TerraForm Power NY (TERP) 10-Q 21 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	TerraForm Power, Inc.
Entity Central Index Key	1,599,947
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		148,086,027

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Operating revenues, net	$ 127,547	$ 151,135
Operating costs and expenses:
Cost of operations	37,323	34,338
Cost of operations - affiliate	0	5,598
General and administrative expenses	24,284	36,725
General and administrative expenses - affiliate	3,474	1,419
Acquisition and related costs	3,685	0
Impairment of renewable energy facilities	15,240	0
Depreciation, accretion and amortization expense	65,590	60,987
Total operating costs and expenses	149,596	139,067
Operating (loss) income	(22,049)	12,068
Other expenses:
Interest expense, net	53,554	68,312
Loss on foreign currency exchange, net	891	587
Other expenses, net	849	360
Total other expenses, net	55,294	69,259
Loss before income tax benefit	(77,343)	(57,191)
Income tax benefit	(976)	(918)
Net loss	(76,367)	(56,273)
Less: Net (loss) income attributable to redeemable non-controlling interests	(2,513)	835
Less: Net loss attributable to non-controlling interests	(157,087)	(25,339)
Net income (loss) attributable to Class A common stockholders	$ 83,233	$ (31,769)
Weighted average number of shares:
Class A common stock - Basic (in shares)	148,139	92,072
Class A common stock - Diluted (in shares)	148,166	92,072
Earnings (loss) per share:
Class A common stock - Basic and diluted (dollars per share)	$ 0.56	$ (0.37)
Dividends declared per share:
Class A common stock (dollars per share)	$ 0.19	$ 0

Unaudited Condensed Consolidat3

Unaudited Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (76,367)	$ (56,273)
Foreign currency translation adjustments:
Net unrealized (loss) gain arising during the period	(3,283)	2,680
Hedging activities:
Net unrealized (loss) gain arising during the period	(10,492)	14,054
Reclassification of net realized gain into earnings	(962)	(386)
Other comprehensive (loss) income, net of tax	(14,737)	16,348
Total comprehensive loss	(91,104)	(39,925)
Less: comprehensive (loss) income attributable to non-controlling interests:
Net (loss) income attributable to redeemable non-controlling interests	(2,513)	835
Net loss attributable to non-controlling interests	(157,087)	(25,339)
Foreign currency translation adjustments	0	918
Hedging activities	(1,243)	5,972
Comprehensive loss attributable to non-controlling interests	(160,843)	(17,614)
Comprehensive income (loss) attributable to Class A common stockholders	$ 69,739	$ (22,311)

Unaudited Condensed Consolidat4

Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 157,833	$ 128,087
Restricted cash	47,035	54,006
Accounts receivable, net	70,346	89,680
Prepaid expenses and other current assets	43,473	65,393
Due from affiliates	4,856	4,370
Total current assets	323,543	341,536
Renewable energy facilities, net, including consolidated variable interest entities of $3,238,105 and $3,273,848 in 2018 and 2017, respectively	4,719,808	4,801,925
Intangible assets, net, including consolidated variable interest entities of $810,724 and $823,629 in 2018 and 2017, respectively	1,057,557	1,077,786
Restricted cash	48,529	42,694
Other assets	109,344	123,080
Total assets	6,258,781	6,387,021
Current liabilities:
Current portion of long-term debt and financing lease obligations, including consolidated variable interest entities of $58,971 and $84,691 in 2018 and 2017, respectively	391,656	403,488
Accounts payable, accrued expenses and other current liabilities, including consolidated variable interest entities of $40,109 and $34,199 in 2018 and 2017, respectively	107,439	88,538
Deferred revenue	1,807	17,859
Due to affiliates	3,369	3,968
Total current liabilities	504,271	513,853
Long-term debt and financing lease obligations, less current portion, including consolidated variable interest entities of $852,667 and $833,388 in 2018 and 2017, respectively	3,202,715	3,195,312
Deferred revenue, less current portion	13,134	38,074
Deferred income taxes	16,839	18,636
Asset retirement obligations, including consolidated variable interest entities of $98,812 and $97,467 in 2018 and 2017, respectively	153,557	154,515
Other long-term liabilities	38,155	37,923
Total liabilities	3,928,671	3,958,313
Redeemable non-controlling interests	50,760	58,340
Stockholders' equity:
Class A common stock, $0.01 par value per share, 1,200,000,000 shares authorized, 148,586,447 shares issued and 148,086,027 shares outstanding in 2018 and 2017	1,486	1,486
Additional paid-in capital	1,841,692	1,866,206
Accumulated deficit	(290,818)	(398,629)
Accumulated other comprehensive income	30,360	48,018
Treasury stock, 500,420 shares in 2018 and 2017	(6,712)	(6,712)
Total TerraForm Power, Inc. stockholders' equity	1,576,008	1,510,369
Non-controlling interests	703,342	859,999
Total stockholders' equity	2,279,350	2,370,368
Total liabilities, redeemable non-controlling interests and stockholders' equity	$ 6,258,781	$ 6,387,021

Unaudited Condensed Consolidat5

Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Noncurrent Assets:
Renewable energy facilities, net	$ 4,719,808	$ 4,801,925
Intangible assets, net	1,057,557	1,077,786
Current liabilities:
Current portion of long-term debt and financing lease obligations	391,656	403,488
Accounts payable, accrued expenses and other current liabilities	107,439	88,538
Noncurrent liabilities:
Long-term debt and financing lease obligations, less current portion	3,202,715	3,195,312
Asset retirement obligations	$ 153,557	$ 154,515
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,200,000,000	1,200,000,000
Common stock, shares issued (in shares)	148,586,447	148,586,447
Common stock, shares outstanding (in shares)	148,086,027	148,086,027
Treasury stock (in shares)	500,420	500,420
Consolidated Variable Interest Entities
Noncurrent Assets:
Renewable energy facilities, net	$ 3,238,105	$ 3,273,848
Intangible assets, net	810,724	823,629
Current liabilities:
Current portion of long-term debt and financing lease obligations	58,971	84,691
Accounts payable, accrued expenses and other current liabilities	40,109	34,199
Noncurrent liabilities:
Long-term debt and financing lease obligations, less current portion	852,667	833,388
Asset retirement obligations	$ 98,812	$ 97,467

Unaudited Condensed Consolidat6

Unaudited Condensed Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands		Total		Total		Class A Common Stock Issued	Additional Paid-in Capital	Accumulated Deficit		Accumulated Other Comprehensive Income		Common Stock Held in Treasury	Non-controlling Interests		Capital	Accumulated Deficit, Non-controlling Interests		Accumulated Other Comprehensive Income (Loss), Non-controlling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment		$ 20,106	[1]	$ 20,414	[1]			$ 24,578	[1]	$ (4,164)	[1]		$ (308)	[1]	$ 0	$ (308)	[1]
Beginning balance (in shares) at Dec. 31, 2017		148,086,027				148,586,000						(500,000)
Beginning balance at Dec. 31, 2017		$ 2,370,368		1,510,369		$ 1,486	$ 1,866,206	(398,629)		48,018		$ (6,712)	859,999		1,057,301	(198,196)		$ 894
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(73,854)		83,233				83,233					(157,087)			(157,087)
Dividends	[2]	(28,008)		(28,008)			(28,008)
Other comprehensive loss		(14,737)		(13,494)						(13,494)			(1,243)					(1,243)
Contributions from non-controlling interests in renewable energy facilities		7,685											7,685		7,685
Distributions to non-controlling interests in renewable energy facilities		(5,204)											(5,204)		(5,204)
Other		$ 2,994		3,494			(3,494)						(500)			(500)
Ending balance (in shares) at Mar. 31, 2018		148,086,027				148,586,000						(500,000)
Ending balance at Mar. 31, 2018		$ 2,279,350		$ 1,576,008		$ 1,486	$ 1,841,692	$ (290,818)		$ 30,360		$ (6,712)	$ 703,342		$ 1,059,782	$ (356,091)		$ (349)
[1]	See Note 2. Summary of Significant Accounting Policies for discussion regarding the Company’s adoption of Accounting Standards Update No. 2014-09, Accounting Standards Update No. 2016-08 and Accounting Standards Update No. 2017-12 as of January 1, 2018.
[2]	On February 6, 2018, TerraForm Power, Inc. declared a quarterly dividend with respect to its Class A common stock of $0.19 per share. The dividend was paid on March 30, 2018 to shareholders of record as of February 28, 2018.

Unaudited Condensed Consolidat7

Unaudited Condensed Consolidated Statement of Stockholders' Equity (Parenthetical)	Mar. 30, 2018$ / shares
Statement of Stockholders' Equity [Abstract]
Quarterly dividend (in dollars per share)	$ 0.19

Unaudited Condensed Consolidat8

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net loss	$ (76,367)	$ (56,273)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, accretion and amortization expense	65,590	60,987
Amortization of favorable and unfavorable rate revenue contracts, net	9,817	9,827
Impairment of renewable energy facilities	15,240	0
Amortization of deferred financing costs and debt discounts	2,684	4,639
Unrealized loss (gain) on commodity contract derivatives, net	2,148	(2,231)
Recognition of deferred revenue	(464)	(3,987)
Stock-based compensation expense	0	2,509
Unrealized loss on foreign currency exchange, net	779	748
Deferred taxes	(882)	639
Other, net	2,907	(22)
Changes in assets and liabilities:
Accounts receivable	(6,410)	(10,982)
Prepaid expenses and other current assets	15,390	7,024
Accounts payable, accrued expenses and other current liabilities	18,527	19,858
Due to affiliates	(599)	0
Deferred revenue	368	186
Other, net	3,361	2,306
Net cash provided by operating activities	52,089	35,228
Cash flows from investing activities:
Capital expenditures	(2,720)	(2,076)
Proceeds from reimbursable interconnection costs	4,084	0
Net cash provided by (used in) investing activities	1,364	(2,076)
Cash flows from financing activities:
Revolving credit facility draws	52,000	0
Revolving credit facility repayments	(42,000)	(5,000)
Borrowings of non-recourse long-term debt	0	79,835
Principal payments on Term Loan and non-recourse long-term debt	(9,556)	(11,870)
Debt financing fees	(2,134)	(2,791)
Contributions from non-controlling interests in renewable energy facilities	7,685	6,935
Distributions to non-controlling interests in renewable energy facilities	(5,786)	(9,692)
Due to/from affiliates, net	3,214	(4,841)
SunEdison investment	0	7,371
Payment of dividend	(28,008)	0
Net cash (used in) provided by financing activities	(24,585)	59,947
Net increase in cash, cash equivalents and restricted cash	28,868	93,099
Net change in cash, cash equivalents and restricted cash classified within assets held for sale	0	19,440
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(258)	(471)
Cash, cash equivalents and restricted cash at beginning of period	224,787	682,837
Cash, cash equivalents and restricted cash at end of period	253,397	794,905
Supplemental Disclosures:
Cash paid for interest	20,173	61,318
Cash paid for income taxes	$ 0	$ 0

Nature of Operations and Basis

Nature of Operations and Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations and Basis of Presentation	NATURE OF OPERATIONS AND BASIS OF PRESENTATION Nature of Operations On October 16, 2017, BRE TERP Holdings Inc., a wholly-owned subsidiary of Orion US Holdings 1 L.P. (“Orion Holdings”), merged with and into TerraForm Power, Inc. (“TerraForm Power”), with TerraForm Power continuing as the surviving corporation (the “Merger”). Prior to the consummation of the Merger, TerraForm Power and its subsidiaries (together, the “Company”) were controlled affiliates of SunEdison, Inc. (together with its consolidated subsidiaries excluding the Company and TerraForm Global, Inc. and its subsidiaries, “SunEdison”). As a result of the consummation of the Merger, a change of control of TerraForm Power occurred, and Orion Holdings, which is a controlled affiliate of Brookfield Asset Management Inc. (“Brookfield”), now holds 51% of the voting securities of TerraForm Power. As a result of the Merger closing, TerraForm Power is no longer a controlled affiliate of SunEdison, Inc. and is now a controlled affiliate of Brookfield. TerraForm Power is a holding company and its only material asset is an equity interest in TerraForm Power, LLC (“Terra LLC”), which through its subsidiaries owns and operates renewable energy facilities that have long-term contractual arrangements to sell the electricity generated by these facilities to third parties. The related green energy certificates, ancillary services and other environmental attributes generated by these facilities are also sold to third parties. TerraForm Power is the managing member of Terra LLC and operates, controls and consolidates the business affairs of Terra LLC. The Company is sponsored by Brookfield and has an objective to acquire operating solar and wind assets in North America and Western Europe. Basis of Presentation The accompanying unaudited condensed 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 and have been prepared in accordance with the SEC regulations for interim financial information. Accordingly, they do not include all of the information and notes required by U.S. generally accepted accounting principles (“U.S. GAAP”) for complete financial statements. The financial statements should be read in conjunction with the accounting policies and other disclosures as set forth in the notes to the Company’s annual financial statements for the year ended December 31, 2017 , filed with the SEC on Form 10-K on March 7, 2018. Interim results are not necessarily indicative of results for a full year. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Company's financial position as of March 31, 2018 and the results of operations, comprehensive income (loss) and cash flows for the three months ended March 31, 2018 and 2017 . SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Use of Estimates In preparing the unaudited condensed consolidated financial statements, the Company used estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements. Such estimates also affect the reported amounts of revenues, expenses and cash flows during the reporting period. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations would be affected. Reclassification The Company adopted the provisions of Accounting Standards Update (“ASU”) No. 2016-18 , Statement of Cash Flows (Topic 230), Restricted Cash during the second quarter of 2017, which requires retrospective application, and has revised its unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2017 to include amounts generally described as restricted cash and restricted cash equivalents with cash and cash equivalents in the reconciliation of the beginning-of-period and end-of-period total amounts shown in the statement. Cash flows from investing activities for the three months ended March 31, 2017 decreased by $32.7 million as a result of the adoption of this standard. Further, the Company had $21.3 million of restricted cash classified within assets held for sale as of March 31, 2017, with $54.8 million classified within assets held for sale as of December 31, 2016, and thus had to add the change in this reclassification amount to the net change in cash, cash equivalents and restricted cash classified within assets held for sale line reported in the unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2017 to reconcile the change in the beginning and end-of-period cash, cash equivalents and restricted cash. The effect of exchange rate changes on cash and cash equivalents line was also revised to include the effect of exchange rate changes on restricted cash. Reconciliation of Cash and Cash Equivalents and Restricted Cash as Presented in the Unaudited Condensed Consolidated Statement of Cash Flows The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the unaudited condensed consolidated balance sheets to the total of the same such amounts shown in the unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2018. (In thousands) March 31, 2018 December 31, 2017 Cash and cash equivalents $ 157,833 $ 128,087 Restricted cash - current 47,035 54,006 Restricted cash - non-current 48,529 42,694 Cash, cash equivalents and restricted cash shown in the unaudited condensed consolidated statement of cash flows $ 253,397 $ 224,787 Restricted cash consists of cash on deposit in financial institutions that is restricted to satisfy the requirements of certain debt agreements and funds held within the Company's project companies that are restricted for current debt service payments and other purposes in accordance with the applicable debt agreements. These restrictions include: (i) cash on deposit in collateral accounts, debt service reserve accounts and maintenance reserve accounts; and (ii) cash on deposit in operating accounts but subject to distribution restrictions related to debt defaults existing as of the balance sheet date. As discussed in Note 8 . Long-term Debt , the Company was in default under certain of its non-recourse financing agreements as of the financial statement issuance date for the three months ended March 31, 2018 and for the year ended December 31, 2017. As a result, the Company reclassified $13.9 million and $18.8 million of non-current restricted cash to current as of March 31, 2018 and December 31, 2017, respectively, consistent with the corresponding debt classification, as the restrictions that required the cash balances to be classified as non-current restricted cash were driven by the financing agreements. As of March 31, 2018 and December 31, 2017, $20.5 million and $21.7 million , respectively, of cash and cash equivalents was also reclassified to current restricted cash as the cash balances were subject to distribution restrictions related to debt defaults that existed as of the respective balance sheet date. Non-controlling Interests - Impact of the Tax Cuts and Jobs Act Enactment On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”), which enacted major changes to the U.S. tax code, including a reduction in the U.S. federal corporate income tax rate from 35% to 21% , effective January 1, 2018. Since the 21% rate enacted in December 2017 went into effect on January 1, 2018, the hypothetical liquidation at book value (“HLBV”) methodology utilized by the Company to determine the value of its non-controlling interests began to use the new rate on that date. The HLBV method is a point in time estimate that utilizes inputs and assumptions in effect at each balance sheet date based on the liquidation provisions of the respective operating partnership agreements. During the first quarter of 2018, $151.2 million of the decline in the non-controlling interests balance and a corresponding allocation of net loss attributable to non-controlling interests was driven by this reduction in the tax rate used in the HLBV methodology used by the Company. In the calculation of the carrying values through HLBV, the Company allocated significantly lower amounts to certain non-controlling interests (i.e., tax equity investors) in order to achieve their contracted after-tax rate of return as a result of the reduction of the federal income tax rate from 35% to 21% as specified in the Tax Act. Redeemable Non-controlling Interests The following table presents the activity of the redeemable non-controlling interests balance for the three months ended March 31, 2018 : Redeemable Non-controlling Interests (In thousands) Capital Retained Earnings Total Balance as of December 31, 2017 $ 22,160 $ 36,180 $ 58,340 Cumulative-effect adjustment 1 — (4,485 ) (4,485 ) Distributions (582 ) — (582 ) Net loss — (2,513 ) (2,513 ) Balance as of March 31, 2018 $ 21,578 $ 29,182 $ 50,760 ——— (1) See discussion below regarding the Company’s adoption of ASU No. 2014-09 and ASU No. 2016-08 as of January 1, 2018. Restructuring In connection with the consummation of the Merger and the expected relocation of the headquarters of the Company to New York, New York, the Company announced a restructuring plan that went into effect upon the closing of the Merger, which is expected to be completed early in the third quarter of 2018. The Company recognized $1.3 million of additional severance and transition bonus costs in the first quarter of 2018 within general and administrative expenses in the unaudited condensed consolidated statement of operations. The Company made $0.8 million of payments related to this restructuring in the first quarter of 2018. The balance of the accrued severance and transition bonuses was $3.2 million as of March 31, 2018. Recently Adopted Accounting Standards - Guidance Adopted in 2018 In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) , which replaces most existing revenue recognition guidance in U.S. GAAP and requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. Additionally, the new standard requires an 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 No. 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 No. 2014-09. The Company adopted these standards as of January 1, 2018, which it collectively refers to as “Topic 606.” The Company analyzed the impact of Topic 606 on its revenue contracts which primarily include bundled energy and incentive sales through power purchase agreements (“PPAs”), individual renewable energy certificate (“REC”) sales, and upfront sales of federal & state incentive benefits recorded as deferred revenue and accreted into revenue. The Company elected to apply a modified retrospective approach with a cumulative-effect adjustment to accumulated deficit recognized as of January 1, 2018 for changes to revenue recognition resulting from Topic 606 adoption as described below. The Company adopted Topic 606 for all revenue contracts in-scope that had future performance obligations at January 1, 2018, and elected to use the contract modification practical expedient for purposes of computing the cumulative transition adjustment. See Note 3. Revenue for additional disclosures required by the new guidance. The Company accounts for the majority of its PPAs as operating leases under ASC 840, Leases and recognizes rental income as revenue when the electricity is delivered. The Company elected not to early adopt ASC 842, Leases in fiscal 2018 and therefore these PPAs are currently being evaluated in anticipation of the new lease standard adoption in fiscal 2019. For PPAs under the scope of Topic 606 in fiscal 2018, the Company concluded that there were no material changes to revenue recognition patterns from existing accounting practice. See Note 3. Revenue for the new revenue recognition policy. The Company evaluated the impact of Topic 606 as it relates to the individual sale of RECs. In certain jurisdictions, there may be a lag between physical generation of the underlying energy and the transfer of RECs to the customer due to administrative processes imposed by state regulations. Under the Company’s previous accounting policy, revenue was recognized as the underlying electricity was generated if the sale had been contracted with the customer. Based on the framework in Topic 606, for a portion of the existing individual REC sale arrangements where the transfer of control to the customer is determined to occur upon the transfer of the RECs, the Company now recognizes revenue commensurate with the transfer of RECs to the customer as compared to the generation of the underlying energy under the previous accounting policy. Revenue recognition practices for the remainder of existing individual REC sale arrangements remain the same; that is, revenue is recognized based on the underlying generation of energy because the contracted RECs are produced from a designated facility and control of the RECs transfers to the customer upon generation of the underlying energy. The adoption of Topic 606, as it relates to the individual sale of RECs, resulted in an increase in accumulated deficit on January 1, 2018 of $20.5 million , net of tax, and net of $0.3 million and $4.5 million that was allocated to non-controlling interests and redeemable non-controlling interests, respectively. The adjustments for accumulated deficit and non-controlling interests are reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018 and the redeemable non-controlling interests adjustment is reflected within cumulative-effect adjustment in the redeemable non-controlling interests roll-forward presented above. The impact on the Company’s results of operations for the first quarter of 2018 was minimal and is expected to be minimal for the remainder of 2018. The Company evaluated the impact of Topic 606 as it relates to the upfront sale of investment tax credits (“ITCs”) through its lease pass-through fund arrangements. The amounts allocated to the ITCs were initially recorded as deferred revenue in the consolidated balance sheet, and subsequently, one-fifth of the amounts allocated to the ITCs was recognized annually as incentives revenue in the consolidated statement of operations based on the anniversary of each solar energy system’s placed-in-service date. The Company concluded that revenue related to the sale of ITCs through its lease pass-through arrangements should be recognized at the point in time when the related solar energy systems are placed in service. Previously, the Company recognized this revenue evenly over the five -year ITC recapture period. The Company concluded that the likelihood of a recapture event related to these assessments is remote. The adoption of Topic 606, as it relates to the upfront sale of ITCs, resulted in a decrease in accumulated deficit on January 1, 2018 of $40.9 million , net of tax, which is reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018. The impact on the Company’s results of operations for the first quarter of 2018 resulted in a decrease in non-cash deferred revenue recognition of $3.5 million and is expected to result in a decrease in non-cash deferred revenue recognition of approximately $12.8 million for the remaining nine months of 2018. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230), Classification of Certain Cash Receipts and Cash Payments . The amendments of ASU No. 2016-15 were issued to address eight specific cash flow issues for which stakeholders have indicated to the FASB that a diversity in practice existed in how entities were presenting and classifying these items in the statement of cash flows. The issues addressed by ASU No. 2016-15 include but are not limited to the classification of debt prepayment and debt extinguishment costs, payments made for contingent consideration for a business combination, proceeds from the settlement of insurance proceeds, distributions received from equity method investees and separately identifiable cash flows and the application of the predominance principle. The adoption of ASU No. 2016-15 is required to be applied retrospectively. The Company adopted ASU No. 2016-15 as of January 1, 2018, which did not result in any material adjustments to the Company’s consolidated statements of cash flows. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740), Intra-Entity Transfers of Assets Other Than Inventory . The amendments of ASU No. 2016-16 were issued to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. Previous GAAP prohibited the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset had been sold to an outside party which resulted in diversity in practice and increased complexity within financial reporting. The amendments of ASU No. 2016-16 require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs and do not require new disclosure requirements. The adoption of ASU No. 2016-16 should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The adoption of ASU No. 2016-16 as of January 1, 2018 did not have an impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805), Clarifying the Definition of a Business . The amendment seeks to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. The amendments should be applied prospectively on or after the effective dates. Accordingly, the Company’s adoption of ASU No. 2017-01 as of January 1, 2018 did not have an impact on the Company’s historical financial statements. The Company did not consummate any acquisitions in the first quarter of 2018 but will apply this standard in the future should it consummate any acquisitions. In February 2017, the FASB issued ASU No. 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets . This ASU is meant to clarify the scope of ASC Subtopic 610-20, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets and to add guidance for partial sales of nonfinancial assets. ASU No. 2017-05 is to be applied using a full retrospective method or a modified retrospective method as outlined in the guidance. The adoption of ASU No. 2017-05 as of January 1, 2018 did not have an impact on the Company’s consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting . The amendment clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. The new guidance is expected to reduce diversity in practice and result in fewer changes to the terms of an award being accounted for as a modification. Changes to the terms or conditions of a share-based payment award that do not impact the fair value of the award, vesting conditions and the classification as an equity or liability instrument will not need to be assessed under modification accounting. The amendments in this update should be applied prospectively to an award modified on or after the adoption date. Accordingly, the Company’s adoption of ASU No. 2017-09 as of January 1, 2018 did not have an impact on the Company’s historical financial statements. The Company did not have any unvested share-based payment awards outstanding during the first quarter of 2018 but will apply the impact of this standard in the future should it change the terms or conditions of any share-based payment awards. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . This ASU amends the hedge accounting model to enable entities to better portray the economics of their risk management activities in the financial statements and simplifies the application of hedge accounting in certain situations. ASU No. 2017-12 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2018, with early adoption permitted. ASU 2017-12 requires a modified retrospective transition method in which the Company recognizes the cumulative effect of the change on the opening balance of each affected component of equity as of the date of adoption. The Company adopted ASU 2017-12 on March 26, 2018 with the adoption impact reflected on a modified retrospective basis as of January 1, 2018, which resulted in the following primary changes: • The ineffective hedging portion of derivatives designated as hedging instruments is no longer required to be measured, recognized or reported. Alternatively, the entire change in the fair value of the designated hedging instrument is recorded in accumulated other comprehensive income (“OCI”); • The Company will perform ongoing prospective and retrospective hedge effectiveness assessments qualitatively after performing the initial test of hedge effectiveness on a quantitative basis and only to the extent that an expectation of high effectiveness can be supported on a qualitative basis in subsequent periods; • For derivatives with periodic cash settlements and a non-zero fair value at hedge inception, the accumulated gains or losses recorded in accumulated OCI in a qualifying cash flow hedging relationship are reclassified to earnings on a systematic and rational basis over the hedge term; and • For derivatives with components excluded from the assessment of hedge effectiveness, the accumulated gains or losses recorded in accumulated OCI on such excluded components in a qualifying cash flow hedging relationship are reclassified to earnings on a systematic and rational basis over the hedge term. The adoption of ASU 2017-12 resulted in a cumulative-effect adjustment of $4.2 million , net of tax of $1.6 million , representing a decrease in accumulated deficit and accumulated OCI, which is reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018. In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740) – Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 . The ASU added seven paragraphs to ASC 740, Income Taxes , that contain SEC guidance related to the application of U.S. GAAP when preparing an initial accounting of the income tax effects of the Tax Act which, among other things, allows for a measurement period not to exceed one year for companies to finalize the provisional amounts recorded as of December 31, 2017. The ASU was effective upon issuance. See Note 9. Income Taxes for disclosures on the Company’s accounting for the Tax Act. Recently Issued Accounting Standards Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , which primarily changes the lessee’s accounting for operating leases by requiring recognition of lease right-of-use assets and lease liabilities. The Company expects to adopt the standard on January 1, 2019. The issued guidance requires a modified retrospective transition approach, which requires entities to recognize and measure leases at the beginning of the earliest period presented. In January 2018, the FASB proposed amending the standard to give entities another option for transition. The proposed transition method would allow entities to initially apply the requirements of the standard in the period of adoption (January 1, 2019). The Company will assess this transition option if the FASB issues the revised standard. The Company expects to elect certain of the practical expedients permitted in the issued standard, including the expedient that permits the Company to retain its existing lease assessment and classification. In January 2018, the FASB issued additional guidance which provides another optional transition practical expedient that allows entities to not evaluate existing and expired land easements under the new guidance at adoption if they were not previously accounted for as leases. The Company is currently working through an adoption plan which includes the evaluation of lease contracts compared to the new standard. While the Company is currently evaluating the impact the new guidance will have on its financial position and results of operations, the Company expects to recognize lease liabilities and right of use assets. The extent of the increase to assets and liabilities associated with these amounts remains to be determined pending the Company’s review of its existing lease contracts which may contain embedded leases. In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment . The amendment simplifies the accounting for goodwill impairment by removing Step 2 of the current test, which requires calculation of a hypothetical purchase price allocation. Under the revised guidance, goodwill impairment will be measured as the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill (currently Step 1 of the two-step impairment test). Entities will continue to have the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. The standard is effective January 1, 2020, with early adoption permitted, and must be adopted on a prospective basis. This updated guidance is not currently expected to impact the Company’s financial reporting as the Company does not have any goodwill. The Company will evaluate the impact of this standard in the future should it consummate any acquisition that results in the recognition of goodwill. In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income to help entities address certain stranded income tax effects in accumulated OCI resulting from the U.S. government’s enactment of the Tax Act on December 22, 2017. The amendment provides entities with an option to reclassify stranded tax effects within accumulated OCI to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act (or portion thereof) is recorded. The amendment also includes disclosure requirements regarding the issuer’s accounting policy for releasing income tax effects from accumulated OCI. The optional guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted, and entities should apply the provisions of the amendment either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. The Company is currently evaluating the effect of the new guidance on its consolidated financial statements. In February 2018, the FASB issued ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . This ASU amends and supersedes various paragraphs that contain SEC guidance in ASC 320, Investments - Debt Securities and ASC 980, Regulated Operations . ASU No. 2018-03 is effective for public business entities for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years beginning after June 15, 2018. Public business entities with fiscal years beginning between December 15, 2017 and June 15, 2018 are not required to adopt these amendments until the interim period beginning after June 15, 2018. The Company is currently evaluating the effect of the new guidance on its consolidated financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NATURE OF OPERATIONS AND BASIS OF PRESENTATION Nature of Operations On October 16, 2017, BRE TERP Holdings Inc., a wholly-owned subsidiary of Orion US Holdings 1 L.P. (“Orion Holdings”), merged with and into TerraForm Power, Inc. (“TerraForm Power”), with TerraForm Power continuing as the surviving corporation (the “Merger”). Prior to the consummation of the Merger, TerraForm Power and its subsidiaries (together, the “Company”) were controlled affiliates of SunEdison, Inc. (together with its consolidated subsidiaries excluding the Company and TerraForm Global, Inc. and its subsidiaries, “SunEdison”). As a result of the consummation of the Merger, a change of control of TerraForm Power occurred, and Orion Holdings, which is a controlled affiliate of Brookfield Asset Management Inc. (“Brookfield”), now holds 51% of the voting securities of TerraForm Power. As a result of the Merger closing, TerraForm Power is no longer a controlled affiliate of SunEdison, Inc. and is now a controlled affiliate of Brookfield. TerraForm Power is a holding company and its only material asset is an equity interest in TerraForm Power, LLC (“Terra LLC”), which through its subsidiaries owns and operates renewable energy facilities that have long-term contractual arrangements to sell the electricity generated by these facilities to third parties. The related green energy certificates, ancillary services and other environmental attributes generated by these facilities are also sold to third parties. TerraForm Power is the managing member of Terra LLC and operates, controls and consolidates the business affairs of Terra LLC. The Company is sponsored by Brookfield and has an objective to acquire operating solar and wind assets in North America and Western Europe. Basis of Presentation The accompanying unaudited condensed 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 and have been prepared in accordance with the SEC regulations for interim financial information. Accordingly, they do not include all of the information and notes required by U.S. generally accepted accounting principles (“U.S. GAAP”) for complete financial statements. The financial statements should be read in conjunction with the accounting policies and other disclosures as set forth in the notes to the Company’s annual financial statements for the year ended December 31, 2017 , filed with the SEC on Form 10-K on March 7, 2018. Interim results are not necessarily indicative of results for a full year. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Company's financial position as of March 31, 2018 and the results of operations, comprehensive income (loss) and cash flows for the three months ended March 31, 2018 and 2017 . SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Use of Estimates In preparing the unaudited condensed consolidated financial statements, the Company used estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements. Such estimates also affect the reported amounts of revenues, expenses and cash flows during the reporting period. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations would be affected. Reclassification The Company adopted the provisions of Accounting Standards Update (“ASU”) No. 2016-18 , Statement of Cash Flows (Topic 230), Restricted Cash during the second quarter of 2017, which requires retrospective application, and has revised its unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2017 to include amounts generally described as restricted cash and restricted cash equivalents with cash and cash equivalents in the reconciliation of the beginning-of-period and end-of-period total amounts shown in the statement. Cash flows from investing activities for the three months ended March 31, 2017 decreased by $32.7 million as a result of the adoption of this standard. Further, the Company had $21.3 million of restricted cash classified within assets held for sale as of March 31, 2017, with $54.8 million classified within assets held for sale as of December 31, 2016, and thus had to add the change in this reclassification amount to the net change in cash, cash equivalents and restricted cash classified within assets held for sale line reported in the unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2017 to reconcile the change in the beginning and end-of-period cash, cash equivalents and restricted cash. The effect of exchange rate changes on cash and cash equivalents line was also revised to include the effect of exchange rate changes on restricted cash. Reconciliation of Cash and Cash Equivalents and Restricted Cash as Presented in the Unaudited Condensed Consolidated Statement of Cash Flows The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the unaudited condensed consolidated balance sheets to the total of the same such amounts shown in the unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2018. (In thousands) March 31, 2018 December 31, 2017 Cash and cash equivalents $ 157,833 $ 128,087 Restricted cash - current 47,035 54,006 Restricted cash - non-current 48,529 42,694 Cash, cash equivalents and restricted cash shown in the unaudited condensed consolidated statement of cash flows $ 253,397 $ 224,787 Restricted cash consists of cash on deposit in financial institutions that is restricted to satisfy the requirements of certain debt agreements and funds held within the Company's project companies that are restricted for current debt service payments and other purposes in accordance with the applicable debt agreements. These restrictions include: (i) cash on deposit in collateral accounts, debt service reserve accounts and maintenance reserve accounts; and (ii) cash on deposit in operating accounts but subject to distribution restrictions related to debt defaults existing as of the balance sheet date. As discussed in Note 8 . Long-term Debt , the Company was in default under certain of its non-recourse financing agreements as of the financial statement issuance date for the three months ended March 31, 2018 and for the year ended December 31, 2017. As a result, the Company reclassified $13.9 million and $18.8 million of non-current restricted cash to current as of March 31, 2018 and December 31, 2017, respectively, consistent with the corresponding debt classification, as the restrictions that required the cash balances to be classified as non-current restricted cash were driven by the financing agreements. As of March 31, 2018 and December 31, 2017, $20.5 million and $21.7 million , respectively, of cash and cash equivalents was also reclassified to current restricted cash as the cash balances were subject to distribution restrictions related to debt defaults that existed as of the respective balance sheet date. Non-controlling Interests - Impact of the Tax Cuts and Jobs Act Enactment On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”), which enacted major changes to the U.S. tax code, including a reduction in the U.S. federal corporate income tax rate from 35% to 21% , effective January 1, 2018. Since the 21% rate enacted in December 2017 went into effect on January 1, 2018, the hypothetical liquidation at book value (“HLBV”) methodology utilized by the Company to determine the value of its non-controlling interests began to use the new rate on that date. The HLBV method is a point in time estimate that utilizes inputs and assumptions in effect at each balance sheet date based on the liquidation provisions of the respective operating partnership agreements. During the first quarter of 2018, $151.2 million of the decline in the non-controlling interests balance and a corresponding allocation of net loss attributable to non-controlling interests was driven by this reduction in the tax rate used in the HLBV methodology used by the Company. In the calculation of the carrying values through HLBV, the Company allocated significantly lower amounts to certain non-controlling interests (i.e., tax equity investors) in order to achieve their contracted after-tax rate of return as a result of the reduction of the federal income tax rate from 35% to 21% as specified in the Tax Act. Redeemable Non-controlling Interests The following table presents the activity of the redeemable non-controlling interests balance for the three months ended March 31, 2018 : Redeemable Non-controlling Interests (In thousands) Capital Retained Earnings Total Balance as of December 31, 2017 $ 22,160 $ 36,180 $ 58,340 Cumulative-effect adjustment 1 — (4,485 ) (4,485 ) Distributions (582 ) — (582 ) Net loss — (2,513 ) (2,513 ) Balance as of March 31, 2018 $ 21,578 $ 29,182 $ 50,760 ——— (1) See discussion below regarding the Company’s adoption of ASU No. 2014-09 and ASU No. 2016-08 as of January 1, 2018. Restructuring In connection with the consummation of the Merger and the expected relocation of the headquarters of the Company to New York, New York, the Company announced a restructuring plan that went into effect upon the closing of the Merger, which is expected to be completed early in the third quarter of 2018. The Company recognized $1.3 million of additional severance and transition bonus costs in the first quarter of 2018 within general and administrative expenses in the unaudited condensed consolidated statement of operations. The Company made $0.8 million of payments related to this restructuring in the first quarter of 2018. The balance of the accrued severance and transition bonuses was $3.2 million as of March 31, 2018. Recently Adopted Accounting Standards - Guidance Adopted in 2018 In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) , which replaces most existing revenue recognition guidance in U.S. GAAP and requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. Additionally, the new standard requires an 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 No. 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 No. 2014-09. The Company adopted these standards as of January 1, 2018, which it collectively refers to as “Topic 606.” The Company analyzed the impact of Topic 606 on its revenue contracts which primarily include bundled energy and incentive sales through power purchase agreements (“PPAs”), individual renewable energy certificate (“REC”) sales, and upfront sales of federal & state incentive benefits recorded as deferred revenue and accreted into revenue. The Company elected to apply a modified retrospective approach with a cumulative-effect adjustment to accumulated deficit recognized as of January 1, 2018 for changes to revenue recognition resulting from Topic 606 adoption as described below. The Company adopted Topic 606 for all revenue contracts in-scope that had future performance obligations at January 1, 2018, and elected to use the contract modification practical expedient for purposes of computing the cumulative transition adjustment. See Note 3. Revenue for additional disclosures required by the new guidance. The Company accounts for the majority of its PPAs as operating leases under ASC 840, Leases and recognizes rental income as revenue when the electricity is delivered. The Company elected not to early adopt ASC 842, Leases in fiscal 2018 and therefore these PPAs are currently being evaluated in anticipation of the new lease standard adoption in fiscal 2019. For PPAs under the scope of Topic 606 in fiscal 2018, the Company concluded that there were no material changes to revenue recognition patterns from existing accounting practice. See Note 3. Revenue for the new revenue recognition policy. The Company evaluated the impact of Topic 606 as it relates to the individual sale of RECs. In certain jurisdictions, there may be a lag between physical generation of the underlying energy and the transfer of RECs to the customer due to administrative processes imposed by state regulations. Under the Company’s previous accounting policy, revenue was recognized as the underlying electricity was generated if the sale had been contracted with the customer. Based on the framework in Topic 606, for a portion of the existing individual REC sale arrangements where the transfer of control to the customer is determined to occur upon the transfer of the RECs, the Company now recognizes revenue commensurate with the transfer of RECs to the customer as compared to the generation of the underlying energy under the previous accounting policy. Revenue recognition practices for the remainder of existing individual REC sale arrangements remain the same; that is, revenue is recognized based on the underlying generation of energy because the contracted RECs are produced from a designated facility and control of the RECs transfers to the customer upon generation of the underlying energy. The adoption of Topic 606, as it relates to the individual sale of RECs, resulted in an increase in accumulated deficit on January 1, 2018 of $20.5 million , net of tax, and net of $0.3 million and $4.5 million that was allocated to non-controlling interests and redeemable non-controlling interests, respectively. The adjustments for accumulated deficit and non-controlling interests are reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018 and the redeemable non-controlling interests adjustment is reflected within cumulative-effect adjustment in the redeemable non-controlling interests roll-forward presented above. The impact on the Company’s results of operations for the first quarter of 2018 was minimal and is expected to be minimal for the remainder of 2018. The Company evaluated the impact of Topic 606 as it relates to the upfront sale of investment tax credits (“ITCs”) through its lease pass-through fund arrangements. The amounts allocated to the ITCs were initially recorded as deferred revenue in the consolidated balance sheet, and subsequently, one-fifth of the amounts allocated to the ITCs was recognized annually as incentives revenue in the consolidated statement of operations based on the anniversary of each solar energy system’s placed-in-service date. The Company concluded that revenue related to the sale of ITCs through its lease pass-through arrangements should be recognized at the point in time when the related solar energy systems are placed in service. Previously, the Company recognized this revenue evenly over the five -year ITC recapture period. The Company concluded that the likelihood of a recapture event related to these assessments is remote. The adoption of Topic 606, as it relates to the upfront sale of ITCs, resulted in a decrease in accumulated deficit on January 1, 2018 of $40.9 million , net of tax, which is reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018. The impact on the Company’s results of operations for the first quarter of 2018 resulted in a decrease in non-cash deferred revenue recognition of $3.5 million and is expected to result in a decrease in non-cash deferred revenue recognition of approximately $12.8 million for the remaining nine months of 2018. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230), Classification of Certain Cash Receipts and Cash Payments . The amendments of ASU No. 2016-15 were issued to address eight specific cash flow issues for which stakeholders have indicated to the FASB that a diversity in practice existed in how entities were presenting and classifying these items in the statement of cash flows. The issues addressed by ASU No. 2016-15 include but are not limited to the classification of debt prepayment and debt extinguishment costs, payments made for contingent consideration for a business combination, proceeds from the settlement of insurance proceeds, distributions received from equity method investees and separately identifiable cash flows and the application of the predominance principle. The adoption of ASU No. 2016-15 is required to be applied retrospectively. The Company adopted ASU No. 2016-15 as of January 1, 2018, which did not result in any material adjustments to the Company’s consolidated statements of cash flows. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740), Intra-Entity Transfers of Assets Other Than Inventory . The amendments of ASU No. 2016-16 were issued to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. Previous GAAP prohibited the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset had been sold to an outside party which resulted in diversity in practice and increased complexity within financial reporting. The amendments of ASU No. 2016-16 require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs and do not require new disclosure requirements. The adoption of ASU No. 2016-16 should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The adoption of ASU No. 2016-16 as of January 1, 2018 did not have an impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805), Clarifying the Definition of a Business . The amendment seeks to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. The amendments should be applied prospectively on or after the effective dates. Accordingly, the Company’s adoption of ASU No. 2017-01 as of January 1, 2018 did not have an impact on the Company’s historical financial statements. The Company did not consummate any acquisitions in the first quarter of 2018 but will apply this standard in the future should it consummate any acquisitions. In February 2017, the FASB issued ASU No. 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets . This ASU is meant to clarify the scope of ASC Subtopic 610-20, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets and to add guidance for partial sales of nonfinancial assets. ASU No. 2017-05 is to be applied using a full retrospective method or a modified retrospective method as outlined in the guidance. The adoption of ASU No. 2017-05 as of January 1, 2018 did not have an impact on the Company’s consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting . The amendment clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. The new guidance is expected to reduce diversity in practice and result in fewer changes to the terms of an award being accounted for as a modification. Changes to the terms or conditions of a share-based payment award that do not impact the fair value of the award, vesting conditions and the classification as an equity or liability instrument will not need to be assessed under modification accounting. The amendments in this update should be applied prospectively to an award modified on or after the adoption date. Accordingly, the Company’s adoption of ASU No. 2017-09 as of January 1, 2018 did not have an impact on the Company’s historical financial statements. The Company did not have any unvested share-based payment awards outstanding during the first quarter of 2018 but will apply the impact of this standard in the future should it change the terms or conditions of any share-based payment awards. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . This ASU amends the hedge accounting model to enable entities to better portray the economics of their risk management activities in the financial statements and simplifies the application of hedge accounting in certain situations. ASU No. 2017-12 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2018, with early adoption permitted. ASU 2017-12 requires a modified retrospective transition method in which the Company recognizes the cumulative effect of the change on the opening balance of each affected component of equity as of the date of adoption. The Company adopted ASU 2017-12 on March 26, 2018 with the adoption impact reflected on a modified retrospective basis as of January 1, 2018, which resulted in the following primary changes: • The ineffective hedging portion of derivatives designated as hedging instruments is no longer required to be measured, recognized or reported. Alternatively, the entire change in the fair value of the designated hedging instrument is recorded in accumulated other comprehensive income (“OCI”); • The Company will perform ongoing prospective and retrospective hedge effectiveness assessments qualitatively after performing the initial test of hedge effectiveness on a quantitative basis and only to the extent that an expectation of high effectiveness can be supported on a qualitative basis in subsequent periods; • For derivatives with periodic cash settlements and a non-zero fair value at hedge inception, the accumulated gains or losses recorded in accumulated OCI in a qualifying cash flow hedging relationship are reclassified to earnings on a systematic and rational basis over the hedge term; and • For derivatives with components excluded from the assessment of hedge effectiveness, the accumulated gains or losses recorded in accumulated OCI on such excluded components in a qualifying cash flow hedging relationship are reclassified to earnings on a systematic and rational basis over the hedge term. The adoption of ASU 2017-12 resulted in a cumulative-effect adjustment of $4.2 million , net of tax of $1.6 million , representing a decrease in accumulated deficit and accumulated OCI, which is reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018. In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740) – Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 . The ASU added seven paragraphs to ASC 740, Income Taxes , that contain SEC guidance related to the application of U.S. GAAP when preparing an initial accounting of the income tax effects of the Tax Act which, among other things, allows for a measurement period not to exceed one year for companies to finalize the provisional amounts recorded as of December 31, 2017. The ASU was effective upon issuance. See Note 9. Income Taxes for disclosures on the Company’s accounting for the Tax Act. Recently Issued Accounting Standards Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , which primarily changes the lessee’s accounting for operating leases by requiring recognition of lease right-of-use assets and lease liabilities. The Company expects to adopt the standard on January 1, 2019. The issued guidance requires a modified retrospective transition approach, which requires entities to recognize and measure leases at the beginning of the earliest period presented. In January 2018, the FASB proposed amending the standard to give entities another option for transition. The proposed transition method would allow entities to initially apply the requirements of the standard in the period of adoption (January 1, 2019). The Company will assess this transition option if the FASB issues the revised standard. The Company expects to elect certain of the practical expedients permitted in the issued standard, including the expedient that permits the Company to retain its existing lease assessment and classification. In January 2018, the FASB issued additional guidance which provides another optional transition practical expedient that allows entities to not evaluate existing and expired land easements under the new guidance at adoption if they were not previously accounted for as leases. The Company is currently working through an adoption plan which includes the evaluation of lease contracts compared to the new standard. While the Company is currently evaluating the impact the new guidance will have on its financial position and results of operations, the Company expects to recognize lease liabilities and right of use assets. The extent of the increase to assets and liabilities associated with these amounts remains to be determined pending the Company’s review of its existing lease contracts which may contain embedded leases. In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment . The amendment simplifies the accounting for goodwill impairment by removing Step 2 of the current test, which requires calculation of a hypothetical purchase price allocation. Under the revised guidance, goodwill impairment will be measured as the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill (currently Step 1 of the two-step impairment test). Entities will continue to have the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. The standard is effective January 1, 2020, with early adoption permitted, and must be adopted on a prospective basis. This updated guidance is not currently expected to impact the Company’s financial reporting as the Company does not have any goodwill. The Company will evaluate the impact of this standard in the future should it consummate any acquisition that results in the recognition of goodwill. In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income to help entities address certain stranded income tax effects in accumulated OCI resulting from the U.S. government’s enactment of the Tax Act on December 22, 2017. The amendment provides entities with an option to reclassify stranded tax effects within accumulated OCI to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act (or portion thereof) is recorded. The amendment also includes disclosure requirements regarding the issuer’s accounting policy for releasing income tax effects from accumulated OCI. The optional guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted, and entities should apply the provisions of the amendment either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. The Company is currently evaluating the effect of the new guidance on its consolidated financial statements. In February 2018, the FASB issued ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . This ASU amends and supersedes various paragraphs that contain SEC guidance in ASC 320, Investments - Debt Securities and ASC 980, Regulated Operations . ASU No. 2018-03 is effective for public business entities for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years beginning after June 15, 2018. Public business entities with fiscal years beginning between December 15, 2017 and June 15, 2018 are not required to adopt these amendments until the interim period beginning after June 15, 2018. The Company is currently evaluating the effect of the new guidance on its consolidated financial statements.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	REVENUE As discussed in Note 2. Summary of Significant Accounting Policies , on January 1, 2018, the Company adopted Topic 606. The following tables present revenue disaggregated by segment and major product for the three months ended March 31, 2018 and provide a reconciliation of the adoption impact of Topic 606 on the unaudited condensed consolidated statement of operations for the three months ended March 31, 2018 and unaudited condensed consolidated balance sheet as of March 31, 2018. There was no net impact on net cash provided by operating activities in the unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2018 resulting from the adoption of Topic 606. Topic 606 Adoption Impact on Unaudited Condensed Consolidated Statement of Operations Three Months Ended March 31, 2018 As Reported Adjustments Amounts excluding Topic 606 Adoption (In thousands) Solar Wind Total REC Sales ITC Sales PPA rental income $ 36,768 $ 52,413 $ 89,181 $ — $ — $ 89,181 Commodity derivatives — 11,007 11,007 — — 11,007 PPA revenue 6,507 6,692 13,199 — — 13,199 Amortization of favorable and unfavorable rate revenue contracts, net (1,977 ) (7,840 ) (9,817 ) — — (9,817 ) Energy revenue 41,298 62,272 103,570 — — 103,570 Incentive revenue 18,425 5,552 23,977 (2,560 ) 3,518 24,935 Operating revenues, net 59,723 67,824 127,547 (2,560 ) 3,518 128,505 Operating costs and expenses 149,596 — — 149,596 Operating loss (22,049 ) (2,560 ) 3,518 (21,091 ) Other expenses, net 55,294 — — 55,294 Loss before income tax benefit (77,343 ) (2,560 ) 3,518 (76,385 ) Income tax benefit (976 ) — — (976 ) Net loss $ (76,367 ) $ (2,560 ) $ 3,518 $ (75,409 ) Topic 606 Adoption Impact on Unaudited Condensed Consolidated Balance Sheet As of March 31, 2018 As Reported Adjustments Amounts excluding Topic 606 Adoption (In thousands) REC Sales ITC Sales Accounts receivable, net $ 70,346 $ 22,715 $ — $ 93,061 Other current assets 253,197 — — 253,197 Total current assets 323,543 22,715 — 346,258 Non-current assets 5,935,238 — — 5,935,238 Total assets $ 6,258,781 $ 22,715 $ — $ 6,281,496 Deferred revenue $ 1,807 $ — $ 16,310 $ 18,117 Other current liabilities 502,464 — — 502,464 Total current liabilities 504,271 — 16,310 520,581 Deferred revenue, less current portion 13,134 — 21,069 34,203 Other non-current liabilities 3,411,266 — — 3,411,266 Total liabilities 3,928,671 — 37,379 3,966,050 Redeemable non-controlling interests and total stockholders' equity 2,330,110 22,715 (37,379 ) 2,315,446 Total liabilities, redeemable non-controlling interests and stockholders' equity $ 6,258,781 $ 22,715 $ — $ 6,281,496 PPA rental income The majority of the Company’s energy revenue is derived from long-term PPAs accounted for as operating leases under ASC 840, Leases . Rental income under these leases is recorded as revenue when the electricity is delivered. The Company will adopt ASC 842, Leases on January 1, 2019. The Company is currently working through an adoption plan which includes the evaluation of lease contracts compared to the new standard and may elect certain of the practical expedients permitted in the issued standard, including the expedient that permits the Company to retain its existing lease assessment and classification. Commodity derivatives The Company has certain revenue contracts within its wind fleet that are accounted for as derivatives under the scope of ASC 815, Derivatives and Hedging . Amounts recognized within operating revenues, net in the unaudited condensed consolidated statements of operations consist of cash settlements and unrealized gains and losses representing changes in fair value for the commodity derivatives that are not designated as hedging instruments. See Note 10. Derivatives for further discussion. PPA revenue PPAs that are not accounted for under the scope of leases or derivatives are accounted for under Topic 606. The Company typically delivers bundled goods consisting of energy and incentive products for a singular rate based on a unit of generation at a specified facility over the term of the agreement. In these type of arrangements, volume reflects total energy generation measured in kilowatt hours (“kWhs”) which can vary period to period depending on system and resource availability. The contract rate per unit of generation (kWhs) is generally fixed at contract inception; however, certain pricing arrangements can provide for time-of-delivery, seasonal or market index adjustment mechanisms over time. The customer is invoiced monthly equal to the volume of energy delivered multiplied by the applicable contract rate. The Company considers bundled energy and incentive products within PPAs to be distinct performance obligations. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied under Topic 606. The Company views the sale of energy as a series of distinct goods that is substantially the same and has the same pattern of transfer measured by the output method. Although the Company views incentive products in bundled PPAs to be performance obligations satisfied at a point in time, measurement of satisfaction and transfer of control to the customer in a bundled arrangement coincides with a pattern of revenue recognition with the underlying energy generation. Accordingly, the Company applied the practical expedient in Topic 606 as the right to consideration corresponds directly to the value provided to the customer to recognize revenue at the invoice amount for its PPA contracts. For the three months ended March 31, 2018, the Company’s energy revenue from PPA contracts with customers was $13.2 million . As of March 31, 2018, the Company’s receivable balances related to PPA contracts with customers was approximately $6.4 million . Trade receivables for PPA contracts are reflected in accounts receivable, net in the unaudited condensed consolidated balance sheets. The Company typically receives payment within 30 days for invoiced PPA revenue. The Company does not have any other significant contract asset or liability balances related to PPA revenue. Energy revenues yet to be earned under these contracts are expected to be recognized between 2018 and 2043. The Company applies the practical expedient in Topic 606 to its bundled PPA contract arrangements, and accordingly, does not disclose the value of unsatisfied performance obligations for contracts for which it recognizes revenue at the amount to which it has the right to invoice for services performed. Amortization of favorable and unfavorable rate revenue contracts, net The Company accounts for its business combinations by recognizing in the financial statements the identifiable assets acquired, the liabilities assumed and any non-controlling interests in the acquiree at fair value at the acquisition date. Intangible amortization of certain revenue contracts acquired in business combinations (favorable and unfavorable rate PPAs and REC agreements) is recognized on a straight-line basis over the remaining contract term. The current period amortization for favorable rate revenue contracts is reflected as a reduction to operating revenues, net, and amortization for unfavorable rate revenue contracts is reflected as an increase to operating revenues, net. There was no impact related to the adoption of Topic 606. See Note 6 . Intangibles . Incentive revenue The Company generates incentive revenue from individual incentive agreements relating to the sale of RECs and performance-based incentives (“PBIs”) to third-party customers that are not bundled with the underlying energy output. The majority of individual REC sales reflect a fixed quantity, fixed price structure over a specified term. The Company views REC products in these arrangements as distinct performance obligations satisfied at a point in time. Since the REC products delivered to the customer are not linked to the underlying generation of a specified facility, these RECs are now recognized into revenue when delivered and invoiced under Topic 606. This was a change from the Company’s prior year accounting policy which recognized REC sales upon underlying electricity generation as discussed in Note 2. Summary of Significant Accounting Policies . The impact of the adoption resulted in a decrease in operating revenues, net of $2.6 million during the first quarter of 2018. Incentive revenues yet to be earned for fixed price incentive contracts are expected to be $67.0 million and recognized between 2018 and 2023. The Company typically receives payment within 30 days of invoiced REC revenue. For certain incentive contract arrangements, the quantity delivered to the customer is linked to a specific facility. Similar to PPA revenues under Topic 606, the pattern of revenue recognition for these incentive arrangements is recognized over time coinciding with the underlying revenue generation which is consistent with the Company’s policy prior to the adoption of Topic 606. For the three months ended March 31, 2018, the Company’s incentive revenue from facility-linked contracts with customers was $5.5 million . Revenue accruals for facility linked incentive contracts within accounts receivable, net were $5.5 million as of March 31, 2018. The Company applied the practical expedient in Topic 606 to its variable consideration incentive contract arrangements where revenues are linked to the underlying generation of the renewable energy facilities, and accordingly does not disclose the value of unsatisfied performance obligations for contracts for which it recognizes revenue at the amount to which it has the right to invoice for services performed. Prior to the adoption of Topic 606, the Company deferred sales of ITCs through its lease pass-through fund arrangements as a deferred revenue liability in the unaudited condensed consolidated balance sheet. As discussed in Note 2. Summary of Significant Accounting Policies , the Company now recognizes revenue related to the sales of ITCs at the point in time when the related solar energy systems are placed in service. The Company concluded that the likelihood of a recapture event related to these assessments is remote. Under Topic 605, the Company would have recognized an increase of $3.5 million in non-cash deferred revenue within operating revenues, net for the three months ended March 31, 2018. The remaining deferred revenue balance in the unaudited condensed consolidated balance sheet as of March 31, 2018 consisted of upfront government incentives of $9.0 million and contract liabilities of $5.9 million related to performance obligations that have not yet been satisfied. These contract liabilities represent advanced customer receipts primarily related to future REC deliveries that are recognized into revenue under Topic 606. The amount of revenue recognized during the three months ended March 31, 2018 related to contract liabilities was $0.3 million .

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS Irrevocable Agreements to Launch Tender Offer for the Common Shares of Saeta Yield On February 7, 2018, the Company announced its agreement to launch a voluntary tender offer (the “Tender Offer”) to acquire 100% of the outstanding shares of Saeta Yield, S.A. (“Saeta Yield”), a Spanish corporation and a publicly-listed European owner and operator of wind and solar assets, located primarily in Spain. In April of 2018, the Company received approval from the Spanish National Securities Market Commission (Comisión Nacional del Mercado de Valores) (the “CNMV”) of the prospectus for the Tender Offer, which was launched on May 3, 2018, at a price of 12.20 Euros per share of Saeta Yield. On May 8, 2018, the board of directors of Saeta Yield issued a unanimous favorable opinion of the Tender Offer. The Tender Offer is expected to be completed by mid-summer of 2018, subject to certain closing conditions. In connection with this Tender Offer, on February 6, 2018, TERP Spanish HoldCo, S.L. (“TERP Spanish HoldCo”), a subsidiary of the Company, entered into an irrevocable undertaking agreement for the launch and acceptance of the takeover bid for the shares of Saeta Yield with Cobra Concesiones, S.L., a company incorporated under the laws of Spain (“Cobra”), and GIP II Helios, S.à r.l., a société à responsabilité limitée organized under the laws of the Grand Duchy of Luxembourg (“GIP”), as well as two separate irrevocable undertaking agreements with Mutuactivos, S.A.U., S.G.I.I.C., a company incorporated under the laws of Spain (“Mutuactivos”), and with Sinergia Advisors 2006, A.V., S.A., a company incorporated under the laws of Spain (“Sinergia” and, together with Cobra, GIP and Mutuactivos, the “Selling Stockholders”). Under the terms of these irrevocable undertaking agreements, the Selling Stockholders have irrevocably and unconditionally agreed to tender their combined 50.338% interest in Saeta Yield in the Tender Offer. The Company’s acceptance of the shares of Saeta Yield tendered in the Tender Offer is conditioned upon the Company obtaining compulsory authorization required from the European Commission, which has been obtained, and Cobra and GIP irrevocably accepting the Tender Offer in respect of their shares of Saeta Yield representing no less than 48.222% of Saeta Yield’s voting share capital. The aggregate value of the shares of Saeta Yield held by the Selling Stockholders is approximately $600 million . If the Company successfully acquires all of the remaining Saeta Yield shares in the Tender Offer, the aggregate purchase price (including the value of the Selling Stockholders shares) will be approximately $1.2 billion . Assuming a $1.2 billion acquisition price, the Company intends to finance the acquisition with an equity issuance of the Company’s Class A common stock in a minimum amount of $400 million (the “Equity Offering”). The remainder will be financed from the Company’s available liquidity, which is expected to include borrowings under the Revolver (as defined in Note 8 . Long-term Debt ) and the Sponsor Line Agreement (as defined in Note 14 . Related Parties ) . The Company believes that it may be prudent to consider increasing the Equity Offering used to fund the Tender Offer from $400 million up to a maximum of $650 million . An increase in the Equity Offering may further strengthen the Company’s financial position, ensure ample access to liquidity, and decrease any borrowings needed to fund the acquisition. The Company expects to repay these borrowings with a combination of sources, including new non-recourse financings of the Company’s currently unencumbered wind and solar assets and certain cash released from Saeta Yield’s assets. See Note 14 . Related Parties for discussion regarding the Back-Stop Agreement (as defined therein) that the Company entered into with Brookfield in connection with the expected Equity Offering. In connection with the launch of the Tender Offer, the Company was required to post a bank guarantee (the “Bank Guarantee”) with the CNMV for the maximum amount payable in the Tender Offer of approximately $1.2 billion . On March 6, 2018, TERP Spanish HoldCo entered into two letter of credit facilities (the “LC Agreements”) pursuant to which two banks posted the Bank Guarantee with the CNMV for the maximum amount payable in the Tender Offer. On March 6, 2018, TerraForm Power entered into two letter agreements (the “Letter Agreements” and together with the LC Agreements, the “Letter of Credit Facilities”) with those banks. The LC Agreements govern TERP Spanish HoldCo’s obligations to reimburse those banks upon any drawing under the Bank Guarantee. The Letter Agreements govern TerraForm Power’s obligation to utilize drawings on its Revolver and Sponsor Line Agreement or proceeds from an equity offering of its Class A common stock to contribute funds to TERP Spanish HoldCo to enable TERP Spanish HoldCo to satisfy its reimbursement obligations under the LC Agreements. The Letter of Credit Facilities also contain customary fees, representations and warranties, covenants and events of default. Under the terms of the Letter of Credit Facilities, the Company is required to maintain minimum liquidity requirements of $500.0 million under the Sponsor Line Agreement and $400.0 million under the Revolver. In addition, if any amount is drawn under the Bank Guarantee, or if an event of default occurs under the Letter of Credit Facilities, the Company may be required to cash collateralize the entire amount of the Bank Guarantee that has not been drawn. Acquisition Costs Acquisition costs incurred by the Company related to the pending acquisition of Saeta Yield were $3.7 million for the three months ended March 31, 2018. These costs are reflected as acquisition and related costs in the unaudited condensed consolidated statement of operations (see Note 14. Related Parties ). There were no acquisition costs incurred by the Company for the three months ended March 31, 2017.

Renewable Energy Facilities

Renewable Energy Facilities	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Renewable Energy Facilities	RENEWABLE ENERGY FACILITIES Renewable energy facilities, net consists of the following: (In thousands) March 31, 2018 December 31, 2017 Renewable energy facilities in service, at cost $ 5,344,488 $ 5,378,462 Less accumulated depreciation - renewable energy facilities (626,766 ) (578,474 ) Renewable energy facilities in service, net 4,717,722 4,799,988 Construction in progress - renewable energy facilities 2,086 1,937 Total renewable energy facilities, net $ 4,719,808 $ 4,801,925 Depreciation expense related to renewable energy facilities was $57.1 million and $52.2 million for the three months ended March 31, 2018 and 2017 , respectively. For the periods presented above, construction in progress primarily represents initial costs incurred for the construction of a new battery energy storage system for one of the Company's wind power plants, for which construction began in the fourth quarter of 2017. Impairment Charge The Company reviews long-lived assets that are held and used for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. The Company currently has a REC sales agreement with a customer expiring December 31, 2021 that is significant to an operating project within the Enfinity solar distributed generation portfolio, and on March 31, 2018, this customer filed for protection under Chapter 11 of the U.S. Bankruptcy Code. The potential replacement of this contract would likely result in a significant decrease in expected revenues for this operating project. The Company’s analysis indicated that the bankruptcy filing was a triggering event to perform an impairment evaluation, and the carrying amount of $19.5 million as of March 31, 2018 was no longer considered recoverable based on an undiscounted cash flow forecast. The Company estimated the fair value of the operating project at $4.3 million as of March 31, 2018 and recognized an impairment charge of $15.2 million equal to the difference between the carrying amount and the estimated fair value, which is reflected within impairment of renewable energy facilities in the unaudited condensed consolidated statement of operations for the three months ended March 31, 2018 . The Company used an income approach methodology of valuation to determine fair value by applying a discounted cash flow method to the forecasted cash flows of the operating project, which was categorized as a Level 3 fair value measurement due to the significance of unobservable inputs. Key estimates used in the income approach included forecasted power and incentive prices, customer renewal rates, operating and maintenance costs and the discount rate. There were no long-lived asset impairment charges recognized during the three months ended March 31, 2017.

Intangibles

Intangibles	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangibles	INTANGIBLES The following table presents the gross carrying amount, accumulated amortization and net book value of intangibles as of March 31, 2018 : (In thousands, except weighted average amortization period) Weighted Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Book Value Favorable rate revenue contracts 15 years $ 713,786 $ (110,230 ) $ 603,556 In-place value of market rate revenue contracts 18 years 520,079 (79,349 ) 440,730 Favorable rate land leases 17 years 15,800 (2,529 ) 13,271 Total intangible assets, net $ 1,249,665 $ (192,108 ) $ 1,057,557 Unfavorable rate revenue contracts 7 years $ 33,686 $ (15,952 ) $ 17,734 Unfavorable rate operations and maintenance contracts 2 years 5,000 (2,865 ) 2,135 Unfavorable rate land lease 15 years 1,000 (176 ) 824 Total intangible liabilities, net 1 $ 39,686 $ (18,993 ) $ 20,693 The following table presents the gross carrying amount, accumulated amortization and net book value of intangibles as of December 31, 2017 : (In thousands, except weighted average amortization period) Weighted Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Book Value Favorable rate revenue contracts 15 years $ 718,639 $ (102,543 ) $ 616,096 In-place value of market rate revenue contracts 19 years 521,323 (73,104 ) 448,219 Favorable rate land leases 17 years 15,800 (2,329 ) 13,471 Total intangible assets, net $ 1,255,762 $ (177,976 ) $ 1,077,786 Unfavorable rate revenue contracts 7 years $ 35,086 $ (16,030 ) $ 19,056 Unfavorable rate operations and maintenance contracts 2 years 5,000 (2,552 ) 2,448 Unfavorable rate land lease 15 years 1,000 (162 ) 838 Total intangible liabilities, net 1 $ 41,086 $ (18,744 ) $ 22,342 ——— (1) The Company’s intangible liabilities are classified within other long-term liabilities in the unaudited condensed consolidated balance sheets. Amortization expense related to favorable rate revenue contracts is reflected in the unaudited condensed consolidated statements of operations as a reduction of operating revenues, net. Amortization related to unfavorable rate revenue contracts is reflected in the unaudited condensed consolidated statements of operations as an increase to operating revenues, net. During the three months ended March 31, 2018 and 2017 , net amortization expense related to favorable and unfavorable rate revenue contracts resulted in a reduction of operating revenues, net of $9.8 million . Amortization expense related to the in-place value of market rate revenue contracts is reflected in the unaudited condensed consolidated statements of operations within depreciation, accretion and amortization expense. During the three months ended March 31, 2018 and 2017 , amortization expense related to the in-place value of market rate revenue contracts was $6.4 million . Amortization expense related to favorable rate land leases is reflected in the unaudited condensed consolidated statements of operations within cost of operations. Amortization related to the unfavorable rate land lease and unfavorable rate operations and maintenance (“O&M”) contracts is reflected in the unaudited condensed consolidated statements of operations as a reduction of cost of operations. During the three months ended March 31, 2018 and 2017 , net amortization related to favorable and unfavorable rate land leases and unfavorable rate O&M contracts resulted in a $0.1 million reduction of cost of operations.

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	VARIABLE INTEREST ENTITIES The Company consolidates variable interest entities ("VIEs") in renewable energy facilities when the Company is the primary beneficiary. The VIEs own and operate renewable energy facilities in order to generate contracted cash flows. The VIEs were funded through a combination of equity contributions from the owners and non-recourse, project-level debt. No VIEs were deconsolidated during the three months ended March 31, 2018 and 2017 . The carrying amounts and classification of the consolidated VIEs’ assets and liabilities included in the Company’s unaudited condensed consolidated balance sheets are as follows: (In thousands) March 31, 2018 December 31, 2017 Current assets $ 122,410 $ 142,403 Non-current assets 4,100,306 4,155,558 Total assets $ 4,222,716 $ 4,297,961 Current liabilities $ 99,198 $ 119,021 Non-current liabilities 996,712 975,839 Total liabilities $ 1,095,910 $ 1,094,860 The amounts shown in the table above exclude intercompany balances that are eliminated upon consolidation. All of the assets in the table above are restricted for settlement of the VIE obligations, and all of the liabilities in the table above can only be settled by using VIE resources.

Long-term Debt

Long-term Debt	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Long-term Debt	LONG-TERM DEBT Long-term debt consists of the following: (In thousands, except rates) March 31, 2018 December 31, 2017 Interest Type Interest Rate (%) 1 Financing Type Corporate-level long-term debt 2 : Senior Notes due 2023 $ 500,000 $ 500,000 Fixed 4.25 Senior notes Senior Notes due 2025 300,000 300,000 Fixed 6.63 Senior notes Senior Notes due 2028 700,000 700,000 Fixed 5.00 Senior notes Revolver 3 70,000 60,000 Variable 4.86 Revolving loan Term Loan 4 349,125 350,000 Variable 4.63 Term debt Non-recourse long-term debt 5 : Permanent financing 1,602,675 1,616,729 Blended 6 5.72 7 Term debt / Senior notes Financing lease obligations 114,730 115,787 Imputed 5.60 7 Financing lease obligations Total principal due for long-term debt and financing lease obligations 3,636,530 3,642,516 5.33 7 Unamortized discount, net (18,297 ) (19,027 ) Deferred financing costs, net (23,862 ) (24,689 ) Less current portion of long-term debt and financing lease obligations (391,656 ) (403,488 ) Long-term debt and financing lease obligations, less current portion $ 3,202,715 $ 3,195,312 ——— (1) As of March 31, 2018 . (2) Outstanding corporate-level debt represents debt issued by TerraForm Power Operating, LLC (“Terra Operating LLC”) and guaranteed by Terra LLC and certain subsidiaries of Terra Operating LLC other than non-recourse subsidiaries as defined in the relevant debt agreements (with the exception of certain unencumbered non-recourse subsidiaries). (3) On February 6, 2018, Terra Operating LLC elected to increase the total borrowing capacity of its $450.0 million senior secured revolving credit facility (the “Revolver”), available for revolving loans and letters of credit, to $600.0 million . As discussed in Note 4 . Acquisitions , per the terms of the Letter of Credit Facilities the Company entered into in connection with posting the Bank Guarantee for the maximum amount payable in the Tender Offer, the Company is required to maintain a minimum liquidity requirement of $400.0 million under the Revolver. (4) On May 11, 2018, the Company signed a repricing amendment whereby the interest rate on the Term Loan was reduced by 0.75% per annum. (5) Non-recourse debt represents debt issued by subsidiaries with no recourse to TerraForm Power, Terra LLC, Terra Operating LLC or guarantors of the Company’s corporate-level debt, other than limited or capped contingent support obligations, which in aggregate are not considered to be material to the Company’s business and financial condition. In connection with these financings and in the ordinary course of its business, TerraForm Power and its subsidiaries observe formalities and operating procedures to maintain each of their separate existence and can readily identify each of their separate assets and liabilities as separate and distinct from each other. As a result, these subsidiaries are legal entities that are separate and distinct from TerraForm Power, Terra LLC, Terra Operating LLC and the guarantors of the Company’s corporate-level debt. (6) Includes fixed rate debt and variable rate debt. As of March 31, 2018 , 60% of this balance had a fixed interest rate and the remaining 40% of this balance had a variable interest rate. The Company entered into interest rate swap agreements to fix the interest rates of a majority of the variable rate permanent financing non-recourse debt (see Note 10 . Derivatives ). (7) Represents the weighted average interest rate as of March 31, 2018 . Non-recourse Debt Defaults Over the course of 2016 and 2017, the Company experienced defaults in its non-recourse debt financings that principally arose as a result of the filing for bankruptcy of certain SunEdison subsidiaries that served as providers of O&M or asset management services to its renewable energy facilities (or as guarantors of those service providers) and as a result of the failure of the applicable Company subsidiary or the Company to timely deliver audited or unaudited financial statements and other deliverables required by the applicable financing arrangements. With the exception of its 101.6 MW renewable energy facility in Chile, to date the Company has transitioned all the project-level services provided by SunEdison to third parties or in-house. The Company has also delivered all outstanding Company and project-level financial statements and deliverables as of the date hereof, has substantially obtained all waivers needed for late delivery of financial statements that were delivered after the grace period expired and expects to complete its future project-level financial statement deliverables within the required time periods (taking into account the respective grace periods) for their delivery. As of March 31, 2018 and December 31, 2017, the Company reclassified $216.3 million and $239.7 million , respectively, of the Company's non-recourse long-term indebtedness, net of unamortized debt discounts and deferred financing costs, to current in the unaudited condensed consolidated balance sheets due to defaults still remaining as of the respective financial statement issuance date, which primarily consisted of indebtedness of the Company’s renewable energy facility in Chile. The Company continued to amortize deferred financing costs and debt discounts over the maturities of the respective financing agreements as before the violations, as the Company believed there was a reasonable likelihood that it would be able to successfully negotiate a waiver with the lenders and/or cure the defaults. The Company based this conclusion on (i) its past history of obtaining waivers and/or forbearance agreements with lenders, (ii) the nature and existence of active negotiations between the Company and the respective lenders to secure a waiver, (iii) the Company's timely servicing of these debt instruments and (iv) the fact that no non-recourse financing has been accelerated to date and no project-level lender has notified the Company of such lenders election to enforce project security interests. Refer to Note 2. Summary of Significant Accounting Policies for discussion of corresponding restricted cash reclassifications to current as a result of these defaults. There were no corresponding interest rate swap reclassifications needed as a result of these remaining defaults. Canada Project-level Financing Upsize On February 28, 2017, the Company increased the principal amount of a non-recourse credit facility that is secured by approximately 59 MW of utility-scale solar power plants located in Canada that are owned by the Company’s subsidiaries by an additional 113.9 million Canadian Dollars (“CAD”) (including an additional CAD $6.7 million letter of credit), increasing the total facility to CAD $233.9 million . The proceeds of this additional financing were primarily used for general corporate purposes. Maturities The aggregate contractual principal payments of long-term debt due after March 31, 2018 , including financing lease obligations and excluding amortization of debt discounts, premiums and deferred financing costs, as stated in the financing agreements, are as follows: (In thousands) Remainder of 2018 1 2019 2020 2021 2022 Thereafter Total Maturities of long-term debt 2 $ 162,194 $ 110,248 $ 104,970 $ 108,015 $ 596,658 $ 2,554,445 $ 3,636,530 ——— (1) Includes $70.0 million of Revolver indebtedness, of which the Company repaid $55.0 million with cash on hand in April of 2018. (2) Represents the contractual principal payment due dates for the Company's long-term debt and does not reflect the reclassification of $216.3 million of long-term debt to current as a result of debt defaults under certain of the Company's non-recourse financing arrangements.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES The income tax provision consisted of the following: Three Months Ended March 31, (In thousands, except effective tax rate) 2018 2017 Loss before income tax benefit $ (77,343 ) $ (57,191 ) Income tax benefit (976 ) (918 ) Effective tax rate 1.3 % 1.6 % As of March 31, 2017, TerraForm Power owned 65.7% of Terra LLC and consolidated the results of Terra LLC through its controlling interest. The Company recorded SunEdison’s 34.3% ownership of Terra LLC as a non-controlling interest in the financial statements. Terra LLC is treated as a partnership for income tax purposes. As such, for the three months ended March 31, 2017, the Company recorded income tax on its 65.7% of Terra LLC’s taxable income and SunEdison recorded income tax on its 34.3% share of Terra LLC’s taxable income. On October 16, 2017, pursuant to the settlement agreement the Company entered into with SunEdison on March 6, 2017 (the “Settlement Agreement”), SunEdison transferred its interest in Terra LLC to TerraForm Power. As a result, TerraForm Power now owns 100% of the capital and profits interest in Terra LLC, except for the incentive distribution rights (“IDRs”) which are owned by BRE Delaware, Inc. (the “Brookfield IDR Holder”), an indirect wholly-owned subsidiary of Brookfield, and it recorded income tax on its 100% share of Terra LLC’s taxable income for the three months ended March 31, 2018. For the three months ended March 31, 2018 and 2017, the overall effective tax rate was different than the statutory rate of 21% and 35% , respectively, primarily due to the recording of a valuation allowance on certain tax benefits attributed to the Company, loss allocated to non-controlling interests, and the effect of foreign and state taxes. As of March 31, 2018 , most jurisdictions were in a net deferred tax asset position. A valuation allowance is recorded against the deferred tax assets primarily due to the history of losses in those jurisdictions with the exception of Canada, Puerto Rico and one of the Company’s U.S. portfolios. The recognition of an income tax benefit of $1.0 million for the three months ended March 31, 2018 was mostly driven by the loss generated in Canada. As of March 31, 2018 , the Company had not identified any uncertain tax positions for which a liability was required. Due to the enactment of the Tax Act on December 22, 2017, the U.S. federal corporate income tax rate was reduced from 35% to 21% , effective January 1, 2018. As a result, the Company performed a preliminary analysis to revalue its deferred income taxes and included a net reduction in deferred liabilities of $5 million as of December 31, 2017. While the Company continues to believe that the provisional Tax Act adjustments are reasonable estimates of the effects on its existing deferred taxes, additional analysis and detailed reviews are still being performed to finalize the accounting for the re-measurement of deferred tax assets and liabilities as a result of the enactment of the Tax Act.

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	DERIVATIVES As part of the Company’s risk management strategy, the Company has entered into derivative instruments which include interest rate swaps, foreign currency contracts and commodity contracts to mitigate interest rate, foreign currency and commodity price exposure. If the Company elects to do so and if the instrument meets the criteria specified in ASC 815, Derivatives and Hedging , the Company designates its derivative instruments as cash flow hedges. The Company enters into interest rate swap agreements in order to hedge the variability of expected future cash interest payments. Foreign currency contracts are used to reduce risks arising from the change in fair value of certain foreign currency denominated assets and liabilities. The objective of these practices is to minimize the impact of foreign currency fluctuations on operating results. The Company also enters into commodity contracts to economically hedge price variability inherent in electricity sales arrangements. The objectives of the commodity contracts are to minimize the impact of variability in spot electricity prices and stabilize estimated revenue streams. The Company does not use derivative instruments for speculative purposes. As of March 31, 2018 and December 31, 2017 , fair values of the following derivative instruments were included in the balance sheet captions indicated below: Fair Value of Derivative Instruments Derivatives Designated as Hedging Instruments Derivatives Not Designated as Hedging Instruments (In thousands) Interest Rate Swaps Commodity Contracts Interest Rate Swaps Foreign Currency Contracts Commodity Contracts Gross Amounts of Assets/Liabilities Recognized Gross Amounts Offset in Consolidated Balance Sheet Net Amounts in Consolidated Balance Sheet As of March 31, 2018 Prepaid expenses and other current assets $ 392 $ 1,475 $ — $ 1,491 $ 13,595 $ 16,953 $ (1,491 ) $ 15,462 Other assets 9,469 59,065 — — 11,763 80,297 — 80,297 Total assets $ 9,861 $ 60,540 $ — $ 1,491 $ 25,358 $ 97,250 $ (1,491 ) $ 95,759 Accounts payable, accrued expenses and other current liabilities $ 815 $ 392 $ 130 $ 2,640 $ — $ 3,977 $ (1,491 ) $ 2,486 Other long-term liabilities 2,869 — 184 — — 3,053 — 3,053 Total liabilities $ 3,684 $ 392 $ 314 $ 2,640 $ — $ 7,030 $ (1,491 ) $ 5,539 As of December 31, 2017 Prepaid expenses and other current assets $ — $ 8,961 $ — $ 63 $ 12,609 $ 21,633 $ (63 ) $ 21,570 Other assets 4,686 71,307 — — 14,787 90,780 — 90,780 Total assets $ 4,686 $ 80,268 $ — $ 63 $ 27,396 $ 112,413 $ (63 ) $ 112,350 Accounts payable, accrued expenses and other current liabilities $ 2,490 $ — $ 197 $ 99 $ — $ 2,786 $ (63 ) $ 2,723 Other long-term liabilities 4,796 — 404 — — 5,200 — 5,200 Total liabilities $ 7,286 $ — $ 601 $ 99 $ — $ 7,986 $ (63 ) $ 7,923 As of March 31, 2018 and December 31, 2017 , notional amounts for derivative instruments consisted of the following: Notional Amount as of (In thousands) March 31, 2018 December 31, 2017 Derivatives designated as hedging instruments: Interest rate swaps (USD) 387,681 395,986 Interest rate swaps (CAD) 155,270 156,367 Commodity contracts (MWhs) 15,201 15,579 Derivatives not designated as hedging instruments: Interest rate swaps (USD) 13,482 13,520 Foreign currency contracts (CAD) — 9,875 Foreign currency contracts (EUR) 1 1,000,000 — Commodity contracts (MWhs) 854 987 ——— (1) During the first quarter of 2018, the Company entered into short and long-term foreign currency forward contracts in relation to the Saeta Yield acquisition. As of March 31, 2018, the Company had outstanding contracts to buy and sell 500 million Euros with varying maturities, to hedge a portion of the foreign currency risk. See Note 4 . Acquisitions for discussion regarding the Company’s recently launched Tender Offer for the outstanding shares of Saeta Yield that is expected to close by mid-summer of 2018. The Company elected to present net derivative assets and liabilities on the balance sheet as a right to set-off exists. For interest rate swaps, the Company either nets derivative assets and liabilities on a trade-by-trade basis or nets them in accordance with a master netting arrangement if such an arrangement exists with the counterparties. Foreign currency contracts are netted by currency in accordance with a master netting arrangement. The Company has a master netting arrangement for its commodity contracts for which no amounts were netted as of March 31, 2018 or December 31, 2017 . Gains and losses on derivatives not designated as hedging instruments for the three months ended March 31, 2018 and 2017 consisted of the following: Location of (Gain) Loss in the Statements of Operations Three Months Ended March 31, (In thousands) 2018 2017 Interest rate swaps Interest expense, net $ (226 ) $ 1,374 Foreign currency contracts Loss on foreign currency exchange, net 1,226 213 Commodity contracts Operating revenues, net (410 ) (4,113 ) Gains and losses recognized related to interest rate swaps and commodity contracts designated as hedging instruments for the three months ended March 31, 2018 and 2017 consisted of the following: Three Months Ended March 31, Derivatives in Cash Flow Hedging Relationships Gain (Loss) Included in the Assessment of Effectiveness Recognized in OCI, net of taxes 1 Gain (Loss) Excluded from the Assessment of Effectiveness Recognized in OCI Using an Amortization Approach 2 Location of Amount Reclassified from Accumulated OCI into Income (Gain) Loss Included in the Assessment of Effectiveness Reclassified from Accumulated OCI into Income 3 (Gain) Loss Excluded from the Assessment of Effectiveness that is Amortized through Earnings 2 (In thousands) 2018 2017 2018 2017 2018 2017 2018 2017 Interest rate swaps $ 7,875 $ (1,619 ) $ — $ — Interest expense, net $ 681 $ 2,861 $ — $ — Commodity contracts (19,102 ) 15,673 735 — Operating revenues, net (1,311 ) (3,247 ) (332 ) — Total $ (11,227 ) $ 14,054 $ 735 $ — $ (630 ) $ (386 ) $ (332 ) $ — ———— (1) There were no taxes attributed to interest rate swaps during the three months ended March 31, 2018 and 2017. Net of taxes of zero and $5.8 million for commodity contracts during the three months ended March 31, 2018 and 2017, respectively. (2) As a result of the adoption of ASU No. 2017-12 effective January 1, 2018 (see Note 2. Summary of Significant Accounting Policies ), certain gains and losses were excluded from the assessment of effectiveness that are being amortized through earnings for the three months ended March 31, 2018. No such amounts existed for the three months ended March 31, 2017 prior to the adoption of ASU No. 2017-12. (3) There were no taxes attributed to derivatives designated as hedging instruments during the three months ended March 31, 2018 and 2017. As discussed in Note 2. Summary of Significant Accounting Policies , the Company adopted ASU No. 2017-12 as of January 1, 2018 and recognized a cumulative-effect adjustment of $4.2 million , net of tax of $1.6 million , representing a decrease in beginning accumulated deficit and accumulated OCI, which is reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018. As of March 31, 2018 and December 31, 2017 , the Company had posted letters of credit in the amount of $15.0 million , as collateral related to certain commodity contracts. Certain derivative contracts contain provisions providing the counterparties a lien on specific assets as collateral. There was no cash collateral received or pledged as of March 31, 2018 and December 31, 2017 related to the Company’s derivative transactions. Derivatives Designated as Hedging Instruments Interest Rate Swaps The Company has interest rate swap agreements to hedge variable rate non-recourse debt. These interest rate swaps were designated as hedging instruments and qualify for hedge accounting. Under the interest rate swap agreements, the renewable energy facilities pay a fixed rate and the counterparties to the agreements pay a variable interest rate. The amounts deferred in accumulated OCI and reclassified into e arnings during the three months ended March 31, 2018 and 2017 related to these interest rate swaps are provided in the tables above. The loss expected to be reclassified into earnings over the next twelve months is approximately $0.4 million . The maximum term of outstanding interest rate swaps designated as hedging instruments is 16 years. Commodity Contracts The Company has long-dated physically delivered commodity contracts that hedge variability in cash flows associated with the sales of power from certain renewable energy facilities located in Texas. These commodity contracts qualify for hedge accounting and are designated as cash flow hedges. Accordingly, the effective portions of the change in fair value of these derivatives are reported in accumulated OCI and subsequently reclassified to earnings in the periods when the hedged transactions affect earnings. Prior to adoption of ASU 2017-12, any ineffective portions of the derivatives’ change in fair value were recognized in earnings. The amounts deferred in accumulated OCI and reclassified into earnings during the three months ended March 31, 2018 and 2017 related to these commodity contracts are provided in the ta bles above. The gain expected to be reclassified into earnings over the next twelve months is approximately $8.1 million . The maximum term of outstanding commodity contracts designated as hedges is 12 years. Derivatives Not Designated as Hedges Interest Rate Swaps The Company has interest rate swap agreements that economically hedge the cash flows for non-recourse debt. These interest rate swaps pay a fixed rate and the counterparties to the agreements pay a variable interest rate. The changes in fair value are recorded in interest expense, net in the unaudited condensed consolidated statements of operations as these hedges are not accounted for under hedge accounting. Foreign Currency Contracts The Company has foreign currency contracts in order to economically hedge its exposure to foreign currency fluctuations. The settlement of these hedges occurs on a quarterly basis through maturity. As these hedges are not accounted for under hedge accounting, the changes in fair value are recorded in loss on foreign currency exchange, net in the unaudited condensed consolidated statements of operations. Commodity Contracts The Company has commodity contracts in order to economically hedge commodity price variability inherent in certain electricity sales arrangements. If the Company sells electricity to an independent system operator market and there is no PPA available, it may enter into a commodity contract to hedge all or a portion of their estimated revenue stream. These commodity contracts require periodic settlements in which the Company receives a fixed-price based on specified quantities of electricity and pays the counterparty a variable market price based on the same specified quantity of electricity. As these hedges are not accounted for under hedge accounting, the changes in fair value are recorded in operating revenues net, in the unaudited condensed consolidated statements of operations.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	FAIR VALUE OF FINANCIAL INSTRUMENTS The fair value of assets and liabilities are determined using either unadjusted quoted prices in active markets (Level 1) or pricing inputs that are observable (Level 2) whenever that information is available and using unobservable inputs (Level 3) to estimate fair value only when relevant observable inputs are not available. The Company uses valuation techniques that maximize the use of observable inputs. Assets and liabilities are classified in their entirety based on the lowest priority level of input that is significant to the fair value measurement. Where observable inputs are available for substantially the full term of the asset or liability, the instrument is categorized in Level 2. If the inputs into the valuation are not corroborated by market data, in such instances, the valuation for these contracts is established using techniques including extrapolation from or interpolation between actively traded contracts, as well as calculation of implied volatilities. When such inputs have a significant impact on the measurement of fair value, the instrument is categorized as Level 3. The Company regularly evaluates and validates the inputs used to determine fair value of Level 3 contracts by using pricing services to support the underlying market price of the commodity. The Company uses a discounted cash flow valuation technique to fair value its derivative assets and liabilities. The primary inputs in the valuation models for commodity contracts are market observable forward commodity curves and risk-free discount rates and to a lesser degree credit spreads and volatilities. The primary inputs into the valuation of interest rate swaps and foreign currency contracts are forward interest rates and foreign currency exchange rates and to a lesser degree credit spreads. Recurring Fair Value Measurements The following table summarizes the financial instruments measured at fair value on a recurring basis classified in the fair value hierarchy (Level 1, 2 or 3) based on the inputs used for valuation in the unaudited condensed consolidated balance sheets: (In thousands) As of March 31, 2018 As of December 31, 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Interest rate swaps $ — $ 9,861 $ — $ 9,861 $ — $ 4,686 $ — $ 4,686 Commodity contracts — 25,358 60,540 85,898 — 27,396 80,268 107,664 Foreign currency contracts — — — — — — — — Total derivative assets $ — $ 35,219 $ 60,540 $ 95,759 $ — $ 32,082 $ 80,268 $ 112,350 Liabilities Interest rate swaps $ — $ 3,998 $ — $ 3,998 $ — $ 7,887 $ — $ 7,887 Commodity contracts — — 392 392 — — — — Foreign currency contracts — 1,149 — 1,149 — 36 — 36 Total derivative liabilities $ — $ 5,147 $ 392 $ 5,539 $ — $ 7,923 $ — $ 7,923 The Company's interest rate swaps, commodity contracts not designated as hedges and foreign currency contracts are considered Level 2, since all significant inputs are corroborated by market observable data. The Company's commodity contracts designated as hedges are considered Level 3 as they contain significant unobservable inputs. There were no transfers in or out of Level 1, Level 2 and Level 3 during the three months ended March 31, 2018 . The following table reconciles the changes in the fair value of derivative instruments classified as Level 3 in the fair value hierarchy for the three months ended March 31, 2018 and 2017: Three Months Ended March 31, (In thousands) 2018 2017 Beginning balance $ 80,268 $ 66,138 Realized and unrealized (losses) gains: Included in other comprehensive (loss) income (20,010 ) 18,262 Included in operating revenues, net 1,533 6,165 Settlements (1,643 ) (3,247 ) Balance as of March 31 $ 60,148 $ 87,318 The significant unobservable inputs used in the valuation of the Company's commodity contracts categorized as Level 3 in the fair value hierarchy as of March 31, 2018 are as follows: (In thousands, except range) Fair Value as of March 31, 2018 Transaction Type Assets Liabilities Valuation Technique Unobservable Inputs Range Commodity contracts - power $ 60,540 $ 392 Discounted cash flow Forward price (per MWh) $ 13.9 - $ 165.8 Option model Volatilities 3.0 % - 7.0 % The sensitivity of the Company’s fair value measurements to increases (decreases) in the significant unobservable inputs is as follows: Significant Unobservable Input Position Impact on Fair Value Measurement Increase (decrease) in forward price Forward sale Decrease (increase) Increase (decrease) in implied volatilities Purchase option Increase (decrease) The Company measures the sensitivity of the fair value of its Level 3 commodity contracts to potential changes in commodity prices using a mark-to-market analysis based on the current forward commodity prices and estimates of the price volatility. An increase in power forward prices will produce a mark-to-market loss, while a decrease in prices will result in a mark-to-market gain. Fair Value of Debt The carrying amount and estimated fair value of the Company's long-term debt as of March 31, 2018 and December 31, 2017 is as follows: As of March 31, 2018 As of December 31, 2017 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 3,594,371 $ 3,658,574 $ 3,598,800 $ 3,702,470 The fair value of the Company's long-term debt, except the corporate-level senior notes, was determined using inputs classified as Level 2 and a discounted cash flow approach using market rates for similar debt instruments. The fair value of the corporate-level senior notes is based on market price information which is classified as a Level 1 input. They are measured using the last available trades at the end of each respective fiscal year. The fair value of the Senior Notes due 2023, Senior Notes due 2025 and Senior Notes due 2028 were 96.09% , 108.25% and 93.89% of face value as of March 31, 2018 , respectively, and 99.50% , 109.50% and 99.38% of face value as of December 31, 2017 , respectively.

Earnings (Loss) Per Share

Earnings (Loss) Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings (Loss) Per Share	EARNINGS (LOSS) PER SHARE Basic earnings (loss) per share is computed by dividing net income (loss) attributable to Class A common stockholders by the number of weighted average ordinary shares outstanding during the period, which is the average of shares outstanding and assumed to be outstanding, and includes contingently issuable shares as of the date when the contingent condition has been met. Diluted earnings (loss) per share is computed by adjusting basic earnings (loss) per share for the impact of weighted average dilutive common equivalent shares outstanding during the period, unless the impact is anti-dilutive. Common equivalent shares include the incremental shares issuable for unvested restricted Class A common stock and contingently issuable shares in the period the contingency has been met, for the portion of the period prior to the resolution of such contingent condition. Basic and diluted earnings (loss) per share of the Company's Class A common stock for the three months ended March 31, 2018 and 2017 was calculated as follows: Three Months Ended March 31, (In thousands, except per share amounts) 2018 2017 Basic and diluted earnings (loss) per share: Net income (loss) attributable to Class A common stockholders $ 83,233 $ (31,769 ) Less: accretion of redeemable non-controlling interests — (2,226 ) Net income (loss) attributable to Class A common stockholders after accretion of redeemable non-controlling interests $ 83,233 $ (33,995 ) Weighted average basic Class A shares outstanding 1 148,139 92,072 Weighted average diluted Class A shares outstanding 2 148,166 92,072 Basic and diluted earnings (loss) per share $ 0.56 $ (0.37 ) ——— (1) Includes 53 contingently issuable shares for the three months ended March 31, 2018. (2) Includes 28 additional contingently issuable shares for the three months ended March 31, 2018. There were no potentially dilutive unvested Class A common stock awards outstanding during the three months ended March 31, 2018. The computation for diluted loss per share of the Company’s Class A common stock for the three months ended March 31, 2017 excludes 1,477 of potentially dilutive unvested restricted stock units because the effect would have been anti-dilutive.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Letters of Credit The Company's customers, vendors and regulatory agencies often require the Company to post letters of credit in order to guarantee performance under relevant contracts and agreements. The Company is also required to post letters of credit to secure obligations under various swap agreements and leases and may, from time to time, decide to post letters of credit in lieu of cash deposits in reserve accounts under certain financing arrangements. The amount that can be drawn under some of these letters of credit may be increased from time to time subject to the satisfaction of certain conditions. As of March 31, 2018 , the Company had outstanding letters of credit under the Revolver of $78.1 million and outstanding project-level letters of credit of $147.0 million . In addition, as discussed in Note 4. Acquisitions , on March 6, 2018, TERP Spanish HoldCo and TerraForm Power respectively entered into the LC Agreements and the Letter Agreements pursuant to which two banks posted the Bank Guarantee with the CNMV for the maximum amount payable in the Tender Offer of approximately $1.2 billion . Guarantee Agreements The Company and its subsidiaries have provided guarantees to certain of its institutional tax equity investors and financing parties in connection with its tax equity financing transactions. These guarantees do not guarantee the returns targeted by the tax equity investors or financing parties, but rather support any potential indemnity payments payable under the tax equity agreements, including related to management of tax partnerships and recapture of tax credits or renewable energy grants in connection with transfers of the Company’s direct or indirect ownership interests in the tax partnerships to entities that are not qualified to receive those tax benefits. The Company and its subsidiaries have also provided guarantees in connection with acquisitions of third party assets or to support project contractual obligations, including renewable energy credit sales agreements. The Company and its subsidiaries have also provided other capped or limited contingent guarantees and other support obligations with respect to certain project-level indebtedness. See Note 4. Acquisitions and above for discussion regarding the Bank Guarantee that was posted in connection with the Company’s recently announced Tender Offer for the outstanding shares of Saeta Yield that is expected to close by mid-summer of 2018. Commitments to Acquire Renewable Energy Facilities See Note 4. Acquisitions for discussion regarding the irrevocable undertaking agreements the Company entered into on February 6, 2018 in connection with its Tender Offer for the outstanding shares of Saeta Yield that is expected to close by mid-summer of 2018. The Company did not have any other open commitments to acquire renewable energy facilities as of March 31, 2018 . Legal Proceedings The Company is not a party to any material legal proceedings other than various administrative and regulatory proceedings arising in the ordinary course of the Company's business or as described below. While the Company cannot predict with certainty the ultimate resolution of such proceedings or other claims asserted against the Company, certain of the claims, if adversely concluded, could result in substantial damages or other relief. Securities Class Action On April 4, 2016, a securities class action under federal securities laws (Chamblee v. TerraForm Power, Inc., et al., Case No. 1:16-cv-00981-JFM) (the "Chamblee Class Action") was filed in the United States District Court for the District of Maryland against the Company and two of its former officers ( one of which was also a director of the Company) asserting claims under Section 10(b) and 20(a) of the Exchange Act and SEC Rule 10b-5 on behalf of a putative class. The complaint alleged that the defendants made materially false and misleading statements regarding the Company’s business, operational and compliance policies, including with respect to disclosures regarding SunEdison’s internal controls and the Company's reliance on SunEdison. An amended complaint was filed on September 26, 2016 and a former officer and director of the Company were added as defendants. On October 4, 2016, the Judicial Panel on Multidistrict Litigation transferred this matter to the U.S. District Court for the Southern District of New York (SDNY) for consolidated or coordinated pretrial proceedings. On December 19, 2016, an initial case management conference was held in the multidistrict litigation proceedings in the SDNY. The Court entered an order requiring all parties to the multidistrict litigation to mediate and entered a partial stay of all proceedings through March 31, 2017. On March 24, 2017, the plaintiffs filed an amended complaint adding three additional directors and officers of the Company as defendants, as well as additional factual allegations. On June 9, 2017, the Company filed a motion to dismiss the case. After mediation, the parties agreed in principle to a settlement of $14.8 million on behalf of a putative settlement class containing all persons and entities that purchased or otherwise acquired the publicly traded securities of the Company between July 18, 2014 and March 15, 2016, expressly conditioned on, among other things, funding of the settlement by the Company’s directors’ and officers’ liability insurance providers in the amount of $13.63 million . The Company reserved $1.13 million for its estimated probable loss related to this complaint as of December 31, 2016, which was the amount the Company would have been prepared to fund the settlement out of its own funds. On September 14, 2017, the U.S. District Court for the SDNY preliminarily approved the settlement and provided the Company with an express termination right in the event that the settlement was not timely funded with proceeds from the directors’ and officers’ liability insurance. As of December 31, 2017, the Company recorded an insurance receivable of $13.63 million within prepaid expenses and other current assets and a corresponding additional liability of $13.63 million within accounts payable, accrued expenses and other current liabilities in the consolidated balance sheet. In January of 2018, the insurers funded $13.63 million and the Company funded $1.13 million into the settlement escrow account. The settlement was finally approved at a hearing of the court on January 31, 2018. Pursuant to the definitive merger and sponsorship transaction agreement (the “Merger Agreement”) entered into with Orion Holdings on March 6, 2017, the Company has agreed to issue additional shares of Class A common stock to Orion Holdings for no additional consideration in respect of the Company’s net losses, such as out-of-pocket losses, damages, costs, fees and expenses, within a prescribed period following the final resolution of the Chamblee Class Action. These net losses include the $1.13 million contributed by the Company to the settlement but do not include the $13.63 million contributed by the Company's insurers and certain attorneys’ fees that TerraForm Global, Inc. reimbursed to the Company pursuant to the insurance allocation arrangements entered into with the Company in 2017. Claim relating to First Wind Acquisition On May 27, 2016, D.E. Shaw Composite Holdings, L.L.C. and Madison Dearborn Capital Partners IV, L.P., as the representatives of the sellers (the “First Wind Sellers”) filed an amended complaint for declaratory judgment against TerraForm Power and Terra LLC in the Supreme Court of the State of New York alleging breach of contract with respect to the Purchase and Sale Agreement, dated as of November 17, 2014 (the “FW Purchase Agreement”) between, among others, SunEdison, TerraForm Power and Terra LLC and the First Wind Sellers. The amended complaint alleges that Terra LLC and SunEdison became jointly obligated to make $231.0 million in earn-out payments in respect of certain development assets SunEdison acquired from the First Wind Sellers under the FW Purchase Agreement, when those payments were purportedly accelerated by SunEdison's bankruptcy and by the resignations of two SunEdison employees. The amended complaint further alleges that TerraForm Power, as guarantor of certain Terra LLC obligations under the FW Purchase Agreement, is liable for this sum. The defendants filed a motion to dismiss the amended complaint on July 5, 2016, on the ground that, among other things, SunEdison is a necessary party to this action. The plaintiffs filed an opposition to the motion to dismiss on August 22, 2016. The defendants filed their reply on September 12, 2016. A hearing on the motion to dismiss took place on January 24, 2017. On February 6, 2018, the court denied the Company’s motion to dismiss, and discovery is proceeding in the case. The Company cannot predict the impact on this litigation of any information that may become available in discovery. The Company has agreed to issue additional shares of Class A common stock to Orion Holdings for no additional consideration in respect of the Company’s net losses, such as out-of-pocket losses, damages, costs, fees and expenses, upon the final resolution of the litigation brought by the First Wind Sellers described above. The number of additional shares of Class A common stock to be issued to Orion Holdings is subject to a pre-determined formula as set forth in the Merger Agreement as described in greater detail in the Company’s Definitive Proxy Statement filed on Schedule 14A with the SEC on September 6, 2017. As of the date hereof, the Company is unable to predict the quantum of any net losses arising from the litigation brought by the First Wind Sellers described above or the number of additional shares, if any, that may be required to be issued to Orion Holdings pursuant to the terms of the Merger Agreement in connection with any such final resolution. The issuance of additional shares to Orion Holdings would dilute the holdings of the Company's common stockholders and may negatively affect the value of the Company's common stock. The Company believes the First Wind Sellers’ allegation is without merit and will contest the claim and allegations vigorously. However, the Company cannot predict with certainty the ultimate resolution of any proceedings brought in connection with such a claim. Whistleblower Complaint By Francisco Perez Gundin On May 18, 2016, the Company’s former Director and Chief Operating Officer, Francisco Perez Gundin (“Perez”), filed a complaint against the Company, TerraForm Global, Inc. and certain individuals, with the United States Department of Labor. The complaint alleges that the defendants engaged in a retaliatory termination of Mr. Perez's employment after he allegedly voiced concerns to SunEdison’s Board of Directors about public representations made by SunEdison officers regarding SunEdison’s liquidity position, and after he allegedly voiced his opposition to transactions that he alleges were self-interested and which he alleges SunEdison forced on the Company. He alleges that the Company participated in SunEdison’s retaliatory termination by constructively terminating his position as Chief Operating Officer of the Company in connection with SunEdison’s constructive termination of his employment. He seeks lost wages, bonuses, benefits, and other money that he alleges that he would have received if he had not been subjected to the allegedly retaliatory termination. The Company's Position Statement in response to the complaint was filed in October of 2016. On February 21, 2017, Mr. Perez filed Gundin v. TerraForm Global, Inc. et al. against TerraForm Power, TerraForm Global, Inc. and certain individuals as defendants in the United States District Court for the District of Maryland. The complaint asserts claims for retaliation, breach of the implied covenant of good faith and fair dealing and promissory estoppel based on the same allegation in Mr. Perez's Department of Labor complaint. On March 15, 2017, the Company filed notice with the Judicial Panel on Multidistrict Litigation to transfer this action to the Southern District of New York where the Chamblee Class Action was tried and other cases not involving the Company relating to the SunEdison bankruptcy are being tried. The plaintiff did not oppose the transfer, which was approved by the Judicial Panel on Multidistrict Litigation. On November 6, 2017, TerraForm Power and the other defendants filed a motion to dismiss Mr. Perez's complaint, and Mr. Perez filed a response on December 21, 2017. On March 8, 2018, Mr. Perez voluntarily dismissed the federal action without prejudice, which would permit the action to be refiled. The proceeding before the Department of Labor has not been dismissed. The Company has agreed to issue additional shares of Class A common stock to Orion Holdings for no additional consideration in respect of the Company’s net losses, such as out-of-pocket losses, damages, costs, fees and expenses, upon the final resolution of the litigation brought by Mr. Perez described above. The number of additional shares of Class A common stock to be issued to Orion Holdings is subject to a pre-determined formula as set forth in the Merger Agreement as described in greater detail in the Company’s Definitive Proxy Statement filed on Schedule 14A with the SEC on September 6, 2017. As of the date hereof, the Company is unable to predict the quantum of any net losses arising from the litigation brought by Mr. Perez described above or the number of additional shares, if any, that may be required to be issued to Orion Holdings pursuant to the terms of the Merger Agreement in connection with any such final resolution. The issuance of additional shares to Orion Holdings would dilute the holdings of the Company's common stockholders and may negatively affect the value of the Company's common stock. The Company reserved for its estimated loss related to this complaint in 2016, which was not considered material to the Company's consolidated results of operations, and this amount remains accrued as of March 31, 2018. However, the Company is unable to predict with certainty the ultimate resolution of these proceedings. Whistleblower Complaint By Carlos Domenech Zornoza On May 10, 2016, the Company’s former Director and Chief Executive Officer, Carlos Domenech Zornoza (“Domenech”), filed a complaint against the Company, TerraForm Global, Inc. and certain individuals, with the United States Department of Labor. The complaint alleges that the defendants engaged in a retaliatory termination of Mr. Domenech’s employment on November 20, 2015 after he allegedly voiced concerns to SunEdison’s Board of Directors about public representations made by SunEdison officers regarding SunEdison’s liquidity position, and after he allegedly voiced his opposition to transactions that he alleges were self-interested and which he alleges SunEdison forced on the Company. He alleges that the Company participated in SunEdison’s retaliatory termination by terminating his position as Chief Executive Officer of the Company in connection with SunEdison’s termination of his employment. He seeks lost wages, bonuses, benefits, and other money that he alleges that he would have received if he had not been subjected to the allegedly retaliatory termination. The Company's Position Statement in response to the complaint was filed in October of 2016. On February 21, 2017, Mr. Domenech filed Domenech Zornoza v. TerraForm Global, Inc. et. al against TerraForm Power, TerraForm Global, Inc. and certain individuals as defendants in the United States District Court for the District of Maryland. The complaint asserts claims for retaliation, breach of the implied covenant of good faith and fair dealing and promissory estoppel based on the same allegations in Mr. Domenech's Department of Labor complaint. On March 15, 2017, the Company filed notice with the Judicial Panel on Multidistrict Litigation to transfer this action to the Southern District of New York where the Chamblee Class Action was tried and other cases not involving the Company relating to the SunEdison bankruptcy are being tried. The plaintiff opposed the transfer. However, the transfer was approved by the Judicial Panel on Multidistrict Litigation. On November 6, 2017, TerraForm Power and the other defendants filed a motion to dismiss Mr. Domenech's complaint, and Mr. Domenech filed a response on December 21, 2017. On March 8, 2018, Mr. Domenech voluntarily dismissed the federal action without prejudice, which would permit the action to be refiled. The proceeding before the Department of Labor has not been dismissed. The Company has agreed to issue additional shares of Class A common stock to Orion Holdings for no additional consideration in respect of the Company’s net losses, such as out-of-pocket losses, damages, costs, fees and expenses, upon the final resolution of the litigation brought by Mr. Domenech described above. The number of additional shares of Class A common stock to be issued to Orion Holdings is subject to a pre-determined formula as set forth in the Merger Agreement as described in greater detail in the Company’s Definitive Proxy Statement filed on Schedule 14A with the SEC on September 6, 2017. As of the date hereof, the Company is unable to predict the quantum of any net losses arising from the litigation brought by Mr. Domenech described above or the number of additional shares, if any, that may be required to be issued to Orion Holdings pursuant to the terms of the Merger Agreement in connection with any such final resolution. The issuance of additional shares to Orion Holdings would dilute the holdings of the Company's common stockholders and may negatively affect the value of the Company's common stock. The Company reserved for its estimated loss related to this complaint in 2016, which was not considered material to the Company's consolidated results of operations, and this amount remains accrued as of March 31, 2018. However, the Company is unable to predict with certainty the ultimate resolution of these proceedings.

Related Parties

Related Parties	3 Months Ended
	Mar. 31, 2017
Related Party Transactions [Abstract]
Related Parties	RELATED PARTIES As discussed in Note 1. Nature of Operations and Basis of Presentation , prior to the consummation of the Merger, TerraForm Power was a controlled affiliate of SunEdison, Inc. As a result of the consummation of the Merger on October 16, 2017, a change of control of TerraForm Power occurred, and Orion Holdings, which is an affiliate of Brookfield, now holds 51% of the voting securities of TerraForm Power. As a result of the Merger closing, TerraForm Power is no longer a controlled affiliate of SunEdison, Inc. and is now a controlled affiliate of Brookfield. At or prior to the effective time of the Merger, the Company and Orion Holdings (or one of its affiliates), among other parties, entered into a suite of agreements providing for sponsorship arrangements. These include the agreements discussed below, as well as a governance agreement that established certain rights and obligations of the Company and controlled affiliates of Brookfield that own voting securities of the Company relating to the governance of the Company and a registration rights agreement that governs Orion Holdings’ and the Company’s rights and obligations with respect to the registration for resale of all or a part of the Class A shares that Orion Holdings now holds following the Merger. As discussed in Note 13. Commitments and Contingencies , as part of the Merger, the Company also agreed to issue shares of Class A common stock to Orion Holdings in connection with the final resolution of certain litigation matters described above. Brookfield Master Services Agreement In connection with the consummation of the Merger, the Company entered into a master services agreement (the “Brookfield MSA”) with Brookfield and certain affiliates of Brookfield (collectively, the “MSA Providers”) pursuant to which the MSA Providers provide certain management and administrative services to the Company, including the provision of strategic and investment management services. As consideration for the services provided or arranged for by Brookfield and certain of its affiliates pursuant to this agreement, the Company pays a base management fee on a quarterly basis, paid in arrears. Pursuant to the Brookfield MSA, the Company recorded a $3.3 million charge within general and administrative expenses - affiliate in the unaudited condensed consolidated statement of operations for the three months ended March 31, 2018 with an offsetting payable within due to affiliates in the unaudited condensed consolidated balance sheet as of March 31, 2018 . Relationship Agreement In connection with the consummation of the Merger, the Company entered into a relationship agreement (the “Relationship Agreement”) with Brookfield, which governs certain aspects of the relationship between Brookfield and the Company. Pursuant to the Relationship Agreement, Brookfield agrees that the Company will serve as the primary vehicle through which Brookfield and certain of its affiliates will own operating wind and solar assets in North America and Western Europe and that Brookfield will provide, subject to certain terms and conditions, the Company with a right of first offer on certain operating wind and solar assets that are located in such countries and developed by persons sponsored by or under the control of Brookfield. The Company did not acquire any renewable energy facilities from Brookfield during the three months ended March 31, 2018 . New Terra LLC Agreement SunEdison transferred all of the outstanding IDRs of Terra LLC held by SunEdison or certain of its affiliates to Brookfield IDR Holder at the effective time of the Merger, and the Company and Brookfield IDR Holder entered into an amended and restated limited liability company agreement of Terra LLC (the “New Terra LLC Agreement”). The New Terra LLC Agreement, among other things, reset the IDR thresholds of Terra LLC to establish a first distribution threshold of $0.93 per share of Class A common stock and a second distribution threshold of $1.05 per share of Class A common stock. There were no payments of IDRs made by the Company pursuant to the New Terra LLC Agreement during the three months ended March 31, 2018 , and there were no payments of IDRs made by the Company during the three months ended March 31, 2017 pursuant to the Terra LLC agreement existing as of that time. Due from affiliates As of March 31, 2018, the $4.9 million due from affiliates amount reported in the unaudited condensed consolidated balance sheet represents: (i) a $1.2 million receivable from TerraForm Global, Inc. as a result of payments made by the Company on its behalf regarding rent for its shared corporate headquarters, compensation for certain employees that provided services to both companies and certain information technology services; and (ii) a $3.7 million receivable from Brookfield and certain of its affiliates for the settlement of claims relating to certain transactions under Section 16(b) of the Exchange Act, which was received in April of 2018. The Company recognized the net proceeds of $3.0 million as a capital contribution from a stockholder and recorded it as an increase to additional paid-in capital, which is reflected within the other line in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018. As of December 31, 2017, the $4.4 million due from affiliates amount represented a receivable from TerraForm Global, Inc. as a result of payments made by the Company on its behalf regarding the aforementioned items, of which $3.5 million was received in the first quarter of 2018. There was no right of set-off with respect to these receivables and the payables to the other Brookfield affiliates described below, and thus these amounts were separately reported in due from affiliates in the unaudited condensed consolidated balance sheet at the respective periods. Due to affiliates The $3.4 million due to affiliates amount reported in the unaudited condensed consolidated balance sheet as of March 31, 2018 primarily represents a payable to an affiliate of Brookfield for the Brookfield MSA quarterly base management fee as discussed above. As of December 31, 2017, the $4.0 million due to affiliates amount represented a $3.4 million payable for the Brookfield MSA quarterly base management fee and $0.6 million of accrued standby fee interest that was payable to a Brookfield affiliate under the credit agreement that TerraForm Power entered into with Brookfield and one of its affiliates on October 16, 2017, which established a $500.0 million secured revolving credit facility (the “Sponsor Line Agreement”). As of the date hereof, there have been no amounts drawn under the Sponsor Line Agreement. These payables were paid in the first quarter of 2018, as well as $0.6 million of additional standby fee interest incurred in the first quarter. Saeta Yield Acquisition-Related Agreements with Brookfield On February 6, 2018, the Company entered into a support agreement with Brookfield. Pursuant to this agreement and in connection with the intended financing for the Company’s recently launched Tender Offer for the outstanding shares of Saeta Yield that is expected to close by mid-summer of 2018, Brookfield agreed that, if requested by the Company, Brookfield would provide a back-stop to the Company for up to $400.0 million of the expected Equity Offering discussed in Note 4. Acquisitions (such agreement, the “Back-Stop”) if the offering price per Class A share of the Company in the Equity Offering equals the five-day volume weighted average price of the Class A shares ending the trading day prior to the Company’s announcement of the Tender Offer, which was $10.66 per share. Brookfield’s obligations in relation to the provision of the Back-Stop under the support agreement are subject to successful commencement of the Tender Offer and to prior effectiveness of a registration statement, if required, that the Company would file in connection with the Equity Offering and such obligation would not apply to any Equity Offering commenced prior to May 1, 2018 or after September 30, 2018. Brookfield provided credit support to the Company in connection with the Bank Guarantee, and the Company agreed to pay a fee to Brookfield equal to 50% of the savings realized by the Company as a result of Brookfield’s provision of credit support, up to a maximum of $3.0 million . Historical SunEdison Services As discussed above, the Company was a controlled affiliate of SunEdison, Inc. during the three months ended March 31, 2017 and certain services were provided by SunEdison during that period. Cost of operations - affiliate was $5.6 million for the three months ended March 31, 2017, which represented costs incurred for O&M and asset management services that were provided to the Company by SunEdison pursuant to contractual agreements and certain project-level transition services agreements. General and administrative expenses - affiliate was $1.4 million for the three months ended March 31, 2017, which consisted of $1.0 million of stock-based compensation expense that was allocated to the Company regarding equity awards in the stock of SunEdison, Inc. and TerraForm Global, Inc. (a controlled affiliate of SunEdison, Inc. at that time) that were awarded to the Company’s employees and $0.4 million of costs incurred for certain management and administrative services that were provided by SunEdison. During the first quarter of 2017, the Company received $7.0 million from SunEdison in satisfaction of outstanding claims made under engineering, procurement and construction contracts (“EPC”), of which $4.8 million related to the Company's renewable energy facility located in Chile and compensated the relevant project company as the facility's performance during the warranty period was below that guaranteed by an affiliate of SunEdison under the applicable EPC contract.

Segment Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Segment Reporting	SEGMENT REPORTING The Company has two reportable segments: Solar and Wind. These segments comprise the Company’s entire portfolio of renewable energy facility assets and are determined based on the management approach. This approach designates the internal reporting used by management for making decisions and assessing performance as the source of the reportable segments. The Company’s operating segments consist of Distributed Generation, North America Utility and International Utility that are aggregated into the Solar reportable segment and Northeast Wind, Central Wind and Hawaii Wind that are aggregated into the Wind reportable segment. The operating segments have been aggregated as they have similar economic characteristics and meet all of the aggregation criteria. Corporate expenses include general and administrative expenses, acquisition costs, interest expense on corporate-level indebtedness, stock-based compensation and depreciation, accretion and amortization expense. All net operating revenues for the three months ended March 31, 2018 and 2017 were earned by the Company’s reportable segments from external customers in the United States (including Puerto Rico), Canada, the United Kingdom and Chile. The following table reflects summarized financial information concerning the Company’s reportable segments for the three months ended March 31, 2018 and 2017 : Three Months Ended March 31, 2018 (In thousands) Solar Wind Corporate Total Operating revenues, net $ 59,723 $ 67,824 $ — $ 127,547 Depreciation, accretion and amortization expense 27,601 37,665 324 65,590 Impairment of renewable energy facilities 15,240 — — 15,240 Other operating costs and expenses 14,216 25,814 28,736 68,766 Interest expense, net 14,522 10,769 28,263 53,554 Other non-operating expenses, net — 853 887 1,740 Income tax benefit 1 — — (976 ) (976 ) Net loss $ (11,856 ) $ (7,277 ) $ (57,234 ) $ (76,367 ) Balance Sheet Total assets 2 $ 2,813,878 $ 3,342,181 $ 102,722 $ 6,258,781 Three Months Ended March 31, 2017 (In thousands) Solar Wind Corporate Total Operating revenues, net $ 66,001 $ 85,134 $ — $ 151,135 Depreciation, accretion and amortization expense 26,775 33,451 761 60,987 Other operating costs and expenses 13,908 25,161 39,011 78,080 Interest expense, net 19,581 20,899 27,832 68,312 Other non-operating (income) expenses, net (42 ) 548 441 947 Income tax benefit 1 — — (918 ) (918 ) Net income (loss) $ 5,779 $ 5,075 $ (67,127 ) $ (56,273 ) Balance Sheet Total assets 2 $ 2,897,036 $ 3,400,858 $ 89,127 $ 6,387,021 ——— (1) Income tax benefit is not allocated to the Company’s Solar and Wind segments. (2) Represents total assets as of March 31, 2018 and December 31, 2017 , respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Accumulated Other Comprehensive Income	ACCUMULATED OTHER COMPREHENSIVE INCOME The following tables present the changes in each component of accumulated other comprehensive income, net of tax: (In thousands) Foreign Currency Translation Adjustments Hedging Activities 1 Accumulated Other Comprehensive Income Balance as of December 31, 2016 $ (22,133 ) $ 45,045 $ 22,912 Net unrealized gain arising during the period (net of zero and $5,836 tax expense, respectively) 2,680 14,054 16,734 Reclassification of net realized gain into earnings (net of zero tax impact) — (386 ) (386 ) Other comprehensive income 2,680 13,668 16,348 Accumulated other comprehensive (loss) income (19,453 ) 58,713 39,260 Less: Other comprehensive income attributable to non-controlling interests 918 5,972 6,890 Balance as of March 31, 2017 $ (20,371 ) $ 52,741 $ 32,370 (In thousands) Foreign Currency Translation Adjustments Hedging Activities 1 Accumulated Other Comprehensive Income Balance as of December 31, 2017 $ (13,412 ) $ 61,430 $ 48,018 Cumulative-effect adjustment (net of tax expense of $1,579) 2 — (4,164 ) (4,164 ) Other comprehensive loss: Net unrealized loss arising during the period (net of zero tax impact) (3,283 ) (10,492 ) (13,775 ) Reclassification of net realized gain into earnings (net of zero tax impact) — (962 ) (962 ) Other comprehensive loss (3,283 ) (11,454 ) (14,737 ) Accumulated other comprehensive (loss) income (16,695 ) 45,812 29,117 Less: Other comprehensive loss attributable to non-controlling interests — (1,243 ) (1,243 ) Balance as of March 31, 2018 $ (16,695 ) $ 47,055 $ 30,360 ——— (1) See Note 10 . Derivatives for further breakout of hedging gains and losses between interest rate swaps and commodity contracts. (2) See Note 2. Summary of Significant Accounting Policies for discussion regarding the Company’s adoption of ASU No. 2017-12 as of January 1, 2018.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS On April 30, 2018, the Board of Directors declared a second-quarter 2018 dividend with respect to Class A common stock of $0.19 per share. The dividend is payable on June 15, 2018 to shareholders of record as of June 1, 2018. Information regarding certain other subsequent events have been included within the applicable notes to the Company’s unaudited condensed consolidated financial statements.

Nature of Operations and Basi26

Nature of Operations and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations On October 16, 2017, BRE TERP Holdings Inc., a wholly-owned subsidiary of Orion US Holdings 1 L.P. (“Orion Holdings”), merged with and into TerraForm Power, Inc. (“TerraForm Power”), with TerraForm Power continuing as the surviving corporation (the “Merger”). Prior to the consummation of the Merger, TerraForm Power and its subsidiaries (together, the “Company”) were controlled affiliates of SunEdison, Inc. (together with its consolidated subsidiaries excluding the Company and TerraForm Global, Inc. and its subsidiaries, “SunEdison”). As a result of the consummation of the Merger, a change of control of TerraForm Power occurred, and Orion Holdings, which is a controlled affiliate of Brookfield Asset Management Inc. (“Brookfield”), now holds 51% of the voting securities of TerraForm Power. As a result of the Merger closing, TerraForm Power is no longer a controlled affiliate of SunEdison, Inc. and is now a controlled affiliate of Brookfield. TerraForm Power is a holding company and its only material asset is an equity interest in TerraForm Power, LLC (“Terra LLC”), which through its subsidiaries owns and operates renewable energy facilities that have long-term contractual arrangements to sell the electricity generated by these facilities to third parties. The related green energy certificates, ancillary services and other environmental attributes generated by these facilities are also sold to third parties. TerraForm Power is the managing member of Terra LLC and operates, controls and consolidates the business affairs of Terra LLC. The Company is sponsored by Brookfield and has an objective to acquire operating solar and wind assets in North America and Western Europe.
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed 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 and have been prepared in accordance with the SEC regulations for interim financial information. Accordingly, they do not include all of the information and notes required by U.S. generally accepted accounting principles (“U.S. GAAP”) for complete financial statements. The financial statements should be read in conjunction with the accounting policies and other disclosures as set forth in the notes to the Company’s annual financial statements for the year ended December 31, 2017 , filed with the SEC on Form 10-K on March 7, 2018. Interim results are not necessarily indicative of results for a full year. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Company's financial position as of March 31, 2018 and the results of operations, comprehensive income (loss) and cash flows for the three months ended March 31, 2018 and 2017 .
Use of Estimates	Use of Estimates In preparing the unaudited condensed consolidated financial statements, the Company used estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements. Such estimates also affect the reported amounts of revenues, expenses and cash flows during the reporting period. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations would be affected.
Reclassification	Reclassification The Company adopted the provisions of Accounting Standards Update (“ASU”) No. 2016-18 , Statement of Cash Flows (Topic 230), Restricted Cash during the second quarter of 2017, which requires retrospective application, and has revised its unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2017 to include amounts generally described as restricted cash and restricted cash equivalents with cash and cash equivalents in the reconciliation of the beginning-of-period and end-of-period total amounts shown in the statement. Cash flows from investing activities for the three months ended March 31, 2017 decreased by $32.7 million as a result of the adoption of this standard. Further, the Company had $21.3 million of restricted cash classified within assets held for sale as of March 31, 2017, with $54.8 million classified within assets held for sale as of December 31, 2016, and thus had to add the change in this reclassification amount to the net change in cash, cash equivalents and restricted cash classified within assets held for sale line reported in the unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2017 to reconcile the change in the beginning and end-of-period cash, cash equivalents and restricted cash. The effect of exchange rate changes on cash and cash equivalents line was also revised to include the effect of exchange rate changes on restricted cash.
Cash and Cash Equivalents and Restricted Cash	Restricted cash consists of cash on deposit in financial institutions that is restricted to satisfy the requirements of certain debt agreements and funds held within the Company's project companies that are restricted for current debt service payments and other purposes in accordance with the applicable debt agreements. These restrictions include: (i) cash on deposit in collateral accounts, debt service reserve accounts and maintenance reserve accounts; and (ii) cash on deposit in operating accounts but subject to distribution restrictions related to debt defaults existing as of the balance sheet date. As discussed in Note 8 . Long-term Debt , the Company was in default under certain of its non-recourse financing agreements as of the financial statement issuance date for the three months ended March 31, 2018 and for the year ended December 31, 2017. As a result, the Company reclassified $13.9 million and $18.8 million of non-current restricted cash to current as of March 31, 2018 and December 31, 2017, respectively, consistent with the corresponding debt classification, as the restrictions that required the cash balances to be classified as non-current restricted cash were driven by the financing agreements. As of March 31, 2018 and December 31, 2017, $20.5 million and $21.7 million , respectively, of cash and cash equivalents was also reclassified to current restricted cash as the cash balances were subject to distribution restrictions related to debt defaults that existed as of the respective balance sheet date.
Non-controlling Interests - Impact of the Tax Cuts and Jobs Act Enactment	Non-controlling Interests - Impact of the Tax Cuts and Jobs Act Enactment On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”), which enacted major changes to the U.S. tax code, including a reduction in the U.S. federal corporate income tax rate from 35% to 21% , effective January 1, 2018. Since the 21% rate enacted in December 2017 went into effect on January 1, 2018, the hypothetical liquidation at book value (“HLBV”) methodology utilized by the Company to determine the value of its non-controlling interests began to use the new rate on that date. The HLBV method is a point in time estimate that utilizes inputs and assumptions in effect at each balance sheet date based on the liquidation provisions of the respective operating partnership agreements. During the first quarter of 2018, $151.2 million of the decline in the non-controlling interests balance and a corresponding allocation of net loss attributable to non-controlling interests was driven by this reduction in the tax rate used in the HLBV methodology used by the Company. In the calculation of the carrying values through HLBV, the Company allocated significantly lower amounts to certain non-controlling interests (i.e., tax equity investors) in order to achieve their contracted after-tax rate of return as a result of the reduction of the federal income tax rate from 35% to 21% as specified in the Tax Act.
Restructuring	Restructuring In connection with the consummation of the Merger and the expected relocation of the headquarters of the Company to New York, New York, the Company announced a restructuring plan that went into effect upon the closing of the Merger, which is expected to be completed early in the third quarter of 2018. The Company recognized $1.3 million of additional severance and transition bonus costs in the first quarter of 2018 within general and administrative expenses in the unaudited condensed consolidated statement of operations. The Company made $0.8 million of payments related to this restructuring in the first quarter of 2018. The balance of the accrued severance and transition bonuses was $3.2 million as of March 31, 2018.
Recent Accounting Developments	Recently Adopted Accounting Standards - Guidance Adopted in 2018 In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) , which replaces most existing revenue recognition guidance in U.S. GAAP and requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. Additionally, the new standard requires an 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 No. 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 No. 2014-09. The Company adopted these standards as of January 1, 2018, which it collectively refers to as “Topic 606.” The Company analyzed the impact of Topic 606 on its revenue contracts which primarily include bundled energy and incentive sales through power purchase agreements (“PPAs”), individual renewable energy certificate (“REC”) sales, and upfront sales of federal & state incentive benefits recorded as deferred revenue and accreted into revenue. The Company elected to apply a modified retrospective approach with a cumulative-effect adjustment to accumulated deficit recognized as of January 1, 2018 for changes to revenue recognition resulting from Topic 606 adoption as described below. The Company adopted Topic 606 for all revenue contracts in-scope that had future performance obligations at January 1, 2018, and elected to use the contract modification practical expedient for purposes of computing the cumulative transition adjustment. See Note 3. Revenue for additional disclosures required by the new guidance. The Company accounts for the majority of its PPAs as operating leases under ASC 840, Leases and recognizes rental income as revenue when the electricity is delivered. The Company elected not to early adopt ASC 842, Leases in fiscal 2018 and therefore these PPAs are currently being evaluated in anticipation of the new lease standard adoption in fiscal 2019. For PPAs under the scope of Topic 606 in fiscal 2018, the Company concluded that there were no material changes to revenue recognition patterns from existing accounting practice. See Note 3. Revenue for the new revenue recognition policy. The Company evaluated the impact of Topic 606 as it relates to the individual sale of RECs. In certain jurisdictions, there may be a lag between physical generation of the underlying energy and the transfer of RECs to the customer due to administrative processes imposed by state regulations. Under the Company’s previous accounting policy, revenue was recognized as the underlying electricity was generated if the sale had been contracted with the customer. Based on the framework in Topic 606, for a portion of the existing individual REC sale arrangements where the transfer of control to the customer is determined to occur upon the transfer of the RECs, the Company now recognizes revenue commensurate with the transfer of RECs to the customer as compared to the generation of the underlying energy under the previous accounting policy. Revenue recognition practices for the remainder of existing individual REC sale arrangements remain the same; that is, revenue is recognized based on the underlying generation of energy because the contracted RECs are produced from a designated facility and control of the RECs transfers to the customer upon generation of the underlying energy. The adoption of Topic 606, as it relates to the individual sale of RECs, resulted in an increase in accumulated deficit on January 1, 2018 of $20.5 million , net of tax, and net of $0.3 million and $4.5 million that was allocated to non-controlling interests and redeemable non-controlling interests, respectively. The adjustments for accumulated deficit and non-controlling interests are reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018 and the redeemable non-controlling interests adjustment is reflected within cumulative-effect adjustment in the redeemable non-controlling interests roll-forward presented above. The impact on the Company’s results of operations for the first quarter of 2018 was minimal and is expected to be minimal for the remainder of 2018. The Company evaluated the impact of Topic 606 as it relates to the upfront sale of investment tax credits (“ITCs”) through its lease pass-through fund arrangements. The amounts allocated to the ITCs were initially recorded as deferred revenue in the consolidated balance sheet, and subsequently, one-fifth of the amounts allocated to the ITCs was recognized annually as incentives revenue in the consolidated statement of operations based on the anniversary of each solar energy system’s placed-in-service date. The Company concluded that revenue related to the sale of ITCs through its lease pass-through arrangements should be recognized at the point in time when the related solar energy systems are placed in service. Previously, the Company recognized this revenue evenly over the five -year ITC recapture period. The Company concluded that the likelihood of a recapture event related to these assessments is remote. The adoption of Topic 606, as it relates to the upfront sale of ITCs, resulted in a decrease in accumulated deficit on January 1, 2018 of $40.9 million , net of tax, which is reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018. The impact on the Company’s results of operations for the first quarter of 2018 resulted in a decrease in non-cash deferred revenue recognition of $3.5 million and is expected to result in a decrease in non-cash deferred revenue recognition of approximately $12.8 million for the remaining nine months of 2018. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230), Classification of Certain Cash Receipts and Cash Payments . The amendments of ASU No. 2016-15 were issued to address eight specific cash flow issues for which stakeholders have indicated to the FASB that a diversity in practice existed in how entities were presenting and classifying these items in the statement of cash flows. The issues addressed by ASU No. 2016-15 include but are not limited to the classification of debt prepayment and debt extinguishment costs, payments made for contingent consideration for a business combination, proceeds from the settlement of insurance proceeds, distributions received from equity method investees and separately identifiable cash flows and the application of the predominance principle. The adoption of ASU No. 2016-15 is required to be applied retrospectively. The Company adopted ASU No. 2016-15 as of January 1, 2018, which did not result in any material adjustments to the Company’s consolidated statements of cash flows. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740), Intra-Entity Transfers of Assets Other Than Inventory . The amendments of ASU No. 2016-16 were issued to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. Previous GAAP prohibited the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset had been sold to an outside party which resulted in diversity in practice and increased complexity within financial reporting. The amendments of ASU No. 2016-16 require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs and do not require new disclosure requirements. The adoption of ASU No. 2016-16 should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The adoption of ASU No. 2016-16 as of January 1, 2018 did not have an impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805), Clarifying the Definition of a Business . The amendment seeks to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. The amendments should be applied prospectively on or after the effective dates. Accordingly, the Company’s adoption of ASU No. 2017-01 as of January 1, 2018 did not have an impact on the Company’s historical financial statements. The Company did not consummate any acquisitions in the first quarter of 2018 but will apply this standard in the future should it consummate any acquisitions. In February 2017, the FASB issued ASU No. 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets . This ASU is meant to clarify the scope of ASC Subtopic 610-20, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets and to add guidance for partial sales of nonfinancial assets. ASU No. 2017-05 is to be applied using a full retrospective method or a modified retrospective method as outlined in the guidance. The adoption of ASU No. 2017-05 as of January 1, 2018 did not have an impact on the Company’s consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting . The amendment clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. The new guidance is expected to reduce diversity in practice and result in fewer changes to the terms of an award being accounted for as a modification. Changes to the terms or conditions of a share-based payment award that do not impact the fair value of the award, vesting conditions and the classification as an equity or liability instrument will not need to be assessed under modification accounting. The amendments in this update should be applied prospectively to an award modified on or after the adoption date. Accordingly, the Company’s adoption of ASU No. 2017-09 as of January 1, 2018 did not have an impact on the Company’s historical financial statements. The Company did not have any unvested share-based payment awards outstanding during the first quarter of 2018 but will apply the impact of this standard in the future should it change the terms or conditions of any share-based payment awards. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . This ASU amends the hedge accounting model to enable entities to better portray the economics of their risk management activities in the financial statements and simplifies the application of hedge accounting in certain situations. ASU No. 2017-12 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2018, with early adoption permitted. ASU 2017-12 requires a modified retrospective transition method in which the Company recognizes the cumulative effect of the change on the opening balance of each affected component of equity as of the date of adoption. The Company adopted ASU 2017-12 on March 26, 2018 with the adoption impact reflected on a modified retrospective basis as of January 1, 2018, which resulted in the following primary changes: • The ineffective hedging portion of derivatives designated as hedging instruments is no longer required to be measured, recognized or reported. Alternatively, the entire change in the fair value of the designated hedging instrument is recorded in accumulated other comprehensive income (“OCI”); • The Company will perform ongoing prospective and retrospective hedge effectiveness assessments qualitatively after performing the initial test of hedge effectiveness on a quantitative basis and only to the extent that an expectation of high effectiveness can be supported on a qualitative basis in subsequent periods; • For derivatives with periodic cash settlements and a non-zero fair value at hedge inception, the accumulated gains or losses recorded in accumulated OCI in a qualifying cash flow hedging relationship are reclassified to earnings on a systematic and rational basis over the hedge term; and • For derivatives with components excluded from the assessment of hedge effectiveness, the accumulated gains or losses recorded in accumulated OCI on such excluded components in a qualifying cash flow hedging relationship are reclassified to earnings on a systematic and rational basis over the hedge term. The adoption of ASU 2017-12 resulted in a cumulative-effect adjustment of $4.2 million , net of tax of $1.6 million , representing a decrease in accumulated deficit and accumulated OCI, which is reflected within cumulative-effect adjustment in the unaudited condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2018. In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740) – Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 . The ASU added seven paragraphs to ASC 740, Income Taxes , that contain SEC guidance related to the application of U.S. GAAP when preparing an initial accounting of the income tax effects of the Tax Act which, among other things, allows for a measurement period not to exceed one year for companies to finalize the provisional amounts recorded as of December 31, 2017. The ASU was effective upon issuance. See Note 9. Income Taxes for disclosures on the Company’s accounting for the Tax Act. Recently Issued Accounting Standards Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , which primarily changes the lessee’s accounting for operating leases by requiring recognition of lease right-of-use assets and lease liabilities. The Company expects to adopt the standard on January 1, 2019. The issued guidance requires a modified retrospective transition approach, which requires entities to recognize and measure leases at the beginning of the earliest period presented. In January 2018, the FASB proposed amending the standard to give entities another option for transition. The proposed transition method would allow entities to initially apply the requirements of the standard in the period of adoption (January 1, 2019). The Company will assess this transition option if the FASB issues the revised standard. The Company expects to elect certain of the practical expedients permitted in the issued standard, including the expedient that permits the Company to retain its existing lease assessment and classification. In January 2018, the FASB issued additional guidance which provides another optional transition practical expedient that allows entities to not evaluate existing and expired land easements under the new guidance at adoption if they were not previously accounted for as leases. The Company is currently working through an adoption plan which includes the evaluation of lease contracts compared to the new standard. While the Company is currently evaluating the impact the new guidance will have on its financial position and results of operations, the Company expects to recognize lease liabilities and right of use assets. The extent of the increase to assets and liabilities associated with these amounts remains to be determined pending the Company’s review of its existing lease contracts which may contain embedded leases. In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment . The amendment simplifies the accounting for goodwill impairment by removing Step 2 of the current test, which requires calculation of a hypothetical purchase price allocation. Under the revised guidance, goodwill impairment will be measured as the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill (currently Step 1 of the two-step impairment test). Entities will continue to have the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. The standard is effective January 1, 2020, with early adoption permitted, and must be adopted on a prospective basis. This updated guidance is not currently expected to impact the Company’s financial reporting as the Company does not have any goodwill. The Company will evaluate the impact of this standard in the future should it consummate any acquisition that results in the recognition of goodwill. In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income to help entities address certain stranded income tax effects in accumulated OCI resulting from the U.S. government’s enactment of the Tax Act on December 22, 2017. The amendment provides entities with an option to reclassify stranded tax effects within accumulated OCI to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act (or portion thereof) is recorded. The amendment also includes disclosure requirements regarding the issuer’s accounting policy for releasing income tax effects from accumulated OCI. The optional guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted, and entities should apply the provisions of the amendment either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. The Company is currently evaluating the effect of the new guidance on its consolidated financial statements. In February 2018, the FASB issued ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . This ASU amends and supersedes various paragraphs that contain SEC guidance in ASC 320, Investments - Debt Securities and ASC 980, Regulated Operations . ASU No. 2018-03 is effective for public business entities for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years beginning after June 15, 2018. Public business entities with fiscal years beginning between December 15, 2017 and June 15, 2018 are not required to adopt these amendments until the interim period beginning after June 15, 2018. The Company is currently evaluating the effect of the new guidance on its consolidated financial statements.
Earnings (Loss) Per Share	Basic earnings (loss) per share is computed by dividing net income (loss) attributable to Class A common stockholders by the number of weighted average ordinary shares outstanding during the period, which is the average of shares outstanding and assumed to be outstanding, and includes contingently issuable shares as of the date when the contingent condition has been met. Diluted earnings (loss) per share is computed by adjusting basic earnings (loss) per share for the impact of weighted average dilutive common equivalent shares outstanding during the period, unless the impact is anti-dilutive. Common equivalent shares include the incremental shares issuable for unvested restricted Class A common stock and contingently issuable shares in the period the contingency has been met, for the portion of the period prior to the resolution of such contingent condition.
Segment Reporting	The Company has two reportable segments: Solar and Wind. These segments comprise the Company’s entire portfolio of renewable energy facility assets and are determined based on the management approach. This approach designates the internal reporting used by management for making decisions and assessing performance as the source of the reportable segments. The Company’s operating segments consist of Distributed Generation, North America Utility and International Utility that are aggregated into the Solar reportable segment and Northeast Wind, Central Wind and Hawaii Wind that are aggregated into the Wind reportable segment. The operating segments have been aggregated as they have similar economic characteristics and meet all of the aggregation criteria. Corporate expenses include general and administrative expenses, acquisition costs, interest expense on corporate-level indebtedness, stock-based compensation and depreciation, accretion and amortization expense. All net operating revenues for the three months ended March 31, 2018 and 2017 were earned by the Company’s reportable segments from external customers in the United States (including Puerto Rico), Canada, the United Kingdom and Chile.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Reconciliation of Cash and Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the unaudited condensed consolidated balance sheets to the total of the same such amounts shown in the unaudited condensed consolidated statement of cash flows for the three months ended March 31, 2018. (In thousands) March 31, 2018 December 31, 2017 Cash and cash equivalents $ 157,833 $ 128,087 Restricted cash - current 47,035 54,006 Restricted cash - non-current 48,529 42,694 Cash, cash equivalents and restricted cash shown in the unaudited condensed consolidated statement of cash flows $ 253,397 $ 224,787
Activity of Redeemable Non-controlling Interests	The following table presents the activity of the redeemable non-controlling interests balance for the three months ended March 31, 2018 : Redeemable Non-controlling Interests (In thousands) Capital Retained Earnings Total Balance as of December 31, 2017 $ 22,160 $ 36,180 $ 58,340 Cumulative-effect adjustment 1 — (4,485 ) (4,485 ) Distributions (582 ) — (582 ) Net loss — (2,513 ) (2,513 ) Balance as of March 31, 2018 $ 21,578 $ 29,182 $ 50,760 ——— (1) See discussion below regarding the Company’s adoption of ASU No. 2014-09 and ASU No. 2016-08 as of January 1, 2018.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Impact of Topic 606	Topic 606 Adoption Impact on Unaudited Condensed Consolidated Statement of Operations Three Months Ended March 31, 2018 As Reported Adjustments Amounts excluding Topic 606 Adoption (In thousands) Solar Wind Total REC Sales ITC Sales PPA rental income $ 36,768 $ 52,413 $ 89,181 $ — $ — $ 89,181 Commodity derivatives — 11,007 11,007 — — 11,007 PPA revenue 6,507 6,692 13,199 — — 13,199 Amortization of favorable and unfavorable rate revenue contracts, net (1,977 ) (7,840 ) (9,817 ) — — (9,817 ) Energy revenue 41,298 62,272 103,570 — — 103,570 Incentive revenue 18,425 5,552 23,977 (2,560 ) 3,518 24,935 Operating revenues, net 59,723 67,824 127,547 (2,560 ) 3,518 128,505 Operating costs and expenses 149,596 — — 149,596 Operating loss (22,049 ) (2,560 ) 3,518 (21,091 ) Other expenses, net 55,294 — — 55,294 Loss before income tax benefit (77,343 ) (2,560 ) 3,518 (76,385 ) Income tax benefit (976 ) — — (976 ) Net loss $ (76,367 ) $ (2,560 ) $ 3,518 $ (75,409 ) Topic 606 Adoption Impact on Unaudited Condensed Consolidated Balance Sheet As of March 31, 2018 As Reported Adjustments Amounts excluding Topic 606 Adoption (In thousands) REC Sales ITC Sales Accounts receivable, net $ 70,346 $ 22,715 $ — $ 93,061 Other current assets 253,197 — — 253,197 Total current assets 323,543 22,715 — 346,258 Non-current assets 5,935,238 — — 5,935,238 Total assets $ 6,258,781 $ 22,715 $ — $ 6,281,496 Deferred revenue $ 1,807 $ — $ 16,310 $ 18,117 Other current liabilities 502,464 — — 502,464 Total current liabilities 504,271 — 16,310 520,581 Deferred revenue, less current portion 13,134 — 21,069 34,203 Other non-current liabilities 3,411,266 — — 3,411,266 Total liabilities 3,928,671 — 37,379 3,966,050 Redeemable non-controlling interests and total stockholders' equity 2,330,110 22,715 (37,379 ) 2,315,446 Total liabilities, redeemable non-controlling interests and stockholders' equity $ 6,258,781 $ 22,715 $ — $ 6,281,496

Renewable Energy Facilities (Ta

Renewable Energy Facilities (Tables)	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Renewable Energy Facilities	Renewable energy facilities, net consists of the following: (In thousands) March 31, 2018 December 31, 2017 Renewable energy facilities in service, at cost $ 5,344,488 $ 5,378,462 Less accumulated depreciation - renewable energy facilities (626,766 ) (578,474 ) Renewable energy facilities in service, net 4,717,722 4,799,988 Construction in progress - renewable energy facilities 2,086 1,937 Total renewable energy facilities, net $ 4,719,808 $ 4,801,925

Intangibles (Tables)

Intangibles (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Gross Carrying Amount and Accumulated Amortization of Intangibles	The following table presents the gross carrying amount, accumulated amortization and net book value of intangibles as of March 31, 2018 : (In thousands, except weighted average amortization period) Weighted Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Book Value Favorable rate revenue contracts 15 years $ 713,786 $ (110,230 ) $ 603,556 In-place value of market rate revenue contracts 18 years 520,079 (79,349 ) 440,730 Favorable rate land leases 17 years 15,800 (2,529 ) 13,271 Total intangible assets, net $ 1,249,665 $ (192,108 ) $ 1,057,557 Unfavorable rate revenue contracts 7 years $ 33,686 $ (15,952 ) $ 17,734 Unfavorable rate operations and maintenance contracts 2 years 5,000 (2,865 ) 2,135 Unfavorable rate land lease 15 years 1,000 (176 ) 824 Total intangible liabilities, net 1 $ 39,686 $ (18,993 ) $ 20,693 The following table presents the gross carrying amount, accumulated amortization and net book value of intangibles as of December 31, 2017 : (In thousands, except weighted average amortization period) Weighted Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Book Value Favorable rate revenue contracts 15 years $ 718,639 $ (102,543 ) $ 616,096 In-place value of market rate revenue contracts 19 years 521,323 (73,104 ) 448,219 Favorable rate land leases 17 years 15,800 (2,329 ) 13,471 Total intangible assets, net $ 1,255,762 $ (177,976 ) $ 1,077,786 Unfavorable rate revenue contracts 7 years $ 35,086 $ (16,030 ) $ 19,056 Unfavorable rate operations and maintenance contracts 2 years 5,000 (2,552 ) 2,448 Unfavorable rate land lease 15 years 1,000 (162 ) 838 Total intangible liabilities, net 1 $ 41,086 $ (18,744 ) $ 22,342 ——— (1) The Company’s intangible liabilities are classified within other long-term liabilities in the unaudited condensed consolidated balance sheets.

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Carrying Amounts and Classification of Consolidated VIE's Assets and Liabilities	The carrying amounts and classification of the consolidated VIEs’ assets and liabilities included in the Company’s unaudited condensed consolidated balance sheets are as follows: (In thousands) March 31, 2018 December 31, 2017 Current assets $ 122,410 $ 142,403 Non-current assets 4,100,306 4,155,558 Total assets $ 4,222,716 $ 4,297,961 Current liabilities $ 99,198 $ 119,021 Non-current liabilities 996,712 975,839 Total liabilities $ 1,095,910 $ 1,094,860

Long-term Debt (Tables)

Long-term Debt (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt	Long-term debt consists of the following: (In thousands, except rates) March 31, 2018 December 31, 2017 Interest Type Interest Rate (%) 1 Financing Type Corporate-level long-term debt 2 : Senior Notes due 2023 $ 500,000 $ 500,000 Fixed 4.25 Senior notes Senior Notes due 2025 300,000 300,000 Fixed 6.63 Senior notes Senior Notes due 2028 700,000 700,000 Fixed 5.00 Senior notes Revolver 3 70,000 60,000 Variable 4.86 Revolving loan Term Loan 4 349,125 350,000 Variable 4.63 Term debt Non-recourse long-term debt 5 : Permanent financing 1,602,675 1,616,729 Blended 6 5.72 7 Term debt / Senior notes Financing lease obligations 114,730 115,787 Imputed 5.60 7 Financing lease obligations Total principal due for long-term debt and financing lease obligations 3,636,530 3,642,516 5.33 7 Unamortized discount, net (18,297 ) (19,027 ) Deferred financing costs, net (23,862 ) (24,689 ) Less current portion of long-term debt and financing lease obligations (391,656 ) (403,488 ) Long-term debt and financing lease obligations, less current portion $ 3,202,715 $ 3,195,312 ——— (1) As of March 31, 2018 . (2) Outstanding corporate-level debt represents debt issued by TerraForm Power Operating, LLC (“Terra Operating LLC”) and guaranteed by Terra LLC and certain subsidiaries of Terra Operating LLC other than non-recourse subsidiaries as defined in the relevant debt agreements (with the exception of certain unencumbered non-recourse subsidiaries). (3) On February 6, 2018, Terra Operating LLC elected to increase the total borrowing capacity of its $450.0 million senior secured revolving credit facility (the “Revolver”), available for revolving loans and letters of credit, to $600.0 million . As discussed in Note 4 . Acquisitions , per the terms of the Letter of Credit Facilities the Company entered into in connection with posting the Bank Guarantee for the maximum amount payable in the Tender Offer, the Company is required to maintain a minimum liquidity requirement of $400.0 million under the Revolver. (4) On May 11, 2018, the Company signed a repricing amendment whereby the interest rate on the Term Loan was reduced by 0.75% per annum. (5) Non-recourse debt represents debt issued by subsidiaries with no recourse to TerraForm Power, Terra LLC, Terra Operating LLC or guarantors of the Company’s corporate-level debt, other than limited or capped contingent support obligations, which in aggregate are not considered to be material to the Company’s business and financial condition. In connection with these financings and in the ordinary course of its business, TerraForm Power and its subsidiaries observe formalities and operating procedures to maintain each of their separate existence and can readily identify each of their separate assets and liabilities as separate and distinct from each other. As a result, these subsidiaries are legal entities that are separate and distinct from TerraForm Power, Terra LLC, Terra Operating LLC and the guarantors of the Company’s corporate-level debt. (6) Includes fixed rate debt and variable rate debt. As of March 31, 2018 , 60% of this balance had a fixed interest rate and the remaining 40% of this balance had a variable interest rate. The Company entered into interest rate swap agreements to fix the interest rates of a majority of the variable rate permanent financing non-recourse debt (see Note 10 . Derivatives ). (7) Represents the weighted average interest rate as of March 31, 2018 .
Aggregate Contractual Payments of Long-term Debt	The aggregate contractual principal payments of long-term debt due after March 31, 2018 , including financing lease obligations and excluding amortization of debt discounts, premiums and deferred financing costs, as stated in the financing agreements, are as follows: (In thousands) Remainder of 2018 1 2019 2020 2021 2022 Thereafter Total Maturities of long-term debt 2 $ 162,194 $ 110,248 $ 104,970 $ 108,015 $ 596,658 $ 2,554,445 $ 3,636,530 ——— (1) Includes $70.0 million of Revolver indebtedness, of which the Company repaid $55.0 million with cash on hand in April of 2018. (2) Represents the contractual principal payment due dates for the Company's long-term debt and does not reflect the reclassification of $216.3 million of long-term debt to current as a result of debt defaults under certain of the Company's non-recourse financing arrangements.

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Components of Income Tax Provision	The income tax provision consisted of the following: Three Months Ended March 31, (In thousands, except effective tax rate) 2018 2017 Loss before income tax benefit $ (77,343 ) $ (57,191 ) Income tax benefit (976 ) (918 ) Effective tax rate 1.3 % 1.6 %

Derivatives (Tables)

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Fair Values of Derivative Instruments	As of March 31, 2018 and December 31, 2017 , fair values of the following derivative instruments were included in the balance sheet captions indicated below: Fair Value of Derivative Instruments Derivatives Designated as Hedging Instruments Derivatives Not Designated as Hedging Instruments (In thousands) Interest Rate Swaps Commodity Contracts Interest Rate Swaps Foreign Currency Contracts Commodity Contracts Gross Amounts of Assets/Liabilities Recognized Gross Amounts Offset in Consolidated Balance Sheet Net Amounts in Consolidated Balance Sheet As of March 31, 2018 Prepaid expenses and other current assets $ 392 $ 1,475 $ — $ 1,491 $ 13,595 $ 16,953 $ (1,491 ) $ 15,462 Other assets 9,469 59,065 — — 11,763 80,297 — 80,297 Total assets $ 9,861 $ 60,540 $ — $ 1,491 $ 25,358 $ 97,250 $ (1,491 ) $ 95,759 Accounts payable, accrued expenses and other current liabilities $ 815 $ 392 $ 130 $ 2,640 $ — $ 3,977 $ (1,491 ) $ 2,486 Other long-term liabilities 2,869 — 184 — — 3,053 — 3,053 Total liabilities $ 3,684 $ 392 $ 314 $ 2,640 $ — $ 7,030 $ (1,491 ) $ 5,539 As of December 31, 2017 Prepaid expenses and other current assets $ — $ 8,961 $ — $ 63 $ 12,609 $ 21,633 $ (63 ) $ 21,570 Other assets 4,686 71,307 — — 14,787 90,780 — 90,780 Total assets $ 4,686 $ 80,268 $ — $ 63 $ 27,396 $ 112,413 $ (63 ) $ 112,350 Accounts payable, accrued expenses and other current liabilities $ 2,490 $ — $ 197 $ 99 $ — $ 2,786 $ (63 ) $ 2,723 Other long-term liabilities 4,796 — 404 — — 5,200 — 5,200 Total liabilities $ 7,286 $ — $ 601 $ 99 $ — $ 7,986 $ (63 ) $ 7,923
Schedule of Notional Amounts for Derivative Instruments	As of March 31, 2018 and December 31, 2017 , notional amounts for derivative instruments consisted of the following: Notional Amount as of (In thousands) March 31, 2018 December 31, 2017 Derivatives designated as hedging instruments: Interest rate swaps (USD) 387,681 395,986 Interest rate swaps (CAD) 155,270 156,367 Commodity contracts (MWhs) 15,201 15,579 Derivatives not designated as hedging instruments: Interest rate swaps (USD) 13,482 13,520 Foreign currency contracts (CAD) — 9,875 Foreign currency contracts (EUR) 1 1,000,000 — Commodity contracts (MWhs) 854 987 ——— (1) During the first quarter of 2018, the Company entered into short and long-term foreign currency forward contracts in relation to the Saeta Yield acquisition. As of March 31, 2018, the Company had outstanding contracts to buy and sell 500 million Euros with varying maturities, to hedge a portion of the foreign currency risk. See Note 4 . Acquisitions for discussion regarding the Company’s recently launched Tender Offer for the outstanding shares of Saeta Yield that is expected to close by mid-summer of 2018.
Gains and Losses on Derivatives Not Designated As Hedges	Gains and losses on derivatives not designated as hedging instruments for the three months ended March 31, 2018 and 2017 consisted of the following: Location of (Gain) Loss in the Statements of Operations Three Months Ended March 31, (In thousands) 2018 2017 Interest rate swaps Interest expense, net $ (226 ) $ 1,374 Foreign currency contracts Loss on foreign currency exchange, net 1,226 213 Commodity contracts Operating revenues, net (410 ) (4,113 )
Gains and Losses Recognized Related to Interest Rate Swaps and Commodity Contracts Designated as Cash Flow Hedges	Gains and losses recognized related to interest rate swaps and commodity contracts designated as hedging instruments for the three months ended March 31, 2018 and 2017 consisted of the following: Three Months Ended March 31, Derivatives in Cash Flow Hedging Relationships Gain (Loss) Included in the Assessment of Effectiveness Recognized in OCI, net of taxes 1 Gain (Loss) Excluded from the Assessment of Effectiveness Recognized in OCI Using an Amortization Approach 2 Location of Amount Reclassified from Accumulated OCI into Income (Gain) Loss Included in the Assessment of Effectiveness Reclassified from Accumulated OCI into Income 3 (Gain) Loss Excluded from the Assessment of Effectiveness that is Amortized through Earnings 2 (In thousands) 2018 2017 2018 2017 2018 2017 2018 2017 Interest rate swaps $ 7,875 $ (1,619 ) $ — $ — Interest expense, net $ 681 $ 2,861 $ — $ — Commodity contracts (19,102 ) 15,673 735 — Operating revenues, net (1,311 ) (3,247 ) (332 ) — Total $ (11,227 ) $ 14,054 $ 735 $ — $ (630 ) $ (386 ) $ (332 ) $ — ———— (1) There were no taxes attributed to interest rate swaps during the three months ended March 31, 2018 and 2017. Net of taxes of zero and $5.8 million for commodity contracts during the three months ended March 31, 2018 and 2017, respectively. (2) As a result of the adoption of ASU No. 2017-12 effective January 1, 2018 (see Note 2. Summary of Significant Accounting Policies ), certain gains and losses were excluded from the assessment of effectiveness that are being amortized through earnings for the three months ended March 31, 2018. No such amounts existed for the three months ended March 31, 2017 prior to the adoption of ASU No. 2017-12. (3) There were no taxes attributed to derivatives designated as hedging instruments during the three months ended March 31, 2018 and 2017.

Fair Value of Financial Instr35

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Financial Instruments Measured at Fair Value on a Recurring Basis	The following table summarizes the financial instruments measured at fair value on a recurring basis classified in the fair value hierarchy (Level 1, 2 or 3) based on the inputs used for valuation in the unaudited condensed consolidated balance sheets: (In thousands) As of March 31, 2018 As of December 31, 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Interest rate swaps $ — $ 9,861 $ — $ 9,861 $ — $ 4,686 $ — $ 4,686 Commodity contracts — 25,358 60,540 85,898 — 27,396 80,268 107,664 Foreign currency contracts — — — — — — — — Total derivative assets $ — $ 35,219 $ 60,540 $ 95,759 $ — $ 32,082 $ 80,268 $ 112,350 Liabilities Interest rate swaps $ — $ 3,998 $ — $ 3,998 $ — $ 7,887 $ — $ 7,887 Commodity contracts — — 392 392 — — — — Foreign currency contracts — 1,149 — 1,149 — 36 — 36 Total derivative liabilities $ — $ 5,147 $ 392 $ 5,539 $ — $ 7,923 $ — $ 7,923
Changes in the Fair Value of Derivative Instruments Classified as Level 3	The following table reconciles the changes in the fair value of derivative instruments classified as Level 3 in the fair value hierarchy for the three months ended March 31, 2018 and 2017: Three Months Ended March 31, (In thousands) 2018 2017 Beginning balance $ 80,268 $ 66,138 Realized and unrealized (losses) gains: Included in other comprehensive (loss) income (20,010 ) 18,262 Included in operating revenues, net 1,533 6,165 Settlements (1,643 ) (3,247 ) Balance as of March 31 $ 60,148 $ 87,318
Significant Unobservable Inputs Used in Valuation of Commodity Contracts	The significant unobservable inputs used in the valuation of the Company's commodity contracts categorized as Level 3 in the fair value hierarchy as of March 31, 2018 are as follows: (In thousands, except range) Fair Value as of March 31, 2018 Transaction Type Assets Liabilities Valuation Technique Unobservable Inputs Range Commodity contracts - power $ 60,540 $ 392 Discounted cash flow Forward price (per MWh) $ 13.9 - $ 165.8 Option model Volatilities 3.0 % - 7.0 %
Sensitivity of Fair Value Measurements to Increases (Decreases) in Significant Unobservable Inputs	The sensitivity of the Company’s fair value measurements to increases (decreases) in the significant unobservable inputs is as follows: Significant Unobservable Input Position Impact on Fair Value Measurement Increase (decrease) in forward price Forward sale Decrease (increase) Increase (decrease) in implied volatilities Purchase option Increase (decrease)
Sensitivity of Fair Value Measurements to Increases (Decreases) in Significant Unobservable Inputs	The sensitivity of the Company’s fair value measurements to increases (decreases) in the significant unobservable inputs is as follows: Significant Unobservable Input Position Impact on Fair Value Measurement Increase (decrease) in forward price Forward sale Decrease (increase) Increase (decrease) in implied volatilities Purchase option Increase (decrease)
Carrying Amount and Estimated Fair Value of Long-term Debt	The carrying amount and estimated fair value of the Company's long-term debt as of March 31, 2018 and December 31, 2017 is as follows: As of March 31, 2018 As of December 31, 2017 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 3,594,371 $ 3,658,574 $ 3,598,800 $ 3,702,470

Earnings (Loss) Per Share (Tabl

Earnings (Loss) Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Basic and Diluted Earnings (Loss) Per Share of Class A Common Stock	Basic and diluted earnings (loss) per share of the Company's Class A common stock for the three months ended March 31, 2018 and 2017 was calculated as follows: Three Months Ended March 31, (In thousands, except per share amounts) 2018 2017 Basic and diluted earnings (loss) per share: Net income (loss) attributable to Class A common stockholders $ 83,233 $ (31,769 ) Less: accretion of redeemable non-controlling interests — (2,226 ) Net income (loss) attributable to Class A common stockholders after accretion of redeemable non-controlling interests $ 83,233 $ (33,995 ) Weighted average basic Class A shares outstanding 1 148,139 92,072 Weighted average diluted Class A shares outstanding 2 148,166 92,072 Basic and diluted earnings (loss) per share $ 0.56 $ (0.37 ) ——— (1) Includes 53 contingently issuable shares for the three months ended March 31, 2018. (2) Includes 28 additional contingently issuable shares for the three months ended March 31, 2018. There were no potentially dilutive unvested Class A common stock awards outstanding during the three months ended March 31, 2018. The computation for diluted loss per share of the Company’s Class A common stock for the three months ended March 31, 2017 excludes 1,477 of potentially dilutive unvested restricted stock units because the effect would have been anti-dilutive.

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Summarized Financial Information of Reportable Segments	The following table reflects summarized financial information concerning the Company’s reportable segments for the three months ended March 31, 2018 and 2017 : Three Months Ended March 31, 2018 (In thousands) Solar Wind Corporate Total Operating revenues, net $ 59,723 $ 67,824 $ — $ 127,547 Depreciation, accretion and amortization expense 27,601 37,665 324 65,590 Impairment of renewable energy facilities 15,240 — — 15,240 Other operating costs and expenses 14,216 25,814 28,736 68,766 Interest expense, net 14,522 10,769 28,263 53,554 Other non-operating expenses, net — 853 887 1,740 Income tax benefit 1 — — (976 ) (976 ) Net loss $ (11,856 ) $ (7,277 ) $ (57,234 ) $ (76,367 ) Balance Sheet Total assets 2 $ 2,813,878 $ 3,342,181 $ 102,722 $ 6,258,781 Three Months Ended March 31, 2017 (In thousands) Solar Wind Corporate Total Operating revenues, net $ 66,001 $ 85,134 $ — $ 151,135 Depreciation, accretion and amortization expense 26,775 33,451 761 60,987 Other operating costs and expenses 13,908 25,161 39,011 78,080 Interest expense, net 19,581 20,899 27,832 68,312 Other non-operating (income) expenses, net (42 ) 548 441 947 Income tax benefit 1 — — (918 ) (918 ) Net income (loss) $ 5,779 $ 5,075 $ (67,127 ) $ (56,273 ) Balance Sheet Total assets 2 $ 2,897,036 $ 3,400,858 $ 89,127 $ 6,387,021 ——— (1) Income tax benefit is not allocated to the Company’s Solar and Wind segments. (2) Represents total assets as of March 31, 2018 and December 31, 2017 , respectively.

Accumulated Other Comprehensi38

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Changes in Accumulated Other Comprehensive Income	The following tables present the changes in each component of accumulated other comprehensive income, net of tax: (In thousands) Foreign Currency Translation Adjustments Hedging Activities 1 Accumulated Other Comprehensive Income Balance as of December 31, 2016 $ (22,133 ) $ 45,045 $ 22,912 Net unrealized gain arising during the period (net of zero and $5,836 tax expense, respectively) 2,680 14,054 16,734 Reclassification of net realized gain into earnings (net of zero tax impact) — (386 ) (386 ) Other comprehensive income 2,680 13,668 16,348 Accumulated other comprehensive (loss) income (19,453 ) 58,713 39,260 Less: Other comprehensive income attributable to non-controlling interests 918 5,972 6,890 Balance as of March 31, 2017 $ (20,371 ) $ 52,741 $ 32,370 (In thousands) Foreign Currency Translation Adjustments Hedging Activities 1 Accumulated Other Comprehensive Income Balance as of December 31, 2017 $ (13,412 ) $ 61,430 $ 48,018 Cumulative-effect adjustment (net of tax expense of $1,579) 2 — (4,164 ) (4,164 ) Other comprehensive loss: Net unrealized loss arising during the period (net of zero tax impact) (3,283 ) (10,492 ) (13,775 ) Reclassification of net realized gain into earnings (net of zero tax impact) — (962 ) (962 ) Other comprehensive loss (3,283 ) (11,454 ) (14,737 ) Accumulated other comprehensive (loss) income (16,695 ) 45,812 29,117 Less: Other comprehensive loss attributable to non-controlling interests — (1,243 ) (1,243 ) Balance as of March 31, 2018 $ (16,695 ) $ 47,055 $ 30,360 ——— (1) See Note 10 . Derivatives for further breakout of hedging gains and losses between interest rate swaps and commodity contracts. (2) See Note 2. Summary of Significant Accounting Policies for discussion regarding the Company’s adoption of ASU No. 2017-12 as of January 1, 2018.

Nature of Operations and Basi39

Nature of Operations and Basis of Presentation (Details)	Oct. 16, 2017
Brookfield | TerraForm Power
Noncontrolling Interest [Line Items]
Voting securities held (as a percent)	51.00%

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Line Items]
Decrease in cash flows from investing activities as a result of the adoption		$ (1,364)	$ 2,076
Restricted cash classified within assets held for sale			21,300			$ 54,800
Non-current restricted cash reclassified to current		13,900			$ 18,800
Cash and cash equivalents reclassified to current restricted cash		20,500			21,700
Decline in non-controlling interests balance		151,200
Corresponding allocation of net loss attributable to non-controlling interests		$ 145,000
Cumulative-effect adjustment, decrease (increase) in accumulated deficit	[1]				20,106
ITC recapture period		5 years
Decrease in non-cash deferred revenue recognition		$ 464	3,987
Cumulative effect adjustment, tax					1,579
Severance and transition bonus costs
Accounting Policies [Line Items]
Additional severance and transition bonus costs		1,300
Payments related to the restructuring		800
Accrued severance and transition bonuses		3,200
ASU No. 2016-18
Accounting Policies [Line Items]
Decrease in cash flows from investing activities as a result of the adoption			$ 32,700
Accounting Standards Update 2014-09
Accounting Policies [Line Items]
Decrease in non-cash deferred revenue recognition		$ 3,500
Accumulated Deficit
Accounting Policies [Line Items]
Cumulative-effect adjustment, decrease (increase) in accumulated deficit	[1]				24,578
Accumulated Deficit | Accounting Standards Update 2014-09 | REC sale arrangements
Accounting Policies [Line Items]
Cumulative-effect adjustment, decrease (increase) in accumulated deficit					(20,500)
Accumulated Deficit | Accounting Standards Update 2014-09 | ITCs
Accounting Policies [Line Items]
Cumulative-effect adjustment, decrease (increase) in accumulated deficit					40,900
Non-controlling interests
Accounting Policies [Line Items]
Cumulative-effect adjustment, decrease (increase) in accumulated deficit	[1]				(308)
Non-controlling interests | Accounting Standards Update 2014-09 | REC sale arrangements
Accounting Policies [Line Items]
Cumulative-effect adjustment, decrease (increase) in accumulated deficit					(300)
Redeemable Non-controlling Interests
Accounting Policies [Line Items]
Cumulative-effect adjustment, decrease (increase) in accumulated deficit					(4,485)
Redeemable Non-controlling Interests | Accounting Standards Update 2014-09 | REC sale arrangements
Accounting Policies [Line Items]
Cumulative-effect adjustment, decrease (increase) in accumulated deficit					(4,500)
Accumulated Other Comprehensive Income
Accounting Policies [Line Items]
Cumulative-effect adjustment, decrease (increase) in accumulated deficit	[1]				(4,164)
Cumulative effect adjustment, tax	[1]				$ 1,600
Scenario, Forecast | Accounting Standards Update 2014-09
Accounting Policies [Line Items]
Decrease in non-cash deferred revenue recognition				$ 12,800
[1]	See Note 2. Summary of Significant Accounting Policies for discussion regarding the Company’s adoption of Accounting Standards Update No. 2014-09, Accounting Standards Update No. 2016-08 and Accounting Standards Update No. 2017-12 as of January 1, 2018.

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Reconciliation of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Cash and cash equivalents	$ 157,833	$ 128,087
Restricted cash - current	47,035	54,006
Restricted cash - non-current	48,529	42,694
Cash, cash equivalents and restricted cash shown in the unaudited condensed consolidated statement of cash flows	$ 253,397	$ 224,787	$ 794,905	$ 682,837

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Activity of Redeemable Non-controlling Interests (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Activity of Redeemable Non-controlling Interests
Beginning balance		$ 58,340
Cumulative-effect adjustment	[1]			$ 20,106
Distributions		(582)
Net loss		(2,513)	$ 835
Ending balance		50,760
Capital
Activity of Redeemable Non-controlling Interests
Beginning balance		22,160
Cumulative-effect adjustment				0
Distributions		(582)
Net loss		0
Ending balance		21,578
Retained Earnings
Activity of Redeemable Non-controlling Interests
Beginning balance		36,180
Cumulative-effect adjustment				(4,485)
Distributions		0
Net loss		(2,513)
Ending balance		$ 29,182
Redeemable Non-controlling Interests
Activity of Redeemable Non-controlling Interests
Cumulative-effect adjustment				$ (4,485)
[1]	See Note 2. Summary of Significant Accounting Policies for discussion regarding the Company’s adoption of Accounting Standards Update No. 2014-09, Accounting Standards Update No. 2016-08 and Accounting Standards Update No. 2017-12 as of January 1, 2018.

Revenue - Impact on Statement o

Revenue - Impact on Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 127,547
Amortization of rate contracts	(9,817)
Operating costs and expenses	149,596	$ 139,067
Operating (loss) income	(22,049)	12,068
Other expenses, net	55,294	69,259
Loss before income tax benefit	(77,343)	(57,191)
Income tax benefit	(976)	(918)
Net loss	(76,367)	$ (56,273)
Amounts excluding Topic 606 Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	128,505
Amortization of rate contracts	(9,817)
Operating costs and expenses	149,596
Operating (loss) income	(21,091)
Other expenses, net	55,294
Loss before income tax benefit	(76,385)
Income tax benefit	(976)
Net loss	(75,409)
Solar
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	59,723
Amortization of rate contracts	(1,977)
Wind
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	67,824
Amortization of rate contracts	(7,840)
PPA rental income
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	89,181
PPA rental income | Amounts excluding Topic 606 Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	89,181
PPA rental income | Solar
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	36,768
PPA rental income | Wind
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	52,413
Commodity derivatives
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	11,007
Commodity derivatives | Amounts excluding Topic 606 Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	11,007
Commodity derivatives | Solar
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	0
Commodity derivatives | Wind
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	11,007
PPA revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	13,199
PPA revenue | Amounts excluding Topic 606 Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	13,199
PPA revenue | Solar
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	6,507
PPA revenue | Wind
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	6,692
Energy revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	103,570
Energy revenue | Amounts excluding Topic 606 Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	103,570
Energy revenue | Solar
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	41,298
Energy revenue | Wind
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	62,272
Incentive revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	23,977
Incentive revenue | Amounts excluding Topic 606 Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	24,935
Incentive revenue | Solar
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	18,425
Incentive revenue | Wind
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	5,552
REC Sales | Adjustments | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	(2,560)
Operating costs and expenses	0
Operating (loss) income	(2,560)
Other expenses, net	0
Loss before income tax benefit	(2,560)
Income tax benefit	0
Net loss	(2,560)
ITC Sales | Adjustments | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	3,518
Operating costs and expenses	0
Operating (loss) income	3,518
Other expenses, net	0
Loss before income tax benefit	3,518
Income tax benefit	0
Net loss	$ 3,518

Revenue - Impact on Balance She

Revenue - Impact on Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	$ 70,346	$ 89,680
Other current assets	253,197
Total current assets	323,543	341,536
Non-current assets	5,935,238
Total assets	6,258,781	6,387,021
Deferred revenue	1,807	17,859
Other current liabilities	502,464
Total current liabilities	504,271	513,853
Deferred revenue, less current portion	13,134	38,074
Other non-current liabilities	3,411,266
Total liabilities	3,928,671	3,958,313
Redeemable non-controlling interests and total stockholders' equity	2,330,110
Total liabilities, redeemable non-controlling interests and stockholders' equity	6,258,781	$ 6,387,021
Amounts excluding Topic 606 Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	93,061
Other current assets	253,197
Total current assets	346,258
Non-current assets	5,935,238
Total assets	6,281,496
Deferred revenue	18,117
Other current liabilities	502,464
Total current liabilities	520,581
Deferred revenue, less current portion	34,203
Other non-current liabilities	3,411,266
Total liabilities	3,966,050
Redeemable non-controlling interests and total stockholders' equity	2,315,446
Total liabilities, redeemable non-controlling interests and stockholders' equity	6,281,496
REC Sales | Adjustments | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	22,715
Other current assets	0
Total current assets	22,715
Non-current assets	0
Total assets	22,715
Redeemable non-controlling interests and total stockholders' equity	22,715
Total liabilities, redeemable non-controlling interests and stockholders' equity	22,715
ITC Sales | Adjustments | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue	16,310
Other current liabilities	0
Total current liabilities	16,310
Deferred revenue, less current portion	21,069
Other non-current liabilities	0
Total liabilities	37,379
Redeemable non-controlling interests and total stockholders' equity	(37,379)
Total liabilities, redeemable non-controlling interests and stockholders' equity	$ 0

Revenue - Remaining Performance

Revenue - Remaining Performance Obligation (Details) - REC Sales - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01 $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred revenue	$ 67
Deferred revenue, recognition period	5 years

Revenue - Narrative (Details)

Revenue - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue from External Customer [Line Items]
Revenue	$ 127,547
PPA Contracts
Revenue from External Customer [Line Items]
Revenue	$ 13,200
Payment term	30 days
Accounts receivable	$ 6,400
REC Sales
Revenue from External Customer [Line Items]
Payment term	30 days
Facility Linked Incentive Contracts
Revenue from External Customer [Line Items]
Revenue	$ 5,500
Accounts receivable	5,500
ITC Sales
Revenue from External Customer [Line Items]
Contract liability	5,900
Revenue recognized related to contract liability	300
ITC Sales - Government Incentives
Revenue from External Customer [Line Items]
Deferred revenue	9,000
Adjustments | Accounting Standards Update 2014-09 | REC Sales
Revenue from External Customer [Line Items]
Revenue	(2,560)
Adjustments | Accounting Standards Update 2014-09 | ITC Sales
Revenue from External Customer [Line Items]
Revenue	3,518
Amounts excluding Topic 606 Adoption
Revenue from External Customer [Line Items]
Revenue	128,505
Amounts excluding Topic 606 Adoption | ITC Sales
Revenue from External Customer [Line Items]
Deferred revenue	$ 3,500

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details)	Mar. 06, 2018USD ($)bankdebt_instrument	Feb. 06, 2018USD ($)	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	May 03, 2018€ / shares	Feb. 07, 2018
Business Acquisition [Line Items]
Acquisition and related costs			$ 3,685,000	$ 0
Saeta Yield
Business Acquisition [Line Items]
Voting interests acquired						100.00%
Aggregate value of shares held		$ 600,000,000
Consideration transferred		1,200,000,000
Consideration transferred, equity interests issuable		400,000,000
Bank guarantee	$ 1,200,000,000	$ 1,200,000,000
Letter of credit facilities | debt_instrument	2
Number of lending banks | bank	2
Acquisition and related costs			$ 3,700,000
Selling Stockholders | Saeta Yield
Business Acquisition [Line Items]
Voting interests acquired		50.338%
Grand Duchy of Luxembourg | Saeta Yield
Business Acquisition [Line Items]
Voting interests acquired		48.222%
Sponsor Line Agreement | Revolving Credit Facility
Business Acquisition [Line Items]
Debt covenant, minimum liquidity requirement	$ 500,000,000
New Revolver | Revolving Credit Facility
Business Acquisition [Line Items]
Debt covenant, minimum liquidity requirement	$ 400,000,000
Subsequent Event | Saeta Yield
Business Acquisition [Line Items]
Business acquisition price (dollars per share) | € / shares					€ 12.20
Minimum | Saeta Yield
Business Acquisition [Line Items]
Consideration transferred, equity interests issuable		$ 400,000,000
Maximum | Saeta Yield
Business Acquisition [Line Items]
Consideration transferred, equity interests issuable		$ 650,000,000

Renewable Energy Facilities - (

Renewable Energy Facilities - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Property, Plant and Equipment, Net, by Type [Abstract]
Total renewable energy facilities, net	$ 4,719,808		$ 4,801,925
Depreciation expense	57,100	$ 52,200
Impairment of renewable energy facilities	15,240	$ 0
REC Sales Agreement
Property, Plant and Equipment, Net, by Type [Abstract]
Renewable energy facilities, gross	19,500
Long-lived assets, fair value	4,300
Impairment of renewable energy facilities	15,200
Renewable Energy Facilities in Service
Property, Plant and Equipment, Net, by Type [Abstract]
Renewable energy facilities, gross	5,344,488		5,378,462
Less accumulated depreciation - renewable energy facilities	(626,766)		(578,474)
Total renewable energy facilities, net	4,717,722		4,799,988
Construction in progress - renewable energy facilities
Property, Plant and Equipment, Net, by Type [Abstract]
Renewable energy facilities, gross	$ 2,086		$ 1,937

Intangibles (Details)

Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	$ 39,686		$ 41,086
Accumulated Amortization	(18,993)		(18,744)
Net Book Value	20,693		22,342
Total intangible assets, net
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	1,249,665		1,255,762
Accumulated Amortization	(192,108)		(177,976)
Net Book Value	1,057,557		1,077,786
Favorable rate revenue contracts
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	713,786		718,639
Accumulated Amortization	(110,230)		(102,543)
Net Book Value	$ 603,556		$ 616,096
Favorable rate revenue contracts | Weighted average
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Weighted Average Amortization Period	15 years		15 years
In-place value of market rate revenue contracts
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	$ 520,079		$ 521,323
Accumulated Amortization	(79,349)		(73,104)
Net Book Value	$ 440,730		$ 448,219
In-place value of market rate revenue contracts | Weighted average
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Weighted Average Amortization Period	18 years		19 years
Favorable rate land leases
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	$ 15,800		$ 15,800
Accumulated Amortization	(2,529)		(2,329)
Net Book Value	$ 13,271		$ 13,471
Favorable rate land leases | Weighted average
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Weighted Average Amortization Period	17 years		17 years
Unfavorable rate revenue contracts
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	$ 33,686		$ 35,086
Accumulated Amortization	(15,952)		(16,030)
Net Book Value	$ 17,734		$ 19,056
Unfavorable rate revenue contracts | Weighted average
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Weighted Average Amortization Period	7 years		7 years
Unfavorable rate operations and maintenance contracts
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	$ 5,000		$ 5,000
Accumulated Amortization	(2,865)		(2,552)
Net Book Value	$ 2,135		$ 2,448
Unfavorable rate operations and maintenance contracts | Weighted average
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Weighted Average Amortization Period	2 years		2 years
Unfavorable rate land lease
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	$ 1,000		$ 1,000
Accumulated Amortization	(176)		(162)
Net Book Value	$ 824		$ 838
Unfavorable rate land lease | Weighted average
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Weighted Average Amortization Period	15 years		15 years
Operating Revenues, Net | Total intangible assets, net
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amortization expense	$ (9,800)	$ (9,800)
Depreciation, Accretion, and Amortization | Total intangible assets, net
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amortization expense	6,400	6,400
Cost of Operations | Lease agreements
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amortization expense	$ 100	$ 100

Variable Interest Entities (Det

Variable Interest Entities (Details) - Consolidated Variable Interest Entity, Primary Beneficiary - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current assets	$ 122,410	$ 142,403
Non-current assets	4,100,306	4,155,558
Total assets	4,222,716	4,297,961
Current liabilities	99,198	119,021
Non-current liabilities	996,712	975,839
Total liabilities	$ 1,095,910	$ 1,094,860

Long-term Debt - Debt Schedule

Long-term Debt - Debt Schedule (Details) - USD ($)	May 11, 2018	Mar. 31, 2018	Mar. 06, 2018	Feb. 06, 2018	Feb. 05, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total principal due for long-term debt and financing lease obligations		$ 3,636,530,000				$ 3,642,516,000
Unamortized discount, net		(18,297,000)				(19,027,000)
Deferred financing costs, net		(23,862,000)				(24,689,000)
Less current portion of long-term debt and financing lease obligations		(391,656,000)				(403,488,000)
Long-term debt and financing lease obligations, less current portion		$ 3,202,715,000				3,195,312,000
Interest rate		5.33%
Revolving Credit Facility | Revolver
Debt Instrument [Line Items]
Debt covenant, minimum liquidity requirement			$ 400,000,000
Permanent Financing
Debt Instrument [Line Items]
Total principal due for long-term debt and financing lease obligations		$ 1,602,675,000				1,616,729,000
Interest rate		5.72%
Fixed interest rate		60.00%
Debt at variable rate		40.00%
Permanent Financing | Senior Notes due 2023
Debt Instrument [Line Items]
Total principal due for long-term debt and financing lease obligations		$ 500,000,000				500,000,000
Interest rate		4.25%
Permanent Financing | Senior Notes due 2025
Debt Instrument [Line Items]
Total principal due for long-term debt and financing lease obligations		$ 300,000,000				300,000,000
Interest rate		6.63%
Permanent Financing | Senior Notes Due 2028
Debt Instrument [Line Items]
Total principal due for long-term debt and financing lease obligations		$ 700,000,000				700,000,000
Interest rate		5.00%
Permanent Financing | Term Loan4
Debt Instrument [Line Items]
Total principal due for long-term debt and financing lease obligations		$ 349,125,000				350,000,000
Interest rate		4.63%
Permanent Financing | Term Loan4 | Subsequent Event
Debt Instrument [Line Items]
Interest rate reduction	0.75%
Line of Credit | Revolving Credit Facility | Revolver
Debt Instrument [Line Items]
Total principal due for long-term debt and financing lease obligations		$ 70,000,000				60,000,000
Interest rate		4.86%
Maximum borrowing capacity				$ 600,000,000	$ 450,000,000
Debt covenant, minimum liquidity requirement				$ 400,000,000
Financing lease obligations
Debt Instrument [Line Items]
Total principal due for long-term debt and financing lease obligations		$ 114,730,000				$ 115,787,000
Interest rate		5.60%

Long-term Debt - Debt Narrative

Long-term Debt - Debt Narrative (Details) $ in Millions, $ in Millions	Mar. 31, 2018USD ($)MW	Dec. 31, 2017USD ($)	Feb. 28, 2017CAD ($)MW
Debt Instrument [Line Items]
Defaulted debt, reclassified to current	$ 216.3	$ 239.7
Letter of Credit
Debt Instrument [Line Items]
Letter of credit, increase limit			$ 6.7
Permanent Financing
Debt Instrument [Line Items]
Capacity (MW) | MW			59
Letter of credit, increase limit			$ 113.9
Maximum borrowing capacity			$ 233.9
Chile
Debt Instrument [Line Items]
Capacity (MW) | MW	101.6

Long-term Debt - Maturities (De

Long-term Debt - Maturities (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Aggregate Contractual Payments of Long-term Debt
Remainder of 2018		$ 162,194
2,019		110,248
2,020		104,970
2,021		108,015
2,022		596,658
Thereafter		2,554,445
Total		3,636,530
Defaulted debt, reclassified to current		216,300	$ 239,700
Long-term Debt
Aggregate Contractual Payments of Long-term Debt
Defaulted debt, reclassified to current		216,300
Revolver
Aggregate Contractual Payments of Long-term Debt
Remainder of 2018		$ 70,000
Scenario, Forecast | Revolver
Aggregate Contractual Payments of Long-term Debt
Expected repayments of existing debt	$ 55,000

Income Taxes - Components of In

Income Taxes - Components of Income Tax Provision (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Loss before income tax benefit	$ (77,343)	$ (57,191)
Income tax benefit	$ (976)	$ (918)
Effective tax rate	1.30%	1.60%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Income Taxes [Line Items]
Change in deferred tax assets valuation allowance, income tax benefit	$ 1
Change in tax rate, deferred tax liability, provisional income tax benefit		$ 5
Terra LLC | TerraForm Power
Income Taxes [Line Items]
Ownership percentage	100.00%		65.70%
Terra LLC | SunEdison
Income Taxes [Line Items]
Ownership percentage			34.30%

Derivatives - Schedule of Fair

Derivatives - Schedule of Fair Values of Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	$ 97,250	$ 112,413
Gross assets offset in consolidated balance sheet	(1,491)	(63)
Net assets in consolidated balance sheet	95,759	112,350
Gross amounts of liabilities recognized	7,030	7,986
Gross liabilities offset in consolidated balance sheet	(1,491)	(63)
Net liabilities in consolidated balance sheet	5,539	7,923
Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	16,953	21,633
Gross assets offset in consolidated balance sheet	(1,491)	(63)
Net assets in consolidated balance sheet	15,462	21,570
Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	80,297	90,780
Gross assets offset in consolidated balance sheet	0	0
Net assets in consolidated balance sheet	80,297	90,780
Accounts payable, accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	3,977	2,786
Gross liabilities offset in consolidated balance sheet	(1,491)	(63)
Net liabilities in consolidated balance sheet	2,486	2,723
Other long-term liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	3,053	5,200
Gross liabilities offset in consolidated balance sheet	0	0
Net liabilities in consolidated balance sheet	3,053	5,200
Interest Rate Swaps | Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	9,861	4,686
Gross amounts of liabilities recognized	3,684	7,286
Interest Rate Swaps | Derivatives Designated as Hedging Instruments | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	392	0
Interest Rate Swaps | Derivatives Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	9,469	4,686
Interest Rate Swaps | Derivatives Designated as Hedging Instruments | Accounts payable, accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	815	2,490
Interest Rate Swaps | Derivatives Designated as Hedging Instruments | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	2,869	4,796
Interest Rate Swaps | Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	0	0
Gross amounts of liabilities recognized	314	601
Interest Rate Swaps | Derivatives Not Designated as Hedging Instruments | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	0	0
Interest Rate Swaps | Derivatives Not Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	0	0
Interest Rate Swaps | Derivatives Not Designated as Hedging Instruments | Accounts payable, accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	130	197
Interest Rate Swaps | Derivatives Not Designated as Hedging Instruments | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	184	404
Foreign Currency Contracts | Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	1,491	63
Gross amounts of liabilities recognized	2,640	99
Foreign Currency Contracts | Derivatives Not Designated as Hedging Instruments | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	1,491	63
Foreign Currency Contracts | Derivatives Not Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	0	0
Foreign Currency Contracts | Derivatives Not Designated as Hedging Instruments | Accounts payable, accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	2,640	99
Foreign Currency Contracts | Derivatives Not Designated as Hedging Instruments | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	0	0
Commodity Contracts | Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	60,540	80,268
Gross amounts of liabilities recognized	392	0
Commodity Contracts | Derivatives Designated as Hedging Instruments | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	1,475	8,961
Commodity Contracts | Derivatives Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	59,065	71,307
Commodity Contracts | Derivatives Designated as Hedging Instruments | Accounts payable, accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	392	0
Commodity Contracts | Derivatives Designated as Hedging Instruments | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	0	0
Commodity Contracts | Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	25,358	27,396
Gross amounts of liabilities recognized	0	0
Commodity Contracts | Derivatives Not Designated as Hedging Instruments | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	13,595	12,609
Commodity Contracts | Derivatives Not Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of assets recognized	11,763	14,787
Commodity Contracts | Derivatives Not Designated as Hedging Instruments | Accounts payable, accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	0	0
Commodity Contracts | Derivatives Not Designated as Hedging Instruments | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of liabilities recognized	$ 0	$ 0

Derivatives - Schedule of Notio

Derivatives - Schedule of Notional Amounts for Derivative Instruments (Details) € in Thousands, MWh in Thousands, $ in Thousands, $ in Thousands	Mar. 31, 2018CAD ($)MWh	Mar. 31, 2018USD ($)MWh	Mar. 31, 2018EUR (€)MWh	Dec. 31, 2017CAD ($)MWh	Dec. 31, 2017USD ($)MWh	Dec. 31, 2017EUR (€)MWh
Interest rate swaps | Derivatives designated as hedges
Derivative [Line Items]
Notional amount	$ 155,270	$ 387,681		$ 156,367	$ 395,986
Interest rate swaps | Derivatives not designated as hedges
Derivative [Line Items]
Notional amount | $		$ 13,482			$ 13,520
Foreign currency contracts | Derivatives not designated as hedges
Derivative [Line Items]
Notional amount	$ 0		€ 1,000,000	$ 9,875		€ 0
Commodity contracts | Derivatives designated as hedges
Derivative [Line Items]
Derivative, notional amount (in mwh)	15,201	15,201	15,201	15,579	15,579	15,579
Commodity contracts | Derivatives not designated as hedges
Derivative [Line Items]
Derivative, notional amount (in mwh)	854	854	854	987	987	987
Long | Foreign currency contracts | Derivatives not designated as hedges
Derivative [Line Items]
Notional amount | €			€ 500,000

Derivatives - Gains and Losses

Derivatives - Gains and Losses on Derivatives Not Designated As Hedges (Details) - Derivatives not designated as hedges - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest expense, net | Interest rate swaps
Derivative [Line Items]
Loss (gain) on derivatives	$ (226)	$ 1,374
Loss on foreign currency exchange, net | Foreign currency contracts
Derivative [Line Items]
Loss (gain) on derivatives	1,226	213
Operating revenues, net | Commodity contracts
Derivative [Line Items]
Loss (gain) on derivatives	$ (410)	$ (4,113)

Derivatives - Gains (Losses) Re

Derivatives - Gains (Losses) Recognized Related to Interest Rate Swaps and Commodity Contracts Designated as Cash Flow Hedges (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative [Line Items]
Gain (Loss) Included in the Assessment of Effectiveness Recognized in OCI, net of taxes	$ (11,227,000)	$ 14,054,000
Gain (Loss) Excluded from the Assessment of Effectiveness Recognized in OCI Using an Amortization Approach	735,000	0
(Gain) Loss Included in the Assessment of Effectiveness Reclassified from Accumulated OCI into Income	(630,000)	(386,000)
(Gain) Loss Excluded from the Assessment of Effectiveness that is Amortized through Earnings	(332,000)	0
Interest rate swaps | Interest rate swaps
Derivative [Line Items]
Gain (Loss) Included in the Assessment of Effectiveness Recognized in OCI, net of taxes	7,875,000	(1,619,000)
Gain (Loss) Excluded from the Assessment of Effectiveness Recognized in OCI Using an Amortization Approach	0	0
(Gain) Loss Included in the Assessment of Effectiveness Reclassified from Accumulated OCI into Income	681,000	2,861,000
(Gain) Loss Excluded from the Assessment of Effectiveness that is Amortized through Earnings	0	0
Gain (loss) on derivatives, tax	0	0
Taxes attributed to derivatives designated as cash flow hedges	0	0
Interest rate swaps | Commodity contracts
Derivative [Line Items]
Gain (loss) on derivatives, tax	0	5,800,000
Commodity contracts | Commodity contracts
Derivative [Line Items]
Gain (Loss) Included in the Assessment of Effectiveness Recognized in OCI, net of taxes	(19,102,000)	15,673,000
Gain (Loss) Excluded from the Assessment of Effectiveness Recognized in OCI Using an Amortization Approach	735,000	0
(Gain) Loss Included in the Assessment of Effectiveness Reclassified from Accumulated OCI into Income	(1,311,000)	(3,247,000)
(Gain) Loss Excluded from the Assessment of Effectiveness that is Amortized through Earnings	$ (332,000)	$ 0

Derivatives - Narrative (Detail

Derivatives - Narrative (Details) - USD ($)		3 Months Ended
		Mar. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Cumulative-effect adjustment	[1]		$ 20,106,000
Cumulative effect adjustment, tax			1,579,000
Aggregate fair value of collateral		$ 0	0
Commodity Contract
Derivative Instruments, Gain (Loss) [Line Items]
Maximum term of outstanding interest rate swaps		12 years
Gain expected to be reclassified		$ 8,100,000
Letter of Credit | Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Aggregate fair value of collateral		15,000,000	15,000,000
Secured Debt | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Loss expected to be reclassified into earnings		$ 400,000
Maximum term of outstanding interest rate swaps		16 years
Accumulated Other Comprehensive Income
Derivative Instruments, Gain (Loss) [Line Items]
Cumulative-effect adjustment	[1]		(4,164,000)
Cumulative effect adjustment, tax	[1]		$ 1,600,000
[1]	See Note 2. Summary of Significant Accounting Policies for discussion regarding the Company’s adoption of Accounting Standards Update No. 2014-09, Accounting Standards Update No. 2016-08 and Accounting Standards Update No. 2017-12 as of January 1, 2018.

Fair Value of Financial Instr61

Fair Value of Financial Instruments - Financial Instruments Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets and Liabilities
Assets	$ 97,250	$ 112,413
Liabilities	7,030	7,986
Long-term debt, including current portion
Carrying Amount	3,594,371	3,598,800
Fair Value	$ 3,658,574	$ 3,702,470
Senior Notes due 2023
Long-term debt, including current portion
Fair value as a percentage of face	96.09%	99.50%
Senior Notes due 2025
Long-term debt, including current portion
Fair value as a percentage of face	108.25%	109.50%
Senior Notes Due 2028
Long-term debt, including current portion
Fair value as a percentage of face	93.89%	99.38%
Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	$ 95,759	$ 112,350
Liabilities	5,539	7,923
Interest rate swaps | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	9,861	4,686
Liabilities	3,998	7,887
Commodity contracts | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	85,898	107,664
Liabilities	392	0
Foreign currency contracts | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	0	0
Liabilities	1,149	36
Level 1 | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	0	0
Liabilities	0	0
Level 1 | Interest rate swaps | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	0	0
Liabilities	0	0
Level 1 | Commodity contracts | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	0	0
Liabilities	0	0
Level 1 | Foreign currency contracts | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	0	0
Liabilities	0	0
Level 2 | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	35,219	32,082
Liabilities	5,147	7,923
Level 2 | Interest rate swaps | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	9,861	4,686
Liabilities	3,998	7,887
Level 2 | Commodity contracts | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	25,358	27,396
Liabilities	0	0
Level 2 | Foreign currency contracts | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	0	0
Liabilities	1,149	36
Level 3 | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	60,540	80,268
Liabilities	392	0
Level 3 | Interest rate swaps | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	0	0
Liabilities	0	0
Level 3 | Commodity contracts | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	60,540	80,268
Liabilities	392	0
Level 3 | Foreign currency contracts | Fair Value, Measurements, Recurring
Assets and Liabilities
Assets	0	0
Liabilities	$ 0	$ 0

Fair Value of Financial Instr62

Fair Value of Financial Instruments - Unobservable input reconciliation (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)$ / MWh	Mar. 31, 2017USD ($)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	$ 80,268	$ 66,138
Realized and unrealized (losses) gains:
Included in other comprehensive (loss) income	(20,010)	18,262
Included in operating revenues, net	1,533	6,165
Settlements	(1,643)	(3,247)
Ending Balance	60,148	$ 87,318
Level 3 | Commodity Contract
Realized and unrealized (losses) gains:
Assets	60,540
Liabilities	$ 392
Income Approach Valuation Technique | Minimum | Level 3 | Commodity Contract
Realized and unrealized (losses) gains:
Forward price ($ per MWh) | $ / MWh	13.9
Income Approach Valuation Technique | Maximum | Level 3 | Commodity Contract
Realized and unrealized (losses) gains:
Forward price ($ per MWh) | $ / MWh	165.8
Option Model | Minimum | Level 3 | Commodity Contract
Realized and unrealized (losses) gains:
Volatilities	3.00%
Option Model | Maximum | Level 3 | Commodity Contract
Realized and unrealized (losses) gains:
Volatilities	7.00%

Earnings (Loss) Per Share (Deta

Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income (loss) attributable to Class A common stockholders	$ 83,233	$ (31,769)
Less: accretion of redeemable non-controlling interest	0	(2,226)
Undistributed income (loss) attributable to Class A shares	$ 83,233	$ (33,995)
Weighted average basic Class A shares outstanding (in shares)	148,139,000	92,072,000
Weighted average diluted Class A shares outstanding (in shares)	148,166,000	92,072,000
Basic and diluted earnings (loss) per share (dollars per share)	$ 0.56	$ (0.37)
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Contingently issuable shares, basic (in shares)	53,000
Contingently issuable shares, diluted (in shares)	28,000
Restricted Stock
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Shares excluded from calculation (shares)	0
Restricted Stock Units (RSUs)
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Shares excluded from calculation (shares)		1,477,000

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	Mar. 06, 2018USD ($)bank	Feb. 06, 2018USD ($)	Jun. 09, 2017USD ($)	Mar. 24, 2017employee	May 27, 2016USD ($)employee	Apr. 04, 2016employee	Jan. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2016USD ($)
Loss Contingencies [Line Items]
Outstanding letters of credit									$ 147,000
Securities Class Action
Loss Contingencies [Line Items]
Number of defendants | employee				3		2
Litigation settlement			$ 14,800				$ 1,130	$ 1,130
Portion of settlement covered by insurance providers			$ 13,630
Loss contingency accrual										$ 1,130
Litigation settlement, escrow deposit							$ 13,630	13,630
Insurance settlements payable								$ 13,630
SunEdison | First Wind Acquisition Claim
Loss Contingencies [Line Items]
Obligated earn-out payments					$ 231,000
Number of employee resignations | employee					2
Revolving Credit Facility | Line of Credit
Loss Contingencies [Line Items]
Outstanding letters of credit									$ 78,100
Saeta Yield
Loss Contingencies [Line Items]
Number of lending banks | bank	2
Bank guarantee	$ 1,200,000	$ 1,200,000
Director | Securities Class Action
Loss Contingencies [Line Items]
Number of defendants | employee						1

Related Parties - Narrative (De

Related Parties - Narrative (Details) - USD ($)	Feb. 06, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Oct. 16, 2017
Related Party Transaction [Line Items]
General and administrative expenses - affiliate		$ 3,474,000	$ 1,419,000
Due from affiliates		4,856,000		$ 4,370,000
Capital contribution from stockholder		2,994,000
Revenue from related parties		3,500,000
Due to affiliates		3,369,000		3,968,000
Related party costs		0	5,598,000
Brookfield
Related Party Transaction [Line Items]
Due from affiliates		3,700,000
Accrued standby fee interest		600,000		600,000
Back-stop support agreement, contingent payment due from affiliate (up to)	$ 400,000,000
Backstop support agreement price (dollars per share)	$ 10.66
Credit support, percentage of savings	50.00%
Credit support fee, up to	$ 3,000,000
Brookfield | Management Services Agreement
Related Party Transaction [Line Items]
General and administrative expenses - affiliate		$ 3,300,000
Brookfield | Incentive Distribution Rights
Related Party Transaction [Line Items]
Quarterly distribution rights, level one ($ per share)		$ 0.93
Quarterly distribution rights, level two ($ per share)		$ 1.05
TerraForm Global, LLC
Related Party Transaction [Line Items]
Due from affiliates		$ 1,200,000
Affiliate of Brookfield
Related Party Transaction [Line Items]
Due to affiliate				$ 3,400,000
SunEdison
Related Party Transaction [Line Items]
Related party costs			400,000
General and administrative expenses			1,400,000
Stock-based compensation expense			1,000,000
Proceeds from warranty claims			7,000,000
SunEdison | Incentive Distribution Rights
Related Party Transaction [Line Items]
Payments for related party transactions		$ 0	0
SunEdison | Chile Facility EPC Contract
Related Party Transaction [Line Items]
Proceeds from warranty claims			$ 4,800,000
Orion US Holdings 1 LP | Class A common stock
Related Party Transaction [Line Items]
Ownership percentage					51.00%
Line of Credit | Revolving Credit Facility | Sponsor Line Agreement
Related Party Transaction [Line Items]
Aggregate principal amount					$ 500,000,000

Segment Reporting - Income stat

Segment Reporting - Income statement summary table (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)reportable_segment	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | reportable_segment	2
Segment Reporting Information, Profit (Loss)
Operating revenues, net	$ 127,547	$ 151,135
Depreciation, accretion and amortization expense	65,590	60,987
Impairment of renewable energy facilities	15,240	0
Other operating costs and expenses	68,766	78,080
Interest expense, net	53,554	68,312
Other non-operating expenses, net	1,740	947
Income tax benefit	(976)	(918)
Net loss	(76,367)	(56,273)
Balance Sheet
Total assets	6,258,781		$ 6,387,021
Segments | Solar
Segment Reporting Information, Profit (Loss)
Operating revenues, net	59,723	66,001
Depreciation, accretion and amortization expense	27,601	26,775
Impairment of renewable energy facilities	15,240
Other operating costs and expenses	14,216	13,908
Interest expense, net	14,522	19,581
Other non-operating expenses, net	0	(42)
Income tax benefit	0	0
Net loss	(11,856)	5,779
Balance Sheet
Total assets	2,813,878		2,897,036
Segments | Wind
Segment Reporting Information, Profit (Loss)
Operating revenues, net	67,824	85,134
Depreciation, accretion and amortization expense	37,665	33,451
Impairment of renewable energy facilities	0
Other operating costs and expenses	25,814	25,161
Interest expense, net	10,769	20,899
Other non-operating expenses, net	853	548
Income tax benefit	0	0
Net loss	(7,277)	5,075
Balance Sheet
Total assets	3,342,181		3,400,858
Corporate
Segment Reporting Information, Profit (Loss)
Operating revenues, net	0	0
Depreciation, accretion and amortization expense	324	761
Impairment of renewable energy facilities	0
Other operating costs and expenses	28,736	39,011
Interest expense, net	28,263	27,832
Other non-operating expenses, net	887	441
Income tax benefit	(976)	(918)
Net loss	(57,234)	$ (67,127)
Balance Sheet
Total assets	$ 102,722		$ 89,127

Accumulated Other Comprehensi67

Accumulated Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		$ 2,370,368
Cumulative-effect adjustment (net of tax expense of $1,579)	[1]			$ 20,106
Other comprehensive loss:
Net unrealized gains/losses arising during the period		(13,775)	$ 16,734
Reclassification of net realized gain into earnings (net of zero tax impact)		(962)	(386)
Other comprehensive (loss) income, net of tax		(14,737)	16,348
Accumulated other comprehensive (loss) income		30,360		48,018
Less: Other comprehensive income attributable to non-controlling interests		(1,243)	6,890
Ending balance		2,279,350
Net unrealized gain during the period (loss), tax		0	5,836
Reclassification of net realized gain into earnings, tax		0	0
Cumulative effect adjustment, tax				1,579
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(13,412)	(22,133)
Cumulative-effect adjustment (net of tax expense of $1,579)				0
Other comprehensive loss:
Net unrealized gains/losses arising during the period		(3,283)	2,680
Reclassification of net realized gain into earnings (net of zero tax impact)		0	0
Other comprehensive (loss) income, net of tax		(3,283)	2,680
Accumulated other comprehensive (loss) income				(16,695)	$ (19,453)
Less: Other comprehensive income attributable to non-controlling interests		0	918
Ending balance		(16,695)	(20,371)
Net unrealized gain during the period (loss), tax		0	0
Reclassification of net realized gain into earnings, tax		0	0
Cumulative effect adjustment, tax				0
Hedging Activities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		61,430	45,045
Cumulative-effect adjustment (net of tax expense of $1,579)				(4,164)
Other comprehensive loss:
Net unrealized gains/losses arising during the period		(10,492)	14,054
Reclassification of net realized gain into earnings (net of zero tax impact)		(962)	(386)
Other comprehensive (loss) income, net of tax		(11,454)	13,668
Accumulated other comprehensive (loss) income				45,812	58,713
Less: Other comprehensive income attributable to non-controlling interests		(1,243)	5,972
Ending balance		47,055	52,741
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		48,018	22,912
Cumulative-effect adjustment (net of tax expense of $1,579)				(4,164)
Other comprehensive loss:
Accumulated other comprehensive (loss) income				$ 29,117	$ 39,260
Ending balance		$ 30,360	$ 32,370
[1]	See Note 2. Summary of Significant Accounting Policies for discussion regarding the Company’s adoption of Accounting Standards Update No. 2014-09, Accounting Standards Update No. 2016-08 and Accounting Standards Update No. 2017-12 as of January 1, 2018.

Subsequent Events (Details)

Subsequent Events (Details) - $ / shares	Apr. 30, 2018	Mar. 31, 2018	Mar. 31, 2017
Subsequent Event [Line Items]
Class A common stock (dollars per share)		$ 0.19	$ 0
Subsequent Event
Subsequent Event [Line Items]
Class A common stock (dollars per share)	$ 0.19