerations related to the sale of goods or services to a customer as updated by ASU 2014-09. In April 2016, the FASB issued ASU 2016-10, Revenue from Contracts with Customers (Topic 606) Identifying Performance Obligations and Licensing, which clarifies two aspects of Topic 606: identifying performance obligations and the licensing implementation guidance, while retaining the related principles for those areas, as updated by ASU 2014-09. In May 2016, the FASB issued ASU 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, which makes narrow scope amendments to Topic 606 including implementation issues on collectability, non-cash consideration and completed contracts at transition. In December 2016, the FASB issued ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which make additional narrow scope amendments to Topic 606 including loan guarantee fees, impairment testing of contract costs, provisions for losses on construction-type and production-type contracts. The new standard permits adoption by either using (i) the full retrospective approach for all periods presented in the period of adoption or (ii) a modified retrospective approach with the cumulative effect of initially applying the new standard recognized at the date of initial application and providing certain additional disclosures. The Company plans to adopt using the modified retrospective approach. The new standard is effective for annual reporting periods beginning after December 15, 2017, with early adoption permitted for annual reporting periods beginning after December 15, 2016. The Company will adopt the new standard effective January 1, 2018. The Company is in the initial stages of evaluating the impact of the new standard on its accounting policies, processes and system requirements. The Company has assigned internal resources in addition to the engagement of a third party service provider to assist in evaluation. The Company is also assessing the accounting impact of the new standard as it applies certain elements of its revenue arrangements such as contracts that contain the sale of electricity and related renewable energy credits, contracts that contain volume variability, and contracts that contain modification clauses. The Company is assessing whether revenue agreements that contain the sale of both electricity and renewable energy credits, represent separate performance obligations pursuant to the new standard, which would require the transaction price to be allocated to each of the electricity and the renewable energy credit components based on their relative standalone selling prices. In addition, the Company is assessing if the use of the residual approach is appropriate in determining the standalone selling price for renewable energy credits in situations where the standalone selling price of renewable credits is highly variable or uncertain. Under the residual value approach, the standalone selling price of renewable energy credits would be determined by reference to the total transaction price of the revenue agreement less the sum of the observable standalone selling price of the electricity. Further, the Company is in the process of assessing the disclosure impacts of the new standard to the Company’s systems and processes over revenue recognition. As the Company progresses further in its analysis, the scope of this assessment could be expanded to include other contract elements that could have an accounting impact under the new standard. The Company continues to assess the potential impacts of the new standard and cannot reasonably estimate quantitative information related to the impact of the new standard on its consolidated financial statements at this time.