Via Renewables (VIASP) 10-Q 3 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 01, 2018
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
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
Common Class A
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding (in shares)		13,393,712
Common Class B
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding (in shares)		21,485,126

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)		Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents		$ 35,702,000	$ 29,419,000
Accounts receivable, net of allowance for doubtful accounts of $3.6 million and $4.0 million as of June 30, 2018 and December 31, 2017, respectively		132,011,000	158,814,000
Accounts receivable—affiliates		3,427,000	3,661,000
Inventory		1,860,000	4,470,000
Fair value of derivative assets		11,526,000	31,191,000
Customer acquisition costs, net		17,123,000	22,123,000
Customer relationships, net		20,669,000	18,653,000
Prepaid assets		3,575,000	1,028,000
Deposits		12,109,000	7,701,000
Other current assets		18,863,000	19,678,000
Total current assets		256,865,000	296,738,000
Property and equipment, net		7,190,000	8,275,000
Fair value of derivative assets		595,000	3,309,000
Customer acquisition costs, net		5,315,000	6,949,000
Customer relationships, net		31,600,000	34,839,000
Deferred tax assets		27,581,000	24,185,000
Goodwill		120,343,000	120,154,000
Other assets		11,360,000	11,500,000
Total assets		460,849,000	505,949,000
Current liabilities:
Accounts payable		59,393,000	77,510,000
Accounts payable—affiliates		2,373,000	4,622,000
Accrued liabilities		32,330,000	33,679,000
Fair value of derivative liabilities		2,079,000	1,637,000
Current portion of Senior Credit Facility		0	7,500,000
Current payable pursuant to tax receivable agreement—affiliates		2,508,000
Current contingent consideration for acquisitions		2,980,000	4,024,000
Other current liabilities		1,282,000	2,675,000
Current portion of note payable		13,921,000	13,443,000
Total current liabilities		116,866,000	151,027,000
Long-term liabilities:
Fair value of derivative liabilities		4,380,000	492,000
Payable pursuant to tax receivable agreement—affiliates		26,067,000	26,355,000
Long-term portion of Senior Credit Facility		102,000,000	117,750,000
Subordinated debt—affiliate		10,000,000	0
Contingent consideration for acquisitions		0	626,000
Other long-term liabilities		1,000	172,000
Long-term portion of note payable		0	7,051,000
Total liabilities		259,314,000	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 June 30, 2018 and 1,704,339 shares issued and outstanding at December 31, 2017		90,758,000	41,173,000
Additional paid-in capital		28,846,000	26,914,000
Accumulated other comprehensive loss		(33,000)	(11,000)
Retained earnings		(2,678,000)	11,008,000
Treasury stock, at cost, 99,446 shares at June 30, 2018 and December 31, 2017		(2,011,000)	(2,011,000)
Total stockholders' equity		24,475,000	36,248,000
Non-controlling interest in Spark HoldCo, LLC		86,302,000	125,055,000
Total equity		110,777,000	161,303,000
Total liabilities, Series A Preferred Stock and stockholders' equity		460,849,000	505,949,000
Common Class A
Common stock	[1]	135,000	132,000
Common Class B
Common stock	[1]	$ 216,000	$ 216,000
[1]	Outstanding shares of common stock reflect the two-for-one stock split, which took effect on June 16, 2017. See Note 5 "Equity" for further discussion.

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) $ in Millions	Jun. 30, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares
Statement of Financial Position [Abstract]
Allowance for doubtful accounts | $	$ 3.6	$ 4
Preferred stock par value per share (in dollars per share) | $ / shares	$ 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 (in shares)	99,446	99,446
Common Class A
Common stock par value per share (in dollars per share) | $ / shares	$ 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) | $ / shares	$ 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 (LOSS) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Revenues:
Retail revenues		$ 231,488		$ 151,604		$ 515,489		$ 348,104
Net asset optimization revenues/(expense)		763	[1]	(168)	[2]	3,450	[2]	(361)	[2]
Total Revenues		232,251		151,436		518,939		347,743
Operating Expenses:
Retail cost of revenues		162,669		114,637		452,545		260,398
General and administrative	[1]	27,780		19,346		57,827		43,839
Depreciation and amortization		12,861		9,656		25,880		18,926
Total Operating Expenses		203,310		143,639		536,252		323,163
Operating income (loss)		28,941		7,797		(17,313)		24,580
Other (expense)/income:
Interest expense		(2,316)		(2,452)		(4,561)		(5,897)
Interest and other income		553		(265)		754		(66)
Total other expenses		(1,763)		(2,717)		(3,807)		(5,963)
Income (loss) before income tax expense (benefit)		27,178		5,080		(21,120)		18,617
Income tax expense (benefit)		3,251		409		(3,216)		2,814
Net income (loss)		23,927		4,671		(17,904)		15,803
Less: Net income (loss) attributable to non-controlling interests		16,427		3,592		(13,078)		12,454
Net income (loss) attributable to Spark Energy, Inc. stockholders		7,500		1,079		(4,826)		3,349
Less: Dividend on Series A preferred stock		2,027		991		4,054		1,174
Net income (loss) attributable to stockholders of Class A common stock		5,473		88		(8,880)		2,175
Other comprehensive income (loss), net of tax:
Currency translation gain (loss)		25		(26)		(58)		(75)
Other comprehensive income (loss)		25		(26)		(58)		(75)
Comprehensive income (loss)		23,952		4,645		(17,962)		15,728
Less: Comprehensive income (loss) attributable to non-controlling interests		16,442		3,576		(13,114)		12,407
Comprehensive income (loss) attributable to Spark Energy, Inc. stockholders		$ 7,510		$ 1,069		$ (4,848)		$ 3,321
Net income (loss) attributable to Spark Energy, Inc. per share of Class A common stock
Basic (in dollars per share)		$ 0.41		$ 0.01		$ (0.67)		$ 0.17
Diluted (in dollars per share)		$ 0.41		$ 0.01		$ (0.67)		$ 0.16
Weighted average shares of Class A common stock outstanding
Basic (in shares)		13,229		13,104		13,183		13,050
Diluted (in shares)		13,246		13,376		13,183		13,257
[1]	General and administrative expense includes general and administrative expense—affiliates of $1,600 and $6,100 for the three months ended June 30, 2018 and 2017, respectively, and $8,000 and $13,400 for the six months ended June 30, 2018 and 2017, respectively.
[2]	Net asset optimization revenues (expenses) includes asset optimization revenues—affiliates of $340 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates cost of revenues of $24 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates of $988 and $0 for the six months ended June 30, 2018 and 2017, respectively, and asset optimization revenue—affiliates cost of revenues of $36 and $0 for the six months ended June 30, 2018 and 2017, respectively.

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (Footnotes) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Optimization revenues		$ 763	[1]	$ (168)	[2]	$ 3,450	[2]	$ (361)	[2]
General and administrative	[1]	27,780		19,346		57,827		43,839
Affiliates
Optimization revenues		340		0		988		0
Optimization cost of revenues - affiliates		24		0		36		0
General and administrative		$ 1,600		$ 6,100		$ 8,000		$ 13,400
[1]	General and administrative expense includes general and administrative expense—affiliates of $1,600 and $6,100 for the three months ended June 30, 2018 and 2017, respectively, and $8,000 and $13,400 for the six months ended June 30, 2018 and 2017, respectively.
[2]	Net asset optimization revenues (expenses) includes asset optimization revenues—affiliates of $340 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates cost of revenues of $24 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates of $988 and $0 for the six months ended June 30, 2018 and 2017, respectively, and asset optimization revenue—affiliates cost of revenues of $36 and $0 for the six months ended June 30, 2018 and 2017, respectively.

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - 6 months ended Jun. 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	2,647	2,647					2,647
Restricted stock unit vesting (in shares)			258
Restricted stock unit vesting	(712)	(712)	$ 3				(715)
Consolidated net loss	(17,904)	(4,826)						(4,826)	(13,078)
Foreign currency translation adjustment for equity method investee	(58)	(22)				(22)			(36)
Distributions paid to non-controlling unit holders	(19,501)								(19,501)
Dividends paid to Class A common stockholders	(4,805)	(4,805)						(4,805)
Dividends to Preferred Stock	(4,055)	(4,055)						(4,055)
Acquisition of NG&E Customers	(6,138)								(6,138)
Balance at end of period (in shares) at Jun. 30, 2018			13,493	21,485	(99)
Balance at end of period at Jun. 30, 2018	$ 110,777	$ 24,475	$ 135	$ 216	$ (2,011)	$ (33)	$ 28,846	$ (2,678)	$ 86,302

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net (loss) income	$ (17,904)	$ 15,803
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation and amortization expense	24,639	18,411
Deferred income taxes	(3,396)	3
Change in TRA liability	79	0
Stock based compensation	2,686	2,905
Amortization of deferred financing costs	612	531
Excess tax benefit related to restricted stock vesting	(101)	179
Change in Fair Value of Earnout liabilities	(63)	(2,568)
Accretion on fair value of Earnout liabilities	0	2,660
Bad debt expense	5,725	919
Loss on derivatives, net	19,488	31,473
Current period cash settlements on derivatives, net	7,170	(11,828)
Accretion of discount to convertible subordinated notes to affiliate	0	1,004
Other	(554)	224
Changes in assets and liabilities:
Decrease in accounts receivable	25,957	18,072
Increase in accounts receivable—affiliates	(10)	(1,925)
Decrease in inventory	2,693	310
Increase in customer acquisition costs	(6,254)	(12,074)
(Increase) decrease in prepaid and other current assets	(59)	5,394
Decrease (increase) in other assets	97	(788)
Decrease in accounts payable and accrued liabilities	(20,140)	(18,422)
(Decrease) increase in accounts payable—affiliates	(2,249)	313
Decrease in other current liabilities	(1,545)	(2,862)
Decrease in other non-current liabilities	(461)	(328)
Net cash provided by operating activities	36,410	45,625
Cash flows from investing activities:
Purchases of property and equipment	(1,163)	(371)
Acquisitions of Perigee and other customers	0	(9,353)
Deposit for Verde Acquisition	0	(65,785)
Acquisition of HIKO	(15,041)	0
Acquisition of NG&E customers	(7,796)	0
Net cash used in investing activities	(24,000)	(75,509)
Cash flows from financing activities:
Proceeds from issuance of Series A Preferred Stock, net of issuance costs paid	48,490	37,937
Borrowings on notes payable	146,800	121,000
Payments on notes payable	(160,050)	(93,789)
Payment of the Major Energy Companies Earnout	(1,607)	(6,299)
Payment of the Provider Companies Earnout and installment consideration	0	(6,676)
Payments on the Verde promissory note	(6,573)	0
Proceeds from disgorgement of stockholders short-swing profits	244	666
Restricted stock vesting	(2,589)	(2,009)
Payment of Tax Receivable Agreement liability	(3,577)	0
Payment of dividends to Class A common stockholders	(4,805)	(4,754)
Payment of distributions to non-controlling unitholders	(19,501)	(19,822)
Payment of Dividends to Preferred Stock	(2,959)	0
Purchase of Treasury Stock	0	(1,285)
Net cash (used in) provided by financing activities	(6,127)	24,969
Increase (decrease) in Cash and cash equivalents	6,283	(4,915)
Cash and cash equivalents—beginning of period	29,419	18,960
Cash and cash equivalents—end of period	35,702	14,045
Non-cash items:
Property and equipment purchase accrual	(123)	50
Cash paid during the period for:
Interest	3,884	1,395
Taxes	5,399	7,232
Major Energy Companies
Adjustments to reconcile net income to net cash flows provided by operating activities:
Payments of Earnouts	0	(1,104)
Provider Companies
Adjustments to reconcile net income to net cash flows provided by operating activities:
Payments of Earnouts	$ 0	$ (677)

Formation and Organization

Formation and Organization	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Formation and Organization	1. Formation and Organization Organization Spark Energy, Inc. ("Spark Energy," “Company,” "we" or "us") 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”). Spark HoldCo owns all of the outstanding membership interests or common stock in each of Spark Energy, LLC (“SE”), Spark Energy Gas, LLC (“SEG”), Oasis Power Holdings, LLC ("Oasis"), CenStar Energy Corp. ("CenStar"), Electricity Maine, LLC, Electricity N.H., LLC and Provider Power Mass, LLC (collectively, the "Provider Companies"); Major Energy Services, LLC, Major Energy Electric Services, LLC, and Respond Power, LLC (collectively, the "Major Energy Companies"), Perigee Energy, LLC ("Perigee"), the Verde Companies (as defined below), and HIKO Energy, LLC ("HIKO"), the operating subsidiaries through which the Company operates. 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. Verde Energy USA, Inc.; Verde Energy USA Commodities, LLC; Verde Energy USA Connecticut, LLC; Verde Energy USA DC, LLC; Verde Energy USA Illinois, LLC; Verde Energy USA Maryland, LLC; Verde Energy USA Massachusetts, LLC; Verde Energy USA New Jersey, LLC; Verde Energy USA New York, LLC; Verde Energy USA Ohio, LLC; Verde Energy USA Pennsylvania, LLC; Verde Energy USA Texas Holdings, LLC; Verde Energy USA Trading, LLC; and Verde Energy Solutions, LLC (collectively, the “Verde Companies”) operate as retail energy providers and were formed on various dates from December 27, 2007 to November 13, 2014. We acquired the Verde Companies on July 1, 2017, as described in Note 4 "Acquisitions." 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. Emerging Growth Company Status As a company with less than $1.07 billion in revenues during its last fiscal year, the Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. An emerging growth company may take advantage of specified reduced reporting and other regulatory requirements. The Company will remain an “emerging growth company” until as late as the last day of the Company's 2019 fiscal year, or until the earliest of: (i) the last day of the fiscal year in which the Company has $1.07 billion or more in annual revenues; (ii) the date on which the Company becomes a “large accelerated filer” (the fiscal year-end on which the total market value of the Company’s common equity securities held by non-affiliates is $700 million or more as of June 30); or (iii) the date on which the Company issues more than $1.0 billion of non-convertible debt over a three -year period. As a result of the Company's election to avail itself of certain provisions of the JOBS Act, the information that the Company provides may be different than what you may receive from other public companies in which you hold an equity interest. Exchange and Registration Rights The Spark HoldCo Third Amended and Restated Limited Liability Company Agreement provides that if the Company issues a new share of Class A common stock, par value $0.01 per share (the "Class A common stock"), Series A Preferred Stock (as defined below) or other equity security of the Company (other than shares of Class B common stock, par value $0.01 per share ("Class B common stock"), and excluding issuances of Class A common stock upon an exchange of Class B common stock or Series A Preferred Stock), Spark HoldCo will concurrently issue a corresponding limited liability company unit either to the holder of the Class B common stock, or to the Company in the case of the issuance of shares of Class A common stock, Series A Preferred Stock or such other equity security. As a result, the number of Spark HoldCo units held by the Company always equals the number of shares of Class A common stock, Series A Preferred Stock or such other equity securities of the Company outstanding. Each share of Class B common stock, all of which are held by NuDevco Retail and Retailco, has no economic rights but entitles the holder to one vote on all matters to be voted on by stockholders generally. Holders of Class A common stock and Class B common stock vote together as a single class on all matters presented to our stockholders for their vote or approval, except as otherwise required by applicable law or by our certificate of incorporation. NuDevco Retail and Retailco have the right to exchange (the “Exchange Right”) all or a portion of their Spark HoldCo units (together with a corresponding number of shares of Class B common stock) for Class A common stock (or cash at Spark Energy, Inc.’s or Spark HoldCo’s election (the “Cash Option”)) at an exchange ratio of one share of Class A common stock for each Spark HoldCo unit (and corresponding share of Class B common stock) exchanged. In addition, NuDevco Retail and Retailco have the right, under certain circumstances, to cause the Company to register the offer and resale of NuDevco Retail's and Retailco's shares of Class A common stock obtained pursuant to the Exchange Right.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	2. Basis of Presentation and Summary of Significant Accounting Policies 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"). This information should be read in conjunction with our consolidated financial statements and notes contained in our annual report on Form 10-K for the year ended December 31, 2017 . The Company's 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. The preparation of the Company's 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 six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the full year or for any interim period. Transactions with Affiliates The Company enters into transactions with, and pays certain costs on behalf of, affiliates that are commonly controlled by W. Keith Maxwell III, and these affiliates enter into transactions with, and pay certain costs on behalf of, us in order to reduce risk, reduce administrative expense, create economies of scale, create strategic alliances and supply goods and services. These transactions include, but are not limited to, certain services to the affiliated companies associated with employee benefits provided through the Company’s 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 the Company 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. Additionally, the Company enters into transactions with certain 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. The allocations and related estimates and assumptions are described more fully in Note 14 "Transactions with Affiliates." 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. Recent Accounting Pronouncements Standards adopted in 2018 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. The Company 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, since our contracts with customers identify the delivery of products and services that are individually distinct performance obligations and revenue is recognized when performance obligations are satisfied. As a result, receivable balances related to revenue, including amounts related to unbilled revenue, are reflected as accounts receivable in the condensed consolidated balance sheets. Other than accounts receivable, revenue related contract assets and liabilities are immaterial. 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. The Company’s asset optimization activities meet the definition of trading activities per FASB ASC Topic 815, Derivatives and Hedging , and are therefore excluded from the scope of Revenue from Contracts with Customers (Topic 606). 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 cash flow issues in the statement of cash flows. This ASU has been applied using a retrospective transition method for each period presented. The Company adopted ASU 2016-15 effective January 1, 2018 and 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 six months ended June 30, 2017. We reclassified acquisition related payments of approximately $13.0 million from cash flows from investing activities to cash flows from financing activities for the six months ended June 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. The definition of a business affects many areas of accounting, including acquisitions, disposals, goodwill, and consolidation. ASU 2017-01 is effective for annual periods beginning after December 15, 2017, including interim periods within those periods and is to be applied prospectively to transactions on or after the adoption date. The Company adopted ASU 2017-01 effective January 1, 2018, and applied the guidance in the evaluation of whether the HIKO acquisition should be accounted for as an acquisition of assets or a business. Standards Being Evaluated/Standards 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. The amendments in this ASU 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 the Company expects to elect. 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 believe the primary impact will be related to the recognition of right-of-use assets and liabilities for 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 the amendments in 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. 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. The Company is 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 expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees. An entity should apply the requirements of Topic 718 to non-employee awards except for specific guidance on inputs to an option pricing model and the attribution of cost. The amendments specify that Topic 718 applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor's own operations by issuing share-based payment awards. ASU 2018-07 also clarifies that Topic 718 does not apply to share-based payments used to effectively provide (1) financing to the issuer or (2) awards granted in conjunction with selling goods or services to customers as part of a contract accounted for under Topic 606, Revenue from Contracts with Customers . ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. The Company is currently evaluating the impact of adopting this guidance on its consolidated financial statements.

Revenues

Revenues	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenues	3. Revenues Significant accounting policy The Company’s revenues are derived primarily from the sale of natural gas and electricity to retail customers. The Company also records revenue from sales of natural gas and electricity to wholesale counterparties, including affiliates. Revenue is measured based on consideration specified in a contract with a retail customer or wholesale counterparty, and excludes any sales incentives and amounts collected on behalf of third parties. The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product to a customer, therefore revenue is recognized when natural gas or electricity is delivered. Similarly, cost of revenues is recognized when the commodity is delivered. The Company records gross receipts taxes on a gross basis in retail revenues and retail cost of revenues. During the three months ended June 30, 2018 and 2017 , the Company's retail revenues included gross receipts taxes of $1.9 million and $1.1 million , respectively. During the three months ended June 30, 2018 and 2017 , the Company's retail cost of revenues included gross receipts taxes of $2.3 million and $1.6 million , respectively. During the six months ended June 30, 2018 and 2017 , the Company’s retail revenues included gross receipts taxes of $4.3 million and $2.5 million , respectively. During the six months ended June 30, 2018 and 2017 , the Company’s retail cost of revenues included gross receipts taxes of $5.1 million and $3.9 million , respectively. Sales tax, which represents taxes assessed by individual state and local governmental authorities that are both imposed on and concurrent with a specific revenue-producing transaction, that are collected by the Company from a customer, is excluded from revenue. Nature of goods sold The following is a description of principal activities - separated by reportable segments - from which the Company generates its revenue. For more detailed information about reportable segments, see Note 15 "Segment Reporting." Retail Electricity Segment Revenues for electricity sales are recognized under the accrual method when the Company’s 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 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. Unbilled revenues are calculated by multiplying these volume estimates by the applicable rate by customer class (residential or commercial). Estimates amounts are adjusted when actual usage is known and billed. Retail Natural Gas Segment Revenues for natural gas sales are recognized under the accrual method when the Company’s 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 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. Disaggregation of revenue The following table disaggregates revenue by primary geographical market, customer type, customer credit risk profile. The table also includes a reconciliation of the disaggregated revenue to revenue by reportable segment (in thousands). Reportable segments Three months ended June 30, 2018 Retail Electricity Retail Natural Gas Total reportable segments Primary geographical markets (a) New England $ 93,926 $ 3,228 $ 97,154 Mid-Atlantic 67,928 9,419 77,347 Midwest 18,085 5,428 23,513 Southwest 29,508 3,966 33,474 $ 209,447 $ 22,041 $ 231,488 Customer type Commercial $ 77,255 $ 10,877 $ 88,132 Residential 115,110 20,341 135,451 Unbilled revenue (b) 17,082 (9,177 ) 7,905 $ 209,447 $ 22,041 $ 231,488 Customer credit risk POR $ 144,239 $ 12,782 $ 157,021 Non-POR 65,208 9,259 74,467 $ 209,447 $ 22,041 $ 231,488 Reportable segments Three months ended June 30, 2017 Retail Electricity Retail Natural Gas Total reportable segments Primary geographical markets (a) New England $ 46,009 $ 3,464 $ 49,473 Mid-Atlantic 55,451 6,939 62,390 Midwest 10,778 4,369 15,147 Southwest 19,670 4,924 24,594 $ 131,908 $ 19,696 $ 151,604 Customer type Commercial $ 41,922 $ 11,683 $ 53,605 Residential 83,767 18,346 102,113 Unbilled revenue (b) 6,219 (10,333 ) (4,114 ) $ 131,908 $ 19,696 $ 151,604 Customer credit risk POR $ 87,162 $ 8,960 $ 96,122 Non-POR 44,746 10,736 55,482 $ 131,908 $ 19,696 $ 151,604 Reportable segments Six months ended June 30, 2018 Retail Electricity Retail Natural Gas Total reportable segments Primary geographical markets (a) New England $ 195,024 $ 12,579 $ 207,603 Mid-Atlantic 145,483 35,350 180,833 Midwest 35,920 24,686 60,606 Southwest 53,919 12,528 66,447 $ 430,346 $ 85,143 $ 515,489 Customer type Commercial $ 174,148 $ 35,176 $ 209,324 Residential 263,104 66,070 329,174 Unbilled revenue (b) (6,906 ) (16,103 ) (23,009 ) $ 430,346 $ 85,143 $ 515,489 Customer credit risk POR $ 301,240 $ 49,552 $ 350,792 Non-POR 129,106 35,591 164,697 $ 430,346 $ 85,143 $ 515,489 Reportable segments Six months ended June 30, 2017 Retail Electricity Retail Natural Gas Total reportable segments Primary geographical markets (a) New England $ 95,913 $ 13,095 $ 109,008 Mid-Atlantic 113,922 31,121 145,043 Midwest 22,962 21,323 44,285 Southwest 32,805 16,963 49,768 $ 265,602 $ 82,502 $ 348,104 Customer type Commercial $ 84,919 $ 35,220 $ 120,139 Residential 179,202 62,315 241,517 Unbilled revenue (b) 1,481 (15,033 ) (13,552 ) $ 265,602 $ 82,502 $ 348,104 Customer credit risk POR $ 179,896 $ 41,944 $ 221,840 Non-POR 85,706 40,558 126,264 $ 265,602 $ 82,502 $ 348,104 (a) The geographical regions 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 actualized, at which time it is categorized between commercial customers and residential customers.

Acquisitions

Acquisitions	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Acquisitions	4. Acquisitions Acquisition of HIKO On March 1, 2018, the Company entered into a Membership Interest Purchase Agreement pursuant to which the Company acquired all of the issued and outstanding membership interests of HIKO Energy, LLC, a New York limited liability company, for a total purchase price of $6.0 million in cash, plus working capital. HIKO Energy, LLC ("HIKO") has a total of approximately 29,000 RCEs located in 42 markets in 7 states. The acquisition of HIKO was accounted for under the acquisition method in accordance with ASC 805, Business Combinations (“ASC 805”). The preliminary 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. The preliminary allocation was made to major categories of assets and liabilities based on management’s best estimates, and supported by independent third-party analyses. The preliminary allocation of the purchase consideration is as follows (in thousands): As of June 30, 2018 Cash and restricted cash 309 Intangible assets — customer relationships 6,205 Net working capital, net of cash acquired 9,041 Fair value of derivative liabilities (205 ) Total 15,350 The allocation of the purchase consideration is preliminary as finalization of the Company's actual working capital adjustment with the Seller is pending as of June 30, 2018. An estimated positive working capital adjustment between the Company and the Seller of $0.7 million was recorded as of June 30, 2018 and is included in other assets. Customer relationships The acquired customer relationships intangibles related to the HIKO are reflective of the HIKO's customer base, and were valued using an excess earnings method under the income approach. Using this method, the Company estimated the future cash flows resulting from the existing customer relationships, considering attrition as well as charges for contributory assets, such as net working capital, intangible assets, and assembled workforce. These future cash flows were 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 will be amortized to depreciation and amortization based on the expected future net cash flows by year. We have not included pro forma information for the HIKO acquisition because it did not have a material impact on our financial position or results of operations. The Company’s condensed consolidated statements of operations for the three months ended June 30, 2018 included $5.2 million of revenue and $1.6 million of net income from operations related to the operations of HIKO. The Company’s condensed consolidated statements of operations for the six months ended June 30, 2018 included $8.0 million of revenue and $2.7 million of net income from operations related to the operations of HIKO. Acquisition of Verde On July 1, 2017, the Company, through CenStar, its subsidiary, completed the acquisition from Verde Energy USA Holdings, LLC (the “Seller”) of all of the outstanding membership interests and stock in the Verde Companies. Total consideration was approximately $90.7 million , of which $20.1 million represented positive net working capital, as adjusted. The Company 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 the Company's founder and majority shareholder through an existing subordinated debt facility, (iii) approximately $44.0 million in borrowings under its senior secured revolving credit facility, and (iv) the issuance by CenStar to the Seller of a promissory note in the aggregate principal amount of $20.0 million (the “Promissory Note”). In addition to the consideration paid at closing, CenStar was obligated to pay 100% of the Adjusted EBITDA earned by the Verde Companies for the 18 months following closing that exceeds certain thresholds, subject to the Verde Companies’ ability to achieve defined customer count criteria (the "Verde Earnout"). The Verde Earnout was valued at $5.4 million on the acquisition date. Upon the closing of the acquisition, the Verde Companies became restricted subsidiaries and co-borrowers under the Company's Senior Credit Facility. The Verde Earnout was based on achievement by the Verde Companies of certain performance targets over the 18 month period following the closing of the acquisition of the Verde Companies. The Company and the Seller agreed to terminate the Verde Earnout on January 12, 2018, and settled the obligation with the issuance of a $5.9 million promissory note payable to the Seller in June 2019 (the “Verde Earnout Termination Note”). See discussion of the Verde Earnout Termination Note in Note 9 "Debt." 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. The allocation was made to major categories of assets and liabilities 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 Q2 2018 Adjustments (1) As of June 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 the second quarter of 2018 were due to an agreement to the working capital balances with Verde Companies' sellers per the purchase agreement. The allocation of the purchase consideration was finalized in the second quarter of 2018 as the Company agreed to working capital balances with the Seller and a net positive working capital adjustment between the Company and the Seller of approximately $0.5 million was recorded as of June 30, 2018. A receivable from the Seller is included in other assets as of June 30, 2018. Customer relationships The acquired customer relationships intangibles related to the Verde Companies are reflective of the Verde Companies' customer base, and were valued using an excess earnings method under the income approach. Using this method, the Company estimated the future cash flows resulting from the existing customer relationships, considering attrition as well as charges for contributory assets, such as net working capital, intangible assets, fixed assets, and assembled workforce. These future cash flows were 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 were bifurcated between unhedged and hedged and will be amortized to depreciation and amortization based on the expected future net cash flows by year and expensed to retail cost of revenues based on the expected term of the underlying fixed price contract acquired in each reporting period, respectively. Trademark The fair value of the Verde Companies' trademark is reflective of the value associated with the recognition and reputation of the Verde Companies to target markets. The fair value of the trademark was valued using a royalty savings method under the income approach. The value is based on the savings the Company would realize from owning the trademark rather than paying a royalty for the use of that trademark. Under this approach, the Company estimated the present value of the expected cash flows resulting from avoiding royalty payments to use a third party trademark. 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. The trademark is being amortized over the estimated five -year 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 was recorded as goodwill. Goodwill arose on the acquisition of the Verde Companies primarily due the value of its assembled workforce, its proprietary sales channels, and access to new utility service territories. Goodwill recorded in connection with the acquisition of the Verde Companies is deductible for income tax purposes because the Verde Companies was an acquisition of all of the assets of the Verde Companies. The following unaudited pro forma revenue and earnings summary presents consolidated information of the Company as if the acquisition had occurred on January 1, 2016 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Revenues $ 184,813 $ 150,238 $ 418,103 $ 306,809 Earnings $ 310 $ 3,443 $ 2,644 $ 7,862 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 revenue and earnings for the three months ended March 31, 2017 and 2016 reflects actual results of operations since the financial results were fully combined during that period. The pro forma results include 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. The final allocation could differ materially from the preliminary allocation used in the pro forma adjustments. Acquisition of Perigee On April 1, 2017, the Company and Spark Holdco completed the purchase of all of the outstanding membership interest of Perigee, a Texas limited liability company, with operations across 14 utilities in Connecticut, Delaware, Massachusetts, New York and Ohio. 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 of Perigee by the Company and Spark HoldCo from NG&E was a transfer of equity interests of entities under common control on April 1, 2017. Accordingly, the assets acquired and liabilities assumed were based on their historical value as of April 1, 2017. 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 Customer relationships The acquired customer relationships intangibles related to Perigee are reflective of Perigee's customer base, and were valued at the respective dates of acquisition using an excess earnings method under the income approach. Using this method, the Company estimated the future cash flows resulting from the existing customer relationships, considering attrition as well as charges for contributory assets, such as net working capital, fixed assets, and assembled workforce. These future cash flows were then discounted using an appropriate risk-adjusted rate of return by retail unit 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. 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 was recorded as goodwill. Goodwill arose on the acquisition of Perigee by NG&E primarily due to the value of Perigee's access to a new utility service territory. Goodwill recorded in connection with the acquisition of Perigee is deductible for income tax purposes because the acquisition of Perigee was an acquisition of all of the assets of Perigee. We have not included pro forma information for the Perigee acquisition because it did not have a material impact on our financial position or results of operations.

Equity

Equity	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Equity	5. Equity Non-controlling Interest The Company holds an economic interest and is the sole managing member in Spark HoldCo, with NuDevco Retail and Retailco holding the remaining economic interest in Spark HoldCo. As a result, the Company has consolidated the financial position and results of operations of Spark HoldCo and reflected the economic interest retained 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 June 30, 2018 , respectively. Non-controlling Interest Economic Interest The Company NuDevco Retail and Retailco (1) December 31, 2017 38.12 % 61.88 % June 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net income (loss) allocated to non-controlling interest $ 16,808 $ 3,164 $ (13,080 ) $ 11,569 Income tax expense (benefit) allocated to non-controlling interest 381 (428 ) (2 ) (885 ) Net income (loss) attributable to non-controlling interest $ 16,427 $ 3,592 $ (13,078 ) $ 12,454 Stock Split On May 22, 2017, the Company authorized and approved a two -for-one stock split of the Company's issued Class A common stock and Class B common stock, which was effected through a stock dividend (the "Stock Split"). Shareholders of record at the close of business on June 5, 2017 were issued one additional share of Class A common stock or Class B common stock of the Company for each share of Class A common stock or Class B common stock, respectively, held by such shareholder on that date. Such additional shares of Class A common stock or Class B common stock were distributed on June 16, 2017. All shares and per share amounts in this report have been retrospectively restated to reflect the Stock Split. 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. The Company used the cost method to account for its treasury shares. Purchases of shares of Class A common stock were recorded at cost, and the gross cost of the Class A common stock purchased was charged to a contra equity account entitled "Treasury Stock." Class A Common Stock The Company had a total of 13,393,712 and 13,135,636 shares of its Class A common stock outstanding at June 30, 2018 and December 31, 2017 , respectively, and 99,446 shares of treasury stock at June 30, 2018 and December 31, 2017 . Each share of Class A common stock holds economic rights and entitles its holder to one vote on all matters to be voted on by shareholders generally. Class B Common Stock The Company had a total of 21,485,126 shares of its Class B common stock outstanding at June 30, 2018 and December 31, 2017 . Each share of Class B common stock, all of which are held by NuDevco Retail and Retailco, has no economic rights but entitles its holder to one vote on all matters to be voted on by shareholders generally. Holders of 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. Preferred Stock The Company has 20,000,000 shares of authorized preferred stock for which there were 3,707,256 and 1,704,339 issued and outstanding shares at June 30, 2018 and December 31, 2017 , respectively. 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 the Company. 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 the Company's outstanding unvested restricted stock units and (2) using the if-converted method to determine the potential dilutive effect of the Company's Class B common stock. All shares and per share amounts in this Quarterly Report on Form 10-Q have been retrospectively restated to reflect the Stock Split. The following table presents the computation of earnings (loss) per share for the three and six months ended June 30, 2018 and 2017 (in thousands, except per share data): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net income (loss) attributable to Spark Energy, Inc. stockholders $ 7,500 $ 1,079 $ (4,826 ) $ 3,349 Less: Dividend on Series A preferred stock 2,027 991 4,054 1,174 Net income (loss) attributable to stockholders of Class A common stock $ 5,473 $ 88 $ (8,880 ) $ 2,175 Basic weighted average Class A common shares outstanding 13,229 13,104 13,183 13,050 Basic earnings (loss) per share attributable to stockholders $ 0.41 $ 0.01 $ (0.67 ) $ 0.17 Net income (loss) attributable to stockholders of Class A common stock $ 5,473 $ 88 $ (8,880 ) $ 2,175 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 $ 5,473 $ 88 (8,880 ) 2,175 Basic weighted average Class A common shares outstanding 13,229 13,104 13,183 13,050 Effect of dilutive Class B common stock — — — — Effect of dilutive restricted stock units 17 272 — 207 Diluted weighted average shares outstanding 13,246 13,376 13,183 13,257 Diluted earnings (loss) per share attributable to stockholders $ 0.41 $ 0.01 $ (0.67 ) $ 0.16 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 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 the Company operates. The Company is the sole managing member of Spark HoldCo, manages Spark HoldCo's operating subsidiaries through this managing membership interest, and is considered the primary beneficiary of Spark HoldCo. The assets of Spark HoldCo cannot be used to settle the obligations of the Company except through distributions to the Company, and the liabilities of Spark HoldCo cannot be settled by the Company 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 the Company's condensed consolidated balance sheet as of June 30, 2018 (in thousands): June 30, 2018 Assets Current assets: Cash and cash equivalents $ 35,599 Accounts receivable 132,011 Other current assets 86,734 Total current assets 254,344 Non-current assets: Goodwill 120,343 Other assets 53,923 Total non-current assets 174,266 Total Assets $ 428,610 Liabilities Current liabilities: Accounts payable and Accrued Liabilities $ 94,870 Contingent consideration 2,980 Other current liabilities 19,656 Total current liabilities 117,506 Long-term liabilities: Long-term portion of Senior Credit Facility 102,000 Subordinated debt — affiliate 10,000 Other long-term liabilities 4,380 Total long-term liabilities 116,380 Total Liabilities $ 233,886

Preferred Stock

Preferred Stock	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Preferred Stock	6. Preferred Stock On March 15, 2017, the Company 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 the Company, net of underwriting discounts and commissions). The Company 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, the Company 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, the Company may sell, from time to time through the Agent, the Company's Series A Preferred Stock, having an aggregate offering price of up to $50.0 million . During the year ended December 31, 2017, the Company sold an aggregate of 94,339 shares of Series A Preferred Stock under the ATM Agreement. The Company 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. On January 23, 2018, the Company commenced a public offering of its 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 January 2018 offering, the Company 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 to the Company, 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. During the six months ended June 30, 2018 , the Company sold an aggregate of 2,917 shares of Series A Preferred Stock under the ATM Agreement. The Company 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. 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. From March 15, 2017, the Series A Preferred Stock issuance date, to, but not including, April 15, 2022, the Series A Preferred Stock will accrue dividends at an annual percentage rate of 8.75% . The liquidation preference provisions of the Series A Preferred Stock are considered contingent redemption provisions because there are certain rights granted to the holders of the Series A Preferred Stock that are not solely within the control of the Company upon a change in control of the Company. Accordingly, the Series A Preferred Stock is presented within the mezzanine portion of the accompanying consolidated balance sheet. The Company had a total of 3,707,256 shares of Series A Preferred Stock issued and outstanding at June 30, 2018 and 1,704,339 shares of Series A Preferred Stock issued and outstanding at December 31, 2017 . During the three and six months ended June 30, 2018 , respectively, the Company paid $2.0 million and $2.9 million in dividends to holders of the Series A Preferred Stock. As of June 30, 2018 , the Company had accrued $2.0 million related to dividends to holders of the Series A Preferred Stock. This dividend was paid on July 16, 2018 . A summary of the Company's mezzanine equity for the six months ended June 30, 2018 is as follows: (in thousands) Mezzanine equity 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 Mezzanine equity at June 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 the Company, including specific terms relating to distributions by Spark HoldCo in connection with the payment by the Company of dividends on the Series A Preferred Stock, the priority of liquidating distributions by Spark HoldCo, the allocation of income and loss to the Company in connection with distributions by Spark HoldCo on Series A preferred units, and other terms relating to the redemption and conversion by the Company of the Series A Preferred Stock.

Property and Equipment

Property and Equipment	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment	7. Property and Equipment Property and equipment consist of the following amounts as of (in thousands): Estimated useful June 30, 2018 December 31, 2017 Information technology 2 – 5 $ 35,143 $ 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 42,484 41,444 Accumulated depreciation (35,294 ) (33,169 ) Property and equipment—net $ 7,190 $ 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 June 30, 2018 and December 31, 2017 , information technology includes $0.8 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 $0.9 million and $0.5 million for the three months ended June 30, 2018 and 2017 , respectively, and $2.1 million and $1.0 million for the six months ended June 30, 2018 and 2017 , respectively.

Goodwill, Customer Relationship

Goodwill, Customer Relationships and Trademarks	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Customer Relationships and Trademarks	5 years 3,808 Total $ 60,286" id="sjs-B4">8. Goodwill, Customer Relationships and Trademarks Goodwill, customer relationships and trademarks consist of the following amounts as of (in thousands): June 30, 2018 December 31, 2017 Goodwill $ 120,343 $ 120,154 Customer relationships - Acquired (1) Cost $ 99,576 $ 93,371 Accumulated amortization (54,216 ) (46,681 ) Customer relationships - Acquired, net $ 45,360 $ 46,690 Customer relationships - Other (2) Cost $ 13,994 $ 12,336 Accumulated amortization (7,085 ) (5,534 ) Customer relationships - Other, net $ 6,909 $ 6,802 Trademarks (3) Cost $ 9,770 $ 9,770 Accumulated amortization (1,753 ) (1,212 ) Trademarks, net $ 8,017 $ 8,558 (1) Customer relationships - Acquired represent those customer acquisitions accounted for under the acquisition method in accordance with ASC 805. See Note 4 "Acquisitions" for further discussion. (2) Customer relationships - Other represent portfolios of customer contracts not accounted for in accordance with ASC 805, as these acquisitions were not in conjunction with the acquisition of businesses. (3) Trademarks reflect values associated with the recognition and positive reputation of acquired businesses accounted for as part of the acquisition method in accordance with ASC 805 through the acquisitions of CenStar, Oasis, the Provider Companies, the Major Energy Companies and the Verde Companies. These trademarks are recorded as other assets in the condensed consolidated balance sheets. See Note 4 "Acquisitions" for further discussion. 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 (HIKO) — 6,205 — — Additions (NG&E) — — 1,657 — Adjustment (Verde) (1) 189 — — — Amortization expense — (7,535 ) (1,550 ) (541 ) Balance at June 30, 2018 $ 120,343 $ 45,360 $ 6,909 $ 8,017 (1) Related to Spark's agreement to working capital balances with Verde Companies' sellers. Refer to Note 4 "Acquisitions." The acquired customer relationship intangibles related to the Major Energy Companies, the Provider Companies, and the Verde Companies were bifurcated between hedged and unhedged customer contracts. The unhedged customer contracts are amortized to depreciation and amortization based on the expected future cash flows by year. The hedged customer contracts were evaluated for favorable or unfavorable positions at the time of acquisition and amortized to retail cost of revenue based on the expected term and position of the underlying fixed price contract in each reporting period. For the three months ended June 30, 2018 and 2017 , approximately $0.2 million and $0.6 million , respectively, of customer relationship amortization expense is included in cost of revenues. For the six months ended June 30, 2018 and 2017 , approximately $1.2 million and $0.5 million , respectively, of customer relationship amortization gain is included in cost of revenues. Estimated future amortization expense for customer relationships and trademarks at June 30, 2018 is as follows (in thousands): Year ending December 31, 2018 11,705 2019 16,964 2020 11,715 2021 10,153 2022 5,941 > 5 years 3,808 Total $ 60,286

Debt

Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Debt	9. Debt Debt consists of the following amounts (in thousands): June 30, 2018 December 31, 2017 Current portion of Senior Credit Facility—Bridge Loan (2) $ — $ 7,500 Current portion of Note Payable—Verde 13,921 13,443 Total current debt 13,921 20,943 Long-term portion of Senior Credit Facility (1) (2) 102,000 117,750 Subordinated Debt 10,000 — Long-term portion of Note Payable—Verde — 7,051 Total long-term debt 112,000 124,801 Total debt $ 125,921 $ 145,744 (1) As of June 30, 2018 and December 31, 2017 , the Company had $61.7 million and $47.2 million in letters of credit issued, respectively. (2) As of June 30, 2018 and December 31, 2017 , the weighted average interest rate on the Senior Credit Facility was 4.97% and 4.61% , respectively. Deferred financing costs were $1.2 million and $1.6 million as of June 30, 2018 and December 31, 2017 , respectively. Of these amounts, $1.2 million is recorded in other current assets in the condensed consolidated balance sheet as of June 30, 2018 and December 31, 2017 , and zero and $0.4 million is recorded in other assets in the condensed consolidated balance sheets as of June 30, 2018 and December 31, 2017 , respectively, representing capitalized financing costs related to our Senior Credit Facility. Interest expense consists of the following components for the periods indicated (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Interest incurred on Senior Credit Facility $ 1,208 $ 543 $ 2,472 $ 1,237 Accretion related to Earnouts (1) — 1,433 — 2,660 Letters of credit fees and commitment fees 422 193 780 417 Amortization of deferred financing costs 317 283 612 531 Interest incurred on convertible subordinated notes to affiliate — — — 1,052 Interest incurred on subordinated debt 6 — 7 — Interest on Verde promissory note 363 — 690 — Interest Expense $ 2,316 $ 2,452 $ 4,561 $ 5,897 (1) Includes accretion related to the Provider Earnout of less than $0.1 million and the Major Earnout of $1.4 million for the three months ended June 30, 2017 , and accretion related to the Provider Earnout of $0.1 million and the Major Earnout of $2.6 million for the six months ended June 30, 2017 . Senior Credit Facility On May 19, 2017 (the “Closing Date”), the Company, as guarantor, and Spark HoldCo (the “Borrower” and, together with SE, SEG, CenStar, CenStar Operating Company, LLC, Oasis, Oasis Power, LLC, the Provider Companies, the Major Energy Companies and Perigee Energy, LLC, each subsidiaries 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 , which replaced the Prior Senior Credit Facility (defined below). The Verde Companies and HIKO became Co-Borrowers upon the completion of our acquisition of the Verde Companies and HIKO, respectively. On November 2, 2017, the Company and Co-Borrowers entered into the first amendment to the Senior Credit Facility, which entitled the co-borrowers to elect to increase total commitments under the Senior Credit Facility to $200.0 million . On November 30, 2017, January 11, 2018 and January 23, 2018, the Company and Co-Borrowers exercised the accordion feature in the Senior Credit Facility, bringing total commitments under the Senior Credit Facility to $200.0 million . On July 17, 2018, the Company and Co-Borrowers entered into the second amendment to the Senior Credit Facility, which entitles the Company and Co-Borrowers to elect to increase total commitments to an aggregate amount of $250.0 million . In connection with any such increase in commitments, the various limits on advances for Working Capital Loans, Letters of Credit and Bridge Loans increase accordingly. In addition, the second amendment to the Senior Credit Facility extended the maturity date to May 19, 2020. Initial commitments under the Senior Credit Facility as amended, are $192.5 million . As of June 30, 2018 , there was $102.0 million outstanding under the Senior Credit Facility, and there was approximately $36.3 million available borrowing capacity (which includes $61.7 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 will be repaid 25% per year on a quarterly basis (or 6.25% per quarter), with the remainder due at maturity. As of June 30, 2018, there were no Bridge Loans outstanding. 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 the Company’s Class A common stock and Series A Preferred Stock. 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 • the 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 • the 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 will pay a commitment fee of 0.50% quarterly in arrears on the unused portion of the Senior Credit Facility. In addition, the Co-Borrowers will be 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 as follows: • Minimum Fixed Charge Coverage Ratio . Spark Energy, Inc. 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 Energy Corp 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 of the Company), distributions, the aggregate amount of repurchases of the Company’s Class A common stock, Series A Preferred Stock, or commitments for such purchases, taxes and scheduled amortization payments. • Maximum Total Leverage Ratio . Spark Energy, Inc. 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 . Spark Energy, Inc. 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 the Company’s ability to, among other things, do any of the following: • 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. The Senior Credit Facility is secured by pledges of the equity of the portion of Spark HoldCo owned by the Company, 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. Spark Energy, Inc. is 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 the Company’s 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. In addition, the Senior Credit Facility contains affirmative covenants that are customary for credit facilities of this type. The covenants include delivery of financial statements, including any filings made with the SEC, maintenance of property and insurance, payment of taxes and obligations, material compliance with laws, inspection of property, books and records and audits, use of proceeds, payments to bank blocked accounts, notice of defaults and certain other customary matters. Subordinated Debt Facility On December 27, 2016, we 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. The Company has the right to capitalize interest payments under the subordinated note. The subordinated note is subordinated in certain respects to the Company's Senior Credit Facility pursuant to a subordination agreement. The Company may pay interest and prepay principal on the subordinated note so long as it is 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. As of June 30, 2018 , there was $10.0 million in outstanding borrowings under the subordinated note, and as of December 31, 2017 , there were no outstanding borrowings under the subordinated note. Verde Companies Promissory Note In connection with the financing of the Verde Companies acquisition, on July 1, 2017, CenStar issued a Promissory Note in the aggregate principal amount of $20.0 million (the "Verde Promissory Note") for a portion of the purchase price. The Verde Promissory Note required 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 the Company. Payment of principal and interest under the Verde Promissory Note would be accelerated upon the occurrence of certain events of default. 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, retains the same maturity date as the Verde Promissory Note. The Amended and Restated Verde Promissory Note bears interest at a rate of 9% per annum beginning January 1, 2018. Principal and interest remain payable monthly on the first day of each month in which the Amended and Restated Verde Promissory Note is outstanding. CenStar will continue to deposit 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 has been increased from the Verde Promissory Note. All principal and interest payable under the Amended and Restated Verde Promissory Note remains subject to acceleration upon the occurrence of certain events of default, including the failure to pay any principal or interest when due under the Amended and Restated Verde Promissory Note. As of December 31, 2017 , there was $14.6 million outstanding under the Verde Promissory note. As of June 30, 2018 , there was $8.0 million outstanding under the Amended and Restated Verde Promissory Note, which will be paid in monthly installments through January 2019. Verde Earnout Termination Note On January 12, 2018, we entered into an Agreement to Terminate Earnout Payments (the “Earnout Termination Agreement”) that terminates our obligation to make any required earnout payments under the purchase agreement for our acquisition of the Verde Companies in exchange for CenStar’s issuance to the seller of a promissory note in the principal amount of $5.9 million (the “Verde Earnout Termination Note”). The Verde Earnout Termination Note, effective January 12, 2018, 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 under the purchase agreement for our acquisition of the Verde Companies. Interest is payable monthly on the first day of each month in which the Verde Earnout Termination Note is outstanding, beginning on its issuance date. The principal and any outstanding interest is due on June 30, 2019. All principal and interest payable under the Verde Earnout Termination Note is accelerated upon the occurrence of certain events of default, including the failure to pay any principal or interest when due under the Verde Earnout Termination Note. The Company recorded the Verde Earnout Termination Note of $5.9 million as current debt as of June 30, 2018 and long term debt as of December 31, 2017 . Prior Senior Credit Facility The Company, as guarantor, and Spark HoldCo (together with Spark Energy, LLC, Spark Energy Gas, LLC, CenStar Energy Corp, CenStar Operating Company, LLC, Oasis, Oasis Power, LLC, Electricity Maine, LLC, Electricity N.H., LLC, and Provider Power Mass, LLC, each a subsidiary of Spark HoldCo, as co-borrowers) were party to a senior secured revolving credit facility (“Prior Senior Credit Facility”), which included a senior secured revolving working capital facility up to $82.5 million ("Working Capital Line") and a secured revolving line of credit of $25.0 million ("Acquisition Line") to be used specifically for the financing of up to 75% of the cost of acquisitions with the remainder to be financed by the Company either through cash on hand or the issuance of subordinated debt or equity. The Prior Senior Credit Facility had a maturity date of July 8, 2017. The outstanding balances under the Working Capital Line and the Acquisition Line were paid in full on May 19, 2017 upon execution of the Company's new Senior Credit Facility.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 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 not only the credit standing of counterparties involved and the impact of credit enhancements but also the impact of the Company’s own nonperformance risk on its liabilities. The Company applies fair value measurements to its commodity derivative instruments and a contingent payment arrangement based on the following fair value hierarchy, which prioritizes the inputs to 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 the Company's acquisitions. As the fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3), the Company maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. In these cases, the lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. 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 the Company’s line of credit. The fair value of our convertible subordinated notes to affiliates is not determinable for accounting purposes due to the affiliate nature and terms of the associated debt instrument with the affiliate. The fair value of the payable pursuant to tax receivable agreement—affiliate is not determinable for accounting purposes due to the affiliate nature and terms of the associated agreement 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 the Company’s condensed consolidated balance sheets on a recurring basis by and their level within the fair value hierarchy as of (in thousands): Level 1 Level 2 Level 3 Total June 30, 2018 Non-trading commodity derivative assets $ 178 $ 11,918 $ — $ 12,096 Trading commodity derivative assets — 25 — 25 Total commodity derivative assets $ 178 $ 11,943 $ — $ 12,121 Non-trading commodity derivative liabilities $ (16 ) $ (6,049 ) $ — $ (6,065 ) Trading commodity derivative liabilities (378 ) (16 ) — (394 ) Total commodity derivative liabilities $ (394 ) $ (6,065 ) $ — $ (6,459 ) 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 ) The Company had no transfers of assets or liabilities between any of the above levels during the six months ended June 30, 2018 and the year ended December 31, 2017 . The Company’s derivative contracts include exchange-traded contracts fair valued utilizing readily available quoted market prices and non-exchange-traded contracts fair valued using market price quotations available through brokers or over-the-counter and on-line exchanges. In addition, in determining the fair value of the Company’s derivative contracts, the Company applies 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 June 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 the Company's acq uisitions. As of June 30, 2018 and December 31, 2017 , the estimated earnout obligations were $3.0 million and $4.6 million , respectively, which related to the Major Earnout. The Major Stock Earnout was valued at zero at June 30, 2018 and December 31, 2017 . As of June 30, 2018 , the estimated earnouts are recorded on our condensed consolidated balance sheets in current liabilities—conti ngent consideration in the amount of $3.0 million ; and as of December 31, 2017 , in current liabilities—contingent consideration and long-term liabilities—contingent consideration in the amount of $4.0 million and $0.6 million , respectively. The Provider Earnout was based on achievement by the Provider Companies of a certain customer count criteria over the nine month period following the closing of the Provider Companies acquisition on August 1, 2016. The sellers of the Provider Companies were entitled to a maximum of $9.0 million and a minimum of $5.0 million in earnout payments based on the level of customer count attained, as defined by the Provider Companies membership interest purchase agreement. In March and June 2017, the Company paid the sellers of the Provider Companies $1.0 million and $4.5 million , respectively, related to the earnout based on the achievement of certain customer count and sales targets. During the three months ended March 31, 2017, the Company recorded accretion of $0.1 million to reflect the impact of the time value of the liability prior to the final payment in June 2017. The Company revalued the liability at March 31, 2017 with no expected change of the earnout payments for the three months ended March 31, 2017. The final payment for the Provider Earnout was made in June 2017. In determining the fair value of the Provider Earnout, the Company forecasted an expected customer count and certain other related criteria and calculated the probability of such forecast being attained. As this calculation was based on management's estimates of the liability, we classified the Provider Earnout as a Level 3 measurement. 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, the Company forecasted certain expected performance targets and calculated the probability of such forecast being attained. In March 2018 and 2017, the Company paid the previous members of the Major Energy Companies $1.6 million and $7.4 million , respectively, related to the year ended December 31, 2017 and the period from April 15, 2016 through December 31, 2016, respectively. During the three and six months ended June 30, 2017 , the Company recorded accretion of $1.4 million and $2.6 million , respectively, to reflect the impact of the time value of the liability. During the three and six months ended June 30, 2018, the Company recorded no accretion as the impact of the time value of the liability was immaterial. The Company revalued the liability at June 30, 2018, resulting in a decrease to the fair value of the liability of $0.1 million . As this calculation is based on management's estimates of the liability, we 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 six months ended June 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 June 30, 2018 $ 2,980 Assets and Liabilities Measured at Fair Value on a Non-recurring Basis We apply the provisions of the fair value measurement standard to our non-recurring, non-financial measurements including business combinations as well as impairment related to goodwill and other long-lived assets. For business combinations (see Note 4 "Acquisitions" ), the purchase price is allocated to the assets acquired and liabilities assumed based on a discounted cash flow model for most intangibles as well as market assumptions for the valuation of equipment and other fixed assets. We utilize a discounted cash flow model in evaluating impairment considerations related to goodwill and long-lived assets. Given the unobservable nature of the inputs, the discounted cash flow models are considered to use Level 3 inputs.

Accounting for Derivative Instr

Accounting for Derivative Instruments	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Accounting for Derivative Instruments	11. Accounting for Derivative Instruments The Company is exposed to the impact of market fluctuations in the price of electricity and natural gas, basis costs, storage and ancillary costs, Renewable Energy Credits and capacity charges from independent system operators. The Company uses derivative instruments to manage exposure to these risks, and historically designated certain derivative instruments as cash flow hedges for accounting purposes. The Company holds certain derivative instruments that are not held for trading purposes and are not designated as hedges for accounting purposes. These derivative instruments represent economic hedges that mitigate the Company’s exposure to fluctuations in commodity prices. For these derivative instruments, changes in the fair value are recognized currently in earnings in retail cost of revenues. As part of the Company’s strategy to optimize its assets and manage related risks, it also manages a portfolio of commodity derivative instruments held for trading purposes. The Company’s commodity trading activities are subject to limits within the Company’s 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 the Company’s condensed consolidated balance sheets when the derivative instruments are executed with the same counterparty under a master netting arrangement. The Company’s 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 the Company has 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 June 30, 2018 and December 31, 2017 , the Company had paid $0.5 million and $0.1 million in collateral outstanding, respectively. The specific types of derivative instruments the Company may execute to manage the commodity price risk include the following: • Forward contracts, which commit the Company 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. The Company has entered into other energy-related contracts that do not meet the definition of a derivative instrument or qualify for the normal purchase or normal sale exception and are therefore not accounted for at fair value, including the following: • Forward electricity and natural gas purchase contracts for retail customer load, and • Natural gas transportation contracts and storage agreements. Volumetric Underlying Derivative Transactions The following table summarizes the net notional volume buy/(sell) of the Company’s open derivative financial instruments accounted for at fair value, broken out by commodity, as of (in thousands): Non-trading Commodity Notional June 30, 2018 December 31, 2017 Natural Gas MMBtu 5,644 9,191 Natural Gas Basis MMBtu 143 — Electricity MWh 7,008 8,091 Trading Commodity Notional June 30, 2018 December 31, 2017 Natural Gas MMBtu 117 26 Natural Gas Basis MMBtu — (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 June 30, 2018 2017 Gain (loss) on non-trading derivatives, net $ 16,601 $ (10,202 ) Gain on trading derivatives, net 453 525 Gain (loss) on derivatives, net 17,054 (9,677 ) Current period settlements on non-trading derivatives (1) (2) (3) (4) 8,793 4,020 Current period settlements on trading derivatives (1 ) (24 ) Total current period settlements on derivatives $ 8,792 $ 3,996 (1) Excludes settlements of $0.1 million and $1.3 million , respectively, for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of the Provider Companies and Major Energy Companies. (2) Excludes settlements of less than $0.1 million and $0.4 million , respectively, for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of Perigee and other customers. (3) Excludes settlements of $0.2 million for the three months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the Verde Companies. (4) Excludes settlements of $0.1 million for the three months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the HIKO Companies. Six Months Ended June 30, 2018 2017 Loss on non-trading derivatives, net $ (20,111 ) $ (31,578 ) Gain on trading derivatives, net 623 105 Loss on derivatives, net (19,488 ) (31,473 ) Current period settlements on non-trading derivatives (1) (2) (3) (4) (5) (6,089 ) 11,535 Current period settlements on trading derivatives (656 ) (184 ) Total current period settlements on derivatives $ (6,745 ) $ 11,351 (1) Excludes settlements of zero and less than $0.1 million , respectively, for the six months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of CenStar and Oasis. (2) Excludes settlements of $(0.7) million and less than $0.1 million , respectively, for the six months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of the Provider Companies and Major Energy Companies. (3) Excludes settlements of $(0.1) million and $0.4 million , respectively, for the six months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of Perigee and other customers. (4) Excludes settlements of $0.2 million for the six months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the Verde Companies. (5) Excludes settlements of $0.2 million for the six months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the HIKO Companies. 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 the Company’s derivative instruments by counterparty and collateral received or paid as of (in thousands): June 30, 2018 Description Gross Assets Gross Net Assets Cash Net Amount Non-trading commodity derivatives $ 33,897 $ (22,396 ) $ 11,501 $ — $ 11,501 Trading commodity derivatives 91 (66 ) 25 — 25 Total Current Derivative Assets 33,988 (22,462 ) 11,526 — 11,526 Non-trading commodity derivatives 1,035 (440 ) 595 — 595 Trading commodity derivatives — — — — — Total Non-current Derivative Assets 1,035 (440 ) 595 — 595 Total Derivative Assets $ 35,023 $ (22,902 ) $ 12,121 $ — $ 12,121 June 30, 2018 Description Gross Gross Net Cash Net Amount Non-trading commodity derivatives $ (8,369 ) $ 6,088 $ (2,281 ) $ 218 $ (2,063 ) Trading commodity derivatives (17 ) 1 (16 ) — (16 ) Total Current Derivative Liabilities (8,386 ) 6,089 (2,297 ) 218 (2,079 ) Non-trading commodity derivatives (13,725 ) 9,723 (4,002 ) — (4,002 ) Trading commodity derivatives (425 ) 47 (378 ) — (378 ) Total Non-current Derivative Liabilities (14,150 ) 9,770 (4,380 ) — (4,380 ) Total Derivative Liabilities $ (22,536 ) $ 15,859 $ (6,677 ) $ 218 $ (6,459 ) 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 ) Three Months Ended June 30, (1) Financial information has been recast to include results attributable to the acquisition of Perigee Energy, LLC by an affiliate on February 3, 2017. See Notes 2 and 4, "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion. (2) Excludes settlements of zero and less than $0.1 million , respectively, for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of CenStar and Oasis. (3) Excludes settlements of $(0.8) million and $(1.3) million , respectively, for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of the Provider Companies and Major Energy Companies. (4) Excludes settlements of $(0.1) million and zero for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of Perigee and other customers. (5) Excludes settlements of less than $0.1 million for the three months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the Verde Companies. (6) Excludes settlements of $0.1 million for the three months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the HIKO Companies. 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 the Company’s derivative instruments by counterparty and collateral received or paid as of (in thousands): June 30, 2018 Description Gross Assets Gross Net Assets Cash Net Amount June 30, 2018 Description Gross Gross Net Cash Net Amount December 31, 2017 Description Gross Assets Gross Net Assets Cash Net Amount December 31, 2017 Description Gross Gross Net Cash Net Amount

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes Income Taxes The Company, CenStar and Verde Energy USA, Inc. ("Verde Corp") are each subject to U.S. federal income tax as corporations. CenStar and Verde Corp will 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, the Company is subject to U.S. federal income taxation on its allocable share of Spark HoldCo’s net U.S. taxable income. The Company reports federal and state income taxes for its share of the partnership income attributable to its ownership in Spark HoldCo and for the income taxes attributable to CenStar, a C-corporation, which is owned by Spark HoldCo. The income tax liability for the partnership does not accrue to the partnership, but rather the investors are responsible for the income taxes based upon the investor's share of the partnership's income. Net income attributable to the non-controlling interest in CenStar includes the provision for income taxes. The Company accounts 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. The Company applies existing tax law and the tax rate that the Company expects 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. The Company remeasured its U.S. federal deferred tax assets and liabilities as of December 31, 2017 using the newly enacted 21% corporate tax rate, the rate expected to be applied when the temporary differences are settled. The Company has not revised any of the 2017 provisional estimates under SAB No. 118 and ASU No 2018-05, but is continuing to gather information and is waiting on further guidance from the IRS, SEC and FASB on U.S. Tax Reform. The Company periodically assesses whether it is more likely than not that it will generate sufficient taxable income to realize its deferred income tax assets. In making this determination, the Company considers all available positive and negative evidence and makes certain assumptions. The Company considers, among other things, its deferred tax liabilities, the overall business environment, its historical earnings and losses, current industry trends, and its outlook for future years. The Company believes it is more likely than not that the deferred tax assets will be utilized. The Company had a net deferred tax asset of approximately $15.6 million related to the step up in tax basis resulting from the purchase by the Company of Spark HoldCo units from NuDevco Retail and NuDevco Retail Holdings (predecessor to Retailco) on the IPO date. In addition, as of June 30, 2018 , the Company 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 a long-term liability. As of June 30, 2018, the Company 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 six months ended June 30, 2018 and 2017 is 15.2% and 15.1% , respectively, with respect to pre-tax (loss) income attributable to the Company's stockholders. The effective tax rate for the six months ended June 30, 2018 has been adjusted for the impact of 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 six months ended June 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 interest. 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	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	13. Commitments and Contingencies From time to time, the Company 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 the Company’s 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 The Company is undergoing various types of indirect tax audits spanning from years 2009 to 2017 for which the Company 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 June 30, 2018 , we have accrued $0.5 million related to indirect tax audits. The outcome of these indirect tax audits may result in additional expense. Legal Proceedings The Company is the 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. Halifax-American Energy Company, LLC et al v. Provider Power, LLC, Electricity N.H., LLC, Electricity Maine, LLC, Emile Clavet and Kevin Dean is a lawsuit initially filed on June 12, 2014, in the Rockingham County Superior Court, State of New Hampshire, alleging various claims related to the Provider Companies’ employment of a sales contractor formerly employed with one or more of the plaintiffs, including misappropriation of trade secrets and tortious interference with a contractual relationship. The relief sought included compensatory and punitive damages and attorney's fees. Portions of the original claim proceeded to trial and on January 19, 2016, a jury found in favor of the plaintiffs. On May 4, 2016, following post-verdict motions, the defendants filed an appeal in the State of New Hampshire Supreme Court. The New Hampshire Supreme Court decided the appeal on February 9, 2018, upholding the jury's verdict and the trial court's rulings in all respects. On March 21, 2018, the trial court awarded Final Judgment to plaintiffs in the amount of $0.9 million , pursuant to the parties’ Joint Stipulation regarding Judgment. The judgment, with costs, attorney fees, and interest totaled $1.0 million . The judgment has been fully satisfied, and all accruals on the Company's books have been released as of June 30, 2018. 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 limited to issues relevant to class certification under Rule 23 of the Federal Rules of Civil Procedure is currently scheduled to end in August 2018. 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. The Company believes it is 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. The Company currently cannot predict the outcome or consequences of this case at this time. The Company believes it is 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. 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 the Company is indemnified with 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. 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 the Company is indemnified with 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 the Company, and tortious interference with contract against the Company 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, and the Court's decision to rule or schedule oral argument is pending as of the date these financial statements are issued. 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 initial responsive pleadings in this case on August 1, 2018. Major denies the allegations asserted and intends to vigorously defense 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 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 an inquiry into the marketing practices of one of Spark Energy, LLC’s former outbound telemarketing vendors. 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 June 30, 2018, which represents the Company's 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	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Transactions with Affiliates	14. Transactions with Affiliates The Company enters into transactions with and pays 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. The Company also sells and purchases natural gas and electricity with affiliates. The Company presents 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. Acquisition of Perigee The acquisition of Perigee by the Company from NG&E was a transfer of equity interests of entities under common control on April 1, 2017. Refer to Note 4 "Acquisitions" for further discussion. Master Service Agreement with Retailco Services, LLC We entered into a Master Service Agreement (the “Master Service Agreement”) effective January 1, 2016 with Retailco Services, LLC ("Retailco Services"), which is wholly owned by our Founder. On March 7, 2018, we, Retailco Services and NuDevco Retail mutually agreed to terminate the MSA, effective April 1, 2018. The Master Service Agreement was for a one -year term and renewed automatically for successive one -year terms unless the Master Service Agreement was terminated by either party. Retailco Services 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. Under the terms of the termination agreement, these operational support services were transferred back to the Company on April 1, 2018. See "Cost Allocations" for further discussion of the fees paid in connection with the Master Service Agreement during the three and six months ended June 30, 2018 . Acquisition of Customers from NG&E On March 7, 2018, we entered into an asset purchase agreement with NG&E pursuant to which we agreed to acquire approximately 50,000 RCEs from NG&E for a cash purchase price of $250 for each RCE, or approximately $12.5 million in the aggregate. As of June 30, 2018 , the Company expects to pay an estimated $8.5 million in total to NG&E under the terms of the purchase agreement for approximately 34,000 RCEs, of which $7.8 million was paid as of June 30, 2018 . These customers began transferring after April 1, 2018 and are located in 24 markets in 8 states. The acquisition of RCEs from NG&E was a transfer of assets between entities under common control. Therefore the Company recorded the assets at their historical value at the date of the transfer. The transaction resulted in $6.1 million recorded in equity as a net distribution to NG&E as of June 30, 2018 . Accounts Receivable and Payable — Affiliates The Company recorded current accounts receivable—affiliates of $3.4 million and $3.7 million as of June 30, 2018 and December 31, 2017 , respectively, and current accounts payable—affiliates of $2.4 million and $4.6 million as of June 30, 2018 and December 31, 2017 , respectively, for certain direct billings and cost allocations for services the Company 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 Cost of revenues—affiliates, recorded in net asset optimization revenues in the condensed consolidated statements of operations for the three months ended June 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 six months ended June 30, 2018 and 2017 were less than $0.1 million and zero , respectively. Revenues—affiliates, recorded in net asset optimization revenues in the condensed consolidated statements of operations for the three months ended June 30, 2018 and 2017 were $0.4 million and zero , respectively. Revenues—affiliates, recorded in net asset optimization revenues in the condensed consolidated statements of operations for the six months ended June 30, 2018 and 2017 were $1.0 million and zero , respectively. Cost Allocations The Company paid certain expenses on behalf of affiliates, which are reimbursed by the affiliates to the Company, 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 primarily allocated to the affiliated entities or us based on percentage of departmental usage, wages or headcount. The total net amount direct billed and allocated from affiliates was $1.5 million and $6.3 million , respectively, for the three months ended June 30, 2018 and 2017 , respectively. The total net amount direct billed and allocated from affiliates was $8.4 million and $13.7 million , respectively, for the six months ended June 30, 2018 and 2017 . Of the $1.5 million and $6.3 million total net amounts directly billed and allocated from affiliates, the Company recorded general and administrative expense of $0.5 million and $5.4 million for the three months ended June 30, 2018 and 2017 , respectively, and of the $8.4 million and $13.7 million total net amounts directly billed and allocated from affiliates, the Company recorded general and administrative expense of $5.8 million and $11.9 million for the six months ended June 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 less than $0.1 million and $0.2 million of property and equipment for the application, development and implementation of various systems during the three months ended June 30, 2018 and 2017 , respectively, and we capitalized $0.5 million and $0.3 million of property and equipment for the application, development and implementation of various systems during the six months ended June 30, 2018 and 2017 , respectively. Distributions to and Contributions from Affiliates During the six months ended June 30, 2018 and 2017 , Spark HoldCo made net capital distributions to NuDevco Retail and Retailco of $7.8 million in conjunction with the payment of quarterly distributions attributable to its Spark HoldCo units. During the six months ended June 30, 2018 and 2017 , Spark HoldCo made distributions to NuDevco Retail and Retailco for gross-up distributions of $11.7 million and $12.0 million , respectively, in connection with distributions made between Spark HoldCo and Spark Energy, Inc. for payment of income taxes incurred by Spark Energy, Inc. Proceeds from Disgorgement of Stockholder Short-swing Profits During the three and six months ended June 30, 2018 , the Company 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. The subordinated note matures approximately three and a half years following the date of issuance, and advances thereunder accrue interest at 5% per annum from the date of the advance. The Company has the right to capitalize interest payments under the subordinated note. The subordinated note is subordinated in certain respects to the Company's Senior Credit Facility pursuant to a subordination agreement. The Company may pay interest and prepay principal on the subordinated note so long as it is 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 its 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. As of June 30, 2018 , there was $10.0 million in outstanding borrowings under the subordinated note. As of December 31, 2017 , there were no outstanding borrowings under the subordinated note. Tax Receivable Agreement Concurrently with the closing of the IPO, the Company entered into a Tax Receivable Agreement with Spark HoldCo, NuDevco Retail Holdings and NuDevco Retail. This agreement generally provides for the payment by the Company to Retailco, LLC (as the successor to NuDevco Retail Holdings) and NuDevco Retail of 85% of the net cash savings, if any, in U.S. federal, state and local income tax or franchise tax that the Company actually realizes (or is deemed to realize in certain circumstances) in future periods as a result of (i) any tax basis increases resulting from the purchase by the Company of Spark HoldCo units from NuDevco Retail Holdings, (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 the Company as a result of, and additional tax basis arising from, any payments the Company makes under the Tax Receivable Agreement. The Company retains the benefit of the remaining 15% of these tax savings. See Note 12 "Income Taxes" for further discussion. In certain circumstances, the Company may defer or partially defer any payment due (a “TRA Payment”) to the holders of rights under the Tax Receivable Agreement, which are currently Retailco and NuDevco Retail. During the five -year period ending September 30, 2019, the Company will defer all or a portion of any TRA Payment owed pursuant to the Tax Receivable Agreement 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 the Company to receive distributions of cash equal to (i) the targeted quarterly distribution the Company intends 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 the Company 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. In the event that the TRA Coverage Ratio is not satisfied in any calendar year, the Company will defer all or a portion of the TRA Payment to NuDevco Retail or Retailco under the Tax Receivable Agreement to the extent necessary to permit Spark HoldCo to satisfy the TRA Coverage Ratio (and Spark HoldCo is not required to make and will not make the pro rata distributions to its members with respect to the deferred portion of the TRA Payment). If the TRA Coverage Ratio is satisfied in any calendar year, the Company will pay NuDevco Retail or Retailco the full amount of the TRA Payment. Following the five -year deferral period ending September 30, 2019, the Company will be obligated to pay any outstanding deferred TRA Payments to the extent such deferred TRA Payments do not exceed (i) the lesser of the Company's proportionate share of aggregate Cash Available for Distribution of Spark HoldCo during the five -year deferral period or the cash distributions actually received by the Company 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) the Company's 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 the Company 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 during the four-quarter periods ending September 30, 2016 and 2017. Accordingly, these TRA Payments were paid in April and May 2018. We expect to meet 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. As such, the related TRA Payment will be due in January of 2019. The Company has classified $2.5 million and $5.9 million as a current liability in our consolidated balance sheet at June 30, 2018 and December 31, 2017 , respectively.

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting	15. Segment Reporting The Company’s determination of reportable business segments considers the strategic operating units under which the Company makes financial decisions, allocates resources and assesses performance of its retail and asset optimization businesses. The Company’s 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 price natural gas to serve retail gas load, are part of the retail natural gas segment. The Company recorded asset optimization revenues of $32.7 million and $39.2 million and asset optimization cost of revenues of $31.9 million and $39.4 million for the three months ended June 30, 2018 and 2017 , respectively, which are presented on a net basis in asset optimization revenues. The Company recorded asset optimization revenues of $110.9 million and $101.1 million and asset optimization cost of revenues of $107.4 million and $101.5 million for the six months ended June 30, 2018 and 2017 , 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. To assess the performance of the Company’s operating segments, the Chief Operating Decision Maker analyzes retail gross margin. The Company defines retail gross margin 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. The Company deducts 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 is a primary performance measure used by our management to determine the performance of our retail natural gas and electricity business by removing the impacts of our asset optimization activities and net non-cash income (loss) impact of our economic hedging activities. As an indicator of our retail energy business’ operating performance, 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Reconciliation of Retail Gross Margin to Income (loss) before taxes Income (loss) before income tax expense (benefit) $ 27,178 $ 5,080 $ (21,120 ) $ 18,617 Interest and other income (553 ) 265 (754 ) 66 Interest expense 2,316 2,452 4,561 5,897 Operating income (loss) 28,941 7,797 (17,313 ) 24,580 Depreciation and amortization 12,861 9,656 25,880 18,926 General and administrative 27,780 19,346 57,827 43,839 Less: Net asset optimization revenues / (expenses) 763 (168 ) 3,450 (361 ) Net, gain (loss) on non-trading derivative instruments 16,601 (10,202 ) (20,111 ) (31,578 ) Net, Cash settlements on non-trading derivative instruments 8,793 4,020 (6,089 ) 11,535 Retail Gross Margin $ 43,425 $ 43,149 $ 89,144 $ 107,749 The Company uses retail gross margin and net asset optimization revenues as the measure of profit or loss for its business segments. This measure represents the lowest level of information that is provided to the chief operating decision maker for our reportable segments. Financial data for business segments are as follows (in thousands): Three Months Ended June 30, 2018 Retail Retail Corporate Eliminations Spark Retail Total Revenues $ 209,447 $ 22,804 $ — $ — $ 232,251 Retail cost of revenues 151,953 10,716 — — 162,669 Less: Net asset optimization revenue — 763 — — 763 Gains on non-trading derivatives 16,120 481 — — 16,601 Current period settlements on non-trading derivatives 8,732 61 — — 8,793 Retail Gross Margin $ 32,642 $ 10,783 $ — $ — $ 43,425 Total Assets at June 30, 2018 $ 1,565,495 $ 533,496 $ 249,310 $ (1,887,452 ) $ 460,849 Goodwill at June 30, 2018 $ 117,813 $ 2,530 $ — $ — $ 120,343 Three Months Ended June 30, 2017 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 131,908 $ 19,528 $ — $ — $ 151,436 Retail cost of revenues 102,079 12,558 — — 114,637 Less: Net asset optimization expense — (168 ) — — (168 ) Losses on non-trading derivatives (9,333 ) (869 ) — — (10,202 ) Current period settlements on non-trading derivatives 4,299 (279 ) — — 4,020 Retail Gross Margin $ 34,863 $ 8,286 $ — $ — $ 43,149 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 Six Months Ended June 30, 2018 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 430,346 $ 88,593 $ — $ — $ 518,939 Retail cost of revenues 401,500 51,045 — — 452,545 Less: Net asset optimization revenue — 3,450 — — 3,450 Losses on non-trading derivatives (17,199 ) (2,912 ) — — (20,111 ) Current period settlements on non-trading derivatives (6,316 ) 227 — — (6,089 ) Retail Gross Margin $ 52,361 $ 36,783 $ — $ — $ 89,144 Total Assets at June 30, 2018 $ 1,565,495 $ 533,496 $ 249,310 $ (1,887,452 ) $ 460,849 Goodwill at June 30, 2018 $ 117,813 $ 2,530 $ — $ — $ 120,343

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events Declaration of Dividends On July 19, 2018 , the Company declared a quarterly dividend of $0.18125 to holders of record of our Class A common stock on August 30, 2018 and payable on September 13, 2018 . On July 19, 2018 , the Company declared a quarterly cash dividend in the amount of $0.546875 per share of Series A Preferred Stock. This amount represents an annualized dividend of $2.1875 per share. The dividend will be paid on October 15, 2018 to holders of record on October 1, 2018 of the Series A Preferred Stock. The Company anticipates Series A Preferred Stock dividends declared of $8.1 million in the aggregate for the year ended December 31, 2018 based on the Series A Preferred Stock outstanding as of June 30, 2018 .

Basis of Presentation and Sum24

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
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"). This information should be read in conjunction with our consolidated financial statements and notes contained in our annual report on Form 10-K for the year ended December 31, 2017 . The Company's 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.
Use of Estimates	The preparation of the Company's 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 six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the full year or for any interim period.
Transactions with Affiliates	Transactions with Affiliates The Company enters into transactions with, and pays certain costs on behalf of, affiliates that are commonly controlled by W. Keith Maxwell III, and these affiliates enter into transactions with, and pay certain costs on behalf of, us in order to reduce risk, reduce administrative expense, create economies of scale, create strategic alliances and supply goods and services. These transactions include, but are not limited to, certain services to the affiliated companies associated with employee benefits provided through the Company’s 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 the Company 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. Additionally, the Company enters into transactions with certain 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.
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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Standards adopted in 2018 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. The Company 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, since our contracts with customers identify the delivery of products and services that are individually distinct performance obligations and revenue is recognized when performance obligations are satisfied. As a result, receivable balances related to revenue, including amounts related to unbilled revenue, are reflected as accounts receivable in the condensed consolidated balance sheets. Other than accounts receivable, revenue related contract assets and liabilities are immaterial. 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. The Company’s asset optimization activities meet the definition of trading activities per FASB ASC Topic 815, Derivatives and Hedging , and are therefore excluded from the scope of Revenue from Contracts with Customers (Topic 606). 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 cash flow issues in the statement of cash flows. This ASU has been applied using a retrospective transition method for each period presented. The Company adopted ASU 2016-15 effective January 1, 2018 and 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 six months ended June 30, 2017. We reclassified acquisition related payments of approximately $13.0 million from cash flows from investing activities to cash flows from financing activities for the six months ended June 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. The definition of a business affects many areas of accounting, including acquisitions, disposals, goodwill, and consolidation. ASU 2017-01 is effective for annual periods beginning after December 15, 2017, including interim periods within those periods and is to be applied prospectively to transactions on or after the adoption date. The Company adopted ASU 2017-01 effective January 1, 2018, and applied the guidance in the evaluation of whether the HIKO acquisition should be accounted for as an acquisition of assets or a business. Standards Being Evaluated/Standards 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. The amendments in this ASU 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 the Company expects to elect. 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 believe the primary impact will be related to the recognition of right-of-use assets and liabilities for 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 the amendments in 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. 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. The Company is 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 expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees. An entity should apply the requirements of Topic 718 to non-employee awards except for specific guidance on inputs to an option pricing model and the attribution of cost. The amendments specify that Topic 718 applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor's own operations by issuing share-based payment awards. ASU 2018-07 also clarifies that Topic 718 does not apply to share-based payments used to effectively provide (1) financing to the issuer or (2) awards granted in conjunction with selling goods or services to customers as part of a contract accounted for under Topic 606, Revenue from Contracts with Customers . ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. The Company is 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. The allocation was made to major categories of assets and liabilities 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 not only the credit standing of counterparties involved and the impact of credit enhancements but also the impact of the Company’s own nonperformance risk on its liabilities. The Company applies fair value measurements to its commodity derivative instruments and a contingent payment arrangement based on the following fair value hierarchy, which prioritizes the inputs to 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 the Company's acquisitions. As the fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3), the Company maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. In these cases, the lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy.
Accounting for Derivatives Instruments	The Company is exposed to the impact of market fluctuations in the price of electricity and natural gas, basis costs, storage and ancillary costs, Renewable Energy Credits and capacity charges from independent system operators. The Company uses derivative instruments to manage exposure to these risks, and historically designated certain derivative instruments as cash flow hedges for accounting purposes. The Company holds certain derivative instruments that are not held for trading purposes and are not designated as hedges for accounting purposes. These derivative instruments represent economic hedges that mitigate the Company’s exposure to fluctuations in commodity prices. For these derivative instruments, changes in the fair value are recognized currently in earnings in retail cost of revenues. As part of the Company’s strategy to optimize its assets and manage related risks, it also manages a portfolio of commodity derivative instruments held for trading purposes. The Company’s commodity trading activities are subject to limits within the Company’s Risk Management Policy. For these derivative instruments, changes in the fair value are recognized currently in earnings in net asset optimization revenues.

Revenues (Tables)

Revenues (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Disaggregated Revenue	The following table disaggregates revenue by primary geographical market, customer type, customer credit risk profile. The table also includes a reconciliation of the disaggregated revenue to revenue by reportable segment (in thousands). Reportable segments Three months ended June 30, 2018 Retail Electricity Retail Natural Gas Total reportable segments Primary geographical markets (a) New England $ 93,926 $ 3,228 $ 97,154 Mid-Atlantic 67,928 9,419 77,347 Midwest 18,085 5,428 23,513 Southwest 29,508 3,966 33,474 $ 209,447 $ 22,041 $ 231,488 Customer type Commercial $ 77,255 $ 10,877 $ 88,132 Residential 115,110 20,341 135,451 Unbilled revenue (b) 17,082 (9,177 ) 7,905 $ 209,447 $ 22,041 $ 231,488 Customer credit risk POR $ 144,239 $ 12,782 $ 157,021 Non-POR 65,208 9,259 74,467 $ 209,447 $ 22,041 $ 231,488 Reportable segments Three months ended June 30, 2017 Retail Electricity Retail Natural Gas Total reportable segments Primary geographical markets (a) New England $ 46,009 $ 3,464 $ 49,473 Mid-Atlantic 55,451 6,939 62,390 Midwest 10,778 4,369 15,147 Southwest 19,670 4,924 24,594 $ 131,908 $ 19,696 $ 151,604 Customer type Commercial $ 41,922 $ 11,683 $ 53,605 Residential 83,767 18,346 102,113 Unbilled revenue (b) 6,219 (10,333 ) (4,114 ) $ 131,908 $ 19,696 $ 151,604 Customer credit risk POR $ 87,162 $ 8,960 $ 96,122 Non-POR 44,746 10,736 55,482 $ 131,908 $ 19,696 $ 151,604 Reportable segments Six months ended June 30, 2018 Retail Electricity Retail Natural Gas Total reportable segments Primary geographical markets (a) New England $ 195,024 $ 12,579 $ 207,603 Mid-Atlantic 145,483 35,350 180,833 Midwest 35,920 24,686 60,606 Southwest 53,919 12,528 66,447 $ 430,346 $ 85,143 $ 515,489 Customer type Commercial $ 174,148 $ 35,176 $ 209,324 Residential 263,104 66,070 329,174 Unbilled revenue (b) (6,906 ) (16,103 ) (23,009 ) $ 430,346 $ 85,143 $ 515,489 Customer credit risk POR $ 301,240 $ 49,552 $ 350,792 Non-POR 129,106 35,591 164,697 $ 430,346 $ 85,143 $ 515,489 Reportable segments Six months ended June 30, 2017 Retail Electricity Retail Natural Gas Total reportable segments Primary geographical markets (a) New England $ 95,913 $ 13,095 $ 109,008 Mid-Atlantic 113,922 31,121 145,043 Midwest 22,962 21,323 44,285 Southwest 32,805 16,963 49,768 $ 265,602 $ 82,502 $ 348,104 Customer type Commercial $ 84,919 $ 35,220 $ 120,139 Residential 179,202 62,315 241,517 Unbilled revenue (b) 1,481 (15,033 ) (13,552 ) $ 265,602 $ 82,502 $ 348,104 Customer credit risk POR $ 179,896 $ 41,944 $ 221,840 Non-POR 85,706 40,558 126,264 $ 265,602 $ 82,502 $ 348,104 (a) The geographical regions 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 actualized, at which time it is categorized between commercial customers and residential customers.

Acquisitions (Tables)

Acquisitions (Tables)	6 Months Ended
	Jun. 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 Q2 2018 Adjustments (1) As of June 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 the second quarter of 2018 were due to an agreement to 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 preliminary allocation of the purchase consideration is as follows (in thousands): As of June 30, 2018 Cash and restricted cash 309 Intangible assets — customer relationships 6,205 Net working capital, net of cash acquired 9,041 Fair value of derivative liabilities (205 ) Total 15,350
Unaudited Pro Forma Revenue and Earnings Summary	The following unaudited pro forma revenue and earnings summary presents consolidated information of the Company as if the acquisition had occurred on January 1, 2016 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Revenues $ 184,813 $ 150,238 $ 418,103 $ 306,809 Earnings $ 310 $ 3,443 $ 2,644 $ 7,862

Equity (Tables)

Equity (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Non-controlling Interest Economic Interest	The Company and NuDevco Retail and Retailco owned the following economic interests in Spark HoldCo at December 31, 2017 and June 30, 2018 , respectively. Non-controlling Interest Economic Interest The Company NuDevco Retail and Retailco (1) December 31, 2017 38.12 % 61.88 % June 30, 2018 38.58 % 61.42 %
Schedule 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net income (loss) allocated to non-controlling interest $ 16,808 $ 3,164 $ (13,080 ) $ 11,569 Income tax expense (benefit) allocated to non-controlling interest 381 (428 ) (2 ) (885 ) Net income (loss) attributable to non-controlling interest $ 16,427 $ 3,592 $ (13,078 ) $ 12,454
Earnings Per Share	The following table presents the computation of earnings (loss) per share for the three and six months ended June 30, 2018 and 2017 (in thousands, except per share data): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net income (loss) attributable to Spark Energy, Inc. stockholders $ 7,500 $ 1,079 $ (4,826 ) $ 3,349 Less: Dividend on Series A preferred stock 2,027 991 4,054 1,174 Net income (loss) attributable to stockholders of Class A common stock $ 5,473 $ 88 $ (8,880 ) $ 2,175 Basic weighted average Class A common shares outstanding 13,229 13,104 13,183 13,050 Basic earnings (loss) per share attributable to stockholders $ 0.41 $ 0.01 $ (0.67 ) $ 0.17 Net income (loss) attributable to stockholders of Class A common stock $ 5,473 $ 88 $ (8,880 ) $ 2,175 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 $ 5,473 $ 88 (8,880 ) 2,175 Basic weighted average Class A common shares outstanding 13,229 13,104 13,183 13,050 Effect of dilutive Class B common stock — — — — Effect of dilutive restricted stock units 17 272 — 207 Diluted weighted average shares outstanding 13,246 13,376 13,183 13,257 Diluted earnings (loss) per share attributable to stockholders $ 0.41 $ 0.01 $ (0.67 ) $ 0.16
Carrying Amounts and Classification of Assets and Liabilities of Variable Interest Entity	The following table includes the carrying amounts and classification of the assets and liabilities of Spark HoldCo that are included in the Company's condensed consolidated balance sheet as of June 30, 2018 (in thousands): June 30, 2018 Assets Current assets: Cash and cash equivalents $ 35,599 Accounts receivable 132,011 Other current assets 86,734 Total current assets 254,344 Non-current assets: Goodwill 120,343 Other assets 53,923 Total non-current assets 174,266 Total Assets $ 428,610 Liabilities Current liabilities: Accounts payable and Accrued Liabilities $ 94,870 Contingent consideration 2,980 Other current liabilities 19,656 Total current liabilities 117,506 Long-term liabilities: Long-term portion of Senior Credit Facility 102,000 Subordinated debt — affiliate 10,000 Other long-term liabilities 4,380 Total long-term liabilities 116,380 Total Liabilities $ 233,886

Preferred Stock (Tables)

Preferred Stock (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Summary of Mezzanine Equity	A summary of the Company's mezzanine equity for the six months ended June 30, 2018 is as follows: (in thousands) Mezzanine equity 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 Mezzanine equity at June 30, 2018 $ 90,758

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consist of the following amounts as of (in thousands): Estimated useful June 30, 2018 December 31, 2017 Information technology 2 – 5 $ 35,143 $ 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 42,484 41,444 Accumulated depreciation (35,294 ) (33,169 ) Property and equipment—net $ 7,190 $ 8,275

Goodwill, Customer Relationsh30

Goodwill, Customer Relationships and Trademarks (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill and Intangible Assets	Goodwill, customer relationships and trademarks consist of the following amounts as of (in thousands): June 30, 2018 December 31, 2017 Goodwill $ 120,343 $ 120,154 Customer relationships - Acquired (1) Cost $ 99,576 $ 93,371 Accumulated amortization (54,216 ) (46,681 ) Customer relationships - Acquired, net $ 45,360 $ 46,690 Customer relationships - Other (2) Cost $ 13,994 $ 12,336 Accumulated amortization (7,085 ) (5,534 ) Customer relationships - Other, net $ 6,909 $ 6,802 Trademarks (3) Cost $ 9,770 $ 9,770 Accumulated amortization (1,753 ) (1,212 ) Trademarks, net $ 8,017 $ 8,558 (1) Customer relationships - Acquired represent those customer acquisitions accounted for under the acquisition method in accordance with ASC 805. See Note 4 "Acquisitions" for further discussion. (2) Customer relationships - Other represent portfolios of customer contracts not accounted for in accordance with ASC 805, as these acquisitions were not in conjunction with the acquisition of businesses. (3) Trademarks reflect values associated with the recognition and positive reputation of acquired businesses accounted for as part of the acquisition method in accordance with ASC 805 through the acquisitions of CenStar, Oasis, the Provider Companies, the Major Energy Companies and the Verde Companies. These trademarks are recorded as other assets in the condensed consolidated balance sheets. See Note 4 "Acquisitions" for further discussion. 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 (HIKO) — 6,205 — — Additions (NG&E) — — 1,657 — Adjustment (Verde) (1) 189 — — — Amortization expense — (7,535 ) (1,550 ) (541 ) Balance at June 30, 2018 $ 120,343 $ 45,360 $ 6,909 $ 8,017 (1) Related to Spark's agreement to working capital balances with Verde Companies' sellers. Refer to Note 4 "Acquisitions."
Estimated Future Amortization Expense of Intangible Assets	Estimated future amortization expense for customer relationships and trademarks at June 30, 2018 is as follows (in thousands): Year ending December 31, 2018 11,705 2019 16,964 2020 11,715 2021 10,153 2022 5,941 > 5 years 3,808 Total $ 60,286

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Schedule of Debt	Debt consists of the following amounts (in thousands): June 30, 2018 December 31, 2017 Current portion of Senior Credit Facility—Bridge Loan (2) $ — $ 7,500 Current portion of Note Payable—Verde 13,921 13,443 Total current debt 13,921 20,943 Long-term portion of Senior Credit Facility (1) (2) 102,000 117,750 Subordinated Debt 10,000 — Long-term portion of Note Payable—Verde — 7,051 Total long-term debt 112,000 124,801 Total debt $ 125,921 $ 145,744 (1) As of June 30, 2018 and December 31, 2017 , the Company had $61.7 million and $47.2 million in letters of credit issued, respectively. (2) As of June 30, 2018 and December 31, 2017 , the weighted average interest rate on the Senior Credit Facility was 4.97% and 4.61% , respectively.
Components of Interest Expense	Interest expense consists of the following components for the periods indicated (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Interest incurred on Senior Credit Facility $ 1,208 $ 543 $ 2,472 $ 1,237 Accretion related to Earnouts (1) — 1,433 — 2,660 Letters of credit fees and commitment fees 422 193 780 417 Amortization of deferred financing costs 317 283 612 531 Interest incurred on convertible subordinated notes to affiliate — — — 1,052 Interest incurred on subordinated debt 6 — 7 — Interest on Verde promissory note 363 — 690 — Interest Expense $ 2,316 $ 2,452 $ 4,561 $ 5,897 (1) Includes accretion related to the Provider Earnout of less than $0.1 million and the Major Earnout of $1.4 million for the three months ended June 30, 2017 , and accretion related to the Provider Earnout of $0.1 million and the Major Earnout of $2.6 million for the six months ended June 30, 2017 .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 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 the Company’s condensed consolidated balance sheets on a recurring basis by and their level within the fair value hierarchy as of (in thousands): Level 1 Level 2 Level 3 Total June 30, 2018 Non-trading commodity derivative assets $ 178 $ 11,918 $ — $ 12,096 Trading commodity derivative assets — 25 — 25 Total commodity derivative assets $ 178 $ 11,943 $ — $ 12,121 Non-trading commodity derivative liabilities $ (16 ) $ (6,049 ) $ — $ (6,065 ) Trading commodity derivative liabilities (378 ) (16 ) — (394 ) Total commodity derivative liabilities $ (394 ) $ (6,065 ) $ — $ (6,459 ) 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 six months ended June 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 June 30, 2018 $ 2,980

Accounting for Derivative Ins33

Accounting for Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts of Outstanding Derivative Positions	The following table summarizes the net notional volume buy/(sell) of the Company’s open derivative financial instruments accounted for at fair value, broken out by commodity, as of (in thousands): Non-trading Commodity Notional June 30, 2018 December 31, 2017 Natural Gas MMBtu 5,644 9,191 Natural Gas Basis MMBtu 143 — Electricity MWh 7,008 8,091 Trading Commodity Notional June 30, 2018 December 31, 2017 Natural Gas MMBtu 117 26 Natural Gas Basis MMBtu — (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 June 30, 2018 2017 Gain (loss) on non-trading derivatives, net $ 16,601 $ (10,202 ) Gain on trading derivatives, net 453 525 Gain (loss) on derivatives, net 17,054 (9,677 ) Current period settlements on non-trading derivatives (1) (2) (3) (4) 8,793 4,020 Current period settlements on trading derivatives (1 ) (24 ) Total current period settlements on derivatives $ 8,792 $ 3,996 (1) Excludes settlements of $0.1 million and $1.3 million , respectively, for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of the Provider Companies and Major Energy Companies. (2) Excludes settlements of less than $0.1 million and $0.4 million , respectively, for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of Perigee and other customers. (3) Excludes settlements of $0.2 million for the three months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the Verde Companies. (4) Excludes settlements of $0.1 million for the three months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the HIKO Companies. Six Months Ended June 30, 2018 2017 Loss on non-trading derivatives, net $ (20,111 ) $ (31,578 ) Gain on trading derivatives, net 623 105 Loss on derivatives, net (19,488 ) (31,473 ) Current period settlements on non-trading derivatives (1) (2) (3) (4) (5) (6,089 ) 11,535 Current period settlements on trading derivatives (656 ) (184 ) Total current period settlements on derivatives $ (6,745 ) $ 11,351 (1) Excludes settlements of zero and less than $0.1 million , respectively, for the six months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of CenStar and Oasis. (2) Excludes settlements of $(0.7) million and less than $0.1 million , respectively, for the six months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of the Provider Companies and Major Energy Companies. (3) Excludes settlements of $(0.1) million and $0.4 million , respectively, for the six months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of Perigee and other customers. (4) Excludes settlements of $0.2 million for the six months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the Verde Companies. (5) Excludes settlements of $0.2 million for the six months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the HIKO Companies. Three Months Ended June 30, (1) Financial information has been recast to include results attributable to the acquisition of Perigee Energy, LLC by an affiliate on February 3, 2017. See Notes 2 and 4, "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion. (2) Excludes settlements of zero and less than $0.1 million , respectively, for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of CenStar and Oasis. (3) Excludes settlements of $(0.8) million and $(1.3) million , respectively, for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of the Provider Companies and Major Energy Companies. (4) Excludes settlements of $(0.1) million and zero for the three months ended June 30, 2018 and 2017 related to non-trading derivative liabilities assumed in the acquisitions of Perigee and other customers. (5) Excludes settlements of less than $0.1 million for the three months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the Verde Companies. (6) Excludes settlements of $0.1 million for the three months ended June 30, 2018 related to non-trading derivative liabilities assumed in the acquisition of the HIKO Companies.
Offsetting Assets	The following tables summarize the fair value and offsetting amounts of the Company’s derivative instruments by counterparty and collateral received or paid as of (in thousands): June 30, 2018 Description Gross Assets Gross Net Assets Cash Net Amount Non-trading commodity derivatives $ 33,897 $ (22,396 ) $ 11,501 $ — $ 11,501 Trading commodity derivatives 91 (66 ) 25 — 25 Total Current Derivative Assets 33,988 (22,462 ) 11,526 — 11,526 Non-trading commodity derivatives 1,035 (440 ) 595 — 595 Trading commodity derivatives — — — — — Total Non-current Derivative Assets 1,035 (440 ) 595 — 595 Total Derivative Assets $ 35,023 $ (22,902 ) $ 12,121 $ — $ 12,121 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 Assets Gross Net Assets Cash Net Amount The following tables summarize the fair value and offsetting amounts of the Company’s derivative instruments by counterparty and collateral received or paid as of (in thousands): June 30, 2018 Description Gross Assets Gross Net Assets Cash Net Amount
Offsetting Liabilities	June 30, 2018 Description Gross Gross Net Cash Net Amount Non-trading commodity derivatives $ (8,369 ) $ 6,088 $ (2,281 ) $ 218 $ (2,063 ) Trading commodity derivatives (17 ) 1 (16 ) — (16 ) Total Current Derivative Liabilities (8,386 ) 6,089 (2,297 ) 218 (2,079 ) Non-trading commodity derivatives (13,725 ) 9,723 (4,002 ) — (4,002 ) Trading commodity derivatives (425 ) 47 (378 ) — (378 ) Total Non-current Derivative Liabilities (14,150 ) 9,770 (4,380 ) — (4,380 ) Total Derivative Liabilities $ (22,536 ) $ 15,859 $ (6,677 ) $ 218 $ (6,459 ) 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 ) December 31, 2017 Description Gross Gross Net Cash Net Amount June 30, 2018 Description Gross Gross Net Cash Net Amount

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Reconciliation of Retail Gross Margin to Income (loss) before taxes Income (loss) before income tax expense (benefit) $ 27,178 $ 5,080 $ (21,120 ) $ 18,617 Interest and other income (553 ) 265 (754 ) 66 Interest expense 2,316 2,452 4,561 5,897 Operating income (loss) 28,941 7,797 (17,313 ) 24,580 Depreciation and amortization 12,861 9,656 25,880 18,926 General and administrative 27,780 19,346 57,827 43,839 Less: Net asset optimization revenues / (expenses) 763 (168 ) 3,450 (361 ) Net, gain (loss) on non-trading derivative instruments 16,601 (10,202 ) (20,111 ) (31,578 ) Net, Cash settlements on non-trading derivative instruments 8,793 4,020 (6,089 ) 11,535 Retail Gross Margin $ 43,425 $ 43,149 $ 89,144 $ 107,749
Financial Data for Business Segments	Financial data for business segments are as follows (in thousands): Three Months Ended June 30, 2018 Retail Retail Corporate Eliminations Spark Retail Total Revenues $ 209,447 $ 22,804 $ — $ — $ 232,251 Retail cost of revenues 151,953 10,716 — — 162,669 Less: Net asset optimization revenue — 763 — — 763 Gains on non-trading derivatives 16,120 481 — — 16,601 Current period settlements on non-trading derivatives 8,732 61 — — 8,793 Retail Gross Margin $ 32,642 $ 10,783 $ — $ — $ 43,425 Total Assets at June 30, 2018 $ 1,565,495 $ 533,496 $ 249,310 $ (1,887,452 ) $ 460,849 Goodwill at June 30, 2018 $ 117,813 $ 2,530 $ — $ — $ 120,343 Three Months Ended June 30, 2017 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 131,908 $ 19,528 $ — $ — $ 151,436 Retail cost of revenues 102,079 12,558 — — 114,637 Less: Net asset optimization expense — (168 ) — — (168 ) Losses on non-trading derivatives (9,333 ) (869 ) — — (10,202 ) Current period settlements on non-trading derivatives 4,299 (279 ) — — 4,020 Retail Gross Margin $ 34,863 $ 8,286 $ — $ — $ 43,149 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 Six Months Ended June 30, 2018 Retail Retail Corporate Eliminations Spark Retail Total revenues $ 430,346 $ 88,593 $ — $ — $ 518,939 Retail cost of revenues 401,500 51,045 — — 452,545 Less: Net asset optimization revenue — 3,450 — — 3,450 Losses on non-trading derivatives (17,199 ) (2,912 ) — — (20,111 ) Current period settlements on non-trading derivatives (6,316 ) 227 — — (6,089 ) Retail Gross Margin $ 52,361 $ 36,783 $ — $ — $ 89,144 Total Assets at June 30, 2018 $ 1,565,495 $ 533,496 $ 249,310 $ (1,887,452 ) $ 460,849 Goodwill at June 30, 2018 $ 117,813 $ 2,530 $ — $ — $ 120,343

Formation and Organization (Det

Formation and Organization (Details)	6 Months Ended
	Jun. 30, 2018vote$ / shares	Dec. 31, 2017$ / shares
Class of Stock [Line Items]
Conversion of stock exchange ratio	1
Common Class A
Class of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Common stock voting rights | vote	1
Common Class B
Class of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Common stock voting rights | vote	1

Basis of Presentation and Sum36

Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition [Line Items]
Cash flows from investing activities	$ 24,000	$ 75,509
Cash flows from operating activities	36,410	45,625
Cash flows from financing activities	$ (6,127)	24,969
Accounting Standards Update 2016-15
Business Acquisition [Line Items]
Cash flows from operating activities		1,100
Cash flows from financing activities		13,000
Investing Activities to Operating Activities | Accounting Standards Update 2016-15
Business Acquisition [Line Items]
Cash flows from investing activities		1,800
Investing Activities to Financing Activities | Accounting Standards Update 2016-15
Business Acquisition [Line Items]
Cash flows from investing activities		$ 13,000

Revenues (Details)

Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Retail Revenues
Disaggregation of Revenue [Line Items]
Gross receipts taxes	$ 1.9	$ 1.1	$ 4.3	$ 2.5
Retail Cost of Revenues
Disaggregation of Revenue [Line Items]
Gross receipts taxes	$ 2.3	$ 1.6	$ 5.1	$ 3.9
Retail Electricity
Disaggregation of Revenue [Line Items]
Typical length of contract			12 months
Retail Natural Gas
Disaggregation of Revenue [Line Items]
Typical length of contract			12 months

Revenues - Disaggregation of Re

Revenues - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ (231,488)	$ (151,604)	$ (515,489)	$ (348,104)
Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(209,447)	(131,908)	(430,346)	(265,602)
Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(22,041)	(19,696)	(85,143)	(82,502)
POR
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(157,021)	(96,122)	(350,792)	(221,840)
POR | Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(144,239)	(87,162)	(301,240)	(179,896)
POR | Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(12,782)	(8,960)	(49,552)	(41,944)
Non-POR
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(74,467)	(55,482)	(164,697)	(126,264)
Non-POR | Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(65,208)	(44,746)	(129,106)	(85,706)
Non-POR | Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(9,259)	(10,736)	(35,591)	(40,558)
Commercial
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(88,132)	(53,605)	(209,324)	(120,139)
Commercial | Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(77,255)	(41,922)	(174,148)	(84,919)
Commercial | Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(10,877)	(11,683)	(35,176)	(35,220)
Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(135,451)	(102,113)	(329,174)	(241,517)
Residential | Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(115,110)	(83,767)	(263,104)	(179,202)
Residential | Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(20,341)	(18,346)	(66,070)	(62,315)
New England
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(97,154)	(49,473)	(207,603)	(109,008)
New England | Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(93,926)	(46,009)	(195,024)	(95,913)
New England | Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(3,228)	(3,464)	(12,579)	(13,095)
Mid-Atlantic
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(77,347)	(62,390)	(180,833)	(145,043)
Mid-Atlantic | Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(67,928)	(55,451)	(145,483)	(113,922)
Mid-Atlantic | Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(9,419)	(6,939)	(35,350)	(31,121)
Midwest
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(23,513)	(15,147)	(60,606)	(44,285)
Midwest | Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(18,085)	(10,778)	(35,920)	(22,962)
Midwest | Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(5,428)	(4,369)	(24,686)	(21,323)
Southwest
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(33,474)	(24,594)	(66,447)	(49,768)
Southwest | Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(29,508)	(19,670)	(53,919)	(32,805)
Southwest | Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(3,966)	(4,924)	(12,528)	(16,963)
Unbilled Revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7,905	(4,114)	(23,009)	(13,552)
Unbilled Revenues | Retail Electricity
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	17,082	6,219	(6,906)	1,481
Unbilled Revenues | Retail Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ (9,177)	$ (10,333)	$ (16,103)	$ (15,033)

Acquisitions (Details)

Acquisitions (Details) rce in Thousands	Mar. 01, 2018USD ($)marketrcestate	Jul. 01, 2017USD ($)	Apr. 01, 2017USD ($)utility	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jan. 12, 2018USD ($)	Dec. 31, 2017USD ($)
Business Acquisition [Line Items]
Revenues				$ 232,251,000	$ 151,436,000	$ 518,939,000	$ 347,743,000
Net income from operations				28,941,000	$ 7,797,000	(17,313,000)	$ 24,580,000
Debt outstanding				125,921,000		125,921,000			$ 145,744,000
Verde Earnout Termination Note | Promissory Note
Business Acquisition [Line Items]
Debt outstanding								$ 5,900,000
HIKO Energy, LLC
Business Acquisition [Line Items]
Purchase price	$ 6,000,000
Number of RCEs | rce	29
Number of markets | market	42
Number of states | state	7
Initial positive (negative) working capital estimate						700,000
Revenues				5,200,000		8,000,000
Net income from operations				$ 1,600,000		2,700,000
Verde Companies
Business Acquisition [Line Items]
Purchase price		$ 90,700,000
Initial positive (negative) working capital estimate		20,100,000				$ 500,000
Consideration transferred, amount funded		85,800,000
Consideration transferred, cash on hand		6,800,000
Consideration transferred, liabilities incurred		$ 5,400,000
Adjusted EBITDA obligation, percent		100.00%
Adjusted EBITDA obligation term (in months)		18 months
Earnout period (in months)		18 months
Verde Companies | Trademarks
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life (in years)						5 years
Verde Companies | Promissory Note
Business Acquisition [Line Items]
Consideration transferred, liabilities incurred		$ 20,000,000
Verde Companies | Revolving Credit Facility
Business Acquisition [Line Items]
Consideration transferred, liabilities incurred		44,000,000
Verde Companies | Subordinated debt — affiliate
Business Acquisition [Line Items]
Consideration transferred, liabilities incurred		$ 15,000,000
Perigee Energy, LLC | National Gas & Electric, LLC
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 - Acquisition of H

Acquisitions - Acquisition of HIKO (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition [Line Items]
Revenues	$ 232,251	$ 151,436	$ 518,939	$ 347,743
Operating income (loss)	28,941	$ 7,797	(17,313)	$ 24,580
HIKO Energy, LLC
Business Acquisition [Line Items]
Revenues	5,200		8,000
Cash and restricted cash	309		309
Intangible assets—customer relationships	6,205		6,205
Net working capital, net of cash acquired	9,041		9,041
Fair value of derivative liabilities	(205)		(205)
Total	15,350		15,350
Operating income (loss)	$ 1,600		$ 2,700

Acquisitions - Acquisition of V

Acquisitions - Acquisition of Verde (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 120,343	$ 120,154
Verde Companies
Business Acquisition [Line Items]
Cash and restricted cash	1,653	1,653
Property and equipment	4,560	4,560
Goodwill	39,396	39,207
Goodwill, purchase accounting adjustments	189
Net working capital, net of cash acquired	18,473	19,132
Net working capital, net of cash acquired, purchase accounting adjustments	(659)
Deferred tax liability	(3,126)	(3,126)
Fair value of derivative liabilities	(1,942)	(1,942)
Total	90,714	91,184
Total purchase accounting adjustments	(470)
Customer Relationships | Verde Companies
Business Acquisition [Line Items]
Intangible assets	28,700	28,700
Trademarks | Verde Companies
Business Acquisition [Line Items]
Intangible assets	$ 3,000	$ 3,000

Acquisitions - Summary of Pro F

Acquisitions - Summary of Pro Forma Revenue and Earnings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Business Combinations [Abstract]
Revenues	$ 184,813	$ 150,238	$ 418,103	$ 306,809
Earnings	$ 310	$ 3,443	$ 2,644	$ 7,862

Acquisitions - Acquisition of P

Acquisitions - Acquisition of Perigee (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 120,343	$ 120,154
Perigee Energy, LLC | National Gas & Electric, LLC
Business Acquisition [Line Items]
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

Equity - Non-controlling Intere

Equity - Non-controlling Interest (Details) - The Company	6 Months Ended	12 Months Ended
	Jun. 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 - Net Income and Income

Equity - Net Income and Income Tax on Non-controlling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity [Abstract]
Net income (loss) allocated to non-controlling interest	$ 16,808	$ 3,164	$ (13,080)	$ 11,569
Income tax expense (benefit) allocated to non-controlling interest	381	(428)	(2)	(885)
Net income (loss) attributable to non-controlling interest	$ 16,427	$ 3,592	$ (13,078)	$ 12,454

Equity (Details)

Equity (Details)	Jun. 16, 2017	May 22, 2017	Jun. 30, 2018voteshares	Dec. 31, 2017shares	May 24, 2017USD ($)
Class of Stock [Line Items]
Stock split conversion ratio, common stock	2	2
Treasury stock (in shares)			99,446	99,446
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
Common Class A
Class of Stock [Line Items]
Common stock shares outstanding (in shares)			13,393,712	13,135,636
Common stock voting rights | vote			1
Common Class B
Class of Stock [Line Items]
Common stock shares outstanding (in shares)			21,485,126	21,485,126
Common stock voting rights | vote			1
Share Repurchase Program | Common Class A
Class of Stock [Line Items]
Share repurchase program, amount authorized | $					$ 50,000,000

Equity - Earnings per Share (De

Equity - Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity [Abstract]
Net income (loss) attributable to Spark Energy, Inc. stockholders	$ 7,500	$ 1,079	$ (4,826)	$ 3,349
Less: Dividend on Series A preferred stock	2,027	991	4,054	1,174
Net income (loss) attributable to stockholders of Class A common stock	$ 5,473	$ 88	$ (8,880)	$ 2,175
Basic weighted average Class A common shares outstanding (in shares)	13,229	13,104	13,183	13,050
Basic earnings (loss) per share attributable to stockholders (in dollars per share)	$ 0.41	$ 0.01	$ (0.67)	$ 0.17
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	$ 5,473	$ 88	$ (8,880)	$ 2,175
Effect of dilutive Class B common stock (in shares)	0	0	0	0
Effect of dilutive restricted stock units (in shares)	17	272	0	207
Diluted weighted average shares outstanding (in shares)	13,246	13,376	13,183	13,257
Diluted earnings (loss) per share attributable to stockholders (in dollars per share)	$ 0.41	$ 0.01	$ (0.67)	$ 0.16

Equity - Classification of Asse

Equity - Classification of Assets and Liabilities (Details) - Variable Interest Entity, Primary Beneficiary $ in Thousands	Jun. 30, 2018USD ($)
Variable Interest Entity [Line Items]
Total Assets	$ 428,610
Total Liabilities	233,886
Total current assets
Variable Interest Entity [Line Items]
Total Assets	254,344
Cash and cash equivalents
Variable Interest Entity [Line Items]
Total Assets	35,599
Accounts receivable
Variable Interest Entity [Line Items]
Total Assets	132,011
Other current assets
Variable Interest Entity [Line Items]
Total Assets	86,734
Total non-current assets
Variable Interest Entity [Line Items]
Total Assets	174,266
Goodwill
Variable Interest Entity [Line Items]
Total Assets	120,343
Other assets
Variable Interest Entity [Line Items]
Total Assets	53,923
Total current liabilities
Variable Interest Entity [Line Items]
Total Liabilities	117,506
Accounts payable and Accrued Liabilities
Variable Interest Entity [Line Items]
Total Liabilities	94,870
Contingent consideration
Variable Interest Entity [Line Items]
Total Liabilities	2,980
Other current liabilities
Variable Interest Entity [Line Items]
Total Liabilities	19,656
Total long-term liabilities
Variable Interest Entity [Line Items]
Total Liabilities	116,380
Long-term portion of Senior Credit Facility
Variable Interest Entity [Line Items]
Total Liabilities	102,000
Subordinated debt — affiliate
Variable Interest Entity [Line Items]
Subordinated debt	10,000
Other long-term liabilities
Variable Interest Entity [Line Items]
Total Liabilities	$ 4,380

Preferred Stock - Narrative (De

Preferred Stock - Narrative (Details) - USD ($)	Jan. 23, 2018	Mar. 15, 2017	Jun. 30, 2018	Jun. 30, 2018	Jun. 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	$ 37,937,000
Preferred offering expenses (less than)	$ 500,000	$ 1,000,000
Aggregate offering price							$ 50,000,000
Preferred stock shares outstanding (in shares)			3,707,256	3,707,256		1,704,339
Dividends paid				$ 4,055,000
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	2,900,000
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)				$ 100,000		$ 100,000

Preferred Stock - Mezzanine Equ

Preferred Stock - Mezzanine Equity (Details) - USD ($) $ in Thousands	Jan. 23, 2018	Mar. 15, 2017	Jun. 30, 2018	Jun. 30, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mezzanine equity at December 31, 2017			$ 41,173
Issuance of Series A Preferred Stock, net of issuance cost	$ 48,900	$ 39,000	48,490	$ 37,937
Mezzanine equity at June 30, 2018			90,758
Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mezzanine equity 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
Mezzanine equity at June 30, 2018			$ 90,758

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 42,484	$ 41,444
Accumulated depreciation	(35,294)	(33,169)
Property and equipment—net	7,190	8,275
Information technology
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 35,143	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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation	$ 0.9	$ 0.5	$ 2.1	$ 1
Information technology
Property, Plant and Equipment [Line Items]
Assets not yet placed into service	$ 0.8		$ 0.8		$ 1.2

Goodwill, Customer Relationsh53

Goodwill, Customer Relationships and Trademarks - Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 120,343	$ 120,154
Finite-Lived Intangible Assets [Line Items]
Total	60,286
Customer Relationships - Acquired & Non-Compete Agreements
Finite-Lived Intangible Assets [Line Items]
Cost	99,576	93,371
Accumulated amortization	(54,216)	(46,681)
Total	45,360	46,690
Customer Relationships - Others
Finite-Lived Intangible Assets [Line Items]
Cost	13,994	12,336
Accumulated amortization	(7,085)	(5,534)
Total	6,909	6,802
Trademarks
Finite-Lived Intangible Assets [Line Items]
Cost	9,770	9,770
Accumulated amortization	(1,753)	(1,212)
Total	$ 8,017	$ 8,558

Goodwill, Customer Relationsh54

Goodwill, Customer Relationships and Trademarks - Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Goodwill [Roll Forward]
Balance at beginning of period			$ 120,154
Balance at end of period	$ 120,343		120,343
Finite-lived Intangible Assets [Roll Forward]
Balance at end of period	60,286		60,286
Customer Relationships - Acquired & Non-Compete Agreements
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period			46,690
Amortization expense			(7,535)
Balance at end of period	45,360		45,360
Customer Relationships - Acquired & Non-Compete Agreements | Cost of Revenues
Finite-lived Intangible Assets [Roll Forward]
Amortization expense	(200)	$ (600)	(1,200)	$ (500)
Customer Relationships - Others
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period			6,802
Amortization expense			(1,550)
Balance at end of period	6,909		6,909
Trademarks
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period			8,558
Amortization expense			(541)
Balance at end of period	8,017		8,017
HIKO Energy, LLC
Goodwill [Roll Forward]
Additions			0
HIKO Energy, LLC | Customer Relationships - Acquired & Non-Compete Agreements
Finite-lived Intangible Assets [Roll Forward]
Additions			6,205
HIKO Energy, LLC | Customer Relationships - Others
Finite-lived Intangible Assets [Roll Forward]
Additions			0
HIKO Energy, LLC | Trademarks
Finite-lived Intangible Assets [Roll Forward]
Additions			0
National Gas & Electric, LLC | Customer Relationships - Others
Finite-lived Intangible Assets [Roll Forward]
Additions			1,657
Verde Companies
Goodwill [Roll Forward]
Balance at beginning of period			39,207
Additions			189
Balance at end of period	$ 39,396		$ 39,396

Goodwill, Customer Relationsh55

Goodwill, Customer Relationships and Trademarks - Future Amortization Expense (Details) $ in Thousands	Jun. 30, 2018USD ($)
Year ending December 31,
2,018	$ 11,705
2,019	16,964
2,020	11,715
2,021	10,153
2,022	5,941
More than 5 years	3,808
Total	$ 60,286

Debt - Components of Debt (Deta

Debt - Components of Debt (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total current debt	$ 13,921,000	$ 20,943,000
Total long-term debt	112,000,000	124,801,000
Subordinated debt—affiliate	10,000,000	0
Total debt	125,921,000	145,744,000
Senior Credit Facility
Debt Instrument [Line Items]
Letters of credit issued	$ 61,700,000	$ 47,200,000
Weighted average interest rate on current portion of debt	4.97%	4.61%
Senior Credit Facility | Bridge Loan
Debt Instrument [Line Items]
Total current debt	$ 0	$ 7,500,000
Senior Credit Facility | Acquisition Line
Debt Instrument [Line Items]
Total long-term debt	102,000,000	117,750,000
Note Payable | Note Payable - Verde
Debt Instrument [Line Items]
Total current debt	13,921,000	13,443,000
Total long-term debt	$ 0	$ 7,051,000

Debt (Details)

Debt (Details)

Jul. 01, 2017USD ($)payment

Dec. 27, 2016USD ($)

Jun. 30, 2018USD ($)shares

Jun. 30, 2018USD ($)shares

Sep. 30, 2016USD ($)

Dec. 31, 2018

Jul. 17, 2018USD ($)

Jan. 23, 2018USD ($)

Jan. 12, 2018USD ($)

Dec. 31, 2017USD ($)

Nov. 02, 2017USD ($)

May 19, 2017USD ($)

Sep. 29, 2016USD ($)

Debt Instrument [Line Items]

Deferred financing costs

$ 1,200,000

$ 1,200,000

$ 1,600,000

Subordinated debt—affiliate

10,000,000

10,000,000

0

Debt outstanding

125,921,000

125,921,000

145,744,000

Long-term portion of note payable

$ 0

$ 0

7,051,000

Senior Secured Revolving Credit Facility

Debt Instrument [Line Items]

Maximum leverage ratio

250.00%

Maximum senior secured leverage ratio

185.00%

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) | shares

10,000,000

10,000,000

Senior Secured Revolving Credit Facility | Series A Preferred Stock

Debt Instrument [Line Items]

Share repurchase program, amount authorized

$ 92,700,000

$ 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) | shares

13,600,000

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

$ 61,700,000

$ 61,700,000

47,200,000

Subordinated debt — affiliate | Retailco

Debt Instrument [Line Items]

Subordinated borrowing, interest rate

5.00%

Subordinated debt

$ 25,000,000

Subordinated debt, advances

$ 1,000,000

Subordinated debt, interest rate on advances

5.00%

Minimum availability under the borrowing base

$ 5,000,000

Note Payable | Verde Promissory Note

Debt Instrument [Line Items]

Notes, issued amount

$ 20,000,000

Notes, monthly installment term | payment

18

Interest rate

5.00%

9.00%

Debt outstanding

8,000,000

8,000,000

14,600,000

Note Payable | Verde Earnout Termination Note

Debt Instrument [Line Items]

Debt outstanding

$ 5,900,000

Long-term portion of note payable

5,900,000

Revolving Credit Facility

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 200,000,000

$ 120,000,000

Long-term line of credit

$ 102,000,000

$ 102,000,000

Revolving Credit Facility | Working Capital Line

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

250,000,000

$ 82,500,000

Debt instrument, 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

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 25,000,000

Financing of cost of acquisitions, maximum percentage

75.00%

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%

Revolving Credit Facility | Senior Credit Facility

Debt Instrument [Line Items]

Line of credit facility, remaining borrowing capacity

$ 36,300,000

$ 36,300,000

Senior Credit Facility

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 200,000,000

Total current assets

Debt Instrument [Line Items]

Deferred financing costs

1,200,000

1,200,000

1,200,000

Other assets

Debt Instrument [Line Items]

Deferred financing costs

$ 0

$ 0

$ 400,000

Scenario, Forecast | Revolving Credit Facility | Working Capital Line

Debt Instrument [Line Items]

Debt instrument, repayment, percent

25.00%

Subsequent Event | Senior Credit Facility

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 250,000,000

Line of credit facility, initial commitments

$ 192,500,000

Debt - Interest Expense (Detail

Debt - Interest Expense (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Line of Credit Facility [Line Items]
Amortization of deferred financing costs	$ 317,000	$ 283,000	$ 612,000	$ 531,000
Interest Expense	2,316,000	2,452,000	4,561,000	5,897,000
Provider Earnout
Line of Credit Facility [Line Items]
Accretion related to earnout		100,000		100,000
Major Earnout
Line of Credit Facility [Line Items]
Accretion related to earnout		1,400,000	0	2,600,000
Convertible Subordinated Notes
Line of Credit Facility [Line Items]
Interest incurred on convertible subordinated notes to affiliate	0	0	0	1,052,000
Subordinated debt — affiliate
Line of Credit Facility [Line Items]
Interest incurred on debt	6,000	0	7,000	0
Promissory Note
Line of Credit Facility [Line Items]
Interest incurred on debt	363,000	0	690,000	0
Working Capital Facility
Line of Credit Facility [Line Items]
Letters of credit fees and commitment fees	422,000	193,000	780,000	417,000
Working Capital Facility | Senior Credit Facility
Line of Credit Facility [Line Items]
Interest incurred on debt	1,208,000	543,000	2,472,000	1,237,000
Level 3 | Fair Value, Measurements, Recurring
Line of Credit Facility [Line Items]
Accretion related to earnout	$ 0	$ 1,433,000	$ 0	$ 2,660,000

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis by Level (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangement	$ (3,000)	$ (4,600)
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	12,121	34,500
Derivative liabilities	(6,459)	(2,129)
Contingent payment arrangement	(2,980)	(4,650)
Fair Value, Measurements, Recurring | Non-trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	12,096	34,044
Derivative liabilities	(6,065)	(1,337)
Fair Value, Measurements, Recurring | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	25	456
Derivative liabilities	(394)	(792)
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	178	158
Derivative liabilities	(394)	(942)
Contingent payment arrangement	0	0
Fair Value, Measurements, Recurring | Level 1 | Non-trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	178	158
Derivative liabilities	(16)	(387)
Fair Value, Measurements, Recurring | Level 1 | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	(378)	(555)
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	11,943	34,342
Derivative liabilities	(6,065)	(1,187)
Contingent payment arrangement	0	0
Fair Value, Measurements, Recurring | Level 2 | Non-trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	11,918	33,886
Derivative liabilities	(6,049)	(950)
Fair Value, Measurements, Recurring | Level 2 | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	25	456
Derivative liabilities	(16)	(237)
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Contingent payment arrangement	(2,980)	(4,650)
Fair Value, Measurements, Recurring | Level 3 | Non-trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 3 | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	$ 0	$ 0

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)	Apr. 15, 2016	Mar. 31, 2018	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangements					$ 3,000,000		$ 3,000,000		$ 4,600,000
Contingent consideration, current liabilities					2,980,000		2,980,000		4,024,000
Contingent consideration, noncurrent liabilities					0		0		626,000
Change in fair value of contingent consideration, net							(63,000)	$ (2,568,000)
Major Earnout
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accretion related to earnout						$ 1,400,000	$ 0	2,600,000
Provider Earnout
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accretion related to earnout						100,000		100,000
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
Provider Companies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout period (in months)							9 months
Earnout maximum					9,000,000		$ 9,000,000
Earnout minimum					5,000,000		5,000,000
Earnout payments			$ 4,500,000	$ 1,000,000
Major Energy Companies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout payments		$ 1,600,000		$ 7,400,000
Major Energy Companies | Major Earnout
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accretion related to earnout					0	1,400,000	0	2,600,000
Change in fair value of contingent consideration, net							100,000
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, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangements					2,980,000		2,980,000		4,650,000
Fair Value, Measurements, Recurring | Major Stock Earnout
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangements					0		0		0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangements					2,980,000		2,980,000		4,650,000
Accretion related to earnout					0	$ 1,433,000	0	$ 2,660,000
Fair Value, Measurements, Recurring | Level 3 | Major Earnout and Stock Earnout
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangements					$ 2,980,000		2,980,000		$ 4,650,000
Change in fair value of contingent consideration, net							$ (63,000)

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent payment arrangement, beginning	$ 4,600
Change in fair value of contingent consideration, net	(63)	$ (2,568)
Contingent payment arrangement, ending	3,000
Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent payment arrangement, beginning	4,650
Contingent payment arrangement, ending	2,980
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent payment arrangement, beginning	4,650
Contingent payment arrangement, ending	2,980
Major Earnout and Stock Earnout | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent payment arrangement, beginning	4,650
Change in fair value of contingent consideration, net	(63)
Payments and settlements	(1,607)
Contingent payment arrangement, ending	$ 2,980

Accounting for Derivative Ins62

Accounting for Derivative Instruments - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Collateral fee	$ 0.5	$ 0.1

Accounting for Derivative Ins63

Accounting for Derivative Instruments - Volumetric Underlying Derivative Transactions (Details) MWh in Thousands, MMBTU in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018MWhMMBTU	Dec. 31, 2017MWhMMBTU
Non-trading | Natural Gas | Buy
Derivatives, Fair Value [Line Items]
Net notional volume	5,644	9,191
Non-trading | Natural Gas Basis | Buy
Derivatives, Fair Value [Line Items]
Net notional volume	143	0
Non-trading | Electricity | Buy
Derivatives, Fair Value [Line Items]
Net notional volume | MWh	7,008	8,091
Trading | Natural Gas | Buy
Derivatives, Fair Value [Line Items]
Net notional volume	117	26
Trading | Natural Gas Basis | Buy
Derivatives, Fair Value [Line Items]
Net notional volume	0
Trading | Natural Gas Basis | Sell
Derivatives, Fair Value [Line Items]
Net notional volume		225

Accounting for Derivative Ins64

Accounting for Derivative Instruments - Gains (Losses) on Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives, net	$ 17,054	$ (9,677)	$ (19,488)	$ (31,473)
Total current period settlements on derivatives	8,792	3,996	(6,745)	11,351
Non-trading
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives, net	16,601	(10,202)	(20,111)	(31,578)
Total current period settlements on derivatives	8,793	4,020	(6,089)	11,535
Non-trading | Censtar and Oasis Power Holdings
Derivative Instruments, Gain (Loss) [Line Items]
Total current period settlements on derivatives			0	100
Non-trading | Provider Companies and Major Energy Companies
Derivative Instruments, Gain (Loss) [Line Items]
Total current period settlements on derivatives	100	1,300	(700)	100
Non-trading | Perigee and Other Customers
Derivative Instruments, Gain (Loss) [Line Items]
Total current period settlements on derivatives	100	400	(100)	400
Non-trading | Verde Companies
Derivative Instruments, Gain (Loss) [Line Items]
Total current period settlements on derivatives	200		200
Non-trading | HIKO Companies
Derivative Instruments, Gain (Loss) [Line Items]
Total current period settlements on derivatives	100		200
Trading
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives, net	453	525	623	105
Total current period settlements on derivatives	$ (1)	$ (24)	$ (656)	$ (184)

Accounting for Derivative Ins65

Accounting for Derivative Instruments - Offsetting Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Commodity Contract
Offsetting Assets [Line Items]
Gross Assets	$ 35,023	$ 77,140
Gross Amounts Offset	(22,902)	(42,640)
Net Assets	12,121	34,500
Cash Collateral Offset	0	0
Net Amount Presented	12,121	34,500
Commodity Contract, Current
Offsetting Assets [Line Items]
Gross Assets	33,988	61,085
Gross Amounts Offset	(22,462)	(29,894)
Net Assets	11,526	31,191
Cash Collateral Offset	0	0
Net Amount Presented	11,526	31,191
Non-trading Commodity Contract, Current
Offsetting Assets [Line Items]
Gross Assets	33,897	60,167
Gross Amounts Offset	(22,396)	(29,432)
Net Assets	11,501	30,735
Cash Collateral Offset	0	0
Net Amount Presented	11,501	30,735
Trading Commodity Contract, Current
Offsetting Assets [Line Items]
Gross Assets	91	918
Gross Amounts Offset	(66)	(462)
Net Assets	25	456
Cash Collateral Offset	0	0
Net Amount Presented	25	456
Commodity Contract, Noncurrent
Offsetting Assets [Line Items]
Gross Assets	1,035	16,055
Gross Amounts Offset	(440)	(12,746)
Net Assets	595	3,309
Cash Collateral Offset	0	0
Net Amount Presented	595	3,309
Non-trading Commodity Contract, Noncurrent
Offsetting Assets [Line Items]
Gross Assets	1,035	16,055
Gross Amounts Offset	(440)	(12,746)
Net Assets	595	3,309
Cash Collateral Offset	0	0
Net Amount Presented	595	3,309
Trading Commodity Contract, Noncurrent
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 Ins66

Accounting for Derivative Instruments - Offsetting Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Commodity Contract
Offsetting Liabilities [Line Items]
Gross Liabilities	$ (22,536)	$ (6,276)
Gross Amounts Offset	15,859	4,082
Net Liabilities	(6,677)	(2,194)
Cash Collateral Offset	218	65
Net Amount Presented	(6,459)	(2,129)
Commodity Contract, Current
Offsetting Liabilities [Line Items]
Gross Liabilities	(8,386)	(5,034)
Gross Amounts Offset	6,089	3,332
Net Liabilities	(2,297)	(1,702)
Cash Collateral Offset	218	65
Net Amount Presented	(2,079)	(1,637)
Non-trading Commodity Contract, Current
Offsetting Liabilities [Line Items]
Gross Liabilities	(8,369)	(4,517)
Gross Amounts Offset	6,088	3,059
Net Liabilities	(2,281)	(1,458)
Cash Collateral Offset	218	65
Net Amount Presented	(2,063)	(1,393)
Trading Commodity Contract, Current
Offsetting Liabilities [Line Items]
Gross Liabilities	(17)	(517)
Gross Amounts Offset	1	273
Net Liabilities	(16)	(244)
Cash Collateral Offset	0	0
Net Amount Presented	(16)	(244)
Commodity Contract, Noncurrent
Offsetting Liabilities [Line Items]
Gross Liabilities	(14,150)	(1,242)
Gross Amounts Offset	9,770	750
Net Liabilities	(4,380)	(492)
Cash Collateral Offset	0	0
Net Amount Presented	(4,380)	(492)
Non-trading Commodity Contract, Noncurrent
Offsetting Liabilities [Line Items]
Gross Liabilities	(13,725)	(676)
Gross Amounts Offset	9,723	732
Net Liabilities	(4,002)	56
Cash Collateral Offset	0	0
Net Amount Presented	(4,002)	56
Trading Commodity Contract, Noncurrent
Offsetting Liabilities [Line Items]
Gross Liabilities	(425)	(566)
Gross Amounts Offset	47	18
Net Liabilities	(378)	(548)
Cash Collateral Offset	0	0
Net Amount Presented	$ (378)	$ (548)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Short-term deferred tax liability	$ 2,508
Income tax rate	15.20%	15.10%
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	Apr. 09, 2018USD ($)investigation	Mar. 21, 2018USD ($)	Jun. 30, 2018USD ($)claim
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
Provider Companies | Pending Litigation | Halifax-American Energy Company, LLC et al v. Provider Power, LLC, Electricity N.H., LLC, Electricity Maine, LLC, Emile Clavet and Kevin Dean
Loss Contingencies [Line Items]
Litigation settlement amount		$ 0.9
Attorney fees			$ 1
Indirect Tax Audits
Loss Contingencies [Line Items]
Contingent liabilities			0.5
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

Transactions with Affiliates (D

Transactions with Affiliates (Details) $ / shares in Units, rce in Thousands		Jun. 30, 2018USD ($)rce	Mar. 07, 2018USD ($)usd_per_rcemarketrcestate	Dec. 27, 2016USD ($)	Jan. 01, 2016	Jun. 30, 2018USD ($)		Jun. 30, 2017USD ($)		Jun. 30, 2018USD ($)$ / shares		Jun. 30, 2017USD ($)		Dec. 31, 2017USD ($)
Related Party Transaction [Line Items]
Accounts receivable—affiliates		$ 3,427,000				$ 3,427,000				$ 3,427,000				$ 3,661,000
Accounts payable—affiliates		2,373,000				2,373,000				2,373,000				4,622,000
Net asset optimization revenues/(expense)						763,000	[1]	$ (168,000)	[2]	3,450,000	[2]	$ (361,000)	[2]
General and administrative expense - affiliates	[1]					27,780,000		19,346,000		57,827,000		43,839,000
Proceeds from disgorgement of stockholders short-swing profits										244,000		666,000
Subordinated debt—affiliate		10,000,000				10,000,000				$ 10,000,000				0
Tax receivable agreement, net cash savings (as a percent)										15.00%
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, maturity term				3 years 6 months
Subordinated debt, interest rate on advances				5.00%
Minimum availability under the borrowing base				$ 5,000,000
Affiliated Entity | Purchased Natural Gas From Affiliate
Related Party Transaction [Line Items]
Cost of revenues						100,000		0		$ 100,000		0
Affiliated Entity | Purchased Natural Gas Sold To Affiliate
Related Party Transaction [Line Items]
Net asset optimization revenues/(expense)						400,000		0		1,000,000		0
Affiliated Entity | Allocated Overhead Costs
Related Party Transaction [Line Items]
General and administrative expense - affiliates						1,500,000		6,300,000		$ 8,400,000		13,700,000
NuDevco Retail Holdings and NuDevco Retail
Related Party Transaction [Line Items]
Payments of distributions to affiliates												7,800,000
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										$ 11,700,000		12,000,000
NuDevco Retail Holdings and NuDevco Retail | Tax Receivable Agreement
Related Party Transaction [Line Items]
Deferred tax liabilities		28,600,000				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				2,500,000				$ 5,900,000
Retailco
Related Party Transaction [Line Items]
Proceeds from disgorgement of stockholders short-swing profits						0				200,000
Retailco | Affiliated Entity
Related Party Transaction [Line Items]
Service contract term					1 year
Service contract, renewal term					1 year
Retailco | Affiliated Entity | Allocated Overhead Costs
Related Party Transaction [Line Items]
General and administrative expense - affiliates						500,000		5,400,000		5,800,000		11,900,000
Retailco | Affiliated Entity | Property and Equipment Capitalized
Related Party Transaction [Line Items]
Amount capitalized for application, development and implementation of various systems						100,000		$ 200,000		500,000		$ 300,000
National Gas & Electric, LLC | Affiliated Entity | Asset Purchase Agreement
Related Party Transaction [Line Items]
Number of RCEs | rce		34	50
Net distribution to NG&E recorded in equity										6,100,000
Purchase price per RCE (in dollars per RCE) | usd_per_rce			250
Purchase price			$ 12,500,000
Due to related parties		$ 8,500,000				$ 8,500,000				$ 8,500,000
Purchase price, amount paid		$ 7,800,000
Number of markets | market			24
Number of states | state			8
[1]	General and administrative expense includes general and administrative expense—affiliates of $1,600 and $6,100 for the three months ended June 30, 2018 and 2017, respectively, and $8,000 and $13,400 for the six months ended June 30, 2018 and 2017, respectively.
[2]	Net asset optimization revenues (expenses) includes asset optimization revenues—affiliates of $340 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates cost of revenues of $24 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates of $988 and $0 for the six months ended June 30, 2018 and 2017, respectively, and asset optimization revenue—affiliates cost of revenues of $36 and $0 for the six months ended June 30, 2018 and 2017, respectively.

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting [Abstract]
Asset optimization revenue	$ 32.7	$ 39.2	$ 110.9	$ 101.1
Asset optimization cost of revenues	$ 31.9	$ 39.4	$ 107.4	$ 101.5

Segment Reporting - Reconciliat

Segment Reporting - Reconciliation (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Segment Reporting Information [Line Items]
Income (loss) before income tax expense (benefit)		$ 27,178		$ 5,080		$ (21,120)		$ 18,617
Interest and other income		(553)		265		(754)		66
Interest expense		2,316		2,452		4,561		5,897
Operating income (loss)		28,941		7,797		(17,313)		24,580
Depreciation and amortization		12,861		9,656		25,880		18,926
General and administrative	[1]	27,780		19,346		57,827		43,839
Less
Net asset optimization revenues / (expenses)		763	[1]	(168)	[2]	3,450	[2]	(361)	[2]
Net, gain (loss) on non-trading derivative instruments		17,054		(9,677)		(19,488)		(31,473)
Net, Cash settlements on non-trading derivative instruments						(7,170)		11,828
Retail Gross Margin		43,425		43,149		89,144		107,749
Non-trading
Less
Net, gain (loss) on non-trading derivative instruments		16,601		(10,202)		(20,111)		(31,578)
Net, Cash settlements on non-trading derivative instruments		$ 8,793		$ 4,020		$ (6,089)		$ 11,535
[1]	General and administrative expense includes general and administrative expense—affiliates of $1,600 and $6,100 for the three months ended June 30, 2018 and 2017, respectively, and $8,000 and $13,400 for the six months ended June 30, 2018 and 2017, respectively.
[2]	Net asset optimization revenues (expenses) includes asset optimization revenues—affiliates of $340 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates cost of revenues of $24 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates of $988 and $0 for the six months ended June 30, 2018 and 2017, respectively, and asset optimization revenue—affiliates cost of revenues of $36 and $0 for the six months ended June 30, 2018 and 2017, respectively.

Segment Reporting - Financial D

Segment Reporting - Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017		Dec. 31, 2017
Segment Reporting Information [Line Items]
Total Revenues	$ 232,251		$ 151,436		$ 518,939		$ 347,743
Retail cost of revenues	162,669		114,637		452,545		260,398
Less:
Net asset optimization revenues / (expenses)	763	[1]	(168)	[2]	3,450	[2]	(361)	[2]
Gains on non-trading derivatives	17,054		(9,677)		(19,488)		(31,473)
Current period settlements on non-trading derivatives	8,792		3,996		(6,745)		11,351
Retail Gross Margin	43,425		43,149		89,144		107,749
Total Assets	460,849				460,849				$ 505,949
Goodwill	120,343				120,343				120,154
Non-trading
Less:
Gains on non-trading derivatives	16,601		(10,202)		(20,111)		(31,578)
Current period settlements on non-trading derivatives	8,793		4,020		(6,089)		11,535
Operating Segments | Retail Electricity
Segment Reporting Information [Line Items]
Total Revenues	209,447		131,908		430,346		265,602
Retail cost of revenues	151,953		102,079		401,500		210,923
Less:
Net asset optimization revenues / (expenses)	0		0		0		0
Retail Gross Margin	32,642		34,863		52,361		71,634
Total Assets	1,565,495				1,565,495				1,228,552
Goodwill	117,813				117,813				117,624
Operating Segments | Retail Electricity | Non-trading
Less:
Gains on non-trading derivatives	16,120		(9,333)		(17,199)		(28,960)
Current period settlements on non-trading derivatives	8,732		4,299		(6,316)		12,005
Operating Segments | Retail Natural Gas
Segment Reporting Information [Line Items]
Total Revenues	22,804		19,528		88,593		82,141
Retail cost of revenues	10,716		12,558		51,045		49,475
Less:
Net asset optimization revenues / (expenses)	763		(168)		3,450		(361)
Retail Gross Margin	10,783		8,286		36,783		36,115
Total Assets	533,496				533,496				421,896
Goodwill	2,530				2,530				2,530
Operating Segments | Retail Natural Gas | Non-trading
Less:
Gains on non-trading derivatives	481		(869)		(2,912)		(2,618)
Current period settlements on non-trading derivatives	61		(279)		227		(470)
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	249,310				249,310				209,428
Goodwill	0				0				0
Corporate and Other | Non-trading
Less:
Gains 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	(1,887,452)				(1,887,452)				(1,353,927)
Goodwill	0				0				$ 0
Eliminations | Non-trading
Less:
Gains on non-trading derivatives	0		0		0		0
Current period settlements on non-trading derivatives	$ 0		$ 0		$ 0		$ 0
[1]	General and administrative expense includes general and administrative expense—affiliates of $1,600 and $6,100 for the three months ended June 30, 2018 and 2017, respectively, and $8,000 and $13,400 for the six months ended June 30, 2018 and 2017, respectively.
[2]	Net asset optimization revenues (expenses) includes asset optimization revenues—affiliates of $340 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates cost of revenues of $24 and $0 for the three months ended June 30, 2018 and 2017, respectively, and asset optimization revenues—affiliates of $988 and $0 for the six months ended June 30, 2018 and 2017, respectively, and asset optimization revenue—affiliates cost of revenues of $36 and $0 for the six months ended June 30, 2018 and 2017, respectively.

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 15, 2018	Jul. 19, 2018	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2018
Subsequent Event [Line Items]
Dividends paid				$ 4,055
Series A Preferred Stock
Subsequent Event [Line Items]
Dividends paid			$ 2,000	$ 2,900
Series A Preferred Stock | Scenario, Forecast
Subsequent Event [Line Items]
Series A preferred stock dividends declared, annualized (in dollars per share)	$ 2.1875
Dividends paid					$ 8,100
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