Via Renewables (VIASP) 10-Q 2 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	SPKE
Entity Registrant Name	Spark Energy, Inc.
Entity Central Index Key	1,606,268
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	false
Entity Ex Transition Period	true
Class A Common Stock
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		13,393,712
Class B Common Stock
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		21,485,126

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 42,796,000	$ 29,419,000
Accounts receivable, net of allowance for doubtful accounts of $4,324 at September 30 and $4,023 at December 31	134,183,000	158,814,000
Accounts receivable—affiliates	3,807,000	3,661,000
Inventory	4,077,000	4,470,000
Fair value of derivative assets	23,427,000	31,191,000
Customer acquisition costs, net	15,600,000	22,123,000
Customer relationships, net	18,360,000	18,653,000
Deposits	12,631,000	7,701,000
Other current assets	31,074,000	20,706,000
Total current assets	285,955,000	296,738,000
Property and equipment, net	5,383,000	8,275,000
Fair value of derivative assets	1,873,000	3,309,000
Customer acquisition costs, net	3,466,000	6,949,000
Customer relationships, net	28,247,000	34,839,000
Deferred tax assets	24,935,000	24,185,000
Goodwill	120,343,000	120,154,000
Other assets	11,075,000	11,500,000
Total assets	481,277,000	505,949,000
Current liabilities:
Accounts payable	55,496,000	77,510,000
Accounts payable—affiliates	2,836,000	4,622,000
Accrued liabilities	45,518,000	33,679,000
Fair value of derivative liabilities	269,000	1,637,000
Current portion of Senior Credit Facility	0	7,500,000
Current payable pursuant to tax receivable agreement—affiliates	2,508,000	5,937,000
Current contingent consideration for acquisitions	2,980,000	4,024,000
Other current liabilities	856,000	2,675,000
Current portion of note payable	10,535,000	13,443,000
Total current liabilities	120,998,000	151,027,000
Long-term liabilities:
Fair value of derivative liabilities	489,000	492,000
Payable pursuant to tax receivable agreement—affiliates	26,067,000	26,355,000
Long-term portion of Senior Credit Facility	112,000,000	117,750,000
Subordinated debt—affiliate	10,000,000	0
Long-term portion of note payable	0	7,051,000
Contingent consideration for acquisitions	0	626,000
Other long-term liabilities	0	172,000
Total liabilities	269,554,000	303,473,000
Commitments and contingencies (Note 13)
Series A Preferred Stock, par value $0.01 per share, 20,000,000 shares authorized, 3,707,256 shares issued and outstanding at September 30 and 1,704,339 shares issued and outstanding at December 31	90,758,000	41,173,000
Additional paid-in capital	25,387,000	26,914,000
Accumulated other comprehensive loss	(15,000)	(11,000)
Retained earnings	2,885,000	11,008,000
Treasury stock, at cost, 99,446 shares at September 30 and December 31	(2,011,000)	(2,011,000)
Total stockholders' equity	26,597,000	36,248,000
Non-controlling interest in Spark HoldCo, LLC	94,368,000	125,055,000
Total equity	120,965,000	161,303,000
Total liabilities, Series A Preferred Stock and stockholders' equity	481,277,000	505,949,000
Class A Common Stock
Common stock	135,000	132,000
Class B Common Stock
Common stock	$ 216,000	$ 216,000

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 4,324	$ 4,023
Preferred stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	3,707,256	1,704,339
Preferred stock, shares outstanding (in shares)	3,707,256	1,704,339
Treasury stock, at cost (in shares)	99,446	99,446
Common Class A
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	13,493,158	13,235,082
Common stock, shares outstanding (in shares)	13,393,712	13,135,636
Common Class B
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	60,000,000	60,000,000
Common stock, shares issued (in shares)	21,485,126	21,485,126
Common stock, shares outstanding (in shares)	21,485,126	21,485,126

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Retail revenues	$ 258,127	$ 215,856	$ 773,616	$ 563,960
Net asset optimization revenues/(expense)	348	(320)	3,798	(681)
Total Revenues	258,475	215,536	777,414	563,279
Operating Expenses:
Retail cost of revenues	193,409	160,373	645,954	420,771
General and administrative	25,695	25,566	83,522	69,405
Depreciation and amortization	13,917	11,509	39,797	30,435
Total Operating Expenses	233,021	197,448	769,273	520,611
Operating income	25,454	18,088	8,141	42,668
Other (expense)/income:
Interest expense	(2,762)	(2,863)	(7,323)	(8,760)
Interest and other income (loss)	(47)	168	707	102
Total other expenses	(2,809)	(2,695)	(6,616)	(8,658)
Income before income tax expense	22,645	15,393	1,525	34,010
Income tax expense	3,818	2,451	602	5,265
Net income	18,827	12,942	923	28,745
Less: Net income attributable to non-controlling interests	13,218	10,595	140	23,049
Net income attributable to Spark Energy, Inc. stockholders	5,609	2,347	783	5,696
Less: Dividend on Series A preferred stock	2,027	932	6,081	2,106
Net income (loss) attributable to stockholders of Class A common stock	3,582	1,415	(5,298)	3,590
Other comprehensive income, net of tax:
Currency translation gain (loss)	47	(13)	(11)	(88)
Other comprehensive income (loss)	47	(13)	(11)	(88)
Comprehensive income	18,874	12,929	912	28,657
Less: Comprehensive income attributable to non-controlling interests	13,247	10,587	133	22,994
Comprehensive income attributable to Spark Energy, Inc. stockholders	$ 5,627	$ 2,342	$ 779	$ 5,663
Net income (loss) attributable to Spark Energy, Inc. per share of Class A common stock
Basic (in dollars per share)	$ 0.27	$ 0.11	$ (0.40)	$ 0.27
Diluted (in dollars per share)	$ 0.27	$ 0.11	$ (0.40)	$ 0.27
Weighted average shares of Class A common stock outstanding
Basic (in shares)	13,394	13,235	13,254	13,112
Diluted (in shares)	13,394	13,392	13,254	13,315
Dividends declared per Class A common stock (in dollars per share)	$ 0.18125	$ 0.18125	$ 0.54375	$ 0.54375

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - 9 months ended Sep. 30, 2018 - USD ($) shares in Thousands, $ in Thousands	Total	Total Stockholders' Equity	Common StockClass A Common Stock	Common StockClass B Common Stock	Treasury Stock	Accumulated Other Comprehensive Loss	Additional Paid-in Capital	Retained Earnings (Deficit)	Non-controlling Interest
Balance at beginning of period (in shares) at Dec. 31, 2017			13,235	21,485	99
Balance at beginning of period at Dec. 31, 2017	$ 161,303	$ 36,248	$ 132	$ 216	$ (2,011)	$ (11)	$ 26,914	$ 11,008	$ 125,055
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation	3,596	3,596					3,596
Restricted stock unit vesting (in shares)			258
Restricted stock unit vesting	(712)	(712)	$ 3				(715)
Consolidated net income	923	783						783	140
Foreign currency translation adjustment for equity method investee	(11)	(4)				(4)			(7)
Distributions paid to non-controlling unit holders	(23,701)
Dividends paid to Class A common stockholders	(7,233)	(7,233)					(2,381)	(4,852)
Dividends to Preferred Stock	(6,081)	(6,081)					(2,027)	(4,054)
Acquisition of Customers from Affiliate	(7,119)								(7,119)
Balance at end of period (in shares) at Sep. 30, 2018			13,493	21,485	99
Balance at end of period at Sep. 30, 2018	$ 120,965	$ 26,597	$ 135	$ 216	$ (2,011)	$ (15)	$ 25,387	$ 2,885	$ 94,368

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 923,000	$ 28,745,000
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation and amortization expense	38,538,000	30,584,000
Deferred income taxes	(749,000)	681,000
Change in TRA liability	79,000	0
Stock based compensation	3,707,000	4,023,000
Amortization of deferred financing costs	1,243,000	750,000
Excess tax benefit related to restricted stock vesting	(101,000)	179,000
Change in Fair Value of Earnout liabilities	(63,000)	(9,423,000)
Accretion on fair value of Earnout liabilities	0	3,787,000
Bad debt expense	8,480,000	3,436,000
Loss on derivatives, net	1,371,000	34,225,000
Current period cash settlements on derivatives, net	6,189,000	(20,816,000)
Accretion of discount to convertible subordinated notes to affiliate	0	1,004,000
Other	(489,000)	123,000
Changes in assets and liabilities:
Decrease in accounts receivable	21,029,000	18,056,000
Increase in accounts receivable—affiliates	(390,000)	(2,508,000)
Decrease (increase) in inventory	475,000	(1,936,000)
Increase in customer acquisition costs	(8,949,000)	(18,642,000)
(Increase) decrease in prepaid and other current assets	(10,999,000)	1,536,000
Increase in intangible assets—customer acquisitions	(86,000)	(32,000)
Decrease (increase) in other assets	92,000	(664,000)
Decrease in accounts payable and accrued liabilities	(11,062,000)	(9,301,000)
(Decrease) increase in accounts payable—affiliates	(1,786,000)	1,165,000
(Decrease) increase in other current liabilities	(5,140,000)	22,000
Decrease in other non-current liabilities	(459,000)	(1,170,000)
Net cash provided by operating activities	41,853,000	62,043,000
Cash flows from investing activities:
Purchases of property and equipment	(1,097,000)	(1,438,000)
Acquisitions of Perigee and other customers	0	(11,464,000)
Acquisition of the Verde Companies	0	(65,785,000)
Verde working capital settlement	470,000	0
Acquisition of HIKO	(14,290,000)	0
Acquisition of Customers from Affiliate	(8,776,000)	0
Net cash used in investing activities	(23,693,000)	(78,687,000)
Cash flows from financing activities:
Proceeds from issuance of Series A Preferred Stock, net of issuance costs paid	48,490,000	40,312,000
Borrowings on notes payable	277,800,000	139,400,000
Payments on notes payable	(281,050,000)	(119,664,000)
Payments on the Verde promissory note	(6,573,000)	(2,149,000)
Proceeds from disgorgement of stockholders short-swing profits	244,000	872,000
Restricted stock vesting	(2,589,000)	(2,009,000)
Payment of Tax Receivable Agreement liability	(3,577,000)	0
Payment of dividends to Class A common stockholders	(7,233,000)	(7,137,000)
Payment of distributions to non-controlling unitholders	(23,701,000)	(24,270,000)
Payment of Dividends to Preferred Stock	(4,987,000)	(1,174,000)
Purchase of Treasury Stock	0	(1,888,000)
Net cash (used in) provided by financing activities	(4,783,000)	8,933,000
Increase (decrease) in Cash and cash equivalents	13,377,000	(7,711,000)
Cash and cash equivalents—beginning of period	29,419,000	18,960,000
Cash and cash equivalents—end of period	42,796,000	11,249,000
Non-cash items:
Contingent consideration—earnout obligations incurred in connection with the Verde Companies acquisition	0	5,400,000
Net contribution by NG&E in excess of cash	0	1,019,000
Installment consideration incurred in connection with the Verde Companies acquisition	0	17,851,000
Property and equipment purchase accrual	(123,000)	41,000
Cash paid during the period for:
Interest	5,955,000	4,113,000
Taxes	7,461,000	7,769,000
Major Energy Companies
Adjustments to reconcile net income to net cash flows provided by operating activities:
Payments of Earnout	0	(1,104,000)
Cash flows from financing activities:
Payment of the Earnout and installment consideration	(1,607,000)	(6,299,000)
Provider Companies
Adjustments to reconcile net income to net cash flows provided by operating activities:
Payments of Earnout	0	(677,000)
Cash flows from financing activities:
Payment of the Earnout and installment consideration	$ 0	$ (7,061,000)

Formation and Organization

Formation and Organization	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Formation and Organization	1. Formation and Organization Organization Spark Energy is an independent retail energy services company that provides residential and commercial customers in competitive markets across the United States with an alternative choice for natural gas and electricity. The Company is a holding company whose sole material asset consists of units in Spark HoldCo, LLC (“Spark HoldCo”). The Company is the sole managing member of Spark HoldCo, is responsible for all operational, management and administrative decisions relating to Spark HoldCo’s business and consolidates the financial results of Spark HoldCo and its subsidiaries. Spark HoldCo is the direct and indirect owner of the subsidiaries through which we operate. We conduct our business through several brands across our service areas, including Spark Energy, Verde Energy, Oasis Energy, CenStar Energy, Provider Power Massachusetts, Electricity Maine, Electricity N.H., Major Energy, Respond Power, HIKO Energy, and Perigee Energy. Relationship with our Founder and Majority Shareholder W. Keith Maxwell, III (our "Founder") is the owner of a majority in voting power of our common stock through his ownership of NuDevco Retail, LLC ("NuDevco Retail") and Retailco, LLC ("Retailco"). Retailco is a wholly owned subsidiary of TxEx Energy Investments, LLC ("TxEx"), which is wholly owned by Mr. Maxwell. NuDevco Retail is a wholly owned subsidiary of NuDevco Retail Holdings LLC ("NuDevco Retail Holdings"), which is a wholly owned subsidiary of Electric HoldCo, LLC, which is also a wholly owned subsidiary of TxEx.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	2. Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation The accompanying interim unaudited condensed consolidated financial statements (“interim statements”) of the Company have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC") as it applies to interim financial statements. This information should be read along with our consolidated financial statements and notes contained in our annual report on Form 10-K for the year ended December 31, 2017 . Our unaudited condensed consolidated financial statements are presented on a consolidated basis and include all wholly-owned and controlled subsidiaries. We account for investments over which we have significant influence but not a controlling financial interest using the equity method of accounting. All significant intercompany transactions and balances have been eliminated in the unaudited condensed consolidated financial statements. Subsequent Events Subsequent events have been evaluated through the date these financial statements are issued. Any material subsequent events that occurred prior to such date have been properly recognized or disclosed in the condensed consolidated financial statements. See Note 16 "Subsequent Events" for further discussion. Use of Estimates The preparation of our condensed consolidated financial statements requires estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the interim financial statements and the reported amounts of revenues and expenses during the period. Actual results could materially differ from those estimates. Effects on the business, financial condition and results of operations resulting from revisions to estimates are recognized when the facts that give rise to the revision become known. The information furnished herein reflects all normal recurring adjustments that are, in the opinion of management, necessary for a fair presentation of the condensed consolidated financial statements. Operating results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results that may be expected for the full year or for any interim period. Significant Accounting Policies There have been no changes to our significant accounting policies as disclosed in our Annual Report on Form 10-K for the year ended December 31, 2017, except as follows: In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers , which 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. We adopted the new standard effective January 1, 2018 utilizing the full retrospective approach. The adoption of the new standard resulted in no impact to our total revenues and operating income for the years ended December 31, 2017 and 2016. The standard requires expanded disclosures regarding the qualitative and quantitative information of an entity's nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. See Note 3 "Revenues" for further disclosure. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230), Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15"). ASU 2016-15 provides guidance on the presentation and classification of certain items in the statement of cash flows. This ASU has been applied using a retrospective transition method for each period presented. We adopted ASU 2016-15 effective January 1, 2018, which resulted in the reclassification of contingent consideration payments made after a business combination as cash outflows for operating and financing activities on a retrospective basis. Because of the change in accounting guidance, we reclassified acquisition related payments of approximately $1.8 million from cash flows from investing activities to cash flows from operating activities for the nine months ended September 30, 2017 . We also reclassified other acquisition related payments of approximately $15.5 million from cash flows from investing activities to cash flows from financing activities for the nine months ended September 30, 2017 . In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business ("ASU 2017-01"). ASU 2017-01 clarifies 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. We adopted ASU 2017-01 effective January 1, 2018, using it to evaluate all acquisitions after that date. New Accounting Standards Being Evaluated But Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"). Under this new guidance, lessees will be required to recognize assets and liabilities on the balance sheet for the rights and obligations created by all leases with terms of greater than twelve months. The guidance requires qualitative disclosures along with certain specific quantitative disclosures for both lessees and lessors. In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842 , Leases (“ASU 2018-10”), and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements (“ASU 2018-11”), to provide additional guidance for the adoption of Topic 842. The ASU and its related amendments are effective for fiscal years beginning after December 15, 2018, with early adoption permitted, and are effective for interim periods in the year of adoption. The ASU should be applied using a modified retrospective approach, which requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented with an option to use certain practical expedients, which we expect to use. We are continuing to evaluate the impact of this new guidance and have put in place a process to review lease contracts, evaluate existing lease related processes and design training related to the new standard. Although we are in the process of evaluating the impact of the new lease guidance on our consolidated financial statements, we currently believe the primary impact will be related to our real estate operating leases. In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ("ASU 2017-04"). ASU 2017-04 simplifies the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. Under this update, an entity should perform its annual or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, including goodwill. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. However, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. ASU 2017-04 should be applied on a prospective basis and is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We are currently evaluating the impact of adopting this guidance on its consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Non-employee Share-Based Payment Accounting ("ASU 2018-07"). ASU 2018-07 primarily expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. We are currently evaluating the impact of adopting this guidance on its consolidated financial statements. In July 2018, the FASB issued ASU No. 2018-09, Codification Improvements ("ASU 2018-09"). ASU 2018-09 represent changes to clarify, correct errors in, or make minor improvements to the Codification to a variety of topics, including comprehensive income, debt modifications and extinguishment, stock compensation, income taxes, fair value measurement, financial brokers and dealers, and defined contribution plans. The transition and effective date guidance is based on the facts and circumstances of each amendment. Many of the amendments in this Update do have transition guidance with effective dates for annual periods beginning after December 15, 2018. We are currently evaluating the impact of adopting this guidance on its consolidated financial statements.

Revenues

Revenues	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenues	3. Revenues Our revenues are derived primarily from the sale of natural gas and electricity to retail customers. We also record revenue from sales of natural gas and electricity to wholesale counterparties, including affiliates. Revenue is measured based upon the quantity of gas or power delivered to the retail customer or wholesale counterparty at prices contained or referenced in the customer's contract, and excludes any sales incentives (e.g. rebates) and amounts collected on behalf of third parties (e.g. sales tax). We record gross receipts taxes on a gross basis in retail revenues and retail cost of revenues. During the three months ended September 30, 2018 and 2017 , our retail revenues included gross receipts taxes of $2.2 million and $2.1 million , respectively. During the three months ended September 30, 2018 and 2017 , our retail cost of revenues included gross receipts taxes of $2.7 million and $2.7 million , respectively. During the nine months ended September 30, 2018 and 2017 , our retail revenues included gross receipts taxes of $6.5 million and $4.6 million , respectively. During the nine months ended September 30, 2018 and 2017 , our retail cost of revenues included gross receipts taxes of $7.8 million and $6.6 million , respectively. Our revenues also include asset optimization activities. Asset optimization activities consist primarily of purchases and sales of gas that meet the definition of trading activities per FASB ASC Topic 815, Derivatives and Hedging. They are therefore excluded from the scope of Revenue from Contracts with Customers (Topic 606). The following is a description of our principal revenue generating activities. Retail Electricity Revenues for electricity sales are recognized under the accrual method when our performance obligation to a customer is satisfied, which is the point in time when the product is delivered and control of the product passes to the customer. Electricity products may be sold as fixed or variable rate products. The typical length of a contract to provide electricity is 12 months. Customers are billed and typically pay at least monthly, based on usage. Electricity sales that have been delivered but not billed by period end are estimated. Accrued unbilled revenues are based on estimates of customer usage since the date of the last meter read provided by the utility. Volume estimates are based on forecasted volumes and estimated residential and commercial customer usage. Unbilled revenues are calculated by multiplying these volume estimates by the applicable rate by customer class (residential or commercial). Estimated amounts are adjusted when actual usage is known and billed. Retail Natural Gas Revenues for natural gas sales are recognized under the accrual method when our performance obligation to a customer is satisfied, which is the point in time when the product is delivered and control of the product passes to the customer. Natural gas products may be sold as fixed-price or variable-price products. The typical length of a contract to provide natural gas is 12 months. Customers are billed and typically pay at least monthly, based on usage. Natural gas sales that have been delivered but not billed by period end are estimated and recorded as accrued unbilled revenues based on estimates of customer usage since the date of the last meter read provided by the utility. Volume estimates are based on forecasted volumes and estimated residential and commercial customer usage. Unbilled revenues are calculated by multiplying these volume estimates by the applicable rate by customer class (residential or commercial). Estimated amounts are adjusted when actual usage is known and billed. The following table discloses revenue by primary geographical market, customer type, and customer credit risk profile (in thousands). The table also includes a reconciliation of the disaggregated revenue to revenue by reportable segment (in thousands). Reportable Segments Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Retail Electricity Retail Natural Gas Total Reportable Segments Retail Electricity Retail Natural Gas Total Reportable Segments Primary markets (a) New England $ 110,870 $ 2,163 $ 113,033 $ 61,421 $ 2,157 $ 63,578 Mid-Atlantic 83,846 3,762 87,608 83,955 4,543 88,498 Midwest 20,898 2,557 23,455 20,111 2,570 22,681 Southwest 30,568 3,463 34,031 36,772 4,327 41,099 $ 246,182 $ 11,945 $ 258,127 $ 202,259 $ 13,597 $ 215,856 Customer type Commercial $ 101,818 $ 4,650 $ 106,468 $ 55,489 $ 5,004 $ 60,493 Residential 151,918 7,068 158,986 143,152 8,571 151,723 Unbilled revenue (b) (7,554 ) 227 (7,327 ) 3,618 22 3,640 $ 246,182 $ 11,945 $ 258,127 $ 202,259 $ 13,597 $ 215,856 Customer credit risk POR $ 172,198 $ 5,013 $ 177,211 $ 138,544 $ 5,963 $ 144,507 Non-POR 73,984 6,932 80,916 63,715 7,634 71,349 $ 246,182 $ 11,945 $ 258,127 $ 202,259 $ 13,597 $ 215,856 Reportable Segments Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Retail Electricity Retail Natural Gas Total Reportable Segments Retail Electricity Retail Natural Gas Total Reportable Segments Primary markets (a) New England $ 305,894 $ 14,742 $ 320,636 $ 157,334 $ 15,252 $ 172,586 Mid-Atlantic 229,329 39,112 268,441 197,877 35,664 233,541 Midwest 56,818 27,243 84,061 43,073 23,893 66,966 Southwest 84,487 15,991 100,478 69,577 21,290 90,867 $ 676,528 $ 97,088 $ 773,616 $ 467,861 $ 96,099 $ 563,960 Customer type Commercial $ 275,966 $ 39,826 $ 315,792 $ 140,408 $ 40,224 $ 180,632 Residential 415,022 73,138 488,160 322,354 70,886 393,240 Unbilled revenue (b) (14,460 ) (15,876 ) (30,336 ) 5,099 (15,011 ) (9,912 ) $ 676,528 $ 97,088 $ 773,616 $ 467,861 $ 96,099 $ 563,960 Customer credit risk POR $ 473,438 $ 54,565 $ 528,003 $ 318,440 $ 47,907 $ 366,347 Non-POR 203,090 42,523 245,613 149,421 48,192 197,613 $ 676,528 $ 97,088 $ 773,616 $ 467,861 $ 96,099 $ 563,960 (a) The primary markets noted above include the following states: • New England - Connecticut, Maine, Massachusetts, New Hampshire; • Mid-Atlantic - Delaware, Maryland (including the District of Colombia), New Jersey, New York and Pennsylvania; • Midwest - Illinois, Indiana, Michigan and Ohio; and • Southwest - Arizona, California, Colorado, Florida, Nevada, and Texas. (b) Unbilled revenue is recorded in total until it is actualized, at which time it is categorized between commercial and residential customers.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions	4. Acquisitions Acquisition of HIKO On March 1, 2018, we entered into a Membership Interest Purchase Agreement under which we acquired all of the membership interests of HIKO Energy, LLC ("HIKO"), a New York limited liability company, for a total purchase price of $6.0 million in cash, plus working capital. At the time of acquisition, HIKO had a total of approximately 29,000 RCEs located in 42 markets in seven states. The acquisition was accounted for under the acquisition method in accordance with ASC 805, Business Combinations (“ASC 805”). Our preliminary allocation of the purchase price was based upon the estimated fair value of the tangible and identified intangible assets acquired and liabilities assumed in the acquisition. The preliminary allocation was made based on management’s best estimates, and supported by independent third-party analyses. The allocation of the purchase consideration is as follows (in thousands): Reported as of March 31, 2018 2018 Adjustments (1) As of September 30, 2018 Cash and restricted cash $ 309 $ 66 $ 375 Intangible assets — customer relationships 6,205 (174 ) 6,031 Net working capital, net of cash acquired 9,041 (576 ) 8,465 Fair value of derivative liabilities (205 ) — (205 ) Total $ 15,350 $ (684 ) $ 14,666 (1) Changes to the purchase price allocation in 2018 were due to an agreement to settle the working capital balances with HIKO sellers per the purchase agreement. Our condensed consolidated statements of operations for the three months ended September 30, 2018 included $4.9 million of revenue and $1.1 million of net income related to the operations of HIKO. Our condensed consolidated statements of operations for the nine months ended September 30, 2018 included $12.9 million of revenue and $3.7 million of net income related to the operations of HIKO. Acquisition of Verde On July 1, 2017, we acquired, through our subsidiary CenStar Energy Corp. ("CenStar"), all of the outstanding membership interests and stock in a group of companies (the "Verde Companies") from Verde Energy USA Holdings, LLC (the "Seller"). Total consideration was approximately $90.7 million , of which $20.1 million represented positive net working capital, as adjusted. We funded the closing consideration of $85.8 million through: (i) approximately $6.8 million of cash on hand, (ii) approximately $15.0 million in subordinated debt from our Founder through a subordinated debt facility, (iii) approximately $44.0 million in borrowings under our senior secured revolving credit facility, and (iv) the issuance of a promissory note to the Seller in the aggregate principal amount of $20.0 million (the “Promissory Note”). In addition to the consideration paid at closing, we were obligated to pay an additional amount based on achievement by the Verde Companies of certain performance targets over the 18 month period following the closing of the acquisition (the "Verde Earnout"). The Verde Earnout was initially valued at $5.4 million . In January 2018, Spark and the Seller agreed to terminate the Verde Earnout and settled the Verde Earnout obligation with the issuance of a $5.9 million promissory note payable to the Seller due in June 2019. The acquisition of the Verde Companies was accounted for under the acquisition method in accordance with ASC 805, Business Combinations (“ASC 805”). The allocation of purchase consideration was based upon the estimated fair value of the tangible and identifiable intangible assets acquired and liabilities assumed in the acquisition based on management’s best estimates, and supported by independent third-party analyses. The excess of the purchase price over the estimated fair value of tangible and intangible assets acquired and liabilities assumed was allocated to goodwill. The final allocation of the purchase consideration is as follows (in thousands): Reported as of December 31, 2017 Adjustments (1) As of September 30, 2018 Cash and restricted cash $ 1,653 $ — $ 1,653 Property and equipment 4,560 — 4,560 Intangible assets — customer relationships 28,700 — 28,700 Intangible assets — trademarks 3,000 — 3,000 Goodwill (1) 39,207 189 39,396 Net working capital, net of cash acquired (1) 19,132 (659 ) 18,473 Deferred tax liability (3,126 ) — (3,126 ) Fair value of derivative liabilities (1,942 ) — (1,942 ) Total $ 91,184 $ (470 ) $ 90,714 (1) Changes to the purchase price allocation in 2018 were due to an agreement to settle the working capital balances with Verde Companies' sellers per the purchase agreement. The following unaudited pro forma revenue and earnings summary presents our consolidated information as if the acquisition had occurred on January 1, 2016 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Revenues $ 215,536 $ 206,158 $ 633,639 $ 512,967 Earnings $ 2,347 $ 1,761 $ 4,991 $ 9,623 The pro forma results are not necessarily indicative of our consolidated results of operations in future periods or the results that actually would have been realized had the companies operated on a combined basis during the periods presented. The pro forma results above include actual results and costs as well as adjustments primarily related to amortization of acquired intangibles, and certain accounting policy alignments as well as direct and incremental acquisition related costs reflected in the historical financial statements. The preliminary purchase price allocation was used to prepare the pro forma adjustments. Acquisition of Perigee On April 1, 2017, the Company and Spark Holdco acquired all of the outstanding membership interests of Perigee Energy, LLC, a Texas limited liability company ("Perigee"), with operations across 14 utilities in Connecticut, Delaware, Massachusetts, New York and Ohio from our affiliate, National Gas & Electric ("NG&E"). The purchase price for Perigee from NG&E was approximately $4.1 million , which consisted of a base price of $2.0 million , $0.2 million additional customer option payment, and $1.9 million in working capital, subject to adjustments. The acquisition was a transfer of equity interests between entities under common control, and accordingly, the assets acquired and liabilities assumed were based on their historical value as of the acquisition date. NG&E acquired Perigee on February 3, 2017 and the fair value of the net assets acquired was as follows (in thousands): Final as of December 31, 2017 Cash $ 23 Intangible assets — customer relationships 1,100 Goodwill 1,540 Net working capital, net of cash acquired 2,085 Fair value of derivative liabilities (443 ) Total $ 4,305 In each of our acquisitions, we evaluate and allocate purchase price based on the following general assumptions. Customer relationships Acquired customer relationships intangibles are reflective of the acquired companies' customer bases, and were valued using an excess earnings method under the income approach. Using this method, we estimate the future cash flows resulting from the existing customer relationships, considering estimated attrition as well as charges for contributory assets, such as net working capital, intangible assets, fixed assets, and any assembled workforce. These future cash flows are then discounted using an appropriate risk-adjusted rate of return to arrive at the present value of the expected future cash flows. These customer relationships are amortized to depreciation and amortization based on the expected future net cash flows by year. In the Verde acquisition, customer relationships were bifurcated between unhedged and hedged and are being amortized based on the expected term of the underlying fixed price contract acquired in each reporting period, respectively. Trademarks The fair value of acquired trademarks is reflective of the value associated with the recognition and reputation of the acquired company to target markets. The fair value of trademarks are valued using a royalty savings method under the income approach. The value is based on the savings we would realize from owning the trademark rather than paying a royalty for the use of that trademark. Under this approach, we estimate the present value of the expected cash flows resulting from avoiding royalty payments to use a third party trademark. In the Verde acquisition, we analyzed market royalty rates charged for licensing trademarks and applied an expected royalty rate to a forecast of estimated revenue, which was then discounted using an appropriate risk adjusted rate of return. Trademarks are amortized over the estimated life of the asset on a straight-line basis. Goodwill The excess of the purchase consideration over the estimated fair value of the amounts initially assigned to the identifiable assets acquired and liabilities assumed is recorded as goodwill. Goodwill arose on the acquisitions of the Verde Companies and Perigee primarily due to the value of their assembled workforce, proprietary sales channels, and/or access to new utility service territories. Goodwill recorded in connection with these acquisitions is deductible for income tax purposes because these were acquisitions of all of the assets of the companies.

Equity

Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Equity	5. Equity Non-controlling Interest We hold an economic interest and are the sole managing member in Spark HoldCo, with NuDevco Retail and Retailco holding the remaining economic interests in Spark HoldCo. As a result, we have consolidated the financial position and results of operations of Spark HoldCo and reflected the economic interests owned by NuDevco Retail and Retailco as a non-controlling interest. The Company and NuDevco Retail and Retailco owned the following economic interests in Spark HoldCo at December 31, 2017 and September 30, 2018 , respectively. The Company NuDevco Retail and Retailco (1) December 31, 2017 38.12 % 61.88 % September 30, 2018 38.58 % 61.42 % The following table summarizes the portion of net income and income tax benefit attributable to non-controlling interest (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Net income allocated to non-controlling interest $ 13,910 $ 9,525 $ 830 $ 21,094 Income tax expense (benefit) allocated to non-controlling interest 692 (1,070 ) 690 (1,955 ) Net income attributable to non-controlling interest $ 13,218 $ 10,595 $ 140 $ 23,049 Share Repurchase Program On May 24, 2017, the Company authorized a share repurchase program of up to $50.0 million of Spark Class A common stock through December 31, 2017. The Company funded the program through available cash balances, its credit facilities, and operating cash flows. The share repurchase program expired on December 31, 2017. Treasury Stock We use the cost method to account for our treasury shares. Purchases of shares of Class A common stock are recorded at cost. Class A Common Stock and Class B Common Stock Holders of the Company's Class A common stock and Class B common stock vote together as a single class on all matters presented to our shareholders for their vote or approval, except as otherwise required by applicable law or by our certificate of incorporation. Dividends declared for the Company's Class A common stock are reported as a reduction of retained earnings, or additional paid in capital in the case retained earnings is exhausted. Earnings Per Share Basic earnings per share (“EPS”) is computed by dividing net income attributable to stockholders (the numerator) by the weighted-average number of Class A common shares outstanding for the period (the denominator). Class B common shares are not included in the calculation of basic earnings per share because they are not participating securities and have no economic interest in us. Diluted earnings per share is similarly calculated except that the denominator is increased (1) using the treasury stock method to determine the potential dilutive effect of our outstanding unvested restricted stock units and (2) using the if-converted method to determine the potential dilutive effect of our Class B common stock. The following table presents the computation of earnings (loss) per share for the three and nine months ended September 30, 2018 and 2017 (in thousands, except per share data): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Net income attributable to Spark Energy, Inc. stockholders $ 5,609 $ 2,347 $ 783 $ 5,696 Less: Dividend on Series A preferred stock 2,027 932 6,081 2,106 Net income (loss) attributable to stockholders of Class A common stock $ 3,582 $ 1,415 $ (5,298 ) $ 3,590 Basic weighted average Class A common shares outstanding 13,394 13,235 13,254 13,112 Basic earnings (loss) per share attributable to stockholders $ 0.27 $ 0.11 $ (0.40 ) $ 0.27 Net income (loss) attributable to stockholders of Class A common stock $ 3,582 $ 1,415 $ (5,298 ) $ 3,590 Effect of conversion of Class B common stock to shares of Class A common stock — — — — Diluted net income (loss) attributable to stockholders of Class A common stock $ 3,582 $ 1,415 $ (5,298 ) $ 3,590 Basic weighted average Class A common shares outstanding 13,394 13,235 13,254 13,112 Effect of dilutive Class B common stock — — — — Effect of dilutive restricted stock units — 157 — 203 Diluted weighted average shares outstanding 13,394 13,392 13,254 13,315 Diluted earnings (loss) per share attributable to stockholders $ 0.27 $ 0.11 $ (0.40 ) $ 0.27 The computation of diluted earnings per share for the three and nine months ended September 30, 2018 excludes 21.5 million shares of Class B common stock and 0.8 million restricted stock units because of their antidilutive effect. The Company's outstanding shares of Series A Preferred Stock were not included in the calculation of diluted earnings per share because they contain only contingent redemption provisions which have not occurred. Variable Interest Entity Spark HoldCo is a variable interest entity due to its lack of rights to participate in significant financial and operating decisions and its inability to dissolve or otherwise remove its management. Spark HoldCo owns all of the outstanding membership interests in each of the operating subsidiaries through which we operate. We are the sole managing member of Spark HoldCo, manage Spark HoldCo's operating subsidiaries through this managing membership interest, and are considered the primary beneficiary of Spark HoldCo. The assets of Spark HoldCo cannot be used to settle our obligations except through distributions to us, and the liabilities of Spark HoldCo cannot be settled by us except through contributions to Spark HoldCo. The following table includes the carrying amounts and classification of the assets and liabilities of Spark HoldCo that are included in our condensed consolidated balance sheet as of September 30, 2018 (in thousands): September 30, 2018 Assets Current assets: Cash and cash equivalents $ 42,677 Accounts receivable 134,183 Other current assets 102,338 Total current assets 279,198 Non-current assets: Goodwill 120,343 Other assets 47,958 Total non-current assets 168,301 Total Assets $ 447,499 Liabilities Current liabilities: Accounts payable and accrued liabilities $ 101,004 Contingent consideration 2,980 Other current liabilities 14,496 Total current liabilities 118,480 Long-term liabilities: Long-term portion of Senior Credit Facility 112,000 Subordinated debt — affiliate 10,000 Other long-term liabilities 489 Total long-term liabilities 122,489 Total Liabilities $ 240,969

Preferred Stock

Preferred Stock	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Preferred Stock	6. Preferred Stock On March 15, 2017, we issued 1,610,000 shares of 8.75% Series A Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock ("Series A Preferred Stock"), par value $0.01 per share and liquidation preference $25.00 per share, plus accumulated and unpaid dividends, at a price to the public of $25.00 per share ( $24.21 per share to us, net of underwriting discounts and commissions). We received approximately $39.0 million in net proceeds from the offering, after deducting underwriting discounts and commissions and a structuring fee. Offering expenses of $1.0 million were recorded as a reduction to the carrying value of the Series A Preferred Stock. The net proceeds from the offering were contributed to Spark HoldCo to use for general corporate purposes. On July 21, 2017, we entered into an At-the-Market Issuance Sales Agreement ("the ATM Agreement") with FBR Capital Markets & Co. as sales agent (the "Agent"). Pursuant to the terms of the ATM Agreement, we may sell, from time to time through the Agent, our Series A Preferred Stock, having an aggregate offering price of up to $50.0 million . During the year ended December 31, 2017, we sold an aggregate of 94,339 shares of Series A Preferred Stock under the ATM Agreement. We received net proceeds of $2.4 million and paid compensation to the sales agent of less than $0.1 million with respect to these sales. During the nine months ended September 30, 2018 , we sold an aggregate of 2,917 shares of Series A Preferred Stock under the ATM Agreement. We received net proceeds of $0.1 million and paid compensation to the sales agent of less than $0.1 million with respect to these sales. On January 23, 2018, we commenced a public offering of our Series A Preferred Stock pursuant to an effective shelf registration statement on Form S-3 previously filed with the SEC. The offering closed on January 26, 2018. As part of the offering, we issued 2,000,000 shares of Series A Preferred Stock, plus accumulated and unpaid dividends, at a price to the public of $25.25 per share ( $24.45 per share, net of underwriting discounts and commissions). The Company received approximately $48.9 million in net proceeds from the offering, after deducting underwriting discounts and commissions and a structuring fee. Offering expenses of $0.5 million were recorded as a reduction to the carrying value of the Series A Preferred Stock. The net proceeds from the offering were contributed to Spark HoldCo to use for general corporate purposes. Holders of the Series A Preferred Stock have no voting rights, except in specific circumstances of delisting or in the case the dividends are in arrears as specified in the Series A Preferred Stock Certificate of Designations. The Series A Preferred Stock accrue dividends at an annual percentage rate of 8.75% , and the liquidation preference provisions of the Series A Preferred Stock are considered contingent redemption provisions because there are rights granted to the holders of the Series A Preferred Stock that are not solely within our control upon a change in control of the Company. Accordingly, the Series A Preferred Stock is presented between liabilities and the equity sections in the accompanying consolidated balance sheet. During the three and nine months ended September 30, 2018 , respectively, we paid $2.0 million and $5.0 million in dividends to holders of the Series A Preferred Stock. As of September 30, 2018 , we had accrued $2.0 million related to dividends to holders of the Series A Preferred Stock. This dividend was paid on October 15, 2018 . A summary of our preferred equity balance for the nine months ended September 30, 2018 is as follows: (in thousands) Balance at December 31, 2017 $ 41,173 Issuance of Series A Preferred Stock, net of issuance cost 48,490 Accumulated dividends on Series A Preferred Stock 1,095 Balance at September 30, 2018 $ 90,758 In connection with the issuance of the Series A Preferred Stock, the Company and Spark HoldCo entered into the Third Amended and Restated Spark HoldCo Limited Liability Company Agreement to amend the prior agreement to provide for, among other things, the designation and issuance of Spark HoldCo Series A preferred units, as another equity security of Spark HoldCo to be issued concurrently with the issuance of Series A Preferred Stock by us, including specific terms relating to distributions by Spark HoldCo in connection with the payment by us of dividends on the Series A Preferred Stock, the priority of liquidating distributions by Spark HoldCo, the allocation of income and loss to us in connection with distributions by Spark HoldCo on Series A preferred units, and other terms relating to the redemption and conversion by us of the Series A Preferred Stock.

Property and Equipment

Property and Equipment	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment	7. Property and Equipment Property and equipment consist of the following amounts (in thousands): Estimated useful September 30, 2018 December 31, 2017 Information technology 2 – 5 $ 34,279 $ 34,103 Leasehold improvements 2 – 5 4,568 4,568 Furniture and fixtures 2 – 5 1,964 1,964 Building improvements 2 – 5 809 809 Total 41,620 41,444 Accumulated depreciation (36,237 ) (33,169 ) Property and equipment—net $ 5,383 $ 8,275 Information technology assets include software and consultant time used in the application, development and implementation of various systems including customer billing and resource management systems. As of September 30, 2018 and December 31, 2017 , information technology includes $0.5 million and $1.2 million , respectively, of costs associated with assets not yet placed into service. Depreciation expense recorded in the condensed consolidated statements of operations was $1.0 million and $0.8 million for the three months ended September 30, 2018 and 2017 , respectively, and $3.1 million and $1.8 million for the nine months ended September 30, 2018 and 2017 , respectively.

Goodwill, Customer Relationship

Goodwill, Customer Relationships and Trademarks	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Customer Relationships and Trademarks	5 years 3,802 Total $ 54,354" id="sjs-B4">8. Goodwill, Customer Relationships and Trademarks Goodwill, customer relationships and trademarks consist of the following amounts (in thousands): September 30, 2018 December 31, 2017 Goodwill $ 120,343 $ 120,154 Customer relationships - Acquired Cost $ 99,402 $ 93,371 Accumulated amortization (58,671 ) (46,681 ) Customer relationships - Acquired, net $ 40,731 $ 46,690 Customer relationships - Other Cost $ 14,080 $ 12,336 Accumulated amortization (8,204 ) (5,534 ) Customer relationships - Other, net $ 5,876 $ 6,802 Trademarks Cost $ 9,770 $ 9,770 Accumulated amortization (2,023 ) (1,212 ) Trademarks, net $ 7,747 $ 8,558 Changes in goodwill, customer relationships and trademarks consisted of the following (in thousands): Goodwill Customer Relationships - Acquired & Non-Compete Agreements Customer Relationships - Others Trademarks Balance at December 31, 2017 $ 120,154 $ 46,690 $ 6,802 $ 8,558 Additions — 6,205 1,744 — Adjustments (1) 189 (174 ) — — Amortization — (11,990 ) (2,670 ) (811 ) Balance at September 30, 2018 $ 120,343 $ 40,731 $ 5,876 $ 7,747 (1) Related to Spark's agreement to working capital balances with Verde Companies and HIKO sellers. Refer to Note 4 "Acquisitions." Estimated future amortization expense for customer relationships and trademarks at September 30, 2018 is as follows (in thousands): Year ending December 31, 2018 $ 5,877 2019 16,958 2020 11,692 2021 10,118 2022 5,907 > 5 years 3,802 Total $ 54,354

Debt

Debt	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt	9. Debt Debt consists of the following amounts as of September 30, 2018 and December 31, 2017 (in thousands): September 30, 2018 December 31, 2017 Current: Senior Credit Facility—Bridge Loan (2) $ — $ 7,500 Note Payable—Verde 10,535 13,443 Total current portion of debt 10,535 20,943 Long-term debt: Senior Credit Facility (1) (2) 112,000 117,750 Subordinated Debt 10,000 — Note Payable—Verde — 7,051 Total long-term debt 122,000 124,801 Total debt $ 132,535 $ 145,744 (1) As of September 30, 2018 and December 31, 2017 , we had $61.2 million and $47.2 million in letters of credit issued, respectively. (2) As of September 30, 2018 and December 31, 2017 , the weighted average interest rate on the Senior Credit Facility was 5.13% and 4.61% , respectively. Capitalized financing costs associated with our Senior Credit Facility were $1.5 million and $1.6 million as of September 30, 2018 and December 31, 2017 , respectively. Of these amounts, $1.5 million and $1.2 million are recorded in other current assets, and zero and $0.4 million are recorded in other non-current assets in the condensed consolidated balance sheet as of September 30, 2018 and December 31, 2017 , respectively. Interest expense consists of the following components for the periods indicated (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Senior Credit Facility $ 1,423 $ 988 $ 3,895 $ 2,216 Convertible subordinated notes to affiliate — — — 1,052 Subordinated debt 13 153 20 161 Verde promissory note 288 162 978 162 Accretion related to Earnouts — 1,127 — 3,787 Letters of credit and commitment fees 407 214 1,187 632 Amortization of deferred financing costs 631 219 1,243 750 Interest Expense $ 2,762 $ 2,863 $ 7,323 $ 8,760 Senior Credit Facility On May 19, 2017, the Company, as guarantor, and Spark HoldCo (the “Borrower” and, together with each subsidiary of Spark HoldCo (the “Co-Borrowers”), entered into a senior secured borrowing base credit facility (as amended, the “Senior Credit Facility”) in an aggregate amount of $120.0 million . The Verde Companies and HIKO became Co-Borrowers upon the completion of our acquisition of these companies. During November 2017, January 2018, and July 2018, the Company and Co-Borrowers entered into amendments to the Senior Credit Facility to increase commitments under the facility. In connection with the increase in commitments, the various limits on advances for Working Capital Loans, Letters of Credit and Bridge Loans were increased accordingly. Subject to applicable sublimits and terms of the Senior Credit Facility, as amended, borrowings are available for the issuance of letters of credit (“Letters of Credit”), working capital and general purpose revolving credit loans up to $250.0 million (“Working Capital Loans”), and bridge loans up to $62.5 million (“Bridge Loans”) for the purpose of partial funding for acquisitions. Borrowings under the Senior Credit Facility may be used to pay fees and expenses in connection with the current Senior Credit Facility, finance ongoing working capital requirements and general corporate purpose requirements of the Co-Borrowers, to provide partial funding for acquisitions, as allowed under terms of the Senior Credit Facility, and to make open market purchases of our Class A common stock and Series A Preferred Stock. As of September 30, 2018 , we had a maximum borrowing capacity of $192.5 million and $112.0 million outstanding under the Senior Credit Facility, as well as $61.2 million of outstanding letters of credit. The Senior Credit Facility, as amended, will mature on May 19, 2020, and all amounts outstanding thereunder will be payable on the maturity date. Borrowings under the Bridge Loan sublimit, if any, will be repaid 25% per year on a quarterly basis (or 6.25% per quarter), with the remainder due at maturity. As of September 30, 2018 , there were no Bridge Loans outstanding. At our election, the interest rate for Working Capital Loans and Letters of Credit under the Senior Credit Facility is generally determined by reference to the Eurodollar rate plus an applicable margin of up to 3.00% per annum (based on the prevailing utilization) or an alternate base rate plus an applicable margin of up to 2.00% per annum (based on the prevailing utilization). The alternate base rate is equal to the highest of (i) the prime rate (as published in the Wall Street Journal), (ii) the federal funds rate plus 0.50% per annum, or (iii) the reference Eurodollar rate plus 1.00% . Bridge Loan borrowings, if any, under the Senior Credit Facility are generally determined by reference to the Eurodollar rate plus an applicable margin of 3.75% per annum or an alternate base rate plus an applicable margin of 2.75% per annum. The alternate base rate is equal to the highest of (i) the prime rate (as published in the Wall Street Journal), (ii) the federal funds rate plus 0.50% per annum, or (iii) the reference Eurodollar rate plus 1.00% . The Co-Borrowers pay a commitment fee of 0.50% quarterly in arrears on the unused portion of the Senior Credit Facility. In addition, the Co-Borrowers are subject to additional fees including an upfront fee, an annual agency fee, and letter of credit fees based on a percentage of the face amount of letters of credit payable to any syndicate member that issues a letter of credit. The Senior Credit Facility contains covenants that, among other things, require the maintenance of specified ratios or conditions including: • Minimum Fixed Charge Coverage Ratio . We must maintain a minimum fixed charge coverage ratio of not less than 1.25 to 1.00. The Fixed Charge Coverage Ratio is defined as the ratio of (a) Adjusted EBITDA to (b) the sum of consolidated (with respect to the Company and the Co-Borrowers) interest expense (other than interest paid-in-kind in respect of any subordinated debt but including interest in respect of that certain promissory note made by CenStar in connection with the permitted acquisition from Verde Energy USA Holdings, LLC, letter of credit fees, commitment fees, acquisition earn-out payments (excluding earnout payments funded with proceeds from newly issued preferred or common equity), distributions, the aggregate amount of repurchases of our Class A common stock, Series A Preferred Stock, or commitments for such purchases, taxes and scheduled amortization payments. • Maximum Total Leverage Ratio . We must maintain a ratio of total indebtedness (excluding eligible subordinated debt and letter of credit obligations) to Adjusted EBITDA of no more than 2.50 to 1.00. • Maximum Senior Secured Leverage Ratio . We must maintain a Senior Secured Leverage Ratio of no more than 1.85 to 1.00. The Senior Secured Leverage Ratio is defined as the ratio of (a) all indebtedness of the loan parties on a consolidated basis that is secured by a lien on any property of any loan party (including the effective amount of all loans then outstanding (but, in any case, limited to 50% of the effective amount of letter of credit obligations attributable to performance standby letters of credit) but excluding subordinated debt permitted by the Credit Agreement as amended by the Amendment) to (b) Adjusted EBITDA. The Senior Credit Facility contains various negative covenants that limit our ability to, among other things, incur certain additional indebtedness, grant certain liens, engage in certain asset dispositions, merge or consolidate, make certain payments, distributions, investments, acquisitions or loans, materially modify certain agreements, or enter into transactions with affiliates. In addition, the Senior Credit Facility also contains affirmative covenants that are customary for credit facilities of this type. As of September 30, 2018 , we are in compliance with our various covenants under the Senior Credit Facility. The Senior Credit Facility is secured by pledges of the equity of the portion of Spark HoldCo owned by us, the equity of Spark HoldCo’s subsidiaries, the Co-Borrowers’ present and future subsidiaries, and substantially all of the Co-Borrowers’ and their subsidiaries’ present and future property and assets, including accounts receivable, inventory and liquid investments, and control agreements relating to bank accounts. We are entitled to pay cash dividends to the holders of the Series A Preferred Stock and Class A common stock and will be entitled to repurchase up to an aggregate amount of 10,000,000 shares of our Class A common stock, and up to $92.7 million of Series A Preferred Stock through one or more normal course open market purchases through NASDAQ so long as: (a) no default exists or would result therefrom; (b) the Co-Borrowers are in pro forma compliance with all financial covenants before and after giving effect thereto; and (c) the outstanding amount of all loans and letters of credit does not exceed the borrowing base limits. The Senior Credit Facility contains certain customary representations and warranties and events of default. Events of default include, among other things, payment defaults, breaches of representations and warranties, covenant defaults, cross-defaults and cross-acceleration to certain indebtedness, certain events of bankruptcy, certain events under ERISA, material judgments in excess of $5.0 million , certain events with respect to material contracts, actual or asserted failure of any guaranty or security document supporting the Senior Credit Facility to be in full force and effect, failure of Nathan Kroeker to retain his position as President and Chief Executive Officer of the Company, and failure of W. Keith Maxwell III to retain his position as chairman of the board of directors. A default will also occur if at any time W. Keith Maxwell III ceases to, directly or indirectly, own at least 13,600,000 Class A and Class B shares on a combined basis (to be adjusted for any stock split, subdivisions or other stock reclassification or recapitalization), and a controlling percentage of the voting equity interest of the Company, and certain other changes in control. If such an event of default occurs, the lenders under the Senior Credit Facility would be entitled to take various actions, including the acceleration of amounts due under the facility and all actions permitted to be taken by a secured creditor. Subordinated Debt Facility On December 27, 2016, the Company and Spark HoldCo jointly issued to Retailco, an entity owned by our Founder, a 5% subordinated note in the principal amount of up to $25.0 million . The subordinated note allows the Company and Spark HoldCo to draw advances in increments of no less than $1.0 million per advance up to the maximum principal amount of the subordinated note. The subordinated note matures in July 2020, and advances thereunder accrue interest at 5% per annum from the date of the advance. We have the right to capitalize interest payments under the subordinated note. The subordinated note is subordinated in certain respects to our Senior Credit Facility pursuant to a subordination agreement. We may pay interest and prepay principal on the subordinated note so long as we are in compliance with its covenants under the Senior Credit Facility, is not in default under the Senior Credit Facility and has minimum availability of $5.0 million under the borrowing base under the Senior Credit Facility. Payment of principal and interest under the subordinated note is accelerated upon the occurrence of certain change of control or sale transactions. Verde Companies Promissory Note In connection with the acquisition of the Verde Companies, on July 1, 2017, we entered into a Promissory Note in the aggregate principal amount of $20.0 million (the "Verde Promissory Note"). The Verde Promissory Note required repayment in eighteen monthly installments beginning on August 1, 2017, and accrued interest at 5% per annum from the date of issuance. The Verde Promissory Note, including principal and interest, was unsecured, but is guaranteed by us. On January 12, 2018, in connection with the Earnout Termination Agreement (defined below), CenStar issued to the seller of the Verde Companies an amended and restated promissory note (the “Amended and Restated Verde Promissory Note”), which amended and restated the Verde Promissory Note. The Amended and Restated Verde Promissory Note, effective January 12, 2018, matures in January 2019, and bears interest at a rate of 9% per annum beginning January 1, 2018. Principal and interest are payable monthly on the first day of each month in which the Amended and Restated Verde Promissory Note is outstanding. CenStar deposits a portion of each payment under the Amended and Restated Verde Promissory Note into an escrow account, which serves as security for certain indemnification claims and obligations under the purchase agreement. The amount deposited into the escrow account was increased from the Verde Promissory Note. As of December 31, 2017 , there was $14.6 million outstanding under the Verde Promissory note, and as of September 30, 2018 , there was $4.6 million outstanding under the Amended and Restated Verde Promissory Note. Verde Earnout Termination Note On January 12, 2018, we issued a promissory note in the principal amount of $5.9 million in connection with an agreement to terminate the earnout obligations arising in connection with our acquisition of the Verde Companies (the “Verde Earnout Termination Note”). The Verde Earnout Termination Note matures on June 30, 2019 (subject to early maturity upon certain events) and bears interest at a rate of 9% per annum. CenStar is permitted to withhold amounts otherwise due at maturity related to certain indemnifiable matters. Interest is payable monthly on the first day of each month in which the Verde Earnout Termination Note is outstanding. The principal and any outstanding interest is due on June 30, 2019.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	10. Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants at the measurement date. Fair values are based on assumptions that market participants would use when pricing an asset or liability, including assumptions about risk and the risks inherent in valuation techniques and the inputs to valuations. This includes the credit standing of counterparties involved and the impact of credit enhancements. We apply fair value measurements to our commodity derivative instruments and contingent payment arrangements based on the following fair value hierarchy, which prioritizes the inputs to the valuation techniques used to measure fair value into three broad levels: • Level 1—Quoted prices in active markets for identical assets and liabilities. Instruments categorized in Level 1 primarily consist of financial instruments such as exchange-traded derivative instruments. • Level 2—Inputs other than quoted prices recorded in Level 1 that are either directly or indirectly observable for the asset or liability, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability, and inputs that are derived from observable market data by correlation or other means. Instruments categorized in Level 2 primarily include non-exchange traded derivatives such as over-the-counter commodity forwards and swaps and options. • Level 3—Unobservable inputs for the asset or liability, including situations where there is little, if any, observable market activity for the asset or liability. The Level 3 category includes estimated earnout obligations related to our acquisitions. Other Financial Instruments The carrying amount of cash and cash equivalents, accounts receivable, accounts receivable—affiliates, accounts payable, accounts payable—affiliates, and accrued liabilities recorded in the condensed consolidated balance sheets approximate fair value due to the short-term nature of these items. The carrying amounts of the Senior Credit Facility and Prior Senior Credit Facility recorded in the condensed consolidated balance sheets approximate fair value because of the variable rate nature of our line of credit, and are considered Level 2 measurements because interest rates charged are similar to other financial instruments with similar terms and maturities. The fair value of our convertible subordinated notes to affiliates and the payable pursuant to tax receivable agreement—affiliate is not determinable for accounting purposes due to the affiliate nature and terms of the associated agreements with the affiliate. Assets and Liabilities Measured at Fair Value on a Recurring Basis The following table presents assets and liabilities measured and recorded at fair value in our condensed consolidated balance sheets on a recurring basis by and their level within the fair value hierarchy (in thousands): Level 1 Level 2 Level 3 Total September 30, 2018 Non-trading commodity derivative assets $ 223 $ 25,077 $ — $ 25,300 Trading commodity derivative assets — — — — Total commodity derivative assets $ 223 $ 25,077 $ — $ 25,300 Non-trading commodity derivative liabilities $ (63 ) $ (502 ) $ — $ (565 ) Trading commodity derivative liabilities (189 ) (4 ) — (193 ) Total commodity derivative liabilities $ (252 ) $ (506 ) $ — $ (758 ) Contingent payment arrangement $ — $ — $ (2,980 ) $ (2,980 ) Level 1 Level 2 Level 3 Total December 31, 2017 Non-trading commodity derivative assets $ 158 $ 33,886 $ — $ 34,044 Trading commodity derivative assets — 456 — 456 Total commodity derivative assets $ 158 $ 34,342 $ — $ 34,500 Non-trading commodity derivative liabilities $ (387 ) $ (950 ) $ — $ (1,337 ) Trading commodity derivative liabilities (555 ) (237 ) — (792 ) Total commodity derivative liabilities $ (942 ) $ (1,187 ) $ — $ (2,129 ) Contingent payment arrangement $ — $ — $ (4,650 ) $ (4,650 ) We had no transfers of assets or liabilities between any of the above levels during the nine months ended September 30, 2018 and the year ended December 31, 2017 . Our derivative contracts include exchange-traded contracts valued utilizing readily available quoted market prices and non-exchange-traded contracts valued using market price quotations available through brokers or over-the-counter and on-line exchanges. In addition, in determining the fair value of our derivative contracts, we apply a credit risk valuation adjustment to reflect credit risk, which is calculated based on the Company’s or the counterparty’s historical credit risks. As of September 30, 2018 and December 31, 2017 , the credit risk valuation adjustment was not material. The contingent payment arrangements referred to above reflect estimated earnout obligations incurred in relation to our acq uisition of the Major Energy Companies in 2016. Of these amounts, $3.0 million and $4.0 million were classified as current liabili ties as of September 30, 2018 and December 31, 2017 , respectively, and zero and $0.6 million were classified as long-term liabilities as of September 30, 2018 and December 31, 2017 , respectively. The Major Earnout is based on the achievement by the Major Energy Companies of certain performance targets over the 33 month period following NG&E's closing of the Major Energy Companies acquisition (i.e., April 15, 2016). The previous members of Major Energy Companies are entitled to a maximum of $20.0 million in earnout payments based on the level of performance targets attained, as defined by the Major Purchase Agreement. The Stock Earnout obligation is contingent upon the Major Energy Companies achieving the Major Earnout's performance target ceiling, thereby earning the maximum Major Earnout payments. If the Major Energy Companies earn such maximum Major Earnout payments, NG&E would be entitled to a maximum of 400,000 shares of Class B common stock (and a corresponding number of Spark HoldCo units). In determining the fair value of the Major Earnout and the Stock Earnout, we forecasted certain expected performance targets and calculated the probability of such forecast being attained. For the nine months ended September 30, 2018 and 2017 , we paid $1.6 million and $7.4 million , respectively, related to the Major Earnout. We have classified the Major Earnout as a Level 3 measurement. The following table presents a reconciliation of liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the nine months ended September 30, 2018 . Major Earnout and Stock Earnout Fair Value at December 31, 2017 $ 4,650 Change in fair value of contingent consideration, net (63 ) Payments and settlements (1,607 ) Fair Value at September 30, 2018 $ 2,980

Accounting for Derivative Instr

Accounting for Derivative Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Accounting for Derivative Instruments	11. Accounting for Derivative Instruments We are exposed to the impact of market fluctuations in the price of electricity and natural gas, basis differences in the price of natural gas, storage charges, Renewable Energy Credits, capacity charges from independent system operators, and other ancillary costs. We use derivative instruments in an effort to manage our cash flow exposure to these risks. These instruments are not designated as hedges for accounting purposes, and accordingly, changes in the market value of these derivative instruments are recorded in the cost of revenues. As part of our strategy to optimize pricing in our natural gas related activities, we manage a portfolio of commodity derivative instruments held for trading purposes. Our commodity trading activities are subject to limits within our Risk Management Policy. For these derivative instruments, changes in the fair value are recognized currently in earnings in net asset optimization revenues. Derivative assets and liabilities are presented net in our condensed consolidated balance sheets when the derivative instruments are executed with the same counterparty under a master netting arrangement. Our derivative contracts include transactions that are executed both on an exchange and centrally cleared as well as over-the-counter, bilateral contracts that are transacted directly with a third party. To the extent we have paid or received collateral related to the derivative assets or liabilities, such amounts would be presented net against the related derivative asset or liability’s fair value. As of September 30, 2018 and December 31, 2017 , we had paid zero and $0.1 million in collateral outstanding, respectively. The specific types of derivative instruments we may execute to manage the commodity price risk include the following: • Forward contracts, which commit us to purchase or sell energy commodities in the future; • Futures contracts, which are exchange-traded standardized commitments to purchase or sell a commodity or financial instrument; • Swap agreements, which require payments to or from counterparties based upon the differential between two prices for a predetermined notional quantity; and • Option contracts, which convey to the option holder the right but not the obligation to purchase or sell a commodity. Interest Rate Swaps During the three months ended September 30, 2018 , we entered into two interest rate swap agreements to manage interest rate risk. The interest rate swap agreements were not designated as hedges for accounting purposes. As such, all changes in fair value were recognized in earnings, within interest and other income. As of September 30, 2018 , the notional amount of the interest swap was $10.0 million . A fair value liability of less than $0.1 million was recorded in other current liabilities on the condensed consolidated balance sheet as of September 30, 2018 . Volumetric Underlying Derivative Transactions The following table summarizes the net notional volume buy/(sell) of our open derivative financial instruments accounted for at fair value, broken out by commodity (in thousands): Non-trading Commodity Notional September 30, 2018 December 31, 2017 Natural Gas MMBtu 6,099 9,191 Natural Gas Basis MMBtu 140 — Electricity MWh 5,980 8,091 Trading Commodity Notional September 30, 2018 December 31, 2017 Natural Gas MMBtu 221 26 Natural Gas Basis MMBtu 78 (225 ) Gains (Losses) on Derivative Instruments Gains (losses) on derivative instruments, net and current period settlements on derivative instruments were as follows for the periods indicated (in thousands): Three Months Ended September 30, 2018 2017 Gain (loss) on non-trading derivatives, net $ 17,888 $ (2,568 ) Gain (loss) on trading derivatives, net 229 (184 ) Gain (loss) on derivatives, net 18,117 (2,752 ) Current period settlements on non-trading derivatives (1) 1,035 7,481 Current period settlements on trading derivatives (113 ) (24 ) Total current period settlements on derivatives $ 922 $ 7,457 (1) Excludes settlements of $0.1 million and $1.5 million , respectively, for the three months ended September 30, 2018 and 2017 related to non-trading derivative liabilities assumed in various acquisitions. Nine Months Ended September 30, 2018 2017 Loss on non-trading derivatives, net $ (2,223 ) $ (34,146 ) Gain (loss) on trading derivatives, net 852 (79 ) Loss on derivatives, net (1,371 ) (34,225 ) Current period settlements on non-trading derivatives (1) (5,054 ) 19,016 Current period settlements on trading derivatives (769 ) (208 ) Total current period settlements on derivatives $ (5,823 ) $ 18,808 (1) Excludes settlements of $(0.4) million and $2.0 million , respectively, for the nine months ended September 30, 2018 and 2017 related to non-trading derivative liabilities assumed in various acquisitions. Gains (losses) on trading derivative instruments are recorded in net asset optimization revenues and gains (losses) on non-trading derivative instruments are recorded in retail cost of revenues on the condensed consolidated statements of operations. Fair Value of Derivative Instruments The following tables summarize the fair value and offsetting amounts of our derivative instruments by counterparty and collateral received or paid (in thousands): September 30, 2018 Description Gross Assets Gross Net Assets Cash Net Amount Non-trading commodity derivatives $ 42,794 $ (19,367 ) $ 23,427 $ — $ 23,427 Trading commodity derivatives — — — — — Total Current Derivative Assets 42,794 (19,367 ) 23,427 — 23,427 Non-trading commodity derivatives 10,003 (8,130 ) 1,873 — 1,873 Trading commodity derivatives — — — — — Total Non-current Derivative Assets 10,003 (8,130 ) 1,873 — 1,873 Total Derivative Assets $ 52,797 $ (27,497 ) $ 25,300 $ — $ 25,300 September 30, 2018 Description Gross Gross Net Cash Net Amount Non-trading commodity derivatives $ (280 ) $ 15 $ (265 ) $ — $ (265 ) Trading commodity derivatives (4 ) — (4 ) — (4 ) Total Current Derivative Liabilities (284 ) 15 (269 ) — (269 ) Non-trading commodity derivatives (1,118 ) 818 (300 ) — (300 ) Trading commodity derivatives (255 ) 66 (189 ) — (189 ) Total Non-current Derivative Liabilities (1,373 ) 884 (489 ) — (489 ) Total Derivative Liabilities $ (1,657 ) $ 899 $ (758 ) $ — $ (758 ) December 31, 2017 Description Gross Assets Gross Net Assets Cash Net Amount Non-trading commodity derivatives $ 60,167 $ (29,432 ) $ 30,735 $ — $ 30,735 Trading commodity derivatives 918 (462 ) 456 — 456 Total Current Derivative Assets 61,085 (29,894 ) 31,191 — 31,191 Non-trading commodity derivatives 16,055 (12,746 ) 3,309 — 3,309 Trading commodity derivatives — — — — — Total Non-current Derivative Assets 16,055 (12,746 ) 3,309 — 3,309 Total Derivative Assets $ 77,140 $ (42,640 ) $ 34,500 $ — $ 34,500 December 31, 2017 Description Gross Gross Net Cash Net Amount Non-trading commodity derivatives $ (4,517 ) $ 3,059 $ (1,458 ) $ 65 $ (1,393 ) Trading commodity derivatives (517 ) 273 (244 ) — (244 ) Total Current Derivative Liabilities (5,034 ) 3,332 (1,702 ) 65 (1,637 ) Non-trading commodity derivatives (676 ) 732 56 — 56 Trading commodity derivatives (566 ) 18 (548 ) — (548 ) Total Non-current Derivative Liabilities (1,242 ) 750 (492 ) — (492 ) Total Derivative Liabilities $ (6,276 ) $ 4,082 $ (2,194 ) $ 65 $ (2,129 )

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes Income Taxes We and our subsidiaries, CenStar and Verde Energy USA, Inc. ("Verde Corp"), are each subject to U.S. federal income tax as corporations. CenStar and Verde Corp file consolidated tax returns in jurisdictions that allow combined reporting. Spark HoldCo and its subsidiaries, with the exception of CenStar and Verde Corp, are treated as flow-through entities for U.S. federal income tax purposes, and, as such, are generally not subject to U.S. federal income tax at the entity level. Rather, the tax liability with respect to their taxable income is passed through to their members or partners. Accordingly, we are subject to U.S. federal income taxation on our allocable share of Spark HoldCo’s net U.S. taxable income. In our financial statements, we report federal and state income taxes for our share of the partnership income attributable to our ownership in Spark HoldCo and for the income taxes attributable to CenStar and Verde Corp. Net income attributable to non-controlling interests includes the provision for income taxes related to CenStar and Verde Corp. We account for income taxes using the assets and liabilities method. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and the tax bases of the assets and liabilities. We apply existing tax law and the tax rate that we expect to apply to taxable income in the years in which those differences are expected to be recovered or settled in calculating the deferred tax assets and liabilities. Effects of changes in tax rates on deferred tax assets and liabilities are recognized in income in the period of the tax rate enactment. A valuation allowance is recorded when it is not more likely than not that some or all of the benefit from the deferred tax asset will be realized. On December 22, 2017 , the President signed the Tax Cuts and Jobs Act (“U.S. Tax Reform”), which enacts a wide range of changes to the U.S. Corporate income tax system. For U.S. federal purposes, a corporate statutory income tax rate of 21% was utilized for the 2018 tax year. We remeasured our U.S. federal deferred tax assets and liabilities as of December 31, 2017 using the newly enacted 21% corporate tax rate. We have not revised any of the 2017 provisional estimates under SAB No. 118 and ASU No 2018-05, but continue to gather information and wait on further guidance from the IRS, SEC and FASB on U.S. Tax Reform. On a quarterly basis, we assess whether it is more likely than not that we will generate sufficient taxable income to realize our deferred income tax assets. In making this determination, we consider all available positive and negative evidence and makes certain assumptions. We consider, among other things, our deferred tax liabilities, the overall business environment, our historical earnings and losses, current industry trends, and our outlook for future years. We believe it is more likely than not that our deferred tax assets will be realized. As of September 30, 2018 , we had a net deferred tax asset of approximately $15.6 million related to the original step up in tax basis resulting from the initial purchase of Spark HoldCo units from NuDevco Retail and NuDevco Retail Holdings (predecessor to Retailco) in connection with our initial public offering. In addition, as of September 30, 2018 , we had a total liability of $28.6 million for the effect of the Tax Receivable Agreement liability, with approximately $2.5 million classified as short-term liability and the remainder as long-term. As of September 30, 2018 , we had a long-term deferred tax asset of approximately $7.2 million related to the Tax Receivable Agreement liability. See Note 14 "Transactions with Affiliates" for further discussion. The effective U.S. federal and state income tax rate for the nine months ended September 30, 2018 and 2017 is 39.5% and 15.5% , respectively. The effective tax rate for the nine months ended September 30, 2018 reflects the lower corporate U.S. federal statutory tax rate of 21% enacted for 2018, applied to the mix of earnings between corporate and partnership income, offset by the tax effect of Series A Preferred Stock dividends. Total income tax benefit for the nine months ended September 30, 2018 differed from amounts computed by applying the U.S. federal statutory tax rates to pre-tax income primarily due to state taxes and the impact of permanent differences between book and taxable income, most notably the income attributable to non-controlling interests. The effective tax rate includes a rate benefit attributable to the fact that Spark HoldCo operates as a limited liability company treated as a partnership for federal and state income tax purposes and is not subject to federal and state income taxes. Accordingly, the portion of earnings attributable to non-controlling interest is subject to tax when reported as a component of the non-controlling interest’s taxable income.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	13. Commitments and Contingencies From time to time, we may be involved in legal, tax, regulatory and other proceedings in the ordinary course of business. Other than proceedings discussed below, management does not believe that we are a party to any litigation, claims or proceedings that will have a material impact on our condensed consolidated financial condition or results of operations. Liabilities for loss contingencies arising from claims, assessments, litigations or other sources are recorded when it is probable that a liability has been incurred and the amount can be reasonably estimated. Indirect Tax Audits We are undergoing various types of indirect tax audits spanning from years 2009 to 2017 for which we may have additional liabilities arise. At the time of filing these condensed consolidated financial statements, these indirect tax audits are at an early stage and subject to substantial uncertainties concerning the outcome of audit findings and corresponding responses. As of September 30, 2018 , we have accrued $1.0 million related to indirect tax audits. The outcome of these indirect tax audits may result in additional expense. Legal Proceedings We are subject to lawsuits and claims arising in the ordinary course of business from time to time. We are also subject of the following lawsuits. At the time of filing these combined and consolidated financial statements, this litigation is at an early stage and subject to substantial uncertainties concerning the outcome of material factual and legal issues. Accordingly, we cannot currently predict the manner and timing of the resolution of this litigation or estimate a range of possible losses or a minimum loss that could result from an adverse verdict in a potential lawsuit. While the lawsuits and claims are asserted for amounts that may be material should an unfavorable outcome occur, management does not currently expect that any currently pending matters will have a material adverse effect on our financial position or results of operations, except as described below. Katherine Veilleux and Jennifer Chon, individually and on behalf of all other similarly situated v. Electricity Maine. LLC, Provider Power, LLC, Spark HoldCo, LLC, Kevin Dean and Emile Clavet is a purported class action lawsuit filed on November 18, 2016 in the United States District Court of Maine, alleging that Electricity Maine, LLC, an entity acquired by Spark HoldCo, LLC in mid-2016, enrolled and re-enrolled customers through fraudulent and misleading advertising, promotions, and other communications prior to the acquisition. Plaintiffs further allege that some improper enrollment and re-enrollment practices have continued to the present date. Plaintiffs alleged claims under RICO, the Maine Unfair Trade Practice Act, negligence, negligent misrepresentation, fraudulent misrepresentation, unjust enrichment and breach of contract. Plaintiffs seek damages for themselves and the purported class, rescission of contracts with Electricity Maine, injunctive relief, restitution, and attorney’s fees. By order dated November 15, 2017, the Court, pursuant to Rule 12(b)(6), dismissed all claims against Spark HoldCo except the claims for violation of the Maine Unfair Trade Practices Act and for unjust enrichment. Discovery is limited to issues relevant to class certification under Rule 23 of the Federal Rules of Civil Procedure. Plaintiffs have recently filed a motion seeking leave to amend their complaint to reassert RICO claims against Spark, in addition to claims for civil conspiracy, unjust enrichment and unfair trade practices. The proposed amended complaint involves allegations relating to Spark’s and Electricity Maine’s door-to-door sales practices in Maine. Spark and Electricity Maine opposed the motion and the Court has not yet ruled on these motions. Spark HoldCo intends to vigorously defend this matter and the allegations asserted therein, including the request to certify a class. We cannot predict the outcome or consequences of this case at this time. We believe we are fully indemnified for this litigation matter, subject to certain limitations. Gillis et al. v. Respond Power, LLC is a purported class action lawsuit that was originally filed on May 21, 2014 in the Philadelphia Court of Common Pleas. On June 23, 2014, the case was removed to the United States District Court for the Eastern District of Pennsylvania. On September 15, 2014, the plaintiffs filed an amended class action complaint seeking a declaratory judgment that the disclosure statement contained in Respond Power, LLC’s variable rate contracts with Pennsylvania consumers limited the variable rate that could be charged to no more than the monthly rate charged by the consumers’ local utility company. The plaintiffs also allege that Respond Power, LLC (i) breached its variable rate contract with Pennsylvania consumers, and the covenant of good faith and fair dealing therein, by charging rates in excess of the monthly rate charged by the consumers’ local utility company; (ii) engaged in deceptive conduct in violation of the Pennsylvania Unfair Trade Practices and Consumer Protection Law; and (iii) engaged in negligent misrepresentation and fraudulent concealment in connection with purported promises of savings. The amount of damages sought is not specified. By order dated August 31, 2015, the district court denied class certification. The plaintiffs appealed the district court’s denial of class certification to the United States Court of Appeals for the Third Circuit. The United States Court of Appeals for the Third Circuit vacated the district court’s denial of class certification and remanded the matter to the district court for further proceedings. The district court ordered briefing on defendant’s motion to dismiss. On July 16, 2018, the court granted Respond Power LLCs motion to dismiss the Plaintiff’s class action claims. Plaintiffs filed their notice of appeal to the Third Circuit Court on August 7, 2018. The final appellate briefing has not yet been completed. The Third Circuit has not yet ruled or set any hearings on this appeal. We currently cannot predict the outcome or consequences of this case at this time. We believe we are fully indemnified for this litigation matter, subject to certain limitations. Jurich v. Verde Energy USA, Inc. , is a class action originally filed on March 3, 2015 in the United States District Court for the District of Connecticut and subsequently re-filed on October 8, 2015 in the Superior Court of Judicial District of Hartford, State of Connecticut. The Amended Complaint asserts that the Verde Companies charged rates in violation of its contracts with Connecticut customers and alleges (i) violation of the Connecticut Unfair Trade Practices Act, Conn. Gen. Stat. §§ 42-110a et seq. , and (ii) breach of the covenant of good faith and fair dealing. Plaintiffs are seeking unspecified actual and punitive damages for the class and injunctive relief. The parties have exchanged initial discovery. On December 6, 2017, the Court granted the plaintiffs’ class certification motion. However, the Court opted not to send out class notices, and instead directed the parties to submit briefing on legal issues that could result in a modification or decertification of the class. On June 21, 2018, the Court issued an opinion granting in part and denying in part the Plaintiffs’ motion for partial summary judgment. The Court granted the motion as to liability on a limited and discrete issue (whether Verde’s terms of service complied with a Connecticut statute’s requirement of sufficient clarity regarding rates). The full implications of that ruling are not yet clear. The Court has questioned whether such a statutory violation could justify an award of any compensatory damages. In its order, the Court also rejected the Plaintiffs’ principal theory that Verde’s Terms of Service obligated Verde to track Verde’s wholesale costs in setting its retail rates. Verde filed a motion for summary judgment and motion to decertify the class in August 2018 and plaintiffs filed their reply to that motion in September 2018. No hearing has been set on these motions. As part of an agreement in connection with the acquisition of the Verde Companies, the original owners of the Verde Companies are handling this matter, and we believe we are fully indemnified for this matter, subject to certain limitations. Given the early stage of this matter, we cannot predict the outcome or consequences of this case at this time. Richardson et al v. Verde Energy USA, Inc. is a purported class action filed on November 25, 2015 in the United States District Court for the Eastern District of Pennsylvania alleging that the Verde Companies violated the Telephone Consumer Protection Act by placing marketing calls using an automatic telephone dialing system or a prerecorded voice to the purported class members’ cellular phones without prior express consent and by continuing to make such calls after receiving requests for the calls to cease. Plaintiffs are seeking statutory damages for the purported class and injunctive relief prohibiting Verde Companies' alleged conduct. Discovery on the claims of the named plaintiffs closed on November 10, 2017, and dispositive motions on the named plaintiffs’ claims were filed on November 24, 2017. The parties are now awaiting the Court’s decision on the pending dispositive motions. The case was recently reassigned to a new judge and the first status conference was held on October 12, 2018. As part of an agreement in connection with the acquisition of the Verde Companies, the original owners of the Verde Companies are handling this matter, and we believe we are fully indemnified for this matter, subject to certain limitations. Given the early stages of this matter, we cannot predict the outcome or consequences of this case at this time. Saul Horowitz, as Sellers’ Representative for the former owners of the Major Energy Companies v. National Gas & Electric, LLC (NG&E) and Spark Energy, Inc. (Spark) , has filed a lawsuit asserting claims of fraudulent inducement against NG&E, breach of contract against NG&E and us, and tortious interference with contract against us related to the membership interest purchase, subsequent transfer, and associated earnout agreements with the Major Energy Companies' former owners. The relief sought includes unspecified compensatory and punitive damages, prejudgment and post judgment interest, and attorneys’ fees. The lawsuit was filed on October 10, 2017 in the United States District Court for the Southern District of New York, and after the Company and NG&E filed a motion to dismiss, Horowitz filed an Amended Complaint, asserting the same four claims. The Company and NG&E filed a motion to dismiss the fraud and tortious interference claims on January 15, 2018. Briefing on the motion to dismiss concluded on March 1, 2018, On September 24, 2018. the court granted the motion in part and dismissed the plaintiffs’ fraudulent inducement claims but allowed the tortious interference claims to remain as well as the claims for consequential damages and punitive damages. NG&E and Spark filed their affirmative defenses and answer to the remaining claims on October 15, 2018. Discovery has commenced and written discovery requests have been exchanged between the parties. This case is currently set for trial on September 9, 2019. The Company and NG&E deny the allegations asserted and intend to vigorously defend this matter. Given the early stages of this matter, we cannot predict the outcome or consequences of this case at this time. Regulatory Matters On April 9, 2018 the Attorney General for the State of Illinois filed a complaint against Major Energy Electric Services, LLC (Major) asserting claims that Major engaged in a pattern and practice of deceptive conduct intended to defraud Illinois consumers through door-to-door and telephone solicitations, in-person solicitations at retail establishments, advertisements on its website and direct mail advertisements to sign up for electricity services. The complaint seeks injunctive relief and monetary damages representing the amounts Illinois consumers have allegedly lost due to fraudulent marketing activities. The Attorney General also requests civil penalties under the Consumer Fraud Act and to revoke Major’s authority to operate in the state. The complaint was filed in the Circuit Court of Cook County, Illinois, County Department, Chancery Division. Major filed its motion to dismiss on August 1, 2018. On October 10, 2018, the court denied Major’s Motion to Dismiss. A status conference is set with the judge on October 24, 2018. Major denies the allegations asserted and intends to vigorously defend this matter. Given the early stages of this matter, we cannot predict the outcome or consequences of this case at this time. Spark Energy, LLC is the subject of two current investigations by the Connecticut Public Utilities Regulatory Authority (“PURA”). The first investigation constitutes a notice of violation and assessment of a proposed civil penalty in the amount of $0.9 million primarily for Spark Energy, LLC’s alleged failure to comply with regulations implemented in 2016 requiring that customer bills include any changes to existing rates effective for the next billing cycle. PURA has granted a motion by the Office of Consumer Counsel of the State of Connecticut to postpone briefing on this matter pending settlement negotiations. The second investigation involves a notice of violation into the marketing practices of one of Spark Energy, LLC’s former outbound telemarketing vendors and assessment of a proposed civil penalty of $0.8 million . Certain agents managed by this vendor were allegedly using an unauthorized script in outbound marketing calls. Spark Energy, LLC has already responded to several interrogatories regarding this matter and is awaiting further instruction from PURA. We are unable to predict the outcome of these proceedings but have accrued $0.2 million as of September 30, 2018, which represents our current estimate for a negotiated penalty for the matter. While investigations of this nature have become common and are often resolved in a manner that allows the retailer to continue operating in Connecticut, there can be no assurance that PURA will not take more severe action.

Transactions with Affiliates

Transactions with Affiliates	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Transactions with Affiliates	14. Transactions with Affiliates Transactions with Affiliates We enter into transactions with and pay certain costs on behalf of affiliates that are commonly controlled in order to reduce risk, reduce administrative expense, create economies of scale, create strategic alliances and supply goods and services to these related parties. We also sell and purchase natural gas and electricity with affiliates. We present receivables and payables with the same affiliate on a net basis in the condensed consolidated balance sheets as all affiliate activity is with parties under common control. These transactions include certain services to the affiliated companies associated with employee benefits provided through our benefit plans, insurance plans, leased office space, administrative salaries for management, due diligence work, recurring management consulting, and accounting, tax, legal, or technology services based on services provided, departmental usage, or headcount, which are considered reasonable by management. As such, the accompanying condensed consolidated financial statements include costs that have been incurred by us and then directly billed or allocated to affiliates, as well as costs that have been incurred by our affiliates and then directly billed or allocated to us, and are recorded net in general and administrative expense on the condensed consolidated statements of operations with a corresponding accounts receivable—affiliates or accounts payable—affiliates, respectively, recorded in the condensed consolidated balance sheets. Transactions with affiliates for sales or purchases of natural gas and electricity, which are recorded in retail revenues, retail cost of revenues, and net asset optimization revenues in the condensed consolidated statements of operations with a corresponding accounts receivable—affiliate or accounts payable—affiliate in the condensed consolidated balance sheets. Acquisitions from Related Parties In April 2017, we acquired Perigee from our affiliate, NG&E, for total consideration of approximately $4.1 million . The acquisition was treated as a transfer of equity interests of entities under common control. On March 7, 2018, we entered into an asset purchase agreement with NG&E pursuant to which we agreed to acquire up to 50,000 RCEs from NG&E for a cash purchase price of $250 for each RCE, or up to $12.5 million in the aggregate. These customers began transferring after April 1, 2018 and are located in 24 markets in 8 states. For the nine months ended September 30, 2018 , we paid NG&E $8.8 million under the terms of the purchase agreement for approximately 35,000 RCEs. We do not anticipate any additional customer transfers or consideration will be paid on this transaction. The acquisition was treated as a transfer of assets between entities under common control, and accordingly, the assets were recorded at their historical value at the date of transfer. The transaction resulted in $7.1 million recorded in equity as a net distribution to affiliate as of September 30, 2018 . Master Service Agreement with Retailco Services, LLC Prior to April 1, 2018, we were a party to a Master Service Agreement with companies owned by our Founder. The Master Service Agreement provided us with operational support services such as: enrollment and renewal transaction services; customer billing and transaction services; electronic payment processing services; customer services and information technology infrastructure and application support services under the Master Service Agreement. Effective April 1, 2018, we terminated the agreement, and these operational support services were transferred back to us. See "Cost Allocations" for further discussion of the fees paid in connection with the Master Service Agreement during the three and nine months ended September 30, 2018 . Accounts Receivable and Payable — Affiliates We recorded current accounts receivable—affiliates of $3.8 million and $3.7 million as of September 30, 2018 and December 31, 2017 , respectively, and current accounts payable—affiliates of $2.8 million and $4.6 million as of September 30, 2018 and December 31, 2017 , respectively, for certain direct billings and cost allocations for services we provided to affiliates, services our affiliates provided to us, and sales or purchases of natural gas and electricity with affiliates. Revenues and Cost of Revenues — Affiliates Revenues—affiliates, recorded in net asset optimization revenues in the condensed consolidated statements of operations for the three months ended September 30, 2018 and 2017 were $0.3 million and zero , respectively. Revenues—affiliates, recorded in net asset optimization revenues in the condensed consolidated statements of operations for the nine months ended September 30, 2018 and 2017 were $1.3 million and zero , respectively. Cost of revenues—affiliates, recorded in net asset optimization revenues in the condensed consolidated statements of operations for the three months ended September 30, 2018 and 2017 were less than $0.1 million and zero , respectively. Cost of revenues—affiliates, recorded in net asset optimization revenues in the condensed consolidated statements of operations for the nine months ended September 30, 2018 and 2017 were $0.1 million and zero , respectively. Cost Allocations We paid certain expenses on behalf of affiliates, which are reimbursed by our affiliates, and our affiliates paid certain expenses on our behalf, which are reimbursed by us. These transactions include costs that can be specifically identified and certain allocated overhead costs associated with general and administrative services, including executive management, due diligence work, recurring management consulting, facilities, banking arrangements, professional fees, insurance, information services, human resources and other support departments to the affiliates. Where costs incurred on behalf of the affiliate or us could not be determined by specific identification for direct billing, the costs were allocated to the affiliated entities or us based on estimates of percentage of departmental usage, wages or headcount. The total net amount direct billed and allocated from affiliates was $0.3 million and $5.7 million , respectively, for the three months ended September 30, 2018 and 2017 , respectively. The total net amount direct billed and allocated from affiliates was $8.7 million and $19.4 million , respectively, for the nine months ended September 30, 2018 and 2017 . Of the $0.3 million and $5.7 million total net amounts directly billed and allocated from affiliates, we recorded general and administrative expense of less than $0.1 million and $5.1 million for the three months ended September 30, 2018 and 2017 , respectively, and of the $8.7 million and $19.4 million total net amounts directly billed and allocated from affiliates, we recorded general and administrative expense of $5.8 million and $17.0 million for the nine months ended September 30, 2018 and 2017 , respectively, in the condensed consolidated statement of operations in connection with fees paid under the Master Service Agreement with Retailco Services. Additionally under the Master Service Agreement, we capitalized zero and $0.2 million of property and equipment for the application, development and implementation of various systems during the three months ended September 30, 2018 and 2017 , respectively, and we capitalized $0.5 million and $0.5 million of property and equipment for the application, development and implementation of various systems during the nine months ended September 30, 2018 and 2017 , respectively. Distributions to and Contributions from Affiliates During the nine months ended September 30, 2018 and 2017 , Spark HoldCo made distributions to NuDevco Retail and Retailco of $11.7 million , for payments of quarterly distributions on its Spark HoldCo units. During the nine months ended September 30, 2018 and 2017 , Spark HoldCo made distributions to NuDevco Retail and Retailco for gross-up distributions of $12.0 million and $12.6 million , respectively, in connection with distributions made between Spark HoldCo and Spark Energy, Inc. for payment of income taxes incurred by us. Proceeds from Disgorgement of Stockholder Short-swing Profits During the three and nine months ended September 30, 2018 , we received zero and $0.2 million cash, respectively, for the disgorgement of stockholder short-swing profits under Section 16(b) under the Exchange Act accrued at December 31, 2017. The amount was recorded as an increase to additional paid-in capital in our consolidated balance sheet as of December 31, 2017. Subordinated Debt Facility On December 27, 2016, the Company and Spark HoldCo jointly issued to Retailco, an entity owned by our Founder, a 5% subordinated note in the principal amount of up to $25.0 million . The subordinated note allows the Company and Spark HoldCo to draw advances in increments of no less than $1.0 million per advance up to the maximum principal amount of the subordinated note. Advances thereunder accrue interest at 5% per annum from the date of the advance. As of September 30, 2018 , there was $10.0 million in outstanding borrowings under the subordinated note, which was repaid in full in October 2018. As of December 31, 2017 , there were no outstanding borrowings under the subordinated note. See Note 9 "Debt" for a further description of terms and conditions under the facility. Tax Receivable Agreement We maintain a Tax Receivable Agreement with affiliates that generally provides for the payment by us to affiliates of 85% of the net cash savings, if any, in U.S. federal, state and local income tax or franchise tax that we realize or will realize (or are deemed to realize in certain circumstances) in future periods as a result of (i) any tax basis increases resulting from the initial purchase by us of Spark HoldCo units from Retailco LLC (a successor to NuDevco Retail Holdings) and NuDevco Retail, (ii) any tax basis increases resulting from the exchange of Spark HoldCo units for shares of Class A common stock pursuant to the Exchange Right (or resulting from an exchange of Spark HoldCo units for cash pursuant to the Cash Option) and (iii) any imputed interest deemed to be paid by us as a result of, and additional tax basis arising from, any payments we make under the Tax Receivable Agreement. We retain the benefit of the remaining 15% of these tax savings. See Note 12 "Income Taxes" for further discussion. In certain circumstances, we may defer or partially defer any payment due (a “TRA Payment”) to the holders of rights under the Tax Receivable Agreement for the five year period ending September 30, 2019. Deferral of payment is required to the extent that Spark HoldCo does not generate sufficient Cash Available for Distribution (as defined below) during the four-quarter period ending September 30th of the applicable year in which the TRA Payment is to be made in an amount that equals or exceeds 130% (the “TRA Coverage Ratio”) of the Total Distributions (as defined below) paid in such four-quarter period by Spark HoldCo. For purposes of computing the TRA Coverage Ratio: • “Cash Available for Distribution” is generally defined as the Adjusted EBITDA of Spark HoldCo for the applicable period, less (i) cash interest paid by Spark HoldCo, (ii) capital expenditures of Spark HoldCo (exclusive of customer acquisition costs) and (iii) any taxes payable by Spark HoldCo; and • “Total Distributions” are defined as the aggregate distributions necessary to cause us to receive distributions of cash equal to (i) the targeted quarterly distribution we intend to pay to holders of its Class A common stock and Series A Preferred Stock payable during the applicable four-quarter period, plus (ii) the estimated taxes payable by us during such four-quarter period, plus (iii) the expected TRA Payment payable during the calendar year for which the TRA Coverage Ratio is being tested. Following the five -year deferral period ending September 30, 2019, we will be obligated to pay any outstanding deferred TRA Payments to the extent such deferred TRA Payments do not exceed (i) the lesser of our proportionate share of aggregate Cash Available for Distribution of Spark HoldCo during the five -year deferral period or the cash distributions actually received by us during the five -year deferral period, reduced by (ii) the sum of (a) the aggregate target quarterly dividends (which, for the purposes of the Tax Receivable Agreement, will be $0.18125 per Class A common stock share and $0.546875 per Series A Preferred Stock share per quarter) during the five -year deferral period, (b) our estimated taxes during the five -year deferral period, and (c) all prior TRA Payments and (d) if with respect to the quarterly period during which the deferred TRA Payment is otherwise paid or payable, Spark HoldCo has or reasonably determines it will have amounts necessary to cause us to receive distributions of cash equal to the target quarterly distribution payable during that quarterly period. Any portion of the deferred TRA Payments not payable due to these limitations will no longer be payable. We met the threshold coverage ratio required to fund the TRA Payments to Retailco and NuDevco Retail under the Tax Receivable Agreement for the four-quarter periods ending September 30, 2016 and 2017. Retailco and NuDevco Retail granted the Company the right to defer the TRA payment related to the four-quarter period ending September 30, 2016 until May 2018. Accordingly, these TRA Payments were made in April and May 2018. We also met the threshold coverage ratio required to fund the payment to Retailco and NuDevco Retail under the Tax Receivable Agreement during the four-quarter period ending September 30, 2018, resulting in the related TRA Payment being due in January of 2019. We have classified $2.5 million and $5.9 million as a current liability in our consolidated balance sheet at September 30, 2018 and December 31, 2017 , respectively. A TRA Payment of $2.3 million was made in October 2018 for the 2017 tax year, and the remainder of the current portion of the liability as of September 30, 2018 will be due in January 2019.

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segment Reporting	15. Segment Reporting Our determination of reportable business segments considers the strategic operating units under which we make financial decisions, allocate resources and assess performance of our business. Our reportable business segments are retail natural gas and retail electricity. The retail natural gas segment consists of natural gas sales to, and natural gas transportation and distribution for, residential and commercial customers. Asset optimization activities, considered an integral part of securing the lowest priced natural gas to serve retail gas load, are included in the retail natural gas segment. For the three months ended September 30, 2018 and 2017 , we recorded asset optimization revenues of $28.3 million and $31.7 million and asset optimization cost of revenues of $28.0 million and $32.0 million , respectively. For the nine months ended September 30, 2018 and 2017 , we recorded asset optimization revenues of $139.2 million and $132.8 million and asset optimization cost of revenues of $135.4 million and $133.5 million , respectively, which are presented on a net basis in asset optimization revenues. The retail electricity segment consists of electricity sales and transmission to residential and commercial customers. Corporate and other consists of expenses and assets of the retail natural gas and retail electricity segments that are managed at a consolidated level such as general and administrative expenses. The acquisitions of Perigee and the Verde Companies in 2017 and the acquisition of HIKO in 2018 had no impact on our reportable business segments as the portions of those acquisitions related to retail natural gas and retail electricity have been included in those existing business segments. We use retail gross margin to assess the performance of our operating segments. Retail gross margin is defined as operating income (loss) plus (i) depreciation and amortization expenses and (ii) general and administrative expenses, less (i) net asset optimization revenues (expenses), (ii) net gains (losses) on non-trading derivative instruments, and (iii) net current period cash settlements on non-trading derivative instruments. We deduct net gains (losses) on non-trading derivative instruments, excluding current period cash settlements, from the retail gross margin calculation in order to remove the non-cash impact of net gains and losses on non-trading derivative instruments. Retail gross margin should not be considered an alternative to, or more meaningful than, operating income, as determined in accordance with GAAP. Below is a reconciliation of retail gross margin to income before income tax expense (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Reconciliation of Retail Gross Margin to Income before taxes Income before income tax expense $ 22,645 $ 15,393 $ 1,525 $ 34,010 Interest and other income 47 (168 ) (707 ) (102 ) Interest expense 2,762 2,863 7,323 8,760 Operating income 25,454 18,088 8,141 42,668 Depreciation and amortization 13,917 11,509 39,797 30,435 General and administrative 25,695 25,566 83,522 69,405 Less: Net asset optimization revenues / (expenses) 348 (320 ) 3,798 (681 ) Net, gain (loss) on non-trading derivative instruments 17,888 (2,568 ) (2,223 ) (34,146 ) Net, Cash settlements on non-trading derivative instruments 1,035 7,481 (5,054 ) 19,016 Retail Gross Margin $ 45,795 $ 50,570 $ 134,939 $ 158,319 Financial data for business segments are as follows (in thousands): Three Months Ended September 30, 2018 Retail Retail Corporate Eliminations Spark Retail Total Revenues $ 246,182 $ 12,293 $ — $ — $ 258,475 Retail cost of revenues 186,449 6,960 — — 193,409 Less: Net asset optimization revenue — 348 — — 348 Gains (losses) on non-trading derivatives 18,415 (527 ) — — 17,888 Current period settlements on non-trading derivatives 1,066 (31 ) — — 1,035 Retail Gross Margin $ 40,252 $ 5,543 $ — $ — $ 45,795 Total Assets at September 30, 2018 $ 1,719,297 $ 581,530 $ 249,814 $ (2,069,364 ) $ 481,277 Goodwill at September 30, 2018 $ 117,813 $ 2,530 $ — $ — $ 120,343 2017 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 202,259 $ 13,277 $ — $ — $ 215,536 Retail cost of revenues 153,594 6,779 — — 160,373 Less: Net asset optimization expense — (320 ) — — (320 ) Gains (losses) on non-trading derivatives (2,762 ) 194 — — (2,568 ) Current period settlements on non-trading derivatives 6,932 549 — — 7,481 Retail Gross Margin $ 44,495 $ 6,075 $ — $ — $ 50,570 Total Assets at December 31, 2017 $ 1,228,552 $ 421,896 $ 209,428 $ (1,353,927 ) $ 505,949 Goodwill at December 31, 2017 $ 117,624 $ 2,530 $ — $ — $ 120,154 Nine Months Ended September 30, 2018 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 676,528 $ 100,886 $ — $ — $ 777,414 Retail cost of revenues 587,949 58,005 — — 645,954 Less: Net asset optimization revenue — 3,798 — — 3,798 Losses on non-trading derivatives 1,216 (3,439 ) — — (2,223 ) Current period settlements on non-trading derivatives (5,250 ) 196 — — (5,054 ) Retail Gross Margin $ 92,613 $ 42,326 $ — $ — $ 134,939 Total Assets at September 30, 2018 $ 1,719,297 $ 581,530 $ 249,814 $ (2,069,364 ) $ 481,277 Goodwill at September 30, 2018 $ 117,813 $ 2,530 $ — $ — $ 120,343 2017 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 467,861 $ 95,418 $ — $ — $ 563,279 Retail cost of revenues 364,518 56,253 — — 420,771 Less: Net asset optimization expenses — (681 ) — — (681 ) Losses on non-trading derivatives (31,722 ) (2,424 ) — — (34,146 ) Current period settlements on non-trading derivatives 18,936 80 — — 19,016 Retail Gross Margin $ 116,129 $ 42,190 $ — $ — $ 158,319 Total Assets at December 31, 2017 $ 1,228,552 $ 421,896 $ 209,428 $ (1,353,927 ) $ 505,949 Goodwill at December 31, 2017 $ 117,624 $ 2,530 $ — $ — $ 120,154

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events Declaration of Dividends On October 18, 2018 , we declared a quarterly dividend of $0.18125 to holders of record of our Class A common stock on November 30, 2018 and payable on December 14, 2018 . We also declared a quarterly cash dividend in the amount of $0.546875 per share of Series A Preferred Stock. The dividend will be paid January 15, 2019 to holders of record of the Series A Preferred Stock on January 1, 2019 . Acquisition of Customer Book On October 19, 2018, we entered into an asset purchase agreement pursuant to which we will acquire approximately 60,000 RCEs from Starion Energy Inc., Starion Energy NY Inc. and Starion Energy PA Inc. for a cash purchase price of up to a maximum of $10.7 million . These customers are expected to begin transferring in late November 2018, and are located in our existing markets.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying interim unaudited condensed consolidated financial statements (“interim statements”) of the Company have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC") as it applies to interim financial statements. This information should be read along with our consolidated financial statements and notes contained in our annual report on Form 10-K for the year ended December 31, 2017 . Our unaudited condensed consolidated financial statements are presented on a consolidated basis and include all wholly-owned and controlled subsidiaries. We account for investments over which we have significant influence but not a controlling financial interest using the equity method of accounting. All significant intercompany transactions and balances have been eliminated in the unaudited condensed consolidated financial statements.
Subsequent Events	Subsequent Events Subsequent events have been evaluated through the date these financial statements are issued. Any material subsequent events that occurred prior to such date have been properly recognized or disclosed in the condensed consolidated financial statements.
Use of Estimates	Use of Estimates The preparation of our condensed consolidated financial statements requires estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the interim financial statements and the reported amounts of revenues and expenses during the period. Actual results could materially differ from those estimates. Effects on the business, financial condition and results of operations resulting from revisions to estimates are recognized when the facts that give rise to the revision become known. The information furnished herein reflects all normal recurring adjustments that are, in the opinion of management, necessary for a fair presentation of the condensed consolidated financial statements.
Recent Accounting Pronouncements	In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers , which 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. We adopted the new standard effective January 1, 2018 utilizing the full retrospective approach. The adoption of the new standard resulted in no impact to our total revenues and operating income for the years ended December 31, 2017 and 2016. The standard requires expanded disclosures regarding the qualitative and quantitative information of an entity's nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. See Note 3 "Revenues" for further disclosure. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230), Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15"). ASU 2016-15 provides guidance on the presentation and classification of certain items in the statement of cash flows. This ASU has been applied using a retrospective transition method for each period presented. We adopted ASU 2016-15 effective January 1, 2018, which resulted in the reclassification of contingent consideration payments made after a business combination as cash outflows for operating and financing activities on a retrospective basis. Because of the change in accounting guidance, we reclassified acquisition related payments of approximately $1.8 million from cash flows from investing activities to cash flows from operating activities for the nine months ended September 30, 2017 . We also reclassified other acquisition related payments of approximately $15.5 million from cash flows from investing activities to cash flows from financing activities for the nine months ended September 30, 2017 . In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business ("ASU 2017-01"). ASU 2017-01 clarifies 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. We adopted ASU 2017-01 effective January 1, 2018, using it to evaluate all acquisitions after that date. New Accounting Standards Being Evaluated But Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"). Under this new guidance, lessees will be required to recognize assets and liabilities on the balance sheet for the rights and obligations created by all leases with terms of greater than twelve months. The guidance requires qualitative disclosures along with certain specific quantitative disclosures for both lessees and lessors. In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842 , Leases (“ASU 2018-10”), and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements (“ASU 2018-11”), to provide additional guidance for the adoption of Topic 842. The ASU and its related amendments are effective for fiscal years beginning after December 15, 2018, with early adoption permitted, and are effective for interim periods in the year of adoption. The ASU should be applied using a modified retrospective approach, which requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented with an option to use certain practical expedients, which we expect to use. We are continuing to evaluate the impact of this new guidance and have put in place a process to review lease contracts, evaluate existing lease related processes and design training related to the new standard. Although we are in the process of evaluating the impact of the new lease guidance on our consolidated financial statements, we currently believe the primary impact will be related to our real estate operating leases. In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ("ASU 2017-04"). ASU 2017-04 simplifies the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. Under this update, an entity should perform its annual or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, including goodwill. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. However, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. ASU 2017-04 should be applied on a prospective basis and is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We are currently evaluating the impact of adopting this guidance on its consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Non-employee Share-Based Payment Accounting ("ASU 2018-07"). ASU 2018-07 primarily expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. We are currently evaluating the impact of adopting this guidance on its consolidated financial statements. In July 2018, the FASB issued ASU No. 2018-09, Codification Improvements ("ASU 2018-09"). ASU 2018-09 represent changes to clarify, correct errors in, or make minor improvements to the Codification to a variety of topics, including comprehensive income, debt modifications and extinguishment, stock compensation, income taxes, fair value measurement, financial brokers and dealers, and defined contribution plans. The transition and effective date guidance is based on the facts and circumstances of each amendment. Many of the amendments in this Update do have transition guidance with effective dates for annual periods beginning after December 15, 2018. We are currently evaluating the impact of adopting this guidance on its consolidated financial statements.
Business Combinations	The acquisition of the Verde Companies was accounted for under the acquisition method in accordance with ASC 805, Business Combinations (“ASC 805”). The allocation of purchase consideration was based upon the estimated fair value of the tangible and identifiable intangible assets acquired and liabilities assumed in the acquisition based on management’s best estimates, and supported by independent third-party analyses. The excess of the purchase price over the estimated fair value of tangible and intangible assets acquired and liabilities assumed was allocated to goodwill.
Fair Value Measurements	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants at the measurement date. Fair values are based on assumptions that market participants would use when pricing an asset or liability, including assumptions about risk and the risks inherent in valuation techniques and the inputs to valuations. This includes the credit standing of counterparties involved and the impact of credit enhancements. We apply fair value measurements to our commodity derivative instruments and contingent payment arrangements based on the following fair value hierarchy, which prioritizes the inputs to the valuation techniques used to measure fair value into three broad levels: • Level 1—Quoted prices in active markets for identical assets and liabilities. Instruments categorized in Level 1 primarily consist of financial instruments such as exchange-traded derivative instruments. • Level 2—Inputs other than quoted prices recorded in Level 1 that are either directly or indirectly observable for the asset or liability, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability, and inputs that are derived from observable market data by correlation or other means. Instruments categorized in Level 2 primarily include non-exchange traded derivatives such as over-the-counter commodity forwards and swaps and options. • Level 3—Unobservable inputs for the asset or liability, including situations where there is little, if any, observable market activity for the asset or liability. The Level 3 category includes estimated earnout obligations related to our acquisitions.
Accounting for Derivatives Instruments	Our commodity trading activities are subject to limits within our Risk Management Policy. For these derivative instruments, changes in the fair value are recognized currently in earnings in net asset optimization revenues. Derivative assets and liabilities are presented net in our condensed consolidated balance sheets when the derivative instruments are executed with the same counterparty under a master netting arrangement. Our derivative contracts include transactions that are executed both on an exchange and centrally cleared as well as over-the-counter, bilateral contracts that are transacted directly with a third party. To the extent we have paid or received collateral related to the derivative assets or liabilities, such amounts would be presented net against the related derivative asset or liability’s fair value.

Revenues (Tables)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Disaggregated Revenue	The following table discloses revenue by primary geographical market, customer type, and customer credit risk profile (in thousands). The table also includes a reconciliation of the disaggregated revenue to revenue by reportable segment (in thousands). Reportable Segments Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Retail Electricity Retail Natural Gas Total Reportable Segments Retail Electricity Retail Natural Gas Total Reportable Segments Primary markets (a) New England $ 110,870 $ 2,163 $ 113,033 $ 61,421 $ 2,157 $ 63,578 Mid-Atlantic 83,846 3,762 87,608 83,955 4,543 88,498 Midwest 20,898 2,557 23,455 20,111 2,570 22,681 Southwest 30,568 3,463 34,031 36,772 4,327 41,099 $ 246,182 $ 11,945 $ 258,127 $ 202,259 $ 13,597 $ 215,856 Customer type Commercial $ 101,818 $ 4,650 $ 106,468 $ 55,489 $ 5,004 $ 60,493 Residential 151,918 7,068 158,986 143,152 8,571 151,723 Unbilled revenue (b) (7,554 ) 227 (7,327 ) 3,618 22 3,640 $ 246,182 $ 11,945 $ 258,127 $ 202,259 $ 13,597 $ 215,856 Customer credit risk POR $ 172,198 $ 5,013 $ 177,211 $ 138,544 $ 5,963 $ 144,507 Non-POR 73,984 6,932 80,916 63,715 7,634 71,349 $ 246,182 $ 11,945 $ 258,127 $ 202,259 $ 13,597 $ 215,856 Reportable Segments Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Retail Electricity Retail Natural Gas Total Reportable Segments Retail Electricity Retail Natural Gas Total Reportable Segments Primary markets (a) New England $ 305,894 $ 14,742 $ 320,636 $ 157,334 $ 15,252 $ 172,586 Mid-Atlantic 229,329 39,112 268,441 197,877 35,664 233,541 Midwest 56,818 27,243 84,061 43,073 23,893 66,966 Southwest 84,487 15,991 100,478 69,577 21,290 90,867 $ 676,528 $ 97,088 $ 773,616 $ 467,861 $ 96,099 $ 563,960 Customer type Commercial $ 275,966 $ 39,826 $ 315,792 $ 140,408 $ 40,224 $ 180,632 Residential 415,022 73,138 488,160 322,354 70,886 393,240 Unbilled revenue (b) (14,460 ) (15,876 ) (30,336 ) 5,099 (15,011 ) (9,912 ) $ 676,528 $ 97,088 $ 773,616 $ 467,861 $ 96,099 $ 563,960 Customer credit risk POR $ 473,438 $ 54,565 $ 528,003 $ 318,440 $ 47,907 $ 366,347 Non-POR 203,090 42,523 245,613 149,421 48,192 197,613 $ 676,528 $ 97,088 $ 773,616 $ 467,861 $ 96,099 $ 563,960 (a) The primary markets noted above include the following states: • New England - Connecticut, Maine, Massachusetts, New Hampshire; • Mid-Atlantic - Delaware, Maryland (including the District of Colombia), New Jersey, New York and Pennsylvania; • Midwest - Illinois, Indiana, Michigan and Ohio; and • Southwest - Arizona, California, Colorado, Florida, Nevada, and Texas. (b) Unbilled revenue is recorded in total until it is actualized, at which time it is categorized between commercial and residential customers.

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Allocation of Purchase Consideration	The final allocation of the purchase consideration is as follows (in thousands): Reported as of December 31, 2017 Adjustments (1) As of September 30, 2018 Cash and restricted cash $ 1,653 $ — $ 1,653 Property and equipment 4,560 — 4,560 Intangible assets — customer relationships 28,700 — 28,700 Intangible assets — trademarks 3,000 — 3,000 Goodwill (1) 39,207 189 39,396 Net working capital, net of cash acquired (1) 19,132 (659 ) 18,473 Deferred tax liability (3,126 ) — (3,126 ) Fair value of derivative liabilities (1,942 ) — (1,942 ) Total $ 91,184 $ (470 ) $ 90,714 (1) Changes to the purchase price allocation in 2018 were due to an agreement to settle the working capital balances with Verde Companies' sellers per the purchase agreement. NG&E acquired Perigee on February 3, 2017 and the fair value of the net assets acquired was as follows (in thousands): Final as of December 31, 2017 Cash $ 23 Intangible assets — customer relationships 1,100 Goodwill 1,540 Net working capital, net of cash acquired 2,085 Fair value of derivative liabilities (443 ) Total $ 4,305 The allocation of the purchase consideration is as follows (in thousands): Reported as of March 31, 2018 2018 Adjustments (1) As of September 30, 2018 Cash and restricted cash $ 309 $ 66 $ 375 Intangible assets — customer relationships 6,205 (174 ) 6,031 Net working capital, net of cash acquired 9,041 (576 ) 8,465 Fair value of derivative liabilities (205 ) — (205 ) Total $ 15,350 $ (684 ) $ 14,666 (1) Changes to the purchase price allocation in 2018 were due to an agreement to settle the working capital balances with HIKO sellers per the purchase agreement.
Unaudited Pro Forma Revenue and Earnings Summary	The following unaudited pro forma revenue and earnings summary presents our consolidated information as if the acquisition had occurred on January 1, 2016 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Revenues $ 215,536 $ 206,158 $ 633,639 $ 512,967 Earnings $ 2,347 $ 1,761 $ 4,991 $ 9,623

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Schedule of Economic Interests	The Company and NuDevco Retail and Retailco owned the following economic interests in Spark HoldCo at December 31, 2017 and September 30, 2018 , respectively. The Company NuDevco Retail and Retailco (1) December 31, 2017 38.12 % 61.88 % September 30, 2018 38.58 % 61.42 %
Summary of Net Income and Income Tax Benefit Attributable to Non-controlling Interest	The following table summarizes the portion of net income and income tax benefit attributable to non-controlling interest (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Net income allocated to non-controlling interest $ 13,910 $ 9,525 $ 830 $ 21,094 Income tax expense (benefit) allocated to non-controlling interest 692 (1,070 ) 690 (1,955 ) Net income attributable to non-controlling interest $ 13,218 $ 10,595 $ 140 $ 23,049
Computation of Earnings (Loss) Per Share	The following table presents the computation of earnings (loss) per share for the three and nine months ended September 30, 2018 and 2017 (in thousands, except per share data): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Net income attributable to Spark Energy, Inc. stockholders $ 5,609 $ 2,347 $ 783 $ 5,696 Less: Dividend on Series A preferred stock 2,027 932 6,081 2,106 Net income (loss) attributable to stockholders of Class A common stock $ 3,582 $ 1,415 $ (5,298 ) $ 3,590 Basic weighted average Class A common shares outstanding 13,394 13,235 13,254 13,112 Basic earnings (loss) per share attributable to stockholders $ 0.27 $ 0.11 $ (0.40 ) $ 0.27 Net income (loss) attributable to stockholders of Class A common stock $ 3,582 $ 1,415 $ (5,298 ) $ 3,590 Effect of conversion of Class B common stock to shares of Class A common stock — — — — Diluted net income (loss) attributable to stockholders of Class A common stock $ 3,582 $ 1,415 $ (5,298 ) $ 3,590 Basic weighted average Class A common shares outstanding 13,394 13,235 13,254 13,112 Effect of dilutive Class B common stock — — — — Effect of dilutive restricted stock units — 157 — 203 Diluted weighted average shares outstanding 13,394 13,392 13,254 13,315 Diluted earnings (loss) per share attributable to stockholders $ 0.27 $ 0.11 $ (0.40 ) $ 0.27
Carrying Amounts and Classification of Assets and Liabilities	The following table includes the carrying amounts and classification of the assets and liabilities of Spark HoldCo that are included in our condensed consolidated balance sheet as of September 30, 2018 (in thousands): September 30, 2018 Assets Current assets: Cash and cash equivalents $ 42,677 Accounts receivable 134,183 Other current assets 102,338 Total current assets 279,198 Non-current assets: Goodwill 120,343 Other assets 47,958 Total non-current assets 168,301 Total Assets $ 447,499 Liabilities Current liabilities: Accounts payable and accrued liabilities $ 101,004 Contingent consideration 2,980 Other current liabilities 14,496 Total current liabilities 118,480 Long-term liabilities: Long-term portion of Senior Credit Facility 112,000 Subordinated debt — affiliate 10,000 Other long-term liabilities 489 Total long-term liabilities 122,489 Total Liabilities $ 240,969

Preferred Stock (Tables)

Preferred Stock (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Summary of Preferred Equity Balance	A summary of our preferred equity balance for the nine months ended September 30, 2018 is as follows: (in thousands) Balance at December 31, 2017 $ 41,173 Issuance of Series A Preferred Stock, net of issuance cost 48,490 Accumulated dividends on Series A Preferred Stock 1,095 Balance at September 30, 2018 $ 90,758

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consist of the following amounts (in thousands): Estimated useful September 30, 2018 December 31, 2017 Information technology 2 – 5 $ 34,279 $ 34,103 Leasehold improvements 2 – 5 4,568 4,568 Furniture and fixtures 2 – 5 1,964 1,964 Building improvements 2 – 5 809 809 Total 41,620 41,444 Accumulated depreciation (36,237 ) (33,169 ) Property and equipment—net $ 5,383 $ 8,275

Goodwill, Customer Relationsh_2

Goodwill, Customer Relationships and Trademarks (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Customer Relationships and Trademarks	Goodwill, customer relationships and trademarks consist of the following amounts (in thousands): September 30, 2018 December 31, 2017 Goodwill $ 120,343 $ 120,154 Customer relationships - Acquired Cost $ 99,402 $ 93,371 Accumulated amortization (58,671 ) (46,681 ) Customer relationships - Acquired, net $ 40,731 $ 46,690 Customer relationships - Other Cost $ 14,080 $ 12,336 Accumulated amortization (8,204 ) (5,534 ) Customer relationships - Other, net $ 5,876 $ 6,802 Trademarks Cost $ 9,770 $ 9,770 Accumulated amortization (2,023 ) (1,212 ) Trademarks, net $ 7,747 $ 8,558 Changes in goodwill, customer relationships and trademarks consisted of the following (in thousands): Goodwill Customer Relationships - Acquired & Non-Compete Agreements Customer Relationships - Others Trademarks Balance at December 31, 2017 $ 120,154 $ 46,690 $ 6,802 $ 8,558 Additions — 6,205 1,744 — Adjustments (1) 189 (174 ) — — Amortization — (11,990 ) (2,670 ) (811 ) Balance at September 30, 2018 $ 120,343 $ 40,731 $ 5,876 $ 7,747 (1) Related to Spark's agreement to working capital balances with Verde Companies and HIKO sellers. Refer to Note 4 "Acquisitions."
Estimated Future Amortization Expense for Customer Relationships and Trademarks	Estimated future amortization expense for customer relationships and trademarks at September 30, 2018 is as follows (in thousands): Year ending December 31, 2018 $ 5,877 2019 16,958 2020 11,692 2021 10,118 2022 5,907 > 5 years 3,802 Total $ 54,354

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Debt	Debt consists of the following amounts as of September 30, 2018 and December 31, 2017 (in thousands): September 30, 2018 December 31, 2017 Current: Senior Credit Facility—Bridge Loan (2) $ — $ 7,500 Note Payable—Verde 10,535 13,443 Total current portion of debt 10,535 20,943 Long-term debt: Senior Credit Facility (1) (2) 112,000 117,750 Subordinated Debt 10,000 — Note Payable—Verde — 7,051 Total long-term debt 122,000 124,801 Total debt $ 132,535 $ 145,744 (1) As of September 30, 2018 and December 31, 2017 , we had $61.2 million and $47.2 million in letters of credit issued, respectively. (2) As of September 30, 2018 and December 31, 2017 , the weighted average interest rate on the Senior Credit Facility was 5.13% and 4.61% , respectively.
Components of Interest Expense	Interest expense consists of the following components for the periods indicated (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Senior Credit Facility $ 1,423 $ 988 $ 3,895 $ 2,216 Convertible subordinated notes to affiliate — — — 1,052 Subordinated debt 13 153 20 161 Verde promissory note 288 162 978 162 Accretion related to Earnouts — 1,127 — 3,787 Letters of credit and commitment fees 407 214 1,187 632 Amortization of deferred financing costs 631 219 1,243 750 Interest Expense $ 2,762 $ 2,863 $ 7,323 $ 8,760

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table presents assets and liabilities measured and recorded at fair value in our condensed consolidated balance sheets on a recurring basis by and their level within the fair value hierarchy (in thousands): Level 1 Level 2 Level 3 Total September 30, 2018 Non-trading commodity derivative assets $ 223 $ 25,077 $ — $ 25,300 Trading commodity derivative assets — — — — Total commodity derivative assets $ 223 $ 25,077 $ — $ 25,300 Non-trading commodity derivative liabilities $ (63 ) $ (502 ) $ — $ (565 ) Trading commodity derivative liabilities (189 ) (4 ) — (193 ) Total commodity derivative liabilities $ (252 ) $ (506 ) $ — $ (758 ) Contingent payment arrangement $ — $ — $ (2,980 ) $ (2,980 ) Level 1 Level 2 Level 3 Total December 31, 2017 Non-trading commodity derivative assets $ 158 $ 33,886 $ — $ 34,044 Trading commodity derivative assets — 456 — 456 Total commodity derivative assets $ 158 $ 34,342 $ — $ 34,500 Non-trading commodity derivative liabilities $ (387 ) $ (950 ) $ — $ (1,337 ) Trading commodity derivative liabilities (555 ) (237 ) — (792 ) Total commodity derivative liabilities $ (942 ) $ (1,187 ) $ — $ (2,129 ) Contingent payment arrangement $ — $ — $ (4,650 ) $ (4,650 )
Reconciliation of Liabilities Measured at Fair Value on a Recurring Basis	The following table presents a reconciliation of liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the nine months ended September 30, 2018 . Major Earnout and Stock Earnout Fair Value at December 31, 2017 $ 4,650 Change in fair value of contingent consideration, net (63 ) Payments and settlements (1,607 ) Fair Value at September 30, 2018 $ 2,980

Accounting for Derivative Ins_2

Accounting for Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts	The following table summarizes the net notional volume buy/(sell) of our open derivative financial instruments accounted for at fair value, broken out by commodity (in thousands): Non-trading Commodity Notional September 30, 2018 December 31, 2017 Natural Gas MMBtu 6,099 9,191 Natural Gas Basis MMBtu 140 — Electricity MWh 5,980 8,091 Trading Commodity Notional September 30, 2018 December 31, 2017 Natural Gas MMBtu 221 26 Natural Gas Basis MMBtu 78 (225 )
Gains (Losses) on Derivative Instruments	Gains (losses) on derivative instruments, net and current period settlements on derivative instruments were as follows for the periods indicated (in thousands): Three Months Ended September 30, 2018 2017 Gain (loss) on non-trading derivatives, net $ 17,888 $ (2,568 ) Gain (loss) on trading derivatives, net 229 (184 ) Gain (loss) on derivatives, net 18,117 (2,752 ) Current period settlements on non-trading derivatives (1) 1,035 7,481 Current period settlements on trading derivatives (113 ) (24 ) Total current period settlements on derivatives $ 922 $ 7,457 (1) Excludes settlements of $0.1 million and $1.5 million , respectively, for the three months ended September 30, 2018 and 2017 related to non-trading derivative liabilities assumed in various acquisitions. Nine Months Ended September 30, 2018 2017 Loss on non-trading derivatives, net $ (2,223 ) $ (34,146 ) Gain (loss) on trading derivatives, net 852 (79 ) Loss on derivatives, net (1,371 ) (34,225 ) Current period settlements on non-trading derivatives (1) (5,054 ) 19,016 Current period settlements on trading derivatives (769 ) (208 ) Total current period settlements on derivatives $ (5,823 ) $ 18,808 (1) Excludes settlements of $(0.4) million and $2.0 million , respectively, for the nine months ended September 30, 2018 and 2017 related to non-trading derivative liabilities assumed in various acquisitions.
Offsetting Assets	The following tables summarize the fair value and offsetting amounts of our derivative instruments by counterparty and collateral received or paid (in thousands): September 30, 2018 Description Gross Assets Gross Net Assets Cash Net Amount Non-trading commodity derivatives $ 42,794 $ (19,367 ) $ 23,427 $ — $ 23,427 Trading commodity derivatives — — — — — Total Current Derivative Assets 42,794 (19,367 ) 23,427 — 23,427 Non-trading commodity derivatives 10,003 (8,130 ) 1,873 — 1,873 Trading commodity derivatives — — — — — Total Non-current Derivative Assets 10,003 (8,130 ) 1,873 — 1,873 Total Derivative Assets $ 52,797 $ (27,497 ) $ 25,300 $ — $ 25,300 December 31, 2017 Description Gross Assets Gross Net Assets Cash Net Amount Non-trading commodity derivatives $ 60,167 $ (29,432 ) $ 30,735 $ — $ 30,735 Trading commodity derivatives 918 (462 ) 456 — 456 Total Current Derivative Assets 61,085 (29,894 ) 31,191 — 31,191 Non-trading commodity derivatives 16,055 (12,746 ) 3,309 — 3,309 Trading commodity derivatives — — — — — Total Non-current Derivative Assets 16,055 (12,746 ) 3,309 — 3,309 Total Derivative Assets $ 77,140 $ (42,640 ) $ 34,500 $ — $ 34,500
Offsetting Liabilities	September 30, 2018 Description Gross Gross Net Cash Net Amount Non-trading commodity derivatives $ (280 ) $ 15 $ (265 ) $ — $ (265 ) Trading commodity derivatives (4 ) — (4 ) — (4 ) Total Current Derivative Liabilities (284 ) 15 (269 ) — (269 ) Non-trading commodity derivatives (1,118 ) 818 (300 ) — (300 ) Trading commodity derivatives (255 ) 66 (189 ) — (189 ) Total Non-current Derivative Liabilities (1,373 ) 884 (489 ) — (489 ) Total Derivative Liabilities $ (1,657 ) $ 899 $ (758 ) $ — $ (758 ) December 31, 2017 Description Gross Gross Net Cash Net Amount Non-trading commodity derivatives $ (4,517 ) $ 3,059 $ (1,458 ) $ 65 $ (1,393 ) Trading commodity derivatives (517 ) 273 (244 ) — (244 ) Total Current Derivative Liabilities (5,034 ) 3,332 (1,702 ) 65 (1,637 ) Non-trading commodity derivatives (676 ) 732 56 — 56 Trading commodity derivatives (566 ) 18 (548 ) — (548 ) Total Non-current Derivative Liabilities (1,242 ) 750 (492 ) — (492 ) Total Derivative Liabilities $ (6,276 ) $ 4,082 $ (2,194 ) $ 65 $ (2,129 )

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Reconciliation of Retail Gross Margin to Income Before Income Tax Expense	Below is a reconciliation of retail gross margin to income before income tax expense (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Reconciliation of Retail Gross Margin to Income before taxes Income before income tax expense $ 22,645 $ 15,393 $ 1,525 $ 34,010 Interest and other income 47 (168 ) (707 ) (102 ) Interest expense 2,762 2,863 7,323 8,760 Operating income 25,454 18,088 8,141 42,668 Depreciation and amortization 13,917 11,509 39,797 30,435 General and administrative 25,695 25,566 83,522 69,405 Less: Net asset optimization revenues / (expenses) 348 (320 ) 3,798 (681 ) Net, gain (loss) on non-trading derivative instruments 17,888 (2,568 ) (2,223 ) (34,146 ) Net, Cash settlements on non-trading derivative instruments 1,035 7,481 (5,054 ) 19,016 Retail Gross Margin $ 45,795 $ 50,570 $ 134,939 $ 158,319
Financial Data for Business Segments	Financial data for business segments are as follows (in thousands): Three Months Ended September 30, 2018 Retail Retail Corporate Eliminations Spark Retail Total Revenues $ 246,182 $ 12,293 $ — $ — $ 258,475 Retail cost of revenues 186,449 6,960 — — 193,409 Less: Net asset optimization revenue — 348 — — 348 Gains (losses) on non-trading derivatives 18,415 (527 ) — — 17,888 Current period settlements on non-trading derivatives 1,066 (31 ) — — 1,035 Retail Gross Margin $ 40,252 $ 5,543 $ — $ — $ 45,795 Total Assets at September 30, 2018 $ 1,719,297 $ 581,530 $ 249,814 $ (2,069,364 ) $ 481,277 Goodwill at September 30, 2018 $ 117,813 $ 2,530 $ — $ — $ 120,343 2017 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 202,259 $ 13,277 $ — $ — $ 215,536 Retail cost of revenues 153,594 6,779 — — 160,373 Less: Net asset optimization expense — (320 ) — — (320 ) Gains (losses) on non-trading derivatives (2,762 ) 194 — — (2,568 ) Current period settlements on non-trading derivatives 6,932 549 — — 7,481 Retail Gross Margin $ 44,495 $ 6,075 $ — $ — $ 50,570 Total Assets at December 31, 2017 $ 1,228,552 $ 421,896 $ 209,428 $ (1,353,927 ) $ 505,949 Goodwill at December 31, 2017 $ 117,624 $ 2,530 $ — $ — $ 120,154 Nine Months Ended September 30, 2018 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 676,528 $ 100,886 $ — $ — $ 777,414 Retail cost of revenues 587,949 58,005 — — 645,954 Less: Net asset optimization revenue — 3,798 — — 3,798 Losses on non-trading derivatives 1,216 (3,439 ) — — (2,223 ) Current period settlements on non-trading derivatives (5,250 ) 196 — — (5,054 ) Retail Gross Margin $ 92,613 $ 42,326 $ — $ — $ 134,939 Total Assets at September 30, 2018 $ 1,719,297 $ 581,530 $ 249,814 $ (2,069,364 ) $ 481,277 Goodwill at September 30, 2018 $ 117,813 $ 2,530 $ — $ — $ 120,343 2017 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 467,861 $ 95,418 $ — $ — $ 563,279 Retail cost of revenues 364,518 56,253 — — 420,771 Less: Net asset optimization expenses — (681 ) — — (681 ) Losses on non-trading derivatives (31,722 ) (2,424 ) — — (34,146 ) Current period settlements on non-trading derivatives 18,936 80 — — 19,016 Retail Gross Margin $ 116,129 $ 42,190 $ — $ — $ 158,319 Total Assets at December 31, 2017 $ 1,228,552 $ 421,896 $ 209,428 $ (1,353,927 ) $ 505,949 Goodwill at December 31, 2017 $ 117,624 $ 2,530 $ — $ — $ 120,154

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Decrease in cash flows from investing activities	$ 23,693	$ 78,687
Cash flows from operating activities	41,853	62,043
Cash flows from financing activities	$ (4,783)	8,933
Accounting Standards Update 2016-15
Business Acquisition [Line Items]
Cash flows from operating activities		1,800
Cash flows from financing activities		13,400
Accounting Standards Update 2016-15 | Investing Activities to Operating Activities
Business Acquisition [Line Items]
Decrease in cash flows from investing activities		1,800
Accounting Standards Update 2016-15 | Investing Activities to Financing Activities
Business Acquisition [Line Items]
Decrease in cash flows from investing activities		$ 15,500

Revenues - Narrative (Details)

Revenues - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Retail Revenues
Disaggregation of Revenue [Line Items]
Gross receipts taxes	$ 2.2	$ 2.1	$ 6.5	$ 4.6
Retail Cost of Revenues
Disaggregation of Revenue [Line Items]
Gross receipts taxes	$ 2.7	$ 2.7	$ 7.8	$ 6.6
Retail Electricity
Disaggregation of Revenue [Line Items]
Typical length of contract			The typical length of a contract to provide electricity is 12 months.
Retail Natural Gas
Disaggregation of Revenue [Line Items]
Typical length of contract			Natural gas products may be sold as fixed-price or variable-price products. The typical length of a contract to provide natural gas is 12 months.

Revenues - Disaggregation of Re

Revenues - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 258,127	$ 215,856	$ 773,616	$ 563,960
POR
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	177,211	144,507	528,003	366,347
Non-POR
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	80,916	71,349	245,613	197,613
Unbilled revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(7,327)	3,640	30,336	9,912
Commercial
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	106,468	60,493	315,792	180,632
Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	158,986	151,723	488,160	393,240
New England
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	113,033	63,578	320,636	172,586
Mid-Atlantic
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	87,608	88,498	268,441	233,541
Midwest
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	23,455	22,681	84,061	66,966
Southwest
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	34,031	41,099	100,478	90,867
Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	246,182	202,259	676,528	467,861
Retail Electricity | POR
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	172,198	138,544	473,438	318,440
Retail Electricity | Non-POR
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	73,984	63,715	203,090	149,421
Retail Electricity | Unbilled revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(7,554)	3,618	14,460	(5,099)
Retail Electricity | Commercial
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	101,818	55,489	275,966	140,408
Retail Electricity | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	151,918	143,152	415,022	322,354
Retail Electricity | New England
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	110,870	61,421	305,894	157,334
Retail Electricity | Mid-Atlantic
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	83,846	83,955	229,329	197,877
Retail Electricity | Midwest
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	20,898	20,111	56,818	43,073
Retail Electricity | Southwest
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	30,568	36,772	84,487	69,577
Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11,945	13,597	97,088	96,099
Retail Natural Gas | POR
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5,013	5,963	54,565	47,907
Retail Natural Gas | Non-POR
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	6,932	7,634	42,523	48,192
Retail Natural Gas | Unbilled revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	227	22	15,876	15,011
Retail Natural Gas | Commercial
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	4,650	5,004	39,826	40,224
Retail Natural Gas | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7,068	8,571	73,138	70,886
Retail Natural Gas | New England
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,163	2,157	14,742	15,252
Retail Natural Gas | Mid-Atlantic
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3,762	4,543	39,112	35,664
Retail Natural Gas | Midwest
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,557	2,570	27,243	23,893
Retail Natural Gas | Southwest
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 3,463	$ 4,327	$ 15,991	$ 21,290

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) residential_customer_equivalent in Thousands	Mar. 01, 2018USD ($)marketstateresidential_customer_equivalent	Jul. 01, 2017USD ($)	Apr. 01, 2017USD ($)utility	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Jan. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Business Acquisition [Line Items]
Revenues				$ 258,475,000	$ 215,536,000	$ 777,414,000	$ 563,279,000
Net income from operations				25,454,000	$ 18,088,000	8,141,000	42,668,000
Liabilities incurred						0	$ 5,400,000
Debt outstanding				132,535,000		132,535,000			$ 145,744,000
Verde Earnout Termination Note | Promissory Note
Business Acquisition [Line Items]
Debt outstanding								$ 5,900,000
HIKO
Business Acquisition [Line Items]
Purchase price	$ 6,000,000
Number of RCEs | residential_customer_equivalent	29
Number of markets | market	42
Number of states | state	7
Revenues				4,900,000		12,900,000
Net income from operations				$ 1,100,000		$ 3,700,000
Verde Companies
Business Acquisition [Line Items]
Purchase price		$ 90,700,000
Initial positive (negative) working capital estimate		20,100,000
Closing consideration		85,800,000
Cash on hand		$ 6,800,000
Adjusted EBITDA obligation term (in months)		18 months
Initial value of Earnout		$ 5,400,000
Verde Companies | Promissory Note
Business Acquisition [Line Items]
Liabilities incurred		20,000,000
Verde Companies | Revolving Credit Facility
Business Acquisition [Line Items]
Liabilities incurred		44,000,000
Verde Companies | Subordinated debt — affiliate
Business Acquisition [Line Items]
Liabilities incurred		$ 15,000,000
Perigee
Business Acquisition [Line Items]
Purchase price			$ 4,100,000
Perigee | NG&E
Business Acquisition [Line Items]
Purchase price			4,100,000
Initial positive (negative) working capital estimate			$ 1,900,000
Number of utilities | utility			14
Base price			$ 2,000,000
Additional customer option payment			$ 200,000

Acquisitions - Allocation of Pu

Acquisitions - Allocation of Purchase Consideration (Details) - USD ($) $ in Thousands	6 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 120,343	$ 120,343		$ 120,154
HIKO
Business Acquisition [Line Items]
Cash and restricted cash	375	375	$ 309
Intangible assets—customer relationships	6,031	6,031	6,205
Net working capital, net of cash acquired	8,465	8,465	9,041
Fair value of derivative liabilities	(205)	(205)	(205)
Total	14,666	14,666	$ 15,350
Adjustments
Cash and restricted cash	66
Intangible assets	(174)
Net working capital, net of cash acquired	(576)
Total	(684)
Verde Companies
Business Acquisition [Line Items]
Cash and restricted cash	1,653	1,653		1,653
Property and equipment	4,560	4,560		4,560
Goodwill	39,396	39,396		39,207
Net working capital, net of cash acquired	18,473	18,473		19,132
Deferred tax liability	(3,126)	(3,126)		(3,126)
Fair value of derivative liabilities	(1,942)	(1,942)		(1,942)
Total	90,714	90,714		91,184
Adjustments
Intangible assets		189
Net working capital, net of cash acquired		(659)
Total		(470)
Verde Companies | Customer relationships
Business Acquisition [Line Items]
Intangible assets	28,700	28,700		28,700
Verde Companies | Trademarks
Business Acquisition [Line Items]
Intangible assets	$ 3,000	$ 3,000		3,000
Perigee | NG&E
Business Acquisition [Line Items]
Cash and restricted cash				23
Intangible assets—customer relationships				1,100
Goodwill				1,540
Net working capital, net of cash acquired				2,085
Fair value of derivative liabilities				(443)
Total				$ 4,305

Acquisitions - Unaudited Pro Fo

Acquisitions - Unaudited Pro Forma Revenue and Earnings Summary (Details) - Verde Companies - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Revenues	$ 215,536	$ 206,158	$ 633,639	$ 512,967
Earnings	$ 2,347	$ 1,761	$ 4,991	$ 9,623

Equity - Schedule of Economic I

Equity - Schedule of Economic Interests (Details) - The Company	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Economic interests percentage	38.58%	38.12%
NuDevco Retail and Retailco
Class of Stock [Line Items]
Economic interests percentage	61.42%	61.88%

Equity - Summary of Net Income

Equity - Summary of Net Income and Income Tax Benefit Attributable to Non-controlling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Net income allocated to non-controlling interest	$ 13,910	$ 9,525	$ 830	$ 21,094
Income tax expense (benefit) allocated to non-controlling interest	692	(1,070)	690	(1,955)
Net income attributable to non-controlling interest	$ 13,218	$ 10,595	$ 140	$ 23,049

Equity - Narrative (Details)

Equity - Narrative (Details) - USD ($) shares in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	May 24, 2017
Class B Common Stock
Class of Stock [Line Items]
Shares excluded from computation of diluted earnings per share (in shares)	21.5	21.5
Restricted Stock Unit
Class of Stock [Line Items]
Shares excluded from computation of diluted earnings per share (in shares)	0.8	0.8
Share Repurchase Program | Class A Common Stock
Class of Stock [Line Items]
Share repurchase program, amount authorized			$ 50,000,000

Equity - Computation of Earning

Equity - Computation of Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Net income attributable to Spark Energy, Inc. stockholders	$ 5,609	$ 2,347	$ 783	$ 5,696
Less: Dividend on Series A preferred stock	2,027	932	6,081	2,106
Net income (loss) attributable to stockholders of Class A common stock	$ 3,582	$ 1,415	$ (5,298)	$ 3,590
Basic weighted average Class A common shares outstanding (in shares)	13,394	13,235	13,254	13,112
Basic earnings (loss) per share attributable to stockholders (in dollars per share)	$ 0.27	$ 0.11	$ (0.40)	$ 0.27
Net income (loss) attributable to stockholders of Class A common stock	$ 3,582	$ 1,415	$ (5,298)	$ 3,590
Effect of conversion of Class B common stock to shares of Class A common stock	0	0	0	0
Diluted net income (loss) attributable to stockholders of Class A common stock	$ 3,582	$ 1,415	$ (5,298)	$ 3,590
Basic weighted average Class A common shares outstanding (in shares)	13,394	13,235	13,254	13,112
Effect of dilutive Class B common stock (in shares)	0	0	0	0
Effect of dilutive restricted stock units (in shares)	0	157	0	203
Diluted weighted average shares outstanding (in shares)	13,394	13,392	13,254	13,315
Diluted earnings (loss) per share attributable to stockholders (in dollars per share)	$ 0.27	$ 0.11	$ (0.40)	$ 0.27

Equity - Carrying Amounts and C

Equity - Carrying Amounts and Classification of Assets and Liabilities (Details) - Variable Interest Entity, Primary Beneficiary $ in Thousands	Sep. 30, 2018USD ($)
Variable Interest Entity [Line Items]
Total Assets	$ 447,499
Total Liabilities	240,969
Total current assets
Variable Interest Entity [Line Items]
Total Assets	279,198
Cash and cash equivalents
Variable Interest Entity [Line Items]
Total Assets	42,677
Accounts receivable
Variable Interest Entity [Line Items]
Total Assets	134,183
Other current assets
Variable Interest Entity [Line Items]
Total Assets	102,338
Total non-current assets
Variable Interest Entity [Line Items]
Total Assets	168,301
Goodwill
Variable Interest Entity [Line Items]
Total Assets	120,343
Other assets
Variable Interest Entity [Line Items]
Total Assets	47,958
Total current liabilities
Variable Interest Entity [Line Items]
Total Liabilities	118,480
Accounts payable and accrued liabilities
Variable Interest Entity [Line Items]
Total Liabilities	101,004
Contingent consideration
Variable Interest Entity [Line Items]
Total Liabilities	2,980
Other current liabilities
Variable Interest Entity [Line Items]
Total Liabilities	14,496
Total long-term liabilities
Variable Interest Entity [Line Items]
Total Liabilities	122,489
Long-term portion of Senior Credit Facility
Variable Interest Entity [Line Items]
Total Liabilities	112,000
Subordinated debt — affiliate
Variable Interest Entity [Line Items]
Total Liabilities	10,000
Other long-term liabilities
Variable Interest Entity [Line Items]
Total Liabilities	$ 489

Preferred Stock - Narrative (De

Preferred Stock - Narrative (Details) - USD ($)	Jan. 23, 2018	Mar. 15, 2017	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Jul. 21, 2017
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)			3,707,256	3,707,256		1,704,339
Preferred stock, par value per share (in dollars per share)			$ 0.01	$ 0.01		$ 0.01
Proceeds from issuance of Series A Preferred Stock, net of issuance costs paid	$ 48,900,000	$ 39,000,000		$ 48,490,000	$ 40,312,000
Preferred offering expenses (less than for ATM Agreement)	$ 500,000	$ 1,000,000
Aggregate offering price							$ 50,000,000
Dividends paid				6,081,000
LIBOR
Class of Stock [Line Items]
Preferred stock dividend accrual rate		8.75%
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	2,000,000	1,610,000
Preferred stock stated rate (percent)		8.75%
Preferred stock, par value per share (in dollars per share)		$ 0.01
Preferred stock liquidation preference (in dollars per share)		25
Preferred stock price to the public (in dollars per share)	$ 25.25	25
Preferred stock price, net of underwriting discounts and commissions (in dollars per share)	$ 24.45	$ 24.21
Dividends paid			$ 2,000,000	5,000,000
Dividend accrual			$ 2,000,000	$ 2,000,000
Series A Preferred Stock | ATM Agreement
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)			2,917	2,917		94,339
Proceeds from issuance of Series A Preferred Stock, net of issuance costs paid				$ 100,000		$ 2,400,000
Preferred offering expenses (less than for ATM Agreement)				$ 100,000		$ 100,000

Preferred Stock - Summary of Pr

Preferred Stock - Summary of Preferred Equity Balance (Details) - USD ($) $ in Thousands	Jan. 23, 2018	Mar. 15, 2017	Sep. 30, 2018	Sep. 30, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017			$ 41,173
Issuance of Series A Preferred Stock, net of issuance cost	$ 48,900	$ 39,000	48,490	$ 40,312
Balance at September 30, 2018			90,758
Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017			41,173
Issuance of Series A Preferred Stock, net of issuance cost			48,490
Accumulated dividends on Series A Preferred Stock			1,095
Balance at September 30, 2018			$ 90,758

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 41,620	$ 41,444
Accumulated depreciation	(36,237)	(33,169)
Property and equipment—net	5,383	8,275
Information technology
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 34,279	34,103
Information technology | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	2 years
Information technology | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,568	4,568
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	2 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,964	1,964
Furniture and fixtures | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	2 years
Furniture and fixtures | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	5 years
Building improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 809	$ 809
Building improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	2 years
Building improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	5 years

Property and Equipment - Narrat

Property and Equipment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation	$ 1	$ 0.8	$ 3.1	$ 1.8
Information technology
Property, Plant and Equipment [Line Items]
Assets not yet placed into service	$ 0.5		$ 0.5		$ 1.2

Goodwill, Customer Relationsh_3

Goodwill, Customer Relationships and Trademarks - Schedule of Goodwill, Customer Relationships and Trademarks (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 120,343	$ 120,154
Finite-Lived Intangible Assets [Line Items]
Total	54,354
Customer relationships - Acquired
Finite-Lived Intangible Assets [Line Items]
Cost	99,402	93,371
Accumulated amortization	(58,671)	(46,681)
Total	40,731	46,690
Customer relationships - Other
Finite-Lived Intangible Assets [Line Items]
Cost	14,080	12,336
Accumulated amortization	(8,204)	(5,534)
Total	5,876	6,802
Trademarks
Finite-Lived Intangible Assets [Line Items]
Cost	9,770	9,770
Accumulated amortization	(2,023)	(1,212)
Total	$ 7,747	$ 8,558

Goodwill, Customer Relationsh_4

Goodwill, Customer Relationships and Trademarks - Changes in Goodwill, Customer Relationships and Trademarks (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Goodwill [Roll Forward]
Balance at beginning of period	$ 120,154
Adjustments	189
Balance at end of period	120,343
Finite-lived Intangible Assets [Roll Forward]
Balance at end of period	54,354
Customer Relationships - Acquired & Non-Compete Agreements
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	46,690
Additions	6,205
Adjustments	(174)
Amortization	(11,990)
Balance at end of period	40,731
Customer Relationships - Others
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	6,802
Additions	1,744
Amortization	(2,670)
Balance at end of period	5,876
Trademarks
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	8,558
Amortization	(811)
Balance at end of period	$ 7,747

Goodwill, Customer Relationsh_5

Goodwill, Customer Relationships and Trademarks - Future Amortization Expense (Details) $ in Thousands	Sep. 30, 2018USD ($)
Year ending December 31,
2,018	$ 5,877
2,019	16,958
2,020	11,692
2,021	10,118
2,022	5,907
More than 5 years	3,802
Total	$ 54,354

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total current portion of debt	$ 10,535,000	$ 20,943,000
Total long-term debt	122,000,000	124,801,000
Subordinated Debt	10,000,000	0
Total debt	132,535,000	145,744,000
Senior Credit Facility
Debt Instrument [Line Items]
Letters of credit issued	$ 61,200,000	$ 47,200,000
Weighted average interest rate on current portion of debt	5.13%	4.61%
Senior Credit Facility | Bridge Loan
Debt Instrument [Line Items]
Total current portion of debt	$ 0	$ 7,500,000
Senior Credit Facility | Senior Credit Facility
Debt Instrument [Line Items]
Total long-term debt	112,000,000	117,750,000
Note Payable | Note Payable - Verde
Debt Instrument [Line Items]
Total current portion of debt	10,535,000	13,443,000
Total long-term debt	$ 0	$ 7,051,000

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Capitalized financing costs	$ 1,500,000	$ 1,600,000
Capitalized financing costs, current	1,500,000	1,200,000
Capitalized financing costs, other non-current	$ 0	$ 400,000

Debt - Components of Interest E

Debt - Components of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Line of Credit Facility [Line Items]
Accretion related to Earnouts	$ 0	$ 1,127	$ 0	$ 3,787
Amortization of deferred financing costs	631	219	1,243	750
Interest Expense	2,762	2,863	7,323	8,760
Convertible subordinated notes
Line of Credit Facility [Line Items]
Convertible subordinated notes to affiliate	0	0	0	1,052
Subordinated debt
Line of Credit Facility [Line Items]
Interest incurred	13	153	20	161
Verde promissory note
Line of Credit Facility [Line Items]
Interest incurred	288	162	978	162
Working Capital Facility
Line of Credit Facility [Line Items]
Letters of credit and commitment fees	407	214	1,187	632
Working Capital Facility | Senior Credit Facility
Line of Credit Facility [Line Items]
Interest incurred	$ 1,423	$ 988	$ 3,895	$ 2,216

Debt - Senior Credit Facility (

Debt - Senior Credit Facility (Details) - USD ($)	Jul. 17, 2018	Sep. 30, 2018	Jul. 31, 2018	Dec. 31, 2017	May 19, 2017
Senior Secured Revolving Credit Facility
Debt Instrument [Line Items]
Maximum leverage ratio	250.00%
Maximum senior secured leverage ratio	185.00%
Percentage of obligations, limit	50.00%
Debt default, material judgment (in excess of)		$ 5,000,000
Senior Secured Revolving Credit Facility | Common Class A
Debt Instrument [Line Items]
Amount entitled to repurchase of Class A common stock (in shares)		10,000,000
Senior Secured Revolving Credit Facility | Series A Preferred Stock
Debt Instrument [Line Items]
Share repurchase program, amount authorized		$ 92,700,000
Senior Secured Revolving Credit Facility | Common Class A and Common Class B
Debt Instrument [Line Items]
Default share limit, minimum amount (in shares)		13,600,000
Senior Secured Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Fixed charge coverage ratio	125.00%
Senior Credit Facility
Debt Instrument [Line Items]
Letters of credit issued		$ 61,200,000		$ 47,200,000
Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity					$ 120,000,000
Line of credit facility, remaining borrowing capacity		192,500,000
Long-term line of credit		$ 112,000,000
Revolving Credit Facility | Working Capital Line
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 250,000,000
Debt instrument, annual repayment, percent		25.00%
Debt instrument, quarterly repayment, percent		6.25%
Nonutilization fee	0.50%
Revolving Credit Facility | Working Capital Line | Eurodollar
Debt Instrument [Line Items]
Basis spread on variable rate	3.00%
Revolving Credit Facility | Working Capital Line | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
Revolving Credit Facility | Working Capital Line | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Revolving Credit Facility | Working Capital Line | Reference Eurodollar Rate
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Revolving Credit Facility | Bridge Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 62,500,000
Revolving Credit Facility | Acquisition Line | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Revolving Credit Facility | Acquisition Line | Reference Eurodollar Rate
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Revolving Credit Facility | Acquisition Line | Maximum | Eurodollar
Debt Instrument [Line Items]
Basis spread on variable rate	3.75%
Revolving Credit Facility | Acquisition Line | Maximum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate	2.75%

Debt - Subordinated Debt Facili

Debt - Subordinated Debt Facility (Details) - Subordinated debt - Retailco	Dec. 27, 2016USD ($)
Debt Instrument [Line Items]
Subordinated borrowing, interest rate	5.00%
Subordinated debt	$ 25,000,000
Subordinated debt, advances, no less than	$ 1,000,000
Subordinated debt, interest rate on advances	5.00%
Minimum availability under the borrowing base	$ 5,000,000

Debt - Verde Companies Promisso

Debt - Verde Companies Promissory Note (Details)	Jul. 01, 2017USD ($)payment	Sep. 30, 2018USD ($)	Jan. 12, 2018	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Debt outstanding		$ 132,535,000		$ 145,744,000
Verde Promissory Note | Promissory Note
Debt Instrument [Line Items]
Notes, issued amount	$ 20,000,000
Notes, number of installments | payment	18
Interest rate	5.00%		9.00%
Debt outstanding		$ 4,600,000		$ 14,600,000

Debt - Verde Earnout Terminatio

Debt - Verde Earnout Termination Note (Details) - Promissory Note - USD ($)	Jan. 12, 2018	Jul. 01, 2017
Verde Earnout Termination Note
Debt Instrument [Line Items]
Principal amount	$ 5,900,000
Verde Promissory Note
Debt Instrument [Line Items]
Principal amount		$ 20,000,000
Interest rate	9.00%	5.00%

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	$ 25,300	$ 34,500
Total commodity derivative liabilities	(758)	(2,129)
Contingent payment arrangement	(2,980)	(4,650)
Non-trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	25,300	34,044
Total commodity derivative liabilities	(565)	(1,337)
Trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	456
Total commodity derivative liabilities	(193)	(792)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	223	158
Total commodity derivative liabilities	(252)	(942)
Contingent payment arrangement	0	0
Level 1 | Non-trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	223	158
Total commodity derivative liabilities	(63)	(387)
Level 1 | Trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	0
Total commodity derivative liabilities	(189)	(555)
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	25,077	34,342
Total commodity derivative liabilities	(506)	(1,187)
Contingent payment arrangement	0	0
Level 2 | Non-trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	25,077	33,886
Total commodity derivative liabilities	(502)	(950)
Level 2 | Trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	456
Total commodity derivative liabilities	(4)	(237)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	0
Total commodity derivative liabilities	0	0
Contingent payment arrangement	(2,980)	(4,650)
Level 3 | Non-trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	0
Total commodity derivative liabilities	0	0
Level 3 | Trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	0
Total commodity derivative liabilities	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	Apr. 15, 2016	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration, current liabilities		$ 2,980,000		$ 4,024,000
Earnout obligations, long-term liabilities		$ 0		$ 626,000
Major Energy Companies | Common Class B | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Share earnout maximum (in shares)		400,000
Major Energy Companies | Major Earnout
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout payments		$ 1,600,000	$ 7,400,000
Major Energy Companies | National Gas & Electric, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout period (in months)	33 months
Earnout maximum	$ 20,000,000

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in fair value of contingent consideration, net	$ (63)	$ (9,423)
Recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value at beginning of period	4,650
Fair Value at end of period	2,980
Recurring | Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value at beginning of period	4,650
Fair Value at end of period	2,980
Major Earnout and Stock Earnout | Recurring | Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value at beginning of period	4,650
Change in fair value of contingent consideration, net	(63)
Payments and settlements	(1,607)
Fair Value at end of period	$ 2,980

Accounting for Derivative Ins_3

Accounting for Derivative Instruments - Narrative (Details) $ in Millions	Sep. 30, 2018USD ($)derivative_instrument	Dec. 31, 2017USD ($)
Derivative [Line Items]
Collateral fee	$ 0	$ 0.1
Not Designated as Hedges | Interest Rate Swap Agreements
Derivative [Line Items]
Number of instruments held | derivative_instrument	2
Notional amount	$ 10
Fair value liability (less than)	$ 0.1

Accounting for Derivative Ins_4

Accounting for Derivative Instruments - Schedule of Notional Amounts (Details) MWh in Thousands, MMBTU in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018MWhMMBTU	Dec. 31, 2017MWhMMBTU
Non-trading | Natural Gas | Buy
Derivatives, Fair Value [Line Items]
Net notional volume (energy measure)	6,099	9,191
Non-trading | Natural Gas Basis | Buy
Derivatives, Fair Value [Line Items]
Net notional volume (energy measure)	140	0
Non-trading | Electricity | Buy
Derivatives, Fair Value [Line Items]
Net notional volume (energy measure) | MWh	5,980	8,091
Trading | Natural Gas | Buy
Derivatives, Fair Value [Line Items]
Net notional volume (energy measure)	221	26
Trading | Natural Gas Basis | Buy
Derivatives, Fair Value [Line Items]
Net notional volume (energy measure)	78
Trading | Natural Gas Basis | Sell
Derivatives, Fair Value [Line Items]
Net notional volume (energy measure)		225

Accounting for Derivative Ins_5

Accounting for Derivative Instruments - Gains (Losses) on Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives, net	$ 18,117	$ (2,752)	$ (1,371)	$ (34,225)
Total current period settlements on derivatives	922	7,457	(5,823)	18,808
Non-trading
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives, net	17,888	(2,568)	(2,223)	(34,146)
Total current period settlements on derivatives	1,035	7,481	(5,054)	19,016
Non-trading | Various Acquisitions
Derivative Instruments, Gain (Loss) [Line Items]
Total current period settlements on derivatives	100	1,500	(400)	2,000
Trading
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives, net	229	(184)	852	(79)
Total current period settlements on derivatives	$ (113)	$ (24)	$ (769)	$ (208)

Accounting for Derivative Ins_6

Accounting for Derivative Instruments - Offsetting Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Total Derivative Assets
Offsetting Assets [Line Items]
Gross Assets	$ 52,797	$ 77,140
Gross Amounts Offset	(27,497)	(42,640)
Net Assets	25,300	34,500
Cash Collateral Offset	0	0
Net Amount Presented	25,300	34,500
Total Current Derivative Assets
Offsetting Assets [Line Items]
Gross Assets	42,794	61,085
Gross Amounts Offset	(19,367)	(29,894)
Net Assets	23,427	31,191
Cash Collateral Offset	0	0
Net Amount Presented	23,427	31,191
Non-trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	42,794	60,167
Gross Amounts Offset	(19,367)	(29,432)
Net Assets	23,427	30,735
Cash Collateral Offset	0	0
Net Amount Presented	23,427	30,735
Trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	0	918
Gross Amounts Offset	0	(462)
Net Assets	0	456
Cash Collateral Offset	0	0
Net Amount Presented	0	456
Total Non-current Derivative Assets
Offsetting Assets [Line Items]
Gross Assets	10,003	16,055
Gross Amounts Offset	(8,130)	(12,746)
Net Assets	1,873	3,309
Cash Collateral Offset	0	0
Net Amount Presented	1,873	3,309
Non-trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	10,003	16,055
Gross Amounts Offset	(8,130)	(12,746)
Net Assets	1,873	3,309
Cash Collateral Offset	0	0
Net Amount Presented	1,873	3,309
Trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	0	0
Gross Amounts Offset	0	0
Net Assets	0	0
Cash Collateral Offset	0	0
Net Amount Presented	$ 0	$ 0

Accounting for Derivative Ins_7

Accounting for Derivative Instruments - Offsetting Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Total Derivative Liabilities
Offsetting Liabilities [Line Items]
Gross Liabilities	$ (1,657)	$ (6,276)
Gross Amounts Offset	899	4,082
Net Liabilities	(758)	(2,194)
Cash Collateral Offset	0	65
Net Amount Presented	(758)	(2,129)
Total Current Derivative Liabilities
Offsetting Liabilities [Line Items]
Gross Liabilities	(284)	(5,034)
Gross Amounts Offset	15	3,332
Net Liabilities	(269)	(1,702)
Cash Collateral Offset	0	65
Net Amount Presented	(269)	(1,637)
Non-trading commodity derivatives
Offsetting Liabilities [Line Items]
Gross Liabilities	(280)	(4,517)
Gross Amounts Offset	15	3,059
Net Liabilities	(265)	(1,458)
Cash Collateral Offset	0	65
Net Amount Presented	(265)	(1,393)
Trading commodity derivatives
Offsetting Liabilities [Line Items]
Gross Liabilities	(4)	(517)
Gross Amounts Offset	0	273
Net Liabilities	(4)	(244)
Cash Collateral Offset	0	0
Net Amount Presented	(4)	(244)
Total Non-current Derivative Assets
Offsetting Liabilities [Line Items]
Gross Liabilities	(1,373)	(1,242)
Gross Amounts Offset	884	750
Net Liabilities	(489)	(492)
Cash Collateral Offset	0	0
Net Amount Presented	(489)	(492)
Non-trading commodity derivatives
Offsetting Liabilities [Line Items]
Gross Liabilities	(1,118)	(676)
Gross Amounts Offset	818	732
Net Liabilities	(300)	56
Cash Collateral Offset	0	0
Net Amount Presented	(300)	56
Trading commodity derivatives
Offsetting Liabilities [Line Items]
Gross Liabilities	(255)	(566)
Gross Amounts Offset	66	18
Net Liabilities	(189)	(548)
Cash Collateral Offset	0	0
Net Amount Presented	$ (189)	$ (548)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Short-term deferred tax liability	$ 2,508		$ 5,937
Income tax rate	39.50%	15.50%
NuDevco Retail Holdings and NuDevco Retail
Related Party Transaction [Line Items]
Net deferred tax asset	$ 15,600
NuDevco Retail Holdings and NuDevco Retail | Tax Receivable Agreement
Related Party Transaction [Line Items]
Deferred tax liabilities	28,600
Deferred tax assets	7,200
NuDevco Retail Holdings and NuDevco Retail | Tax Receivable Agreement | Taxes Payable, Current, Related Parties
Related Party Transaction [Line Items]
Deferred tax liabilities	2,500		$ 5,900
Short-term deferred tax liability	$ 2,500

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018USD ($)investigationclaim	Dec. 31, 2016USD ($)	Jun. 30, 2018USD ($)
Loss Contingencies [Line Items]
Number of current investigations | investigation	2
Major Energy Companies v. National Gas & Electric, LLC and Spark Energy, Inc.
Loss Contingencies [Line Items]
Number of claims | claim	4
Indirect Tax Audits
Loss Contingencies [Line Items]
Contingent liabilities	$ 1
Failure to Comply With Regulations, Notice of Violation and Assessment of Civil Penalty
Loss Contingencies [Line Items]
Contingent liabilities			$ 0.2
Notice of violation and assessment of civil penalty		$ 0.9
Failure to Comply With Regulations, Notice of Violation of Marketing Practices and Assessment of Civil Penalty
Loss Contingencies [Line Items]
Notice of violation and assessment of civil penalty		$ 0.8

Transactions with Affiliates (D

Transactions with Affiliates (Details)	Mar. 07, 2018USD ($)usd_per_rcemarketstaterce	Apr. 01, 2017USD ($)	Dec. 27, 2016USD ($)	Oct. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)rce$ / shares	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Related Party Transaction [Line Items]
Accounts receivable—affiliates					$ 3,807,000		$ 3,807,000		$ 3,661,000
Accounts payable—affiliates					2,836,000		2,836,000		4,622,000
Net asset optimization revenues/(expense)					348,000	$ (320,000)	3,798,000	$ (681,000)
General and administrative expense - affiliates					25,695,000	25,566,000	83,522,000	69,405,000
Proceeds from disgorgement of stockholders short-swing profits					0		244,000	872,000
Subordinated debt—affiliate					10,000,000		$ 10,000,000		0
Tax receivable agreement, net cash savings (as a percent)							15.00%
TRA payment							$ 3,577,000	0
Subsequent Event
Related Party Transaction [Line Items]
TRA payment				$ 2,300,000
Subordinated debt — affiliate | Retailco
Related Party Transaction [Line Items]
Subordinated borrowing, interest rate			5.00%
Subordinated debt—affiliate			$ 25,000,000
Subordinated debt, advances			$ 1,000,000
Subordinated debt, interest rate on advances			5.00%
Affiliated Entity | Purchased Natural Gas From Affiliate
Related Party Transaction [Line Items]
Cost of revenues (less than for the three months ended September 30, 2018)					100,000	0	100,000	0
Affiliated Entity | Allocated Overhead Costs
Related Party Transaction [Line Items]
General and administrative expense - affiliates					300,000	5,700,000	8,700,000	19,400,000
NuDevco Retail Holdings and NuDevco Retail
Related Party Transaction [Line Items]
Payments of distributions to affiliates							$ 11,700,000	11,700,000
Tax receivable agreement, net cash savings (as a percent)							85.00%
Tax receivable agreement, deferral period							5 years
Tax receivable agreement, coverage percentage							130.00%
NuDevco Retail Holdings and NuDevco Retail | Common Class A
Related Party Transaction [Line Items]
Tax receivable agreement, target dividend (in dollars per share) | $ / shares							$ 0.18125
NuDevco Retail Holdings and NuDevco Retail | Series A Preferred Stock
Related Party Transaction [Line Items]
Tax receivable agreement, target dividend (in dollars per share) | $ / shares							$ 0.546875
NuDevco Retail Holdings and NuDevco Retail | Payment of Income Taxes Incurred by the Company
Related Party Transaction [Line Items]
Payments of distributions to affiliates							$ 12,000,000	12,600,000
NuDevco Retail Holdings and NuDevco Retail | Tax Receivable Agreement
Related Party Transaction [Line Items]
Deferred tax liabilities					28,600,000		28,600,000
NuDevco Retail Holdings and NuDevco Retail | Tax Receivable Agreement | Taxes Payable, Current, Related Parties
Related Party Transaction [Line Items]
Deferred tax liabilities					2,500,000		$ 2,500,000		$ 5,900,000
National Gas & Electric, LLC | Affiliated Entity | Asset Purchase Agreement
Related Party Transaction [Line Items]
Number of RCEs | rce	50,000						35,000
Purchase price per RCE (in dollars per RCE) | usd_per_rce	250
Purchase price	$ 12,500,000
Number of markets | market	24
Number of states | state	8
Due to related parties					8,800,000		$ 8,800,000
Net distribution to NG&E recorded in equity							7,100,000
Retailco | Affiliated Entity | Allocated Overhead Costs
Related Party Transaction [Line Items]
General and administrative expense - affiliates					100,000	5,100,000	5,800,000	17,000,000
Retailco | Affiliated Entity | Property and Equipment Capitalized
Related Party Transaction [Line Items]
Amount capitalized for application, development and implementation of various systems					0	200,000	500,000	500,000
Perigee
Related Party Transaction [Line Items]
Total consideration		$ 4,100,000
Affiliated Entity
Related Party Transaction [Line Items]
Net asset optimization revenues/(expense)					$ 300,000	$ 0	$ 1,300,000	$ 0

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting [Abstract]
Asset optimization revenue	$ 28.3	$ 31.7	$ 139.2	$ 132.8
Asset optimization cost of revenues	$ 28	$ 32	$ 135.4	$ 133.5

Segment Reporting - Reconciliat

Segment Reporting - Reconciliation of Retail Gross Margin to Income Before Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Income before income tax expense	$ 22,645	$ 15,393	$ 1,525	$ 34,010
Interest and other income	47	(168)	(707)	(102)
Interest expense	2,762	2,863	7,323	8,760
Operating income	25,454	18,088	8,141	42,668
Depreciation and amortization	13,917	11,509	39,797	30,435
General and administrative	25,695	25,566	83,522	69,405
Less:
Net asset optimization revenues / (expenses)	348	(320)	3,798	(681)
Net, gain (loss) on non-trading derivative instruments	18,117	(2,752)	(1,371)	(34,225)
Net, Cash settlements on non-trading derivative instruments			(6,189)	20,816
Retail Gross Margin	45,795	50,570	134,939	158,319
Non-trading
Less:
Net, gain (loss) on non-trading derivative instruments	17,888	(2,568)	(2,223)	(34,146)
Net, Cash settlements on non-trading derivative instruments	$ 1,035	$ 7,481	$ (5,054)	$ 19,016

Segment Reporting - Financial D

Segment Reporting - Financial Data for Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total Revenues	$ 258,475	$ 215,536	$ 777,414	$ 563,279
Retail cost of revenues	193,409	160,373	645,954	420,771
Less:
Net asset optimization revenues / (expenses)	348	(320)	3,798	(681)
Gains (losses) on non-trading derivatives	18,117	(2,752)	(1,371)	(34,225)
Current period settlements on non-trading derivatives	922	7,457	(5,823)	18,808
Retail Gross Margin	45,795	50,570	134,939	158,319
Total Assets	481,277		481,277		$ 505,949
Goodwill	120,343		120,343		120,154
Non-trading
Less:
Gains (losses) on non-trading derivatives	17,888	(2,568)	(2,223)	(34,146)
Current period settlements on non-trading derivatives	1,035	7,481	(5,054)	19,016
Operating Segments | Retail Electricity
Segment Reporting Information [Line Items]
Total Revenues	246,182	202,259	676,528	467,861
Retail cost of revenues	186,449	153,594	587,949	364,518
Less:
Net asset optimization revenues / (expenses)	0	0	0	0
Retail Gross Margin	40,252	44,495	92,613	116,129
Total Assets	1,719,297		1,719,297		1,228,552
Goodwill	117,813		117,813		117,624
Operating Segments | Retail Electricity | Non-trading
Less:
Gains (losses) on non-trading derivatives	18,415	(2,762)	1,216	(31,722)
Current period settlements on non-trading derivatives	1,066	6,932	(5,250)	18,936
Operating Segments | Retail Natural Gas
Segment Reporting Information [Line Items]
Total Revenues	12,293	13,277	100,886	95,418
Retail cost of revenues	6,960	6,779	58,005	56,253
Less:
Net asset optimization revenues / (expenses)	348	(320)	3,798	(681)
Retail Gross Margin	5,543	6,075	42,326	42,190
Total Assets	581,530		581,530		421,896
Goodwill	2,530		2,530		2,530
Operating Segments | Retail Natural Gas | Non-trading
Less:
Gains (losses) on non-trading derivatives	(527)	194	(3,439)	(2,424)
Current period settlements on non-trading derivatives	(31)	549	196	80
Corporate and Other
Segment Reporting Information [Line Items]
Total Revenues	0	0	0	0
Retail cost of revenues	0	0	0	0
Less:
Net asset optimization revenues / (expenses)	0	0	0	0
Retail Gross Margin	0	0	0	0
Total Assets	249,814		249,814		209,428
Goodwill	0		0		0
Corporate and Other | Non-trading
Less:
Gains (losses) on non-trading derivatives	0	0	0	0
Current period settlements on non-trading derivatives	0	0	0	0
Eliminations
Segment Reporting Information [Line Items]
Total Revenues	0	0	0	0
Retail cost of revenues	0	0	0	0
Less:
Net asset optimization revenues / (expenses)	0	0	0	0
Retail Gross Margin	0	0	0	0
Total Assets	(2,069,364)		(2,069,364)		(1,353,927)
Goodwill	0		0		$ 0
Eliminations | Non-trading
Less:
Gains (losses) on non-trading derivatives	0	0	0	0
Current period settlements on non-trading derivatives	$ 0	$ 0	$ 0	$ 0

Subsequent Events (Details)

Subsequent Events (Details) $ / shares in Units, residential_customer_equivalent in Thousands, $ in Millions	Oct. 19, 2018USD ($)residential_customer_equivalent	Oct. 18, 2018$ / shares	Sep. 30, 2018$ / shares	Sep. 30, 2017$ / shares	Sep. 30, 2018$ / shares	Sep. 30, 2017$ / shares
Subsequent Event [Line Items]
Class A common stock dividends declared (in dollars per share)			$ 0.18125	$ 0.18125	$ 0.54375	$ 0.54375
Subsequent Event | Starion Energy
Subsequent Event [Line Items]
Number of RCEs | residential_customer_equivalent	60
Purchase price | $	$ 10.7
Subsequent Event | Common Class A
Subsequent Event [Line Items]
Class A common stock dividends declared (in dollars per share)		$ 0.18125
Subsequent Event | Series A Preferred Stock
Subsequent Event [Line Items]
Series A preferred stock dividend declared (in dollars per share)		$ 0.546875