Document And Entity Information - shares	9 Months Ended
Document And Entity Information - shares	Sep. 30, 2018	Oct. 31, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	Vistra Energy Corp.
Entity Central Index Key	0001692819
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		504,446,340

Condensed Statements Of Consolidated Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Operating revenues	$ 3,243	$ 1,833	$ 6,581	$ 4,487
Fuel, purchased power costs and delivery fees	(1,627)	(838)	(3,492)	(2,250)
Operating costs	(346)	(218)	(926)	(626)
Depreciation and amortization	(426)	(178)	(967)	(519)
Selling, general and administrative expenses	(194)	(147)	(711)	(434)
Operating income	650	452	485	658
Other income	6	10	25	29
Other deductions	(1)	0	(4)	(5)
Interest expense and related charges	(154)	(76)	(291)	(169)
Impacts of tax receivable agreement	17	138	(65)	96
Equity in earnings of unconsolidated investments	7	0	11	0
Income before income taxes	525	524	161	609
Income tax expense	(194)	(251)	(31)	(284)
Net income	331	273	130	325
Less: Net (income) loss attributable to noncontrolling interest	1	0	(2)	0
Net income attributable to Vistra Energy	$ 330	$ 273	$ 132	$ 325
Weighted average shares of common stock outstanding:
Weighted average shares of common stock outstanding - basic	533,142,189	427,591,426	500,781,573	427,587,404
Weighted average shares of common stock outstanding - diluted	540,972,802	428,312,438	508,128,988	428,001,869
Net income (loss) per weighted average share of common stock outstanding:
Net income (loss) per weighted average share of common stock outstanding - basic	$ 0.62	$ 0.64	$ 0.26	$ 0.76
Net income (loss) per weighted average share of common stock outstanding - diluted	$ 0.61	$ 0.64	$ 0.26	$ 0.76

Condensed Statements Of Consolidated Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 331	$ 273	$ 130	$ 325
Other comprehensive income, net of tax effects:
Effect related to pension and other retirement benefit obligations (net of tax benefit of $— in all periods)	1	0	2	0
Total other comprehensive income	1	0	2	0
Comprehensive income	332	273	132	325
Less: Comprehensive (income) loss attributable to noncontrolling interest	1	0	(2)	0
Comprehensive income attributable to Vistra Energy	$ 331	$ 273	$ 134	$ 325

Condensed Statements Of Consolidated Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Effects related to pension and other retirement benefit obligations (net of tax benefit of $— in all periods)	$ 0	$ 0	$ 0	$ 0

Condensed Statements Of Consolidated Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows — operating activities:
Net income	$ 130	$ 325
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Depreciation and amortization	1,070	621
Deferred income tax (benefit) expense, net	29	209
Unrealized net (gain) loss from mark-to-market valuations of commodities	207	(202)
Unrealized net (gain) loss from mark-to-market valuations of interest rate swaps	(123)	3
Reversal of debt extinguishment gain	0	0
Loss on extinguishment of debt		0
Accretion expense	37	43
Impacts of Tax Receivable Agreement	65	(96)
Stock-based compensation	59	13
Other, net	64	41
Changes in operating assets and liabilities:
Margin deposits, net	(39)	183
Accrued interest	(59)	(26)
Accrued taxes	(102)	4
Accrued incentive plan	(17)	(46)
Other operating assets and liabilities	(458)	(227)
Cash provided by operating activities	863	845
Cash flows — financing activities:
Issuances of long-term debt	1,000	0
Repayments/repurchases of debt	(2,902)	(32)
Borrowing under accounts receivable securitization program	350	0
Stock repurchase	(414)	0
Debt tender offer and other financing fees	(216)	(5)
Other, net	10	0
Cash used in financing activities	(2,172)	(37)
Cash flows — investing activities:
Capital expenditures	(209)	(86)
Nuclear fuel purchases	(66)	(56)
Cash acquired in the Merger	445	0
Solar development expenditures	(28)	(129)
Odessa acquisition	0	(355)
Proceeds from sales of nuclear decommissioning trust fund securities	211	154
Investments in nuclear decommissioning trust fund securities	(227)	(169)
Other, net	7	10
Cash provided by (used in) investing activities	133	(631)
Net change in cash, cash equivalents and restricted cash	(1,176)	177
Cash, cash equivalents and restricted cash — beginning balance	2,046	1,588
Cash, cash equivalents and restricted cash — ending balance	$ 870	$ 1,765

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 811	$ 1,487
Restricted cash	59	59
Trade accounts receivable — net	1,243	582
Income taxes receivable	12	0
Inventories	393	253
Commodity and other derivative contractual assets	458	190
Margin deposits related to commodity contracts	177	30
Prepaid expense and other current assets	123	72
Total current assets	3,276	2,673
Restricted cash	0	500
Investments	1,357	1,240
Investment in unconsolidated subsidiary	135	0
Property, plant and equipment — net	14,756	4,820
Goodwill	1,907	1,907
Identifiable intangible assets — net	2,711	2,530
Commodity and other derivative contractual assets	265	58
Accumulated deferred income taxes	1,053	710
Other noncurrent assets	428	162
Total assets	25,888	14,600
Current liabilities:
Accounts receivable securitization program	350	0
Less amounts due currently	181	44
Trade accounts payable	812	473
Commodity and other derivative contractual liabilities	981	224
Margin deposits related to commodity contracts	4	4
Accrued income taxes	0	58
Accrued taxes other than income	139	136
Accrued interest	123	16
Asset retirement obligations	183	99
Other current liabilities	329	297
Total current liabilities	3,102	1,351
Long-term debt, less amounts due currently	11,060	4,379
Commodity and other derivative contractual liabilities	254	102
Accumulated deferred income taxes	5	0
Tax Receivable Agreement obligation	402	333
Asset retirement obligation	2,139	1,837
Identifiable intangible liabilities - net	175	36
Other noncurrent liabilities and deferred credits	346	220
Total liabilities	17,483	8,258
Commitments and Contingencies
Total equity:
Common stock (par value — $0.01; number of shares authorized — 1,800,000,000) (shares outstanding: September 30, 2018 — 507,391,134; December 31, 2017 — 428,398,802)	5	4
Additional paid-in-capital	9,670	7,765
Retained deficit	(1,261)	(1,410)
Accumulated other comprehensive income	(15)	(17)
Stockholders' equity	8,399	6,342
Noncontrolling interest in subsidiary	6	0
Total equity	8,405	6,342
Total liabilities and equity	$ 25,888	$ 14,600

Condensed Consolidated Balance Sheets Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Apr. 09, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Statement of Changes in Financial Position [Abstract]
Common stock, par or stated value per share	$ 0.01
Common stock, shares authorized	1,800,000,000			1,800,000,000
Common stock, shares outstanding	507,391,134	522,932,453	428,398,802	427,597,368	427,580,232

Business And Significant Accounting Policies

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Business And Significant Accounting Policies

BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES

Description of Business

References in this report to "we," "our," "us" and "the Company" are to Vistra Energy and/or its subsidiaries, as apparent in the context. See Glossary for defined terms.

Vistra Energy is a holding company operating an integrated retail and generation business in markets throughout the U.S. Through our subsidiaries, we are engaged in competitive electricity market activities including power generation, wholesale energy sales and purchases, commodity risk management and retail sales of electricity to end users.

Vistra Energy has six reportable segments: (i) Retail, (ii) ERCOT, (iii) PJM, (iv) NY/NE (comprising NYISO and ISO-NE), (v) MISO and (vi) Asset Closure. The Asset Closure segment was established as of January 1, 2018, and we have recast prior period information to reflect this change in reportable segments. See Note 19 for further information concerning reportable business segments.

Merger Transaction

On the Merger Date, Vistra Energy and Dynegy completed the transactions contemplated by the Merger Agreement entered into in October 2017. Pursuant to the Merger Agreement, Dynegy merged with and into Vistra Energy, with Vistra Energy continuing as the surviving corporation. Because the Merger closed on April 9, 2018, Vistra Energy's condensed consolidated financial statements and the notes related thereto do not include the financial condition or the operating results of Dynegy prior to April 9, 2018. See Note 2 for a summary of the Merger transaction and business combination accounting.

Basis of Presentation

The condensed consolidated financial statements have been prepared in accordance with U.S. GAAP and on the same basis as the audited financial statements included in our 2017 Form 10-K, with the exception of the changes in reportable segments as detailed above. Adjustments (consisting of normal recurring accruals) necessary for a fair presentation of the results of operations and financial position have been included therein. All intercompany items and transactions have been eliminated in consolidation. Certain information and footnote disclosures normally included in annual consolidated financial statements prepared in accordance with U.S. GAAP have been omitted pursuant to the rules and regulations of the SEC. Because the condensed consolidated interim financial statements do not include all of the information and footnotes required by U.S. GAAP, they should be read in conjunction with the audited financial statements and related notes contained in our 2017 Form 10-K. The results of operations for an interim period may not give a true indication of results for a full year. All dollar amounts in the financial statements and tables in the notes are stated in millions of U.S. dollars unless otherwise indicated.

Use of Estimates

Preparation of financial statements requires estimates and assumptions about future events that affect the reporting of assets and liabilities at the balance sheet dates and the reported amounts of revenue and expense, including fair value measurements, estimates of expected obligations, judgment related to the potential timing of events and other estimates. In the event estimates and/or assumptions prove to be different from actual amounts, adjustments are made in subsequent periods to reflect more current information.

Unconsolidated Investments

We use the equity method of accounting for investments in affiliates over which we exercise significant influence. Our share of net income (loss) from these affiliates is recorded to equity in earnings (loss) of unconsolidated investment in the condensed statements of consolidated net income (loss). We use the cost method of accounting where we do not exercise significant influence. See Note 20.

Noncontrolling Interest

Noncontrolling interest is comprised of the 20% of Electric Energy, Inc. (EEI) that we do not own. EEI is our consolidated subsidiary that owns a coal facility in Joppa, Illinois. This noncontrolling interest is classified as a component of equity separate from stockholders' equity in the condensed consolidated balance sheets.

Treasury Stock

Treasury stock purchases are accounted for under the cost method whereby the entire cost of the acquired stock is recorded as treasury stock, which is presented in our condensed consolidated balance sheets as a reduction to additional paid-in capital. See Note 13.

Adoption of New Accounting Standards

Revenue from Contracts with Customers — On January 1, 2018, we adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606) and all related amendments (new revenue standard) using the modified retrospective method for all contracts outstanding at the time of adoption. We recognized the cumulative effect of initially applying the new revenue standard as an adjustment to the opening balance of retained earnings. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. The impact of the adoption of the new revenue standard was immaterial and we expect the adoption to continue to be immaterial to our net income on an ongoing basis. Our retail energy charges and wholesale generation, capacity and contract revenues will continue to be recognized when electricity and other services are delivered to our customers. The impact of adopting the new revenue standard primarily relates to the deferral of acquisition costs associated with retail contracts with customers that were previously expensed as incurred. Under the new revenue standard, these amounts will be capitalized and amortized over the expected life of the customer.

As of January 1, 2018, the cumulative effect of the changes made to our condensed consolidated balance sheet for the adoption of the new revenue standard was as follows:



	December 31, 2017			Adoption of New Revenue Standard			January 1, 2018
Impact on condensed consolidated balance sheet:
Assets
Prepaid expense and other current assets	$	72		$	5		$	77
Accumulated deferred income taxes	$	710		$	(4	)	$	706
Other noncurrent assets	$	162		$	16		$	178
Equity
Retained deficit	$	(1,410	)	$	17		$	(1,393	)

The disclosure of the impact of adoption on our condensed statement of consolidated income (loss) and condensed consolidated balance sheet was as follows:



	Three Months Ended September 30, 2018								Nine Months Ended September 30, 2018
	As Reported			Amount Without Adoption of New Revenue Standard			Effect of Change Higher (Lower)		As Reported			Amount Without Adoption of New Revenue Standard			Effect of Change Higher (Lower)
Impact on condensed statement of consolidated income (loss):
Operating revenues	$	3,243		$	3,242		$	1	$	6,581		$	6,578		$	3
Selling, general and administrative expenses	(194		)	(196		)	2		(711		)	(720		)	9
Net income (loss)	331			328			3		130			121			9



	September 30, 2018
	As Reported			Balances Without Adoption of New Revenue Standard			Effect of Change Higher (Lower)
Impact on condensed consolidated balance sheet:
Assets
Prepaid expense and other current assets	$	123		$	116		$	7
Accumulated deferred income taxes	1,053			1,057			(4		)
Other noncurrent assets	428			403			25
Equity
Retained deficit	$	(1,261	)	$	(1,287	)	$	26

See Note 5 for the disclosures required by the new revenue standard.

Statement of Cash Flows — In November 2016, the FASB issued ASU 2016-18 Statement of Cash Flows (Topic 230): Restricted Cash. The ASU requires restricted cash to be included in the cash and cash equivalents and a reconciliation between the change in cash and cash equivalents and the amounts presented on the balance sheet (see Note 20). We adopted the standard on January 1, 2018. The ASU modified our presentation of our condensed statements of consolidated cash flows, and retrospective application to comparative periods presented was required. For the nine months ended September 30, 2017, our condensed statement of consolidated cash flows previously reflected a source of cash of $34 million reported as changes in restricted cash that is now reported in net change in cash, cash equivalents and restricted cash. See the condensed statements of consolidated cash flows and Note 20 for disclosures related to the adoption of this accounting standard.

Changes in Accounting Standards

In February 2016, the Financial Accounting Standards Board (FASB) issued ASU 2016-02, Leases. The ASU amends previous GAAP to require the recognition of lease assets and liabilities for operating leases. The ASU will be effective for fiscal years beginning after December 15, 2018, including interim periods within those years. Retrospective application to comparative periods presented will be required in the year of adoption. We have identified the contracts that are within the scope of this ASU and are currently evaluating the impact of this ASU on our financial statements.

In August 2018, the FASB issued ASU 2018-13, Changes to the Disclosure Requirements for Fair Value Measurement. The ASU will be effective for fiscal years beginning after December 15, 2019 and early adoption is permitted. The ASU removes disclosure requirements for (a) the reasons for transfers between Level 1 and Level 2, (b) the policy for timing of transfers between levels and (c) the valuation processes for Level 3. The ASU will require new disclosures around (a) the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and (b) the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. We are currently evaluating the impact of this ASU on our disclosures.

In August 2018, the FASB issued ASU 2018-14, Changes to the Disclosure Requirements for Defined Benefit Plans. The ASU will be effective for fiscal years beginning after December 15, 2020 and early adoption is permitted. The ASU removes disclosure requirements for (a) the amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit cost over the next fiscal year, (b) related party disclosures about the amount of future annual benefits covered by insurance and annuity contracts and significant transactions between the employer or related parties and the plan and (c) the effects of a one-percentage-point change in assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic benefit costs and benefit obligation for postretirement health care benefits. The ASU will require new disclosures for (a) the weighted-average interest crediting rates for cash balance plans and other plans with promised interest crediting rates and (b) an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. We are currently evaluating the impact of this ASU on our disclosures.

In August 2018, the FASB issued ASU 2018-15, Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The ASU will be effective for fiscal years beginning after December 15, 2019 and early adoption is permitted. The ASU requires a customer in a cloud hosting arrangement that is a service contract to determine which implementation costs to capitalize and which costs to expense based on the project stage of the implementation. The ASU also requires the customer to expense the capitalized implementation costs over the term of the hosting arrangement. The customer is required to apply the existing impairment and abandonment guidance on the capitalized implementation costs. We are currently evaluating the impact of this ASU on our financial statements.

Merger Transaction and Business Combination Accounting (Notes)

9 Months Ended

Sep. 30, 2018

Business Combinations [Abstract]

Merger Transaction [Text Block]

MERGER TRANSACTION AND BUSINESS COMBINATION ACCOUNTING

Merger Transaction

On the Merger Date, Vistra Energy and Dynegy completed the transactions contemplated by the Merger Agreement entered into in October 2017. Pursuant to the Merger Agreement, Dynegy merged with and into Vistra Energy, with Vistra Energy continuing as the surviving corporation. The Merger is intended to qualify as a tax-free reorganization under the Internal Revenue Code, as amended, so that none of Vistra Energy, Dynegy or any of the Dynegy stockholders will recognize any gain or loss in the transaction, except that Dynegy stockholders could recognize a gain or loss with respect to cash received in lieu of fractional shares of Vistra Energy's common stock. Vistra Energy is the acquirer for both federal tax and accounting purposes.

At the closing of the Merger, each issued and outstanding share of Dynegy common stock, par value $0.01 per share, other than shares owned by Vistra Energy or its subsidiaries, held in treasury by Dynegy or held by a subsidiary of Dynegy, was automatically converted into 0.652 shares of common stock, par value $0.01 per share, of Vistra Energy (the Exchange Ratio), except that cash was paid in lieu of fractional shares, which resulted in Vistra Energy issuing 94,409,573 shares of Vistra Energy common stock to the former Dynegy stockholders, as well as converting stock options, equity-based awards, tangible equity units and warrants. The total number of Vistra Energy shares outstanding at the close of the Merger was 522,932,453 shares. Dynegy stock options and equity-based awards outstanding immediately prior to the Merger Date were generally automatically converted upon completion of the Merger into stock options and equity-based awards, respectively, with respect to Vistra Energy's common stock, after giving effect to the Exchange Ratio.

Business Combination Accounting

We believe the Merger provides a number of significant potential strategic benefits and opportunities to Vistra Energy, including increased scale and market diversification, rebalanced asset portfolio and improved earnings and cash flow. The Merger is being accounted for in accordance with ASC 805, Business Combinations (ASC 805), with identifiable assets acquired and liabilities assumed recorded at their estimated fair values on the Merger Date. The combined results of operations are reported in our consolidated financial statements beginning as of the Merger Date. A summary of the techniques used to estimate the preliminary fair value of the identifiable assets and liabilities, as well as their classification within the fair value hierarchy (see Note 14), is listed below:


•	Working capital was valued using available market information (Level 2).


•	Acquired property, plant and equipment was valued using a combination of an income approach and a market approach. The income approach utilized a discounted cash flow analysis based upon a debt-free, free cash flow model (Level 3).


•	Acquired derivatives were valued using the methods described in Note 14 (Level 1, Level 2 or Level 3).


•	Contracts with terms that were not at current market prices were also valued using a discounted cash flow analysis (Level 3). The cash flows generated by the contracts were compared with their cash flows based on current market prices with the resulting difference recorded as either an intangible asset or liability.


•	Long-term debt was valued using a market approach (Level 2).


•	AROs were recorded in accordance with ASC 410, Asset Retirement and Environmental Obligations (Level 3).

The following table summarizes the consideration paid and the preliminary allocation of the purchase price to the fair value amounts recognized for the assets acquired and liabilities assumed related to the Merger as of the Merger Date. Based on the opening price of Vistra Energy common stock on the Merger Date, the preliminary purchase price was approximately $2.3 billion. The preliminary values included below represent our current best estimates for property plant and equipment, identifiable intangible assets and liabilities, inventories, asset retirement obligations and deferred taxes. The purchase price allocation is preliminary and each of these may change materially based upon the receipt of more detailed information, additional analyses and completed valuations. The purchase price allocation is ongoing and is dependent upon final valuation determinations, which have not been completed. During the three months ended September 30, 2018, we updated the initial purchase price allocation with revised valuation estimates by increasing property, plant and equipment by $44 million, increasing intangible assets by $76 million, decreasing inventory by $37 million, decreasing accumulated deferred tax asset by $19 million, decreasing other noncurrent assets by $106 million, decreasing other noncurrent liabilities by $47 million as well as other minor adjustments. The valuation revisions were a result of updated inputs used in determining the fair value of the acquired assets and liabilities. We currently expect the final purchase price allocation will be completed no later than the second quarter of 2019.



Dynegy shares outstanding as of April 9, 2018 (in millions)	173
Exchange Ratio	0.652
Vistra Energy shares issued for Dynegy shares outstanding (in millions)	113
Opening price of Vistra Energy common stock on April 9, 2018	$	19.87
Purchase price for common stock	$	2,245
Fair value of outstanding stock compensation awards attributable to pre-combination service	$	26
Fair value of outstanding warrants	$	2
Total purchase price	$	2,273



Preliminary Purchase Price Allocation
Cash and cash equivalents	$	445
Trade accounts receivables, inventories, prepaid expenses and other current assets	826
Property, plant and equipment	10,406
Accumulated deferred income taxes	372
Identifiable intangible assets	463
Other noncurrent assets	426
Total assets acquired	12,938
Trade accounts payable and other current liabilities	645
Commodity and other derivative contractual assets and liabilities, net	422
Asset retirement obligations, including amounts due currently	426
Long-term debt, including amounts due currently	8,920
Other noncurrent liabilities	245
Total liabilities assumed	10,658
Identifiable net assets acquired	2,280
Noncontrolling interest in subsidiary	7
Total purchase price	$	2,273

Acquisition costs incurred in the Merger totaled $25 million for the nine months ended September 30, 2018. For the period from the Merger Date through September 30, 2018, our condensed statements of consolidated income (loss) include revenues and net income (loss) acquired in the Merger totaling $2.684 billion and $193 million, respectively.

Unaudited Pro Forma Financial Information — The following unaudited pro forma financial information for the nine months ended September 30, 2018 and 2017 assumes that the Merger occurred on January 1, 2017. The unaudited pro forma financial information is provided for information purposes only and is not necessarily indicative of the results of operations that would have occurred had the Merger been completed on January 1, 2017, nor is the unaudited pro forma financial information indicative of future results of operations, which may differ materially from the pro forma financial information presented here.



	Nine Months Ended September 30,
	2018			2017
Revenues	$	8,032		$	8,542
Net income (loss)	$	(64	)	$	316
Net income (loss) attributable to Vistra Energy	$	(61	)	$	318
Net income (loss) attributable to Vistra Energy per weighted average share of common stock outstanding — basic	$	(0.12	)	$	0.56
Net income (loss) attributable to Vistra Energy per weighted average share of common stock outstanding — diluted	$	(0.12	)	$	0.56

The unaudited pro forma financial information presented above includes adjustments for incremental depreciation and amortization as a result of the fair value determination of the net assets acquired, interest expense on debt assumed in the Merger, effects of the Merger on tax expense (benefit), changes in the expected impacts of the tax receivable agreement due to the Merger, and other related adjustments.

Acquisition and Development of Generation Facilities (Notes)	9 Months Ended
	Sep. 30, 2018
Acquisition And Development Of Generation Facilities [Abstract]
Business Combination Disclosure [Text Block]	ACQUISITION AND DEVELOPMENT OF GENERATION FACILITIES Odessa Acquisition In August 2017, La Frontera Holdings, LLC (La Frontera), an indirect, wholly owned subsidiary of Vistra Energy, purchased a 1,054 MW CCGT natural gas fueled generation plant (and other related assets and liabilities) located in Odessa, Texas (Odessa Facility) from Odessa-Ector Power Partners, L.P., an indirect, wholly owned subsidiary of Koch Ag & Energy Solutions, LLC (Koch) (altogether, the Odessa Acquisition). La Frontera paid an aggregate purchase price of approximately $355 million, plus a five-year earn-out provision, to acquire the Odessa Facility. The purchase price was funded by cash on hand. The Odessa Acquisition was accounted for as an asset acquisition. Substantially all of the approximately $355 million purchase price was assigned to property, plant and equipment in our consolidated balance sheet. Additionally, the initial fair value associated with an earn-out provision of approximately $16 million was included as consideration in the overall purchase price. The earn-out provision requires cash payments to be made to Koch if spark-spreads related to the pricing point of the Odessa Facility exceed certain thresholds. Subsequent to the acquisition, the earn-out provision has been accounted for as a derivative in our consolidated financial statements, and partial buybacks of the earn-out provision were settled in February and May 2018. Upton Solar Development In May 2017, we acquired the rights to develop, construct and operate a utility scale solar photovoltaic power generation facility in Upton County, Texas (Upton). As part of this project, we entered a turnkey engineering, procurement and construction agreement to construct the approximately 180 MW facility. During 2017 and 2018, we spent approximately $218 million related to this project primarily for payments under the engineering, procurement and construction agreement. The facility began test operations in March 2018 and commercial operations began in June 2018. Battery Energy Storage Projects In October 2018, we were awarded a $1 million grant from the TCEQ for our battery energy storage system at Upton solar facility. The grant is part of the Texas Emissions Reduction Plan. The 10 MW lithium-ion energy storage system will capture excess solar energy produced during the day and release the energy in late afternoon and early evening, when demand is highest. We expect the project to be operational in late 2018. In June 2018, we announced that, subject to approval by the California Public Utilities Commission (CPUC), we will enter into a 20-year resource adequacy contract with Pacific Gas and Electric Company (PG&E) to develop a 300 MW battery energy storage project at our Moss Landing Power Plant site in California. In late June 2018, PG&E filed its application with the CPUC to approve the contract, and a decision is expected in the fourth quarter of 2018. Pending the receipt of CPUC approval, we anticipate the battery storage project will enter commercial operations by the fourth quarter of 2020.

Retirement of Generation Facilities (Notes)

9 Months Ended

Sep. 30, 2018

Retirement of Generation Facilities [Abstract]

Retirement of generation facilities

RETIREMENT OF GENERATION FACILITIES

In August 2018, we filed a notice of suspension of operation with PJM and other mandatory regulatory notifications related to the retirement of our 51 MW Northeastern waste coal facility in McAddo, Pennsylvania. We decided to retire this facility due to its uneconomic operations and financial outlook. Following the receipt of regulatory approvals, the facility is expected to close in late 2018. The decision to retire this facility did not result in a material impact to the financial statements.

Two of our non-operated, jointly held power plants acquired in the Merger, for which our proportional generation capacity was 883 MW, were retired in May 2018. These units were retired as previously scheduled. No gain or loss was recorded in conjunction with the retirement of these units, and the operational results of these facilities are included in our Asset Closure segment. The following table details the units retired.



Name	Location	Fuel Type	Net Generation Capacity (MW)	Ownership Interest	Date Units Taken Offline
Killen	Manchester, Ohio	Coal	204	33%	May 31, 2018
Stuart	Aberdeen, Ohio	Coal	679	39%	May 24, 2018
Total			883

In January and February 2018, we retired three power plants with a total installed nameplate generation capacity of 4,167 MW. We decided to retire these units because they were projected to be uneconomic based on then current market conditions and would have faced significant environmental costs associated with operating such units. In the case of the Sandow units, the decision also reflected the execution of a contract termination agreement pursuant to which the Company and Alcoa agreed to an early settlement of a long-standing power and mining agreement. Expected retirement expenses were accrued in the third and fourth quarter of 2017 and, as a result, no retirement expenses were recorded related to these facilities in both the three and nine months ended September 30, 2018. The operational results of these facilities are included in our Asset Closure segment. The following table details the units retired.



Name	Location (all in the state of Texas)	Fuel Type	Installed Nameplate Generation Capacity (MW)	Number of Units	Date Units Taken Offline
Monticello	Titus County	Lignite/Coal	1,880	3	January 4, 2018
Sandow	Milam County	Lignite	1,137	2	January 11, 2018
Big Brown	Freestone County	Lignite/Coal	1,150	2	February 12, 2018
Total			4,167	7

Revenue (Notes)

9 Months Ended

Sep. 30, 2018

Revenue Recognition and Deferred Revenue [Abstract]

Revenue from Contract with Customer [Text Block]

REVENUE

The following tables disaggregate our revenue by major source:



	Three Months Ended September 30, 2018
	Retail			ERCOT		PJM			NY/NE			MISO			Asset Closure			CAISO/Eliminations			Consolidated
Revenue from contracts with customers:
Retail energy charge in ERCOT	$	1,362		$	—	$	—		$	—		$	—		$	—		$	—		$	1,362
Retail energy charge in Northeast/Midwest	442			—		—			—			—			—			—			442
Wholesale generation revenue from ISO	—			393		502			244			255			1			81			1,476
Capacity revenue	—			—		164			79			15			(4		)	9			263
Revenue from other wholesale contracts	—			72		11			9			5			(2		)	3			98
Total revenue from contracts with customers	1,804			465		677			332			275			(5		)	93			3,641
Other revenues:
Intangible amortization	15			—		—			(4		)	(5		)	—			—			6
Hedging and other revenues (a)	(6		)	52		(275		)	(42		)	(136		)	5			(2		)	(404		)
Affiliate sales	—			879		218			15			96			(1		)	(1,207		)	—
Total other revenues	9			931		(57		)	(31		)	(45		)	4			(1,209		)	(398		)
Total revenues	$	1,813		$	1,396	$	620		$	301		$	230		$	(1	)	$	(1,116	)	$	3,243

____________


(a)	Includes $28 million of unrealized net losses from mark-to-market valuations of commodity positions. See Note 19 for unrealized net gains (losses) by segment.



	Nine Months Ended September 30, 2018
	Retail			ERCOT			PJM			NY/NE			MISO			Asset Closure			CAISO/Eliminations			Consolidated
Revenue from contracts with customers:
Retail energy charge in ERCOT	$	3,423		$	—		$	—		$	—		$	—		$	—		$	—		$	3,423
Retail energy charge in Northeast/Midwest	778			—			—			—			—			—			—			778
Wholesale generation revenue from ISO	—			775			869			362			436			52			95			2,589
Capacity revenue	—			—			283			162			44			6			20			515
Revenue from other wholesale contracts	—			175			18			14			16			(1		)	4			226
Total revenue from contracts with customers	4,201			950			1,170			538			496			57			119			7,531
Other revenues:
Retail contract amortization	(12		)	(1		)	—			(6		)	(12		)	—			—			(31		)
Hedging and other revenues (a)	50			(181		)	(436		)	(71		)	(256		)	(29		)	4			(919		)
Affiliate sales	—			1,422			370			26			260			20			(2,098		)	—
Total other revenues	38			1,240			(66		)	(51		)	(8		)	(9		)	(2,094		)	(950		)
Total revenues	$	4,239		$	2,190		$	1,104		$	487		$	488		$	48		$	(1,975	)	$	6,581

____________


(a)	Includes $239 million of unrealized net losses from mark-to-market valuations of commodity positions. See Note 19 for unrealized net gains (losses) by segment.

Retail Energy Charges

Revenue is recognized when electricity is delivered to our customers in an amount that we expect to invoice for volumes delivered or services provided. Sales tax is excluded from revenue. Payment terms vary from 15 to 45 days from invoice date. Revenue is recognized over-time using the output method based on kilowatt hours delivered. Energy charges are delivered as a series of distinct services and are accounted for as a single performance obligation.

Wholesale Generation Revenue from ISOs

Revenue is recognized when volumes are delivered to the ISO. Revenue is recognized over time using the output method based on kilowatt hours delivered and cash is settled within 10 days of invoicing. Vistra Energy operates as a market participant within ERCOT, PJM, NYISO, ISO-NE, MISO and CAISO and expects to continue to remain under contract with each ISO indefinitely. Wholesale generation revenues are delivered as a series of distinct services and are accounted for as a single performance obligation.

Capacity Revenue

Revenues are recognized when the performance obligation is satisfied ratably over time in accordance with the contracts as our power generation facilities stand ready to deliver power to the customer. We provide capacity to customers through participation in capacity auctions held by the ISO or through bilateral sales. Generation facilities are awarded auction volumes through the ISO auction and bilateral sales are based on executed contracts with customers.

Revenue from Other Wholesale Contracts

Other wholesale contracts include other revenue activity with the ISOs, such as ancillary services, auction revenue, neutrality revenue and revenue from nonaffiliated retail electric providers. Revenue is recognized when the service is performed. Revenue is recognized over time using the output method based on kilowatt hours delivered or other applicable measurements, and cash settles as invoiced. Vistra Energy operates as a market participant within ERCOT, PJM, NYISO, ISO-NE, MISO and CAISO and expects to continue to remain under contract with each ISO indefinitely. Other wholesale contracts are delivered as a series of distinct services and are accounted for as a single performance obligation.

Contract and Other Customer Acquisition Costs

We defer costs to acquire retail contracts and amortize these costs over the expected life of the contract. The expected life of a retail contract is calculated using historical attrition rates, which we believe to be an accurate indicator of future attrition rates. The deferred acquisition and contract cost balance as of September 30, 2018 and January 1, 2018 was $34 million and $22 million, respectively. The amortization related to these costs during the three and nine months ended September 30, 2018 totaled $3 million and $7 million, respectively, recorded as selling, general and administrative expenses, and $2 million and $5 million, respectively, recorded as a reduction to operating revenues in the condensed statement of consolidated income (loss).

Practical Expedients

The vast majority of revenues are recognized under the right to invoice practical expedient, which allows us to recognize revenue in the same amount that we invoice our customers. We do not disclose the value of unsatisfied performance obligations for contracts with variable consideration for which we recognize revenue using the right to invoice practical expedient. We use the portfolio approach in evaluating similar customer contracts with similar performance obligations. Sales taxes are not included in revenue.

Performance Obligations

As of September 30, 2018, we have future performance obligations that are unsatisfied, or partially unsatisfied, relating to capacity auction volumes awarded through capacity auctions held by the ISO or through bilateral sales. Therefore, an obligation exists as of the date of the results of the respective ISO capacity auction or the contract execution date for bilateral customers. The transaction price is also set by the results of the capacity auction and/or executed contract. These obligations total $311 million, $966 million, $718 million, $720 million and $342 million that will be recognized in the years ending December 31, 2018, 2019, 2020, 2021 and 2022, respectively, and $103 million thereafter. Capacity revenue are recognized as capacity services are provided to the related ISOs.

Accounts Receivable

The following table presents trade accounts receivable relating to both contracts with customers and other activities:



	September 30, 2018
Trade accounts receivable from contracts with customers — net	$	1,135
Other trade accounts receivable — net	108
Total trade accounts receivable — net	$	1,243

Goodwill and Identifiable Intangible Assets and Liabilities (Notes)

9 Months Ended

Sep. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill And Identifiable Intangible Assets

GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS AND LIABILITIES

Goodwill

The carrying value of goodwill totaling $1.907 billion at both September 30, 2018 and December 31, 2017 arose in connection with our application of fresh start reporting at Emergence and was allocated entirely to our ERCOT Retail reporting unit. Of the goodwill recorded at Emergence, $1.686 billion is deductible for tax purposes over 15 years on a straight-line basis.

Identifiable Intangible Assets and Liabilities

Identifiable intangible assets and liabilities are comprised of the following:



	September 30, 2018						December 31, 2017
Identifiable Intangible Asset	Gross Carrying Amount		Accumulated Amortization		Net		Gross Carrying Amount		Accumulated Amortization		Net
Retail customer relationship	$	1,681	$	799	$	882	$	1,648	$	572	$	1,076
Software and other technology-related assets	239		80		159		183		47		136
Retail and wholesale contracts	445		123		322		154		87		67
Contractual service agreements	72		—		72		—		—		—
Other identifiable intangible assets (a)	40		14		26		33		11		22
Total identifiable intangible assets subject to amortization	$	2,477	$	1,016	1,461		$	2,018	$	717	1,301
Retail trade names (not subject to amortization)					1,246						1,225
Mineral interests (not currently subject to amortization)					4						4
Total identifiable intangible assets					$	2,711					$	2,530
______________
(a) Includes mining development costs and environmental allowances and credits.

Identifiable Intangible Liability									September 30, 2018		December 31, 2017
Contractual service agreements									$93		$0
Purchase and sales contracts									46		36
Environmental allowances									36		—
Total identifiable intangible liabilities									$	175	$	36

Amortization expense related to finite-lived identifiable intangible assets and liabilities (including the classification in the condensed statements of consolidated income (loss)) consisted of:



Identifiable Intangible Assets and Liabilities	Condensed Statements of Consolidated Income (Loss) Line	Three Months Ended September 30,						Nine Months Ended September 30,
Identifiable Intangible Assets and Liabilities	Condensed Statements of Consolidated Income (Loss) Line	2018			2017			2018		2017
Retail customer relationship	Depreciation and amortization	$	77		$	105		$	227	$	315
Software and other technology-related assets	Depreciation and amortization	6			10			36		27
Retail and wholesale contracts/purchase and sales contracts	Operating revenues/fuel, purchased power costs and delivery fees	(5		)	(19		)	28		27
Other identifiable intangible assets	Operating revenues/fuel, purchased power costs and delivery fees/depreciation and amortization	10			5			14		14
Total amortization expense (a)		$	88		$	101		$	305	$	383

____________


(a)	Amounts recorded in depreciation and amortization totaled $84 million and $116 million for the three months ended September 30, 2018 and 2017, respectively, and $266 million and $347 million for the nine months ended September 30, 2018 and 2017, respectively.

Following is a description of the separately identifiable intangible assets and liabilities recorded in connection with the Merger (see Note 2) that were adjusted based on their estimated fair value as of the Merger Date, based on observable prices or estimates of fair value using valuation models. The purchase price allocation is ongoing and is dependent upon final valuation determinations, which have not been completed.

•

Retail customer relationship – The acquired retail customer relationship intangible asset represents the estimated fair value of our non-contracted Northeast/Midwest retail customer base, including residential and business customers, and is being amortized using an accelerated method based on historical customer attrition rates and reflecting the expected pattern in which economic benefits are realized over their estimated useful life.

•

Retail trade names – Our acquired retail trade name intangible asset represents the fair value of the Homefield and Dynegy Energy Services trade names and was determined to be an indefinite-lived asset not subject to amortization. This intangible asset will be evaluated for impairment at least annually in accordance with accounting guidance related to goodwill and other indefinite-lived intangible assets.

•

Retail and wholesale contracts/purchase and sales contracts – Our acquired retail and wholesale contracts and purchase and sales contracts represent various types of customer and supplier contracts, including municipal supplier contracts, capacity contracts, gas transportation contracts, and other contracts. The contracts were identified as either assets or liabilities based on the respective fair values at the time of the Merger utilizing prevailing market prices for commodities or services compared to fixed prices contained in these agreements. The intangible assets and liabilities are being amortized in relation to the economic terms of the related contracts.

•

Contractual service agreements – Our acquired contractual service agreements represent the estimated fair value of favorable or unfavorable contract obligations with respect to long-term plant maintenance agreements and are being amortized based on the expected usage of the service agreements over the contract terms. For the portion of the services that relate to capital improvements, the amortization of the contractual services agreements is recorded to property, plant and equipment.

Estimated Amortization of Identifiable Intangible Assets and Liabilities

As of September 30, 2018, the estimated aggregate amortization expense of identifiable intangible assets and liabilities for each of the next five fiscal years is as shown below.



Year	Estimated Amortization Expense
2018	$	402
2019	$	331
2020	$	250
2021	$	180
2022	$	111

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Income Taxes (Notes)

9 Months Ended

Sep. 30, 2018

Income Tax Disclosure [Abstract]

Income Taxes

INCOME TAXES

Income Tax Expense

The calculation of our effective tax rate is as follows:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Income before income taxes	$	525		$	524		$	161		$	609
Income tax expense	$	(194	)	$	(251	)	$	(31	)	$	(284	)
Effective tax rate	37.0		%	47.9		%	19.3		%	46.6		%

For the three months ended September 30, 2018, the effective tax rate of 37.0% related to our income tax expense was higher than the U.S. federal statutory rate of 21% due primarily to nondeductible impacts of the TRA and and state income taxes including the impact of a partial valuation allowance on the state of Illinois net operating loss, partially offset by the return to provision adjustment for permanent book-tax differences. For the nine months ended September 30, 2018, the effective tax rate of 19.3% related to our income tax expense was lower than the U.S. federal statutory rate of 21% due primarily to Vistra Energy's expanded state tax footprint requiring a remeasurement of historical Vistra Energy deferred tax balances and the return to provision adjustment for permanent book-tax differences, partially offset by an increase in state tax expense including a partial valuation allowance on the state of Illinois net operating loss.

For the three months ended September 30, 2017, the effective tax rate of 47.9% related to our income tax expense was higher than the U.S. federal statutory rate of 35% due primarily to nondeductible impacts of the TRA and the Texas margin tax and a reduction in the tax basis of certain of our assets based on the finalization of tax returns related to the pre-Emergence period. For the nine months ended September 30, 2017, the effective tax rate of 46.6% related to our income tax expense was higher than the U.S. federal statutory rate of 35% due primarily to nondeductible impacts of the TRA and the Texas margin tax and a reduction in the tax basis of certain of our assets based on the finalization of tax returns related to the pre-Emergence period.

Liability for Uncertain Tax Positions

Vistra Energy and its subsidiaries file income tax returns in U.S. federal and state jurisdictions and are expected to be subject to examinations by the IRS and other taxing authorities. Vistra Energy has limited operational history and filed its first federal tax return in October 2017. Vistra Energy is not currently under audit for any period. Uncertain tax positions totaling $41 million at September 30, 2018 arose in connection with the Merger and our assessment of the assumed liabilities is not complete as discussed in Note 2. We had no uncertain tax positions at December 31, 2017.

Tax Receivable Agreement Obligation (Notes)

9 Months Ended

Sep. 30, 2018

Income Tax Disclosure [Abstract]

Tax Receivables Agreement Obligation

TAX RECEIVABLE AGREEMENT OBLIGATION

On the Effective Date, Vistra Energy entered into a tax receivable agreement (the TRA) with a transfer agent on behalf of certain former first lien creditors of our predecessor. The TRA generally provides for the payment by us to holders of TRA Rights of 85% of the amount of cash savings, if any, in U.S. federal and state income tax that we realize in periods after Emergence as a result of (a) certain transactions consummated pursuant to the Plan of Reorganization (including the step-up in tax basis in our assets resulting from the PrefCo Preferred Stock Sale), (b) the tax basis of all assets acquired in connection with the acquisition of two CCGT natural gas fueled generation facilities in April 2016 and (c) tax benefits related to imputed interest deemed to be paid by us as a result of payments under the TRA, plus interest accruing from the due date of the applicable tax return.

Pursuant to the TRA, we issued the TRA Rights for the benefit of the first lien secured creditors of TCEH entitled to receive such TRA Rights under the Plan of Reorganization. Such TRA Rights are subject to various transfer restrictions described in the TRA and are entitled to certain registration rights more fully described in the Registration Rights Agreement (see Note 18).

During the three months ended September 30, 2018, we recorded a decrease to the carrying value of the TRA obligation totaling $32 million related to changes in the timing of estimated payments resulting from the Merger. During the nine months ended September 30, 2018, the carrying value of the TRA obligation was increased by approximately $14 million as a result of changes in the timing of estimated payments and new multistate tax impacts resulting from the Merger. During the three months ended September 30, 2017, we recorded a decrease to the carrying value of the TRA obligation totaling $160 million related to changes in the timing of estimated payments resulting from changes in certain tax assumptions including (a) the impacts of Luminant's plan to retire its Monticello generation plant (see Note 4), (b) investment tax credits we expected to receive related to the Upton solar development project, (c) assets acquired in the Odessa Acquisition (see Note 3) and (d) the impacts of other forecasted tax amounts.

The following table summarizes the changes to the TRA obligation, reported as other current liabilities and Tax Receivable Agreement obligation in our condensed consolidated balance sheets, for the nine months ended September 30, 2018 and 2017:



	Nine Months Ended September 30,
	2018			2017
TRA obligation at the beginning of the period	$	357		$	596
Accretion expense	51			64
Changes in tax assumptions impacting timing of payments	14			(160		)
TRA obligation at the end of the period	422			500
Less amounts due currently	(20		)	(24		)
Noncurrent TRA obligation at the end of the period	$	402		$	476

As of September 30, 2018, the estimated carrying value of the TRA obligation totaled $422 million, which represents the discounted amount of projected payments under the TRA. The projected payments are based on certain assumptions, including but not limited to (a) the federal corporate income tax rate of 21% for 2018 and 35% for 2017, (b) estimates of our taxable income in the current and future years and (c) additional states that Vistra Energy now operates in, its relevant tax rate and apportionment factor. Our taxable income takes into consideration the current federal tax code, various relevant state tax laws and reflects our current estimates of future results of the business. These assumptions are subject to change, and those changes could have a material impact on the carrying value of the TRA obligation. As of September 30, 2018, the aggregate amount of undiscounted federal and state payments under the TRA is estimated to be approximately $1.4 billion, with more than half of such amount expected to be attributable to the first 15 tax years following Emergence, and the final payment expected to be made approximately 40 years following Emergence (assuming that the TRA is not terminated earlier pursuant to its terms).

The carrying value of the obligation is being accreted to the amount of the gross expected obligation using the effective interest method. Changes in the amount of this obligation resulting from changes to either the timing or amount of TRA payments are recognized in the period of change and measured using the discount rate inherent in the initial fair value of the obligation. During the three and nine months ended September 30, 2018, the Impacts of Tax Receivable Agreement on the condensed statements of consolidated income (loss) totaled income of $17 million and expense of $65 million, respectively, which represents the changes to the carrying value of the TRA obligation discussed above and accretion expense totaling $15 million and $51 million, respectively. During the three and nine months ended September 30, 2017, the Impacts of Tax Receivable Agreement on the condensed statements of consolidated income (loss) totaled income of $138 million and $96 million, respectively, which represents a decrease to the carrying value of the TRA obligation discussed above and accretion expense totaling $22 million and $64 million, respectively.

Earnings Per Share (Notes)

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

Earnings Per Share

EARNINGS PER SHARE

Basic earnings per share available to common shareholders are based on the weighted average number of common shares outstanding during the period. Diluted earnings per share is calculated using the treasury stock method and includes the effect of all potential issuances of common shares under stock-based incentive compensation arrangements.



	Three Months Ended September 30, 2018					Three Months Ended September 30, 2017
	Net Income		Shares	Per Share Amount		Net Income		Shares	Per Share Amount
Net income available for common stock — basic (a)	$	330	533,142,189	$	0.62	$	273	427,591,426	$	0.64
Dilutive securities:
Stock-based incentive compensation plan	—		7,830,613	0.01		—		721,012	—
Net income available for common stock — diluted	$	330	540,972,802	$	0.61	$	273	428,312,438	$	0.64

	Nine Months Ended September 30, 2018					Nine Months Ended September 30, 2017
	Net Income		Shares	Per Share Amount		Net Income		Shares	Per Share Amount
Net income available for common stock — basic (a)	$	132	500,781,573	$	0.26	$	325	427,587,404	$	0.76
Dilutive securities:
Stock-based incentive compensation plan	—		7,347,415	—		—		414,465	—
Net income available for common stock — diluted	$	132	508,128,988	$	0.26	$	325	428,001,869	$	0.76

____________


(a)	The minimum settlement amount of tangible equity units, or 15,056,260 shares, are considered to be outstanding and are included in the computation of basic net income per share (see Note 13).

Stock-based incentive compensation plan awards excluded from the calculation of diluted earnings per share because the effect would have been antidilutive totaled 7,094,687 and 85,393 shares in the three months ended September 30, 2018 and 2017, respectively, and 5,651,527 and 490,345 shares in the nine months ended September 30, 2018 and 2017, respectively.

Accounts Receivable Securitization Program (Notes)	9 Months Ended
Accounts Receivable Securitization Program (Notes)	Sep. 30, 2018
Accounts Receivable Securitization Program [Abstract]
Accounts Receivable Securitization Program [Text Block]	ACCOUNTS RECEIVABLE SECURITIZATION PROGRAM TXU Energy Receivables Company LLC (RecCo), an indirect subsidiary of Vistra Energy, has an accounts receivable financing facility (Receivables Facility) provided by issuers of asset-backed commercial paper and commercial banks (Purchasers). The Receivables Facility is currently scheduled to terminate in August 2019, unless termination occurs earlier in accordance with the terms of the Receivables Facility. The Receivables Facility provides RecCo with the ability to borrow up to $350 million. Under the Receivables Facility, TXU Energy may sell or contribute, on an ongoing basis and without recourse, its accounts receivable to its special purpose subsidiary, RecCo, a consolidated, wholly owned, bankruptcy-remote, direct subsidiary of TXU Energy. RecCo, in turn, is subject to certain conditions, and may, from time to time, sell an undivided interest in all the receivables to the Purchasers, and its assets and credit are not available to satisfy the debts and obligations of any person, including affiliates of RecCo. Amounts funded by the Purchasers to RecCo are reflected as short-term borrowings on the condensed consolidated balance sheets. Proceeds and repayments under the Receivables Facility are reflected as cash flows from financing activities in our condensed statements of consolidated cash flows. Receivables transferred to the Purchasers remain on Vistra Energy's balance sheet and Vistra Energy reflects a liability equal to the amount advanced by the Purchasers. The Company records interest expense on amounts advanced. TXU Energy continues to service, administer and collect the trade receivables on behalf of RecCo and the Purchasers, as applicable. As of September 30, 2018, the receivables facility is fully drawn and is supported by $587 million of RecCo gross receivables.

Long-Term Debt (Notes)

9 Months Ended

Sep. 30, 2018

Debt Disclosure [Abstract]

Long-Term Debt

LONG-TERM DEBT

Amounts in the table below represent the categories of long-term debt obligations incurred by the Company.



	September 30, 2018			December 31, 2017
Vistra Operations Credit Facilities	$	5,828		$	4,311
Vistra Operations 5.500% Senior Notes, due September 1, 2026	1,000			—
Vistra Energy Senior Notes:
7.375% Senior Notes, due November 1, 2022	1,750			—
5.875% Senior Notes, due June 1, 2023	500			—
7.625% Senior Notes, due November 1, 2024	1,224			—
8.034% Senior Notes, due February 2, 2024	25			—
8.000% Senior Notes, due January 15, 2025	81			—
8.125% Senior Notes, due January 30, 2026	166			—
Total Vistra Energy Senior Notes	3,746			—
Other:
7.000% Amortizing Notes, due July 1, 2019	31			—
Forward Capacity Agreements	238			—
Equipment Financing Agreements	136			—
Mandatorily redeemable subsidiary preferred stock (a)	70			70
8.82% Building Financing due semiannually through February 11, 2022 (b)	21			27
Total other long-term debt	496			97
Unamortized debt premiums, discounts and issuance costs	171			15
Total long-term debt including amounts due currently	11,241			4,423
Less amounts due currently	(181		)	(44		)
Total long-term debt less amounts due currently	$	11,060		$	4,379

____________


(a)	Shares of mandatorily redeemable preferred stock in PrefCo issued as part of the Plan of Reorganization. This subsidiary preferred stock is accounted for as a debt instrument under relevant accounting guidance.


(b)	Obligation related to a corporate office space capital lease. This obligation will be funded by amounts held in an escrow account that is reflected in other noncurrent assets in our condensed consolidated balance sheets.

Vistra Operations Credit Facilities

At September 30, 2018, the Vistra Operations Credit Facilities consisted of up to $8.328 billion in senior secured, first lien revolving credit commitments and outstanding term loans, consisting of revolving credit commitments of up to $2.5 billion, including a $2.3 billion letter of credit sub-facility (Revolving Credit Facility) and term loans of $2.8 billion (Term Loan B-1 Facility), $983 million (Term Loan B-2 Facility) and $2.045 billion (Term Loan B-3 Facility, and together with the Term Loan B-1 Facility and the Term Loan B-2 Facility, the Term Loan B Facility).

These amounts reflect an amendment to the Vistra Operations Credit Facilities in June 2018 whereby we incurred $2.050 billion of borrowings under the new Term Loan B-3 Facility and obtained $1.640 billion of incremental Revolving Credit Facility commitments. The letter of credit sub-facility was also increased by $1.585 billion. The maturity date of the Revolving Credit Facility was extended from August 4, 2021 to June 14, 2023. As discussed below, the proceeds from the Term Loan B-3 Facility were used to repay borrowings under the credit agreement that Vistra Energy assumed from Dynegy in connection with the Merger. Additionally, letter of credit term loans totaling $500 million (Term Loan C Facility) were repaid using $500 million of cash from collateral accounts used to backstop letters of credit. Fees and expenses related to the amendment to the Vistra Operations Credit Facilities totaled $42 million in the nine months ended September 30, 2018, of which $23 million was recorded as interest expense and other charges on the condensed statements of consolidated income (loss), $9 million was capitalized as a reduction in the carrying amount of the debt and $10 million was capitalized as a noncurrent asset.

The Vistra Operations Credit Facilities and related available capacity at September 30, 2018 are presented below.



		September 30, 2018
Vistra Operations Credit Facilities	Maturity Date	Facility Limit		Cash Borrowings		Available Capacity
Revolving Credit Facility (a)	June 14, 2023	$	2,500	$	—	$	1,290
Term Loan B-1 Facility (b)	August 4, 2023	2,800		2,800		—
Term Loan B-2 Facility (b)	December 14, 2023	983		983		—
Term Loan B-3 Facility (b)	December 31, 2025	2,045		2,045		—
Total Vistra Operations Credit Facilities		$	8,328	$	5,828	$	1,290

___________


(a)	Facility to be used for general corporate purposes. Facility includes a $2.3 billion letter of credit sub-facility, of which $1.210 billion of letters of credit were outstanding at September 30, 2018 and which reduce our available capacity.


(b)	Cash borrowings under the Term Loan B Facility reflect required scheduled quarterly payment in annual amount equal to 1% of the original principal amount with the balance paid at maturity. Principal amounts paid cannot be reborrowed.

In February and June 2018, certain pricing terms for the Vistra Operations Credit Facilities were amended. We accounted for these transactions as a modification of debt. At September 30, 2018, cash borrowings under the Revolving Credit Facility would bear interest based on applicable LIBOR rates, plus a fixed spread of 1.75%, and there were no outstanding borrowings. Letters of credit issued under the Revolving Credit Facility bear interest of 1.75%. Amounts borrowed under the Term Loan B-1 Facility bear interest based on applicable LIBOR rates plus a fixed spread of 2.00%. Amounts borrowed under the Term Loan B-2 Facility bear interest based on applicable LIBOR rates plus a fixed spread of 2.25%. Amounts borrowed under the Term Loan B-3 Facility bear interest based on applicable LIBOR rates plus a fixed spread of 2.00%. At September 30, 2018, the weighted average interest rates before taking into consideration interest rate swaps on outstanding borrowings were 4.24%, 4.49% and 4.18% under the Term Loan B-1, B-2 and B-3 Facilities, respectively. The Vistra Operations Credit Facilities also provide for certain additional fees payable to the agents and lenders, including fronting fees with respect to outstanding letters of credit and availability fees payable with respect to any unused portion of the Revolving Credit Facility.

Obligations under the Vistra Operations Credit Facilities are secured by a lien covering substantially all of Vistra Operations' (and its subsidiaries') consolidated assets, rights and properties, subject to certain exceptions set forth in the Vistra Operations Credit Facilities, provided that the amount of loans outstanding under the Vistra Operations Credit Facilities that may be secured by a lien covering certain principal properties of the Company is expressly limited by the terms of the Vistra Operations Credit Facilities.

The Vistra Operations Credit Facilities also permit certain hedging agreements to be secured on a pari-passu basis with the Vistra Operations Credit Facilities in the event those hedging agreements met certain criteria set forth in the Vistra Operations Credit Facilities.

The Vistra Operations Credit Facilities provide for affirmative and negative covenants applicable to Vistra Operations (and its restricted subsidiaries), including affirmative covenants requiring it to provide financial and other information to the agents under the Vistra Operations Credit Facilities and to not change its lines of business, and negative covenants restricting Vistra Operations' (and its restricted subsidiaries') ability to incur additional indebtedness, make investments, dispose of assets, pay dividends, grant liens or take certain other actions, in each case, except as permitted in the Vistra Operations Credit Facilities. Vistra Operations' ability to borrow under the Vistra Operations Credit Facilities is subject to the satisfaction of certain customary conditions precedent set forth therein.

The Vistra Operations Credit Facilities provide for certain customary events of default, including events of default resulting from non-payment of principal, interest or fees when due, material breaches of representations and warranties, material breaches of covenants in the Vistra Operations Credit Facilities or ancillary loan documents, cross-defaults under other agreements or instruments and the entry of material judgments against Vistra Operations. Solely with respect to the Revolving Credit Facility, and solely during a compliance period (which, in general, is applicable when the aggregate revolving borrowings and issued revolving letters of credit (in excess of $300 million) exceed 30% of the revolving commitments), the agreement includes a covenant that requires the consolidated first lien net leverage ratio, which is based on the ratio of net first lien debt compared to an EBITDA calculation defined under the terms of the facilities, not to exceed 4.25 to 1.00. As of September 30, 2018, we were in compliance with this financial covenant. Upon the existence of an event of default, the Vistra Operations Credit Facilities provide that all principal, interest and other amounts due thereunder will become immediately due and payable, either automatically or at the election of specified lenders.

Interest Rate Swaps — Effective January 2017, we entered into $3.0 billion notional amount of interest rate swaps to hedge a portion of our exposure to our variable rate debt. The interest rate swaps expire in July 2023. In May and June 2018, we entered into $3.0 billion notional amount of interest rate swaps that become effective in July 2023 and expire in July 2026.

In June 2018, we completed the novation of $1.959 billion of Vistra Energy (legacy Dynegy) interest rate swaps to Vistra Operations Company LLC (Vistra Operations). In June 2018, $238 million of these interest rate swaps expired. The remaining interest rate swaps expire between March 2019 and February 2024.

The interest rate swaps effectively fix the interest rates between 4.13% and 4.38% on $4.718 billion of our variable rate debt. The interest rate swaps that become effective in July 2023 and expire in July 2026 effectively fix the interest rates between 4.97% and 5.04% on $3.0 billion of our variable rate debt during the period. The interest rate swaps are secured by a first lien secured interest on a pari-passu basis with the Vistra Operations Credit Facilities.

Vistra Energy (legacy Dynegy) Credit Agreement

On the Merger Date, Vistra Energy assumed the obligations under Dynegy's $3.563 billion credit agreement consisting of a $2.018 billion senior secured term loan facility due 2024 and a $1.545 billion senior secured revolving credit facility. As of the Merger Date, there were no cash borrowings and $656 million of letters of credit outstanding under the senior secured revolving credit facility. On April 23, 2018, $70 million of the senior secured revolving credit facility matured. In June 2018, the $2.018 billion senior secured term loan facility due 2024 was repaid using proceeds from the Term Loan B-3 Facility. In addition, all letters of credit outstanding under the senior secured revolving credit facility were replaced with letters of credit under the amended Vistra Operations Credit Facilities discussed above, and the revolving credit facility assumed from Dynegy in connection with the Merger was paid off in full and terminated.

Vistra Operations Senior Notes

In August 2018, Vistra Operations issued $1.0 billion principal amount of 5.500% senior notes due 2026 in an offering to eligible purchasers. The senior notes were sold pursuant to a purchase agreement by and among Vistra Operations, certain direct and indirect subsidiaries of Vistra Operations and Citigroup Global Markets Inc., as representative of the several initial purchasers. Fees and expenses related to the offering totaled $12 million in the three months ended September 30, 2018, which was capitalized as a reduction in the carrying amount of the debt. Net proceeds from the sale of the senior notes totaling approximately $990 million, together with cash on hand and cash received from the funding of the Receivables Facility (see Note 10), were used to pay the purchase price and accrued interest (together with fees and expenses) required in connection with the cash tender offers described below. The 5.500% senior notes mature in September 2026, with interest payable in cash semiannually in arrears on March 1 and September 1 beginning March 1, 2019.

The indenture governing the 5.500% senior notes provides for the full and unconditional guarantee by certain direct and indirect subsidiaries of Vistra Operations of the punctual payment of the principal and interest on the notes. The Indenture contains certain covenants and restrictions, including, among others, restrictions on the ability of the Issuer and its subsidiaries, as applicable, to create certain liens, merge or consolidate with another entity, and sell all or substantially all of their assets.

Vistra Energy Senior Notes

Tender Offers and Consent Solicitations — In August 2018, Vistra Energy used the net proceeds from the issuance of the Vistra Operations 5.500% senior notes due 2026, proceeds from the Receivables Facility (see Note 10) and cash on hand to fund cash tender offers (the Tender Offers) to purchase for cash $1.542 billion of senior notes assumed in the Merger. We recorded an extinguishment loss of $27 million on the transactions in the three months ended September 30, 2018. Notes purchased consisted of the following:


•	$26 million of 7.625% senior notes due 2024;


•	$163 million of 8.034% senior notes due 2024;


•	$669 million of 8.000% senior notes due 2025, and


•	$684 million of 8.125% senior notes due 2026.

In connection with the Tender Offers, Vistra Energy also commenced solicitations of consents from holders of the 7.375% senior notes due 2022, the 7.625% senior notes due 2024, the 8.034% senior notes due 2024, the 8.000% senior notes due 2025 and the 8.125% senior notes due 2026 to amend certain provisions of the applicable indentures governing each series of senior notes and the registration rights agreement with respect to the 8.125% senior notes due 2026. Vistra Energy received the requisite consents from the holders of the 8.034% senior notes due 2024, the 8.000% senior notes due 2025 and the 8.125% senior notes due 2026 (collectively, the Consent Senior Notes) and amended (a) the indentures governing each series of the applicable senior notes to, among other things, eliminate substantially all of the restrictive covenants and certain events of default and (b) the registration rights agreement with respect to the 8.125% senior notes due 2026 to remove, among other things, the requirement that Vistra Energy commence an exchange offer to issue registered securities in exchange for the existing, nonregistered notes.

Assumption of Senior Notes in Merger — On the Merger Date, Vistra Energy assumed $6.138 billion principal amount of Dynegy's senior notes. In May 2018, $850 million of outstanding 6.75% senior notes due 2019 were redeemed at a redemption price of 101.688% of the aggregate principal amount, plus accrued and unpaid interest to but not including the date of redemption. Fees and expenses related to the redemption totaled $14 million in the three months ended June 30, 2018 and were recorded as interest expense and other charges on the condensed statements of consolidated income (loss). In June 2018, each of the Company's subsidiaries that guaranteed the Vistra Operations Credit Facilities (and did not already guarantee the senior notes) provided a guarantee on the senior notes that remained outstanding.

The senior notes that remain outstanding after the closing of the Tender Offers are unsecured and unsubordinated obligations of Vistra Energy and are guaranteed by substantially all of its current and future wholly owned domestic subsidiaries that from time to time are a borrower or guarantor under the agreement governing the Vistra Operations Credit Facilities (Credit Facilities Agreement) (see Note 21). The respective indentures of the senior notes (except with respect to the Consent Senior Notes) limit, among other things, the ability of the Company or any of the guarantors to create liens upon any principal property to secure debt for borrowed money in excess of, among other limitations, 30% of total assets. The respective indentures of the senior notes also contain customary events of default which would permit the holders of the applicable series of senior notes to declare such notes to be immediately due and payable if not cured within applicable grace periods, including the failure to make timely principal or interest payments on such notes or (except with respect to the Consent Senior Notes) other indebtedness aggregating $100 million or more, and, except with respect to the Consent Senior Notes, the failure to satisfy covenants, and specified events of bankruptcy and insolvency.

Amortizing Notes

On the Merger Date, Vistra Energy assumed the obligations of Dynegy's senior amortizing note (Amortizing Notes) maturing on July 1, 2019. The Amortizing Notes were issued in connection with the issuance of the tangible equity units (TEUs) by Dynegy (see Note 13). Each installment payment per Amortizing Note will be paid in cash and will constitute a partial repayment of principal and a payment of interest, computed at an annual rate of 7.00%. Interest will be calculated on the basis of a 360-day year consisting of twelve 30-day months. Payments will be applied first to the interest due and payable and then to the reduction of the unpaid principal amount, allocated as set forth in the indenture.

The indenture for the Amortizing Notes limits, among other things, the ability of the Company to consolidate, merge, sell, or dispose all or substantially all of its assets. If a fundamental change occurs, or if the Company elects to settle the prepaid stock purchase contracts early, then the holders of the Amortizing Notes will have the right to require the Company to repurchase the Amortizing Notes at a repurchase price equal to the principal amount of the Amortizing Notes as of the repurchase date (as described in the supplemental indenture) plus accrued and unpaid interest. The indenture also contains customary events of default which would permit the holders of the Amortizing Notes to declare those Amortizing Notes to be immediately due and payable if not cured within applicable grace periods, including the failure to make timely installment payments on the Amortizing Notes or other material indebtedness aggregating $100 million or more, the failure to satisfy covenants, and specified events of bankruptcy and insolvency.

Forward Capacity Agreements

On the Merger Date, the Company assumed the obligation of Dynegy's agreements under which a portion of the PJM capacity that cleared for Planning Years 2018-2019, 2019-2020 and 2020-2021 was sold to a financial institution (Forward Capacity Agreements). The buyer in this transaction will receive capacity payments from PJM during the Planning Years 2018-2019, 2019-2020 and 2020-2021 in the amounts of $7 million, $121 million and $110 million, respectively. We will continue to be subject to the performance obligations as well as any associated performance penalties and bonus payments for those planning years. As a result, this transaction is accounted for as long-term debt of $238 million with an implied interest rate of 4.90%.

Equipment Financing Agreements

On the Merger Date, the Company assumed Dynegy's Equipment Financing Agreements. Under certain of our contractual service agreements in which we receive maintenance and capital improvements for our gas-fueled generation fleet, we have obtained parts and equipment intended to increase the output, efficiency and availability of our generation units. We have financed these parts and equipment under agreements with maturities ranging from 2019 to 2026. The portion of future payments attributable to principal will be classified as cash outflows from financing activities, and the portion of future payments attributable to interest will be classified as cash outflows from operating activities in our condensed statements of consolidated cash flows.

Maturities

Long-term debt maturities at September 30, 2018 are as follows:



	September 30, 2018
Remainder of 2018	$	54
2019	182
2020	204
2021	130
2022	1,824
Thereafter	8,676
Unamortized premiums, discounts and debt issuance costs	171
Total long-term debt, including amounts due currently	$	11,241

Commitments and Contingencies (Notes)

9 Months Ended

Sep. 30, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments And Contingencies

COMMITMENTS AND CONTINGENCIES

Guarantees

We have entered into contracts, including the assumed Dynegy senior notes described above, that contain guarantees to unaffiliated parties that could require performance or payment under certain conditions. As of September 30, 2018, there are no material outstanding claims related to our guarantee obligations, and we do not anticipate we will be required to make any material payments under these guarantees.

Letters of Credit

At September 30, 2018, we had outstanding letters of credit under the Vistra Operations Credit Facilities totaling $1.210 billion as follows:


•	$1.030 billion to support commodity risk management collateral requirements in the normal course of business, including over-the-counter and exchange-traded transactions and collateral postings with ISOs;


•	$52 million to support executory contracts and insurance agreements;


•	$55 million to support our REP financial requirements with the PUCT, and


•	$73 million for other credit support requirements.

Litigation

Gas Index Pricing Litigation — We, through our subsidiaries, and other energy companies are named as defendants in several lawsuits claiming damages resulting from alleged price manipulation through false reporting of natural gas prices to various index publications, wash trading and churn trading from 2000-2002. The cases allege that the defendants engaged in an antitrust conspiracy to inflate natural gas prices in three states (Kansas, Missouri and Wisconsin) during the relevant time period and seek damages under the respective state antitrust statutes. Four of the cases are putative class actions and one case, Reorganized FLI (nka J.P. Morgan Trust Co., National Assn.) v. Oneok Inc., et al., is an individual action on behalf of Farmland Industries, Inc. (Farmland), with Farmland seeking full consideration damages (i.e., the full amount it paid for natural gas purchases during the relevant timeframe). The cases are consolidated in a multi-district litigation proceeding pending in the U. S. District Court for Nevada. In March 2017, the court denied the class plaintiffs' motions to certify class actions in each of the states, which decision was taken on an interlocutory appeal to U.S Court of Appeals for the Ninth Circuit (Ninth Circuit Court). In August 2018, the Ninth Circuit Court vacated the district court orders denying class certification and remanded the cases to the district court for further consideration of the class certification issue. In September 2018, the defendants filed a joint motion for entry of an order denying class certification, and the plaintiffs filed a motion for remand of the cases to the transferor courts to decide class certification issues. As for the Farmland matter, in March 2018, the Ninth Circuit Court reversed a summary judgment in favor of the defendants and it shortly will be remanded for further discovery and other pretrial proceedings. While we cannot predict the outcome of these legal proceedings, or estimate a range of costs, they could have a material impact on our results of operations, liquidity or financial condition.

Advatech Dispute — In September 2016, Illinois Power Generating Company (Genco), terminated its Second Amended and Restated Newton Flue Gas Desulfurization System Engineering, Procurement, Construction and Commissioning Services Contract dated as of December 15, 2014 with Advatech, LLC (Advatech). Advatech issued Genco its final invoice in September 2016 totaling $81 million. Genco contested the invoice in October 2016 and believes the proper amount is less than $1 million. In October 2016, Advatech initiated the dispute resolution process under the contract and filed for arbitration in March 2017. Settlement discussions required under the dispute resolution process were unsuccessful. The arbitration hearing occurred in October 2018. We dispute the allegations. While we cannot predict the outcome of this legal proceeding, or estimate a range of costs, it could have a material impact on our results of operations, liquidity or financial condition.

Wood River Rail Dispute — In November 2017, Dynegy Midwest Generation, LLC (DMG) received notification that BNSF Railway Company and Norfolk Southern Railway Company were initiating dispute resolution related to DMG's suspension of its Wood River Rail Transportation Agreement with the railroads. Settlement discussions required under the dispute resolution process have been unsuccessful. In March 2018, BNSF Railway Company and Norfolk Southern Railway Company filed a demand for arbitration. We dispute the railroads' allegations and will defend our position vigorously. While we cannot predict the outcome of this legal proceeding, or estimate a range of costs, it could have a material impact on our results of operations, liquidity or financial condition.

Greenhouse Gas Emissions

In August 2015, the EPA finalized rules to address greenhouse gas emissions from new, modified and reconstructed and existing electricity generation units, referred to as the Clean Power Plan, including rules for existing facilities that would establish state-specific emissions rate goals to reduce nationwide CO₂ emissions. Various parties (including Luminant) filed petitions for review in the U.S. Court of Appeals for the District of Columbia Circuit (D.C. Circuit Court) and subsequently, in January 2016, a coalition of states, industry (including Luminant) and other parties filed applications with the U.S. Supreme Court (Supreme Court) asking that the Supreme Court stay the rule while the D.C. Circuit Court reviews the legality of the rule for existing plants. In February 2016, the Supreme Court stayed the rule pending the conclusion of legal challenges on the rule before the D.C. Circuit Court and until the Supreme Court disposes of any subsequent petition for review. Oral argument on the merits of the legal challenges to the rule was heard in September 2016 before the entire D.C. Circuit Court, but the D.C. Circuit Court has not issued a decision. The D.C. Circuit Court's most-recent 60-day abeyance of the case expired in August 2018.

In October 2017, the EPA issued a proposed rule that would repeal the Clean Power Plan, with the proposed repeal focusing on what the EPA believes to be the unlawful nature of the Clean Power Plan and asking for public comment on the EPA's interpretations of its authority under the Clean Air Act. In December 2017, the EPA published an advance notice of proposed rulemaking (ANPR) soliciting information from the public as the EPA considers proposing a future rule. Vistra Energy submitted comments on the ANPR in February 2018. Vistra Energy submitted comments to the proposed repeal in April 2018. In August 2018, the EPA published a proposed replacement rule called the Affordable Clean Energy rule. Comments on the proposed rule are due in October 2018. While we cannot predict the outcome of these rulemakings and related legal proceedings, or estimate a range of reasonably probable costs, if the rules are ultimately implemented or upheld as they were issued, they could have a material impact on our results of operations, liquidity or financial condition.

Regional Haze — Reasonable Progress and Best Available Retrofit Technology (BART) for Texas

In January 2016, the EPA issued a final rule approving in part and disapproving in part Texas's 2009 State Implementation Plan (SIP) as it relates to the reasonable progress component of the Regional Haze program and issuing a Federal Implementation Plan (FIP). The EPA's emission limits in the FIP assume additional control equipment for specific lignite/coal-fueled generation units across Texas, including new flue gas desulfurization systems (scrubbers) at seven electricity generating units (including Big Brown Units 1 and 2, Monticello Units 1 and 2 and Coleto Creek) and upgrades to existing scrubbers at seven generation units (including Martin Lake Units 1, 2 and 3, Monticello Unit 3 and Sandow Unit 4). In March 2016, Luminant and a number of other parties, including the State of Texas, filed petitions for review in the U.S. Court of Appeals for the Fifth Circuit (Fifth Circuit Court) challenging the FIP's Texas requirements. In July 2016, the Fifth Circuit Court granted motions to stay the rule filed by Luminant and the other parties pending final review of the petitions for review. In December 2016, the EPA filed a motion seeking a voluntary remand of the rule back to the EPA for further consideration of Luminant's pending request for administrative reconsideration. In March 2017, the Fifth Circuit Court remanded the rule back to the EPA for reconsideration. The stay of the rule (and the emission control requirements) remains in effect, and the EPA is required to file status reports of its reconsideration every 60 days. The retirements of our Monticello, Big Brown and Sandow 4 plants should have a favorable impact on this rulemaking and litigation. While we cannot predict the outcome of the rulemaking and legal proceedings, or estimate a range of reasonably possible costs, the result could have a material impact on our results of operations, liquidity or financial condition.

In September 2017, the EPA signed a final rule addressing BART for Texas electricity generating units, with the rule serving as a partial approval of Texas's 2009 SIP and a partial FIP. For SO₂, the rule creates an intrastate Texas emission allowance trading program as a "BART alternative" that operates in a similar fashion to a CSAPR trading program. The program includes 39 generating units (including our Martin Lake, Big Brown, Monticello, Sandow 4, Coleto Creek, Stryker 2 and Graham 2 plants). The compliance obligations in the program will start on January 1, 2019, and the identified units will receive an annual allowance allocation that is equal to their most recent annual CSAPR SO₂ allocation. Cumulatively, our units covered by the program are allocated 100,279 allowances annually. Under the rule, a unit that is listed that does not operate for two consecutive years starting after 2018 would no longer receive allowances after the fifth year of non-operation. We believe the retirements of our Monticello, Big Brown and Sandow 4 plants will enhance our ability to comply with this BART rule for SO₂. For NO_X, the rule adopts the CSAPR's ozone program as BART and for particulate matter, the rule approves Texas's SIP that determines that no electric generating units are subject to BART for particulate matter. The National Parks Conservation Association, the Sierra Club and the Environmental Defense Fund filed a petition challenging the rule in the Fifth Circuit Court as well as a petition for reconsideration filed with the EPA. Luminant intervened on behalf of the EPA in the Fifth Circuit Court action. In March 2018, the Fifth Circuit Court granted a joint motion filed by the EPA and the environmental groups involved to abate the Fifth Circuit Court proceedings until the EPA has taken action on the reconsideration petition and concludes the reconsideration process. In August 2018, the EPA issued a proposed rule to affirm the prior BART final rule and seeking comments on that proposal, which are due in October 2018. While we cannot predict the outcome of the rulemaking and legal proceedings, we believe the rule, if ultimately implemented or upheld as issued, will not have a material impact on our results of operations, liquidity or financial condition.

Affirmative Defenses During Malfunctions

In February 2013, the EPA proposed a rule requiring certain states to remove SIP exemptions for excess emissions during malfunctions or replace them with an affirmative defense. In May 2015, the EPA finalized its 2013 proposal to extend the EPA's proposed findings of inadequacy to states that have affirmative defense provisions, including Texas. The final rule impacted 36 states, including Texas, Illinois and Ohio, in which we operate. The EPA's final rule would require covered states to remove or replace their EPA-approved exemptions or affirmative defense provisions for excess emissions during startup, shutdown and maintenance events. Several states (including the State of Texas and the State of Ohio) and various industry parties (including Luminant) filed petitions for review of the EPA's final rule, and all of those petitions were consolidated in the D.C. Circuit Court. Before the oral argument was held, in April 2017, the D.C. Circuit Court granted the EPA's motion to continue oral argument and ordered that the case be held in abeyance with the EPA to provide status reports to the D.C. Circuit Court on the EPA's review of the action at 90-day intervals. In October 2018, the EPA partially granted Texas' petition for reconsideration of the Texas SIP call. We cannot predict the timing or outcome of this proceeding, or estimate a range of reasonably possible costs, but implementation of the rule as finalized could have a material impact on our results of operations, liquidity or financial condition.

SO2 Designations for Texas

In November 2016, the EPA finalized its nonattainment designations for counties surrounding our Big Brown, Monticello and Martin Lake generation plants. The final designations require Texas to develop nonattainment plans for these areas. In February 2017, the State of Texas and Luminant filed challenges to the nonattainment designations in the Fifth Circuit Court. Subsequently, in October 2017, the Fifth Circuit Court granted the EPA's motion to hold the case in abeyance in light of the EPA's representation that it intended to revisit the nonattainment rule. In December 2017, the TCEQ submitted a petition for reconsideration to the EPA. In addition, with respect to Monticello and Big Brown, the retirement of those plants should favorably impact our legal challenge to the nonattainment designations in that the nonattainment designation for Freestone County and Titus County are based solely on the Sierra Club modeling, which we dispute, of alleged SO₂ emissions from Monticello and Big Brown. Regardless, considering these retirements, the nonattainment designation for those counties are no longer supported. While we cannot predict the outcome of this matter, or estimate a range of reasonably possible costs, the result could have a material impact on our results of operations, liquidity or financial condition.

Effluent Limitation Guidelines (ELGs)

In November 2015, the EPA revised the ELGs for steam electric generating facilities, which will impose more stringent standards (as individual permits are renewed) for wastewater streams, flue desulfurization, fly ash, bottom ash and flue gas mercury control. Various parties filed petitions for review of the ELG rule, and the petitions were consolidated in the Fifth Circuit Court. In April 2017, the EPA granted petitions requesting reconsideration of the ELG final rule issued in 2015 and administratively stayed the ELG rule's compliance date deadlines pending ongoing judicial review of the rule. The legal challenges pertaining to bottom ash transport water, flue gas desulfurization wastewater and gasification wastewater have been suspended while the EPA reconsiders the rules.

The EPA issued a final rule in September 2017 postponing the earliest compliance dates in the ELG rule for bottom ash transport water and flue-gas desulfurization wastewater by two years, from November 1, 2018 to November 1, 2020.

Given the EPA's decision to reconsider the bottom ash transport water and flue gas desulfurization wastewater provisions of the ELG rule, the rule postponing the ELG rule's earliest compliance dates for those provisions, and the intertwined relationship of the ELG rule with the Coal Combustion Residuals rule discussed below, which is also being reconsidered by the EPA, as well as pending legal challenges concerning both rules, substantial uncertainty exists regarding our projected capital expenditures for ELG compliance, including the timing of such expenditures. While we cannot predict the outcome of this matter, or estimate a range of costs, it could have a material impact on our results of operations, liquidity or financial condition.

New Source Review and CAA Matters

New Source Review — Since 1999, the EPA has engaged in a nationwide enforcement initiative to determine whether coal-fired power plants failed to comply with the requirements of the New Source Review (NSR) and New Source Performance Standard provisions under the CAA when the plants implemented changes. The EPA's NSR initiative focuses on whether projects performed at power plants triggered various permitting requirements, including the need to install pollution control equipment.

In August 2013, the U.S. Department of Justice (DOJ), acting as the attorneys for the EPA, filed a civil enforcement lawsuit against Luminant in federal district court in Dallas, alleging violations of the CAA, including its New Source Review standards, at our Big Brown and Martin Lake generation facilities. The lawsuit requests (i) the maximum civil penalties available under the CAA to the government of up to $32,500 to $37,500 per day for each alleged violation, depending on the date of the alleged violation, and (ii) injunctive relief, including an order to apply for pre-construction permits which may require the installation of best available control technology at the affected units. In August 2015, the district court granted Luminant's motion to dismiss seven of the nine claims asserted by the EPA in the lawsuit.

In January 2017, the EPA dismissed its two remaining claims with prejudice and the district court entered final judgment in Luminant's favor. In March 2017, the EPA and the Sierra Club appealed the final judgment to the Fifth Circuit Court. After the parties filed their respective briefs in the Fifth Circuit Court, the appeal was argued before the Fifth Circuit Court in March 2018. In October 2018, the Fifth Circuit Court affirmed in part, reversed in part, and remanded to the district court. The Fifth Circuit Court's decision held that the district court properly dismissed all of the civil penalties as time-barred. The Fifth Circuit Court further held that the grounds cited by the district court did not support dismissal of the injunctive relief claims at this early stage of the case and remanded the case back to the district court for further consideration. We believe that we have complied with all requirements of the CAA and intend to continue to vigorously defend against the remaining allegations. An adverse outcome could require substantial capital expenditures that cannot be determined at this time or retirement of the remaining plant at issue, Martin Lake. The retirement of the Big Brown plant should have a favorable impact on this litigation. We cannot predict the outcome of these proceedings, including the financial effects, if any.

Zimmer NOVs — In December 2014, the EPA issued an NOV alleging violation of opacity standards at the Zimmer facility. The EPA previously had issued NOVs to Zimmer in 2008 and 2010 alleging violations of the CAA, the Ohio State Implementation Plan and the station's air permits including standards applicable to opacity, sulfur dioxide, sulfuric acid mist and heat input. The NOVs remain unresolved. We are unable to predict the outcome of these matters.

Edwards CAA Citizen Suit — In April 2013, environmental groups filed a CAA citizen suit in the U.S. District Court for the Central District of Illinois alleging violations of opacity and particulate matter limits at our MISO segment's Edwards facility. In August 2016, the district court granted the plaintiffs’ motion for summary judgment on certain liability issues. We filed a motion seeking interlocutory appeal of the court’s summary judgment ruling. In February 2017, the appellate court denied our motion for interlocutory appeal. The parties completed briefing on motions for summary judgment in October 2018, and the remedy phase trial remains scheduled for March 2019. We dispute the allegations and will defend the case vigorously. We are unable to predict the outcome of these matters.

Ultimate resolution of any of these CAA matters could have a material adverse impact on our future financial condition, results of operations, and cash flows. A resolution could result in increased capital expenditures for the installation of pollution control equipment, increased operations and maintenance expenses, and penalties, or could result in an order or a decision to retire these plants. While we cannot predict the outcome of these legal proceedings, or estimate a range of costs, they could have a material impact on our results of operations, liquidity or financial condition.

Coal Combustion Residuals/Groundwater

On July 30, 2018, the EPA published a final rule that amends certain provisions of the Coal Combustion Residuals (CCR) rule that the agency issued in 2015. The 2018 revisions extend closure deadlines to October 31, 2020, related to the aquifer location restriction and groundwater monitoring requirements. The 2018 revisions also (1) establish groundwater protection standards for cobalt, lithium, molybdenum and lead (2) allow authorized state programs to waive groundwater monitoring requirements when there is a demonstration of no potential for contaminant migration, and (3) allow the permitting authority to issue certifications in lieu of a qualified professional engineer. The 2018 revisions became effective in August 2018, and we are continuing to evaluate the impact on our CCR facilities. Also, on August 21, 2018, the D.C. Circuit Court issued a decision that vacates and remands certain provisions of the 2015 CCR rule. The EPA is expected to undertake further revisions to its CCR regulations in response to the D.C. Circuit Court's ruling. While we cannot predict the impacts of these rule revisions (including whether and if so how the states in which we operate will utilize the authority delegated to the states through the revisions), or estimate a range of reasonably possible costs related to these revisions, the changes that result from these revisions could have a material impact on our results of operations, liquidity or financial condition.

MISO Segment — In 2012, the Illinois EPA (IEPA) issued violation notices alleging violations of groundwater standards onsite at our Baldwin and Vermilion facilities' CCR surface impoundments. In 2016, the IEPA approved our closure and post-closure care plans for the Baldwin old east, east, and west fly ash CCR surface impoundments. We are working towards implementation of those closure plans.

At our retired Vermilion facility, which is not subject to the EPA's 2015 CCR rule, we submitted proposed corrective action plans involving closure of two CCR surface impoundments (i.e., the old east and the north impoundments) to the IEPA in 2012, with revised plans submitted in 2014. In May 2017, in response to a request from the IEPA for additional information regarding the closure of these Vermilion surface impoundments, we agreed to perform additional groundwater sampling and closure options and riverbank stabilizing options. By letter dated January 31, 2018, Prairie Rivers Network provided 60-day notice of its intent to sue our subsidiary Dynegy Midwest Generation, LLC under the federal Clean Water Act for alleged unauthorized discharges from the surface impoundments at our Vermilion facility and alleged related violations of the facility's National Pollutant Discharge Elimination System permit. Prairie Rivers Network filed a citizen suit in May 2018, alleging violations of the Clean Water Act for alleged unauthorized discharges. In August 2018, we filed a motion to dismiss the lawsuit. We dispute the allegations and will vigorously defend our position.

In 2012, the IEPA issued violation notices alleging violations of groundwater standards at the Newton and Coffeen facilities' CCR surface impoundments. We are addressing these CCR surface impoundments in accordance with the federal CCR rule. In June 2018, the IEPA issued a violation notice for alleged seep discharges claimed to be coming from the surface impoundments at our retired Vermilion facility.

If remediation measures concerning groundwater are necessary at any of our coal-fired facilities, we may incur significant costs that could have a material adverse effect on our financial condition, results of operations, and cash flows. At this time, in part because of the revisions to the CCR rule that the EPA published on July 30, 2018 and the D.C. Circuit Court's vacatur and remand of certain provisions of the EPA's 2015 CCR rule, we cannot reasonably estimate the costs, or range of costs, of groundwater remediation, if any, that ultimately may be required. CCR surface impoundment and landfill closure costs, as determined by our operations and environmental services teams, are reflected in our AROs.

MISO 2015-2016 Planning Resource Auction

In May 2015, three complaints were filed at FERC regarding the Zone 4 results for the 2015-2016 Planning Resource Auction (PRA) conducted by MISO. Dynegy is a named party in one of the complaints. The complainants, Public Citizen, Inc., the Illinois Attorney General and Southwestern Electric Cooperative, Inc., have challenged the results of the PRA as unjust and unreasonable, requested rate relief/refunds, and requested changes to the MISO PRA structure going forward. Complainants have also alleged that Dynegy could have engaged in economic or physical withholding in Zone 4 constituting market manipulation in the 2015-2016 PRA. The Independent Market Monitor for MISO (MISO IMM), which was responsible for monitoring the MISO 2015-2016 PRA, determined that all offers were competitive and that no physical or economic withholding occurred. The MISO IMM also stated, in a filing responding to the complaints, that there is no basis for the proposed remedies. We filed our Answer to these complaints and believe that we complied fully with the terms of the MISO tariff in connection with the 2015-2016 PRA, disputed the allegations, and will defend our actions vigorously. In addition, the Illinois Industrial Energy Consumers filed a complaint at FERC against MISO on June 30, 2015 requesting prospective changes to the MISO tariff. Dynegy also responded to this complaint.

On October 1, 2015, FERC issued an order of non-public, formal investigation, stating that shortly after the conclusion of the 2015-2016 PRA, FERC's Office of Enforcement began a non-public informal investigation into whether market manipulation or other potential violations of FERC orders, rules, and regulations occurred before or during the PRA (the Order). The Order noted that the investigation is ongoing, and that the conversion of the informal, non-public investigation to a formal, non-public investigation does not indicate that FERC has determined that any entity has engaged in market manipulation or otherwise violated any FERC order, rule, or regulation. Vistra Energy is participating in the investigation on behalf of Dynegy following the closing of the Merger. We believe that our conduct was proper and will defend our position vigorously, but we cannot predict the outcome of the investigation or the amount, if any, of loss that may result. While we cannot predict the outcome of this matter, or estimate a range of costs, it could have a material impact on our results of operations, liquidity or financial condition.

On December 31, 2015, FERC issued an order on the complaints requiring a number of prospective changes to the MISO tariff provisions associated with calculating Initial Reference Levels and Local Clearing Requirements, effective as of the 2016-2017 PRA. The order did not address the arguments of the complainants regarding the 2015-2016 PRA, and stated that those issues remain under consideration and will be addressed in a future order.

Other Matters

We are involved in various legal and administrative proceedings in the normal course of business, the ultimate resolutions of which, in the opinion of management, are not anticipated to have a material effect on our results of operations, liquidity or financial condition.

Equity (Notes)

9 Months Ended

Sep. 30, 2018

Stockholders' Equity Note [Abstract]

Equity

EQUITY

Equity Issuances

See Note 2 for information regarding Vistra Energy common stock issued as a result of the Merger.

Share Repurchase Program

In June 2018, we announced that our board of directors had authorized a share repurchase program (Program) under which up to $500 million of our outstanding common stock may be repurchased. The Program was effective as of June 13, 2018. Through September 30, 2018, 18,271,105 shares of our common stock had been repurchased for $424 million (including related fees and expenses) at an average price per share of common stock of $23.18. At September 30, 2018, $76 million was available for additional repurchases under the Program. The Program was completed on October 19, 2018.

In November 2018, we announced that our board of directors had authorized an incremental share repurchase program under which up to $1.25 billion of our outstanding stock may be purchased. We intend to implement the program opportunistically from time to time over the next 12 to 18 months.

Shares of the Company's common stock may be repurchased in open market transactions at prevailing market prices, in privately negotiated transactions, pursuant to plans complying with the Securities Exchange Act of 1934, as amended, or by other means in accordance with federal securities laws. The actual timing, number and value of shares repurchased under the Program will be determined at our discretion and will depend on a number of factors, including the market price of our stock, general market and economic conditions, applicable legal requirements and compliance with the terms of our debt agreements and the Tax Matters Agreement.

Dividends and Dividend Restrictions

Dividends — Vistra Energy did not declare or pay any dividends during the nine months ended September 30, 2018 and 2017.

In November 2018, Vistra Energy announced that its board of directors had adopted a dividend program pursuant to which Vistra Energy would initiate an annual dividend of approximately $0.50 per share expected to begin in the first quarter of 2019. Each dividend under the program will be subject to the declaration by the board of directors and, thus, may be subject to numerous factors in existence at the time of any such declaration including, but not limited to, prevailing market conditions, Vistra Energy's results of operations, financial condition and liquidity and Delaware law.

Dividend Restrictions — There are no restrictions in the Vistra Energy senior notes that preclude the payment of dividends. The agreement governing the Credit Facilities Agreement generally restricts the ability of Vistra Operations to make distributions to any direct or indirect parent unless such distributions are expressly permitted thereunder. As of September 30, 2018, Vistra Operations can distribute approximately $9.2 billion to Vistra Energy Corp. (the Parent) under the Credit Facilities Agreement without the consent of any party. The amount that can be distributed by Vistra Operations to the Parent was partially reduced by distributions made by Vistra Operations to the Parent during the year ended December 31, 2017 of approximately $1.1 billion. In the three and nine months ended September 30, 2018, distributions totaling $1.9 billion and $3.928 billion, respectively, were made by Vistra Operations to the Parent. In September 2018, the board of directors approved an additional $400 million distribution by Vistra Operations to the Parent that was paid in October 2018. Additionally, Vistra Operations may make distributions to the Parent in amounts sufficient for the Parent to make any payments required under the TRA or the Tax Matters Agreement or, to the extent arising out of the Parent's ownership or operation of Vistra Operations, to pay any taxes or general operating or corporate overhead expenses. As of September 30, 2018, the maximum amount of restricted net assets of Vistra Operations that may not be distributed to the Parent totaled approximately $7.8 billion.

Under applicable Delaware General Corporate Law, we are prohibited from paying any distribution to the extent that such distribution exceeds the value of our "surplus," which is defined as the excess of our net assets above our capital (the aggregate par value of all outstanding shares of our stock).

Warrants

At the Merger Date, the Company entered into an agreement whereby holders of each outstanding warrant previously issued by Dynegy will be entitled to receive, upon exercise, the equity securities to which the holder would have been entitled to receive of Dynegy common stock converted into shares of Vistra Energy common stock at the Exchange Ratio. As of September 30, 2018, nine million warrants expiring in 2024 with an exercise price of $35.00 were outstanding, each of which can be redeemed for 0.652 share of Vistra Energy common stock. The warrants are recorded as equity in our condensed consolidated balance sheet.

Tangible Equity Units

At the Merger Date, the Company assumed the obligations of Dynegy's 4,600,000 7.00% tangible equity units, each with a stated amount of $100.00 and each comprised of (i) a prepaid stock purchase contract that will deliver to the holder, not later than July 1, 2019, unless earlier redeemed or settled, not more than 4.0421 shares of Vistra Energy common stock and not less than 3.2731 shares of Vistra Energy common stock per contract based upon the applicable fixed settlement rate in the contract and (ii) a senior amortizing note with an outstanding principal amount of $38 million at the Merger Date that pays an equal quarterly cash installment of $1.75 per amortizing note (see Note 11). In the aggregate, the annual quarterly cash installments will be equivalent to a 7.00% cash payment per year with respect to each $100.00 stated amount of tangible equity units. The prepaid stock purchase contracts are classified within equity. The amortizing notes are classified as long-term debt.

Shareholder's Equity

The following table presents the changes to shareholder's equity for the three months ended September 30, 2018:



	Common Stock (a)		Additional Paid-in Capital			Retained Earnings (Deficit)			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interest			Total Equity
Balance at June 30, 2018	$	5	$	10,015		$	(1,591	)	$	(16	)	$	7		$	8,420
Net income	—		—			330			—			—			330
Treasury stock	—		(349		)	—			—			—			(349		)
Effects of stock-based incentive compensation plans	—		6			—			—			—			6
Change in unrecognized losses related to pension and OPEB plans	—		—			—			1			—			1
Investment by noncontrolling interest	—		—			—			—			(1		)	(1		)
Other	—		(2		)	—			—			—			(2		)
Balance at September 30, 2018	$	5	$	9,670		$	(1,261	)	$	(15	)	$	6		$	8,405

The following table presents the changes to shareholder's equity for the nine months ended September 30, 2018:



	Common Stock (a)		Additional Paid-in Capital			Retained Earnings (Deficit)			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interest		Total Equity
Balance at December 31, 2017	$	4	$	7,765		$	(1,410	)	$	(17	)	$	—	$	6,342
Stock issued in connection with the Merger	1		1,891			—			—			—		1,892
Net income	—		—			132			—			—		132
Adoption of accounting standard (Note 1)	—		—			17			—			—		17
Treasury stock	—		(424		)	—			—			—		(424		)
Effects of stock-based incentive compensation plans	—		69			—			—			—		69
Tangible equity units acquired	—		369			—			—			—		369
Warrants acquired	—		2			—			—			—		2
Change in unrecognized losses related to pension and OPEB plans	—		—			—			2			—		2
Investment by noncontrolling interest	—		—			—			—			6		6
Other	—		(2		)	—			—			—		(2		)
Balance at September 30, 2018	$	5	$	9,670		$	(1,261	)	$	(15	)	$	6	$	8,405

________________


(a)	Authorized shares totaled 1,800,000,000 at September 30, 2018. Outstanding shares totaled 507,391,134 and 428,398,802 at September 30, 2018 and December 31, 2017, respectively.

The following table presents the changes to shareholder's equity for the three months ended September 30, 2017:



	Common Stock (a)		Additional Paid-in Capital		Retained Earnings (Deficit)			Accumulated Other Comprehensive Income (Loss)		Total Shareholders' Equity
Balance at June 30, 2017	$	4	$	7,750	$	(1,102	)	$	6	$	6,658
Net income	—		—		273			—		273
Effects of stock-based incentive compensation plans	—		5		—			—		5
Other	—		—		(1		)	—		(1		)
Balance at September 30, 2017	$	4	$	7,755	$	(830	)	$	6	$	6,935

The following table presents the changes to shareholder's equity for the nine months ended September 30, 2017:



	Common Stock (a)		Additional Paid-in Capital		Retained Earnings (Deficit)			Accumulated Other Comprehensive Income (Loss)		Total Shareholders' Equity
Balance at December 31, 2016	$	4	$	7,742	$	(1,155	)	$	6	$	6,597
Net income	—		—		325			—		325
Effects of stock-based incentive compensation plans	—		13		—			—		13
Balance at September 30, 2017	$	4	$	7,755	$	(830	)	$	6	$	6,935

________________


(a)	Authorized shares totaled 1,800,000,000 at September 30, 2017. Outstanding shares totaled 427,597,368 and 427,580,232 at September 30, 2017 and December 31, 2016, respectively.

Fair Value Measurements (Notes)

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

FAIR VALUE MEASUREMENTS

We utilize several different valuation techniques to measure the fair value of assets and liabilities, relying primarily on the market approach of using prices and other market information for identical and/or comparable assets and liabilities for those items that are measured on a recurring basis. We use a mid-market valuation convention (the mid-point price between bid and ask prices) as a practical expedient to measure fair value for the majority of our assets and liabilities and use valuation techniques to maximize the use of observable inputs and minimize the use of unobservable inputs. Our valuation policies and procedures were developed, maintained and validated by a centralized risk management group that reports to the Vistra Energy Chief Financial Officer.

Fair value measurements of derivative assets and liabilities incorporate an adjustment for credit-related nonperformance risk. These nonperformance risk adjustments take into consideration master netting arrangements, credit enhancements and the credit risks associated with our credit standing and the credit standing of our counterparties (see Note 15 for additional information regarding credit risk associated with our derivatives). We utilize credit ratings and default rate factors in calculating these fair value measurement adjustments.

We categorize our assets and liabilities recorded at fair value based upon the following fair value hierarchy:

•

Level 1 valuations use quoted prices in active markets for identical assets or liabilities that are accessible at the measurement date. Our Level 1 assets and liabilities include CME or ICE (electronic commodity derivative exchanges) futures and options transacted through clearing brokers for which prices are actively quoted. We report the fair value of CME and ICE transactions without taking into consideration margin deposits, with the exception of certain margin amounts related to changes in fair value on certain CME transactions that, beginning in January 2017, are legally characterized as settlement of derivative contracts rather than collateral.

•

Level 2 valuations utilize over-the-counter broker quotes, quoted prices for similar assets or liabilities that are corroborated by correlations or other mathematical means, and other valuation inputs such as interest rates and yield curves observable at commonly quoted intervals. We attempt to obtain multiple quotes from brokers that are active in the markets in which we participate and require at least one quote from two brokers to determine a pricing input as observable. The number of broker quotes received for certain pricing inputs varies depending on the depth of the trading market, each individual broker's publication policy, recent trading volume trends and various other factors.

•

Level 3 valuations use unobservable inputs for the asset or liability. Unobservable inputs are used to the extent observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. We use the most meaningful information available from the market combined with internally developed valuation methodologies to develop our best estimate of fair value. Significant unobservable inputs used to develop the valuation models include volatility curves, correlation curves, illiquid pricing delivery periods and locations and credit-related nonperformance risk assumptions. These inputs and valuation models are developed and maintained by employees trained and experienced in market operations and fair value measurements and validated by the Company's risk management group.

With respect to amounts presented in the following fair value hierarchy tables, the fair value measurement of an asset or liability (e.g., a contract) is required to fall in its entirety in one level, based on the lowest level input that is significant to the fair value measurement.

Assets and liabilities measured at fair value on a recurring basis consisted of the following at the respective balance sheet dates shown below:



September 30, 2018
	Level 1		Level 2		Level 3 (a)		Reclassification (b)		Total
Assets:
Commodity contracts	$	192	$	143	$	148	$	65	$	548
Interest rate swaps	—		175		—		—		175
Nuclear decommissioning trust – equity securities (c)	519		—		—		—		519
Nuclear decommissioning trust – debt securities (c)	—		433		—		—		433
Sub-total	$	711	$	751	$	148	$	65	1,675
Assets measured at net asset value (d):
Nuclear decommissioning trust – equity securities (c)									322
Total assets									$	1,997
Liabilities:
Commodity contracts	$	273	$	501	$	392	$	65	$	1,231
Interest rate swaps	—		4		—		—		4
Total liabilities	$	273	$	505	$	392	$	65	$	1,235



December 31, 2017
	Level 1		Level 2		Level 3 (a)		Reclassification (b)		Total
Assets:
Commodity contracts	$	47	$	98	$	75	$	2	$	222
Interest rate swaps	—		18		—		8		26
Nuclear decommissioning trust – equity securities (c)	468		—		—		—		468
Nuclear decommissioning trust – debt securities (c)	—		430		—		—		430
Sub-total	$	515	$	546	$	75	$	10	1,146
Assets measured at net asset value (d):
Nuclear decommissioning trust – equity securities (c)									290
Total assets									$	1,436
Liabilities:
Commodity contracts	$	45	$	143	$	128	$	2	$	318
Interest rate swaps	—		—		—		8		8
Total liabilities	$	45	$	143	$	128	$	10	$	326

____________


(a)	See table below for description of Level 3 assets and liabilities.


(b)	Fair values are determined on a contract basis, but certain contracts result in a current asset and a noncurrent liability, or vice versa, as presented in our condensed consolidated balance sheets.


(c)	The nuclear decommissioning trust investment is included in the other investments line in our condensed consolidated balance sheets. See Note 20.


(d)	The fair value amounts presented in this line are intended to permit reconciliation of the fair value hierarchy to the amounts presented in our condensed consolidated balance sheets. Certain investments measured at fair value using the net asset value per share (or its equivalent) have not been classified in the fair value hierarchy.

Commodity contracts consist primarily of natural gas, electricity, fuel oil, uranium, coal and emissions agreements and include financial instruments entered into for hedging purposes as well as physical contracts that have not been designated as normal purchases or sales. Interest rate swaps are used to reduce exposure to interest rate changes by converting floating-rate interest to fixed rates. See Note 15 for further discussion regarding derivative instruments.

Nuclear decommissioning trust assets represent securities held for the purpose of funding the future retirement and decommissioning of our nuclear generation facility. These investments include equity, debt and other fixed-income securities consistent with investment rules established by the NRC and the PUCT.

The following tables present the fair value of the Level 3 assets and liabilities by major contract type and the significant unobservable inputs used in the valuations at September 30, 2018 and December 31, 2017:



September 30, 2018
	Fair Value
Contract Type (a)	Assets		Liabilities			Total			Valuation Technique	Significant Unobservable Input	Range (b)
Electricity purchases and sales	$	11	$	(173	)	$	(162	)	Valuation Model	Hourly price curve shape (c)	$0 to $90/ MWh
										Illiquid delivery periods for ERCOT hub power prices and heat rates (d)	$20 to $120/ MWh
Electricity and weather options	15		(161		)	(146		)	Option Pricing Model	Gas to power correlation (e)	15% to 95%
										Power volatility (e)	5% to 435%
Financial transmission rights	86		(19		)	67			Market Approach (f)	Illiquid price differences between settlement points (g)	$(10) to $50/ MWh
Other (h)	36		(39		)	(3		)
Total	$	148	$	(392	)	$	(244	)



December 31, 2017
	Fair Value
Contract Type (a)	Assets		Liabilities			Total			Valuation Technique	Significant Unobservable Input	Range (b)
Electricity purchases and sales	$	12	$	(33	)	$	(21	)	Valuation Model	Hourly price curve shape (c)	$0 to $40/ MWh
										Illiquid delivery periods for ERCOT hub power prices and heat rates (d)	$20 to $70/ MWh
Electricity and weather options	10		(91		)	(81		)	Option Pricing Model	Gas to power correlation (e)	30% to 100%
										Power volatility (e)	5% to 180%
Financial transmission rights	45		(4		)	41			Market Approach (f)	Illiquid price differences between settlement points (g)	$0 to $15/ MWh
Other (h)	8		—			8
Total	$	75	$	(128	)	$	(53	)

____________

(a)

Electricity purchase and sales contracts include power and heat rate positions in ERCOT, PJM, NYISO, ISO-NE and MISO regions. The forward purchase contracts (swaps and options) used to hedge electricity price differences between settlement points are referred to as congestion revenue rights contracts in ERCOT and financial transmission rights in PJM, NYISO, ISO-NE and MISO regions. Electricity options consist of physical electricity options and spread options.


(b)	The range of the inputs may be influenced by factors such as time of day, delivery period, season and location.


(c)	Primarily based on the historical range of forward average hourly ERCOT North Hub prices.


(d)	Primarily based on historical forward ERCOT power price and heat rate variability.


(e)	Based on historical forward correlation and volatility within ERCOT.


(f)	While we use the market approach, there is insufficient market data to consider the valuation liquid.


(g)	Primarily based on the historical price differences between settlement points within ERCOT hubs and load zones.


(h)	Other includes contracts for natural gas, coal options and emissions.

There were no transfers between Level 1 and Level 2 of the fair value hierarchy for the three and nine months ended September 30, 2018 and 2017. See the table below for discussion of transfers between Level 2 and Level 3 for the three and nine months ended September 30, 2018 and 2017.

The following table presents the changes in fair value of the Level 3 assets and liabilities for the three and nine months ended September 30, 2018 and 2017.



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Net asset (liability) balance at beginning of period	$	(222	)	$	75		$	(53	)	$	83
Total unrealized valuation gains (losses)	(102		)	132			(333		)	139
Purchases, issuances and settlements (a):
Purchases	41			16			99			51
Issuances	(14		)	(5		)	(22		)	(19		)
Settlements	58			(45		)	104			(87		)
Transfers into Level 3 (b)	1			—			3			4
Transfers out of Level 3 (b)	(6		)	—			(5		)	2
Net liabilities assumed in connection with the Merger (Note 2)	—			—			(37		)	—
Earn-out provision	—			(16		)	—			(16		)
Net change (c)	(22		)	82			(191		)	74
Net asset (liability) balance at end of period	$	(244	)	$	157		$	(244	)	$	157
Unrealized valuation gains (losses) relating to instruments held at end of period	$	(120	)	$	106		$	(273	)	$	110

____________


(a)	Settlements reflect reversals of unrealized mark-to-market valuations previously recognized in net income. Purchases and issuances reflect option premiums paid or received.


(b)	Includes transfers due to changes in the observability of significant inputs. All Level 3 transfers during the periods presented are in and out of Level 2.


(c)	Activity excludes change in fair value in the month positions settle. Substantially all changes in value of commodity contracts (excluding net liabilities assumed in connection with the Merger) are reported as operating revenues in our condensed statements of consolidated income (loss).

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Commodity and Other Derivative Contractual Assets and Liabilities (Notes)

9 Months Ended

Sep. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Commodity And Other Derivative Contractual Assets And Liabilities

COMMODITY AND OTHER DERIVATIVE CONTRACTUAL ASSETS AND LIABILITIES

Strategic Use of Derivatives

We transact in derivative instruments, such as options, swaps, futures and forward contracts, to manage commodity price and interest rate risk. See Note 14 for a discussion of the fair value of derivatives.

Commodity Hedging and Trading Activity — We utilize natural gas and electricity derivatives to reduce exposure to changes in electricity prices primarily to hedge future revenues from electricity sales from our generation assets. We also utilize short-term electricity, natural gas, coal, fuel oil, uranium and emission derivative instruments for fuel hedging and other purposes. Counterparties to these transactions include energy companies, financial institutions, electric utilities, independent power producers, oil and gas producers, local distribution companies and energy marketing companies. Unrealized gains and losses arising from changes in the fair value of derivative instruments as well as realized gains and losses upon settlement of the instruments are reported in our condensed statements of consolidated income (loss) in operating revenues and fuel, purchased power costs and delivery fees.

Interest Rate Swaps — Interest rate swap agreements are used to reduce exposure to interest rate changes by converting floating-rate interest rates to fixed rates, thereby hedging future interest costs and related cash flows. Unrealized gains and losses arising from changes in the fair value of the swaps as well as realized gains and losses upon settlement of the swaps are reported in our condensed statements of consolidated income (loss) in interest expense and related charges.

Financial Statement Effects of Derivatives

Substantially all derivative contractual assets and liabilities are accounted for under mark-to-market accounting consistent with accounting standards related to derivative instruments and hedging activities. The following tables provide detail of derivative contractual assets and liabilities as reported in our condensed consolidated balance sheets at September 30, 2018 and December 31, 2017. Derivative asset and liability totals represent the net value of the contract, while the balance sheet totals represent the gross value of the contract.



	September 30, 2018
	Derivative Assets					Derivative Liabilities
	Commodity Contracts			Interest Rate Swaps		Commodity Contracts			Interest Rate Swaps			Total
Current assets	$	432		$	25	$	1		$	—		$	458
Noncurrent assets	67			150		48			—			265
Current liabilities	(6		)	—		(973		)	(2		)	(981		)
Noncurrent liabilities	(10		)	—		(242		)	(2		)	(254		)
Net assets (liabilities)	$	483		$	175	$	(1,166	)	$	(4	)	$	(512	)



	December 31, 2017
	Derivative Assets					Derivative Liabilities
	Commodity Contracts		Interest Rate Swaps			Commodity Contracts			Interest Rate Swaps			Total
Current assets	$	190	$	—		$	—		$	—		$	190
Noncurrent assets	30		22			2			4			58
Current liabilities	—		(4		)	(216		)	(4		)	(224		)
Noncurrent liabilities	—		—			(102		)	—			(102		)
Net assets (liabilities)	$	220	$	18		$	(316	)	$	—		$	(78	)

At September 30, 2018 and December 31, 2017, there were no derivative positions accounted for as cash flow or fair value hedges. There were no amounts recognized in OCI for both the three and nine months ended September 30, 2018 and 2017.

The following table presents the pretax effect of derivative gains (losses) on net income, including realized and unrealized effects. Amount represents changes in fair value of positions in the derivative portfolio during the period, as realized amounts related to positions settled are assumed to equal reversals of previously recorded unrealized amounts.



Derivative (condensed statements of consolidated income (loss) presentation)	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Commodity contracts (Operating revenues)	$	(278	)	$	166		$	(655	)	$	333
Commodity contracts (Fuel, purchased power costs and delivery fees)	21			9			32			3
Interest rate swaps (Interest expense and related charges)	38			(4		)	115			(24		)
Net gain (loss)	$	(219	)	$	171		$	(508	)	$	312

Balance Sheet Presentation of Derivatives

We elect to report derivative assets and liabilities in our condensed consolidated balance sheets on a gross basis without taking into consideration netting arrangements we have with counterparties to those derivatives. We maintain standardized master netting agreements with certain counterparties that allow for the right to offset assets and liabilities and collateral in order to reduce credit exposure between us and the counterparty. These agreements contain specific language related to margin requirements, monthly settlement netting, cross-commodity netting and early termination netting, which is negotiated with the contract counterparty.

Generally, margin deposits that contractually offset these derivative instruments are reported separately in our condensed consolidated balance sheets, with the exception of certain margin amounts related to changes in fair value on certain CME transactions that are legally characterized as settlement of forward exposure rather than collateral. Margin deposits received from counterparties are primarily used for working capital or other general corporate purposes.

The following tables reconcile our derivative assets and liabilities on a contract basis to net amounts after taking into consideration netting arrangements with counterparties and financial collateral:



	September 30, 2018												December 31, 2017
	Derivative Assets and Liabilities			Offsetting Instruments (a)			Cash Collateral (Received) Pledged (b)			Net Amounts			Derivative Assets and Liabilities			Offsetting Instruments (a)			Cash Collateral (Received) Pledged (b)			Net Amounts
Derivative assets:
Commodity contracts	$	483		$	(338	)	$	(1	)	$	144		$	220		$	(113	)	$	(1	)	$	106
Interest rate swaps	175			(4		)	—			171			18			—			—			18
Total derivative assets	658			(342		)	(1		)	315			238			(113		)	(1		)	124
Derivative liabilities:
Commodity contracts	(1,166		)	338			92			(736		)	(316		)	113			1			(202		)
Interest rate swaps	(4		)	4			—			—			—			—			—			—
Total derivative liabilities	(1,170		)	342			92			(736		)	(316		)	113			1			(202		)
Net amounts	$	(512	)	$	—		$	91		$	(421	)	$	(78	)	$	—		$	—		$	(78	)

____________


(a)	Amounts presented exclude trade accounts receivable and payable related to settled financial instruments.


(b)	Represents cash amounts received or pledged pursuant to a master netting arrangement, including fair value-based margin requirements and, to a lesser extent, initial margin requirements.

Derivative Volumes

The following table presents the gross notional amounts of derivative volumes at September 30, 2018 and December 31, 2017:



	September 30, 2018		December 31, 2017
Derivative type	Notional Volume				Unit of Measure
Natural gas (a)	5,264		1,259		Million MMBtu
Electricity	246,262		114,129		GWh
Financial Transmission Rights (b)	176,207		110,913		GWh
Coal	47		2		Million U.S. tons
Fuel oil	4		5		Million gallons
Uranium	100		325		Thousand pounds
Emissions	25		—		Million tons
Interest rate swaps – floating/fixed (c)	$	7,718	$	3,000	Million U.S. dollars

____________


(a)	Represents gross notional forward sales, purchases and options transactions, locational basis swaps and other natural gas transactions.


(b)	Represents gross forward purchases associated with instruments used to hedge electricity price differences between settlement points within ISOs.


(c)	Includes notional amounts of interest rate swaps with maturity dates through July 2026.

Credit Risk-Related Contingent Features of Derivatives

Our derivative contracts may contain certain credit risk-related contingent features that could trigger liquidity requirements in the form of cash collateral, letters of credit or some other form of credit enhancement. Certain of these agreements require the posting of collateral if our credit rating is downgraded by one or more credit rating agencies or include cross-default contractual provisions that could result in the settlement of such contracts if there was a failure under other financing arrangements related to payment terms or other covenants.

The following table presents the commodity derivative liabilities subject to credit risk-related contingent features that are not fully collateralized:



	September 30, 2018			December 31, 2017
Fair value of derivative contract liabilities (a)	$	(629	)	$	(204	)
Offsetting fair value under netting arrangements (b)	161			103
Cash collateral and letters of credit	222			41
Liquidity exposure	$	(246	)	$	(60	)

____________


(a)	Excludes fair value of contracts that contain contingent features that do not provide specific amounts to be posted if features are triggered, including provisions that generally provide the right to request additional collateral (material adverse change, performance assurance and other clauses).


(b)	Amounts include the offsetting fair value of in-the-money derivative contracts and net accounts receivable under master netting arrangements.

Concentrations of Credit Risk Related to Derivatives

We have concentrations of credit risk with the counterparties to our derivative contracts. At September 30, 2018, total credit risk exposure to all counterparties related to derivative contracts totaled $858 million (including associated accounts receivable). The net exposure to those counterparties totaled $397 million at September 30, 2018, after taking into effect netting arrangements, setoff provisions and collateral, with the largest net exposure to a single counterparty totaling $70 million. At September 30, 2018, the credit risk exposure to the banking and financial sector represented 57% of the total credit risk exposure and 47% of the net exposure.

Exposure to banking and financial sector counterparties is considered to be within an acceptable level of risk tolerance because all of this exposure is with counterparties with investment grade credit ratings. However, this concentration increases the risk that a default by any of these counterparties would have a material effect on our financial condition, results of operations and liquidity. The transactions with these counterparties contain certain provisions that would require the counterparties to post collateral in the event of a material downgrade in their credit rating.

We maintain credit risk policies with regard to our counterparties to minimize overall credit risk. These policies authorize specific risk mitigation tools including, but not limited to, use of standardized master agreements that allow for netting of positive and negative exposures associated with a single counterparty. Credit enhancements such as parent guarantees, letters of credit, surety bonds, liens on assets and margin deposits are also utilized. Prospective material changes in the payment history or financial condition of a counterparty or downgrade of its credit quality result in the reassessment of the credit limit with that counterparty. The process can result in the subsequent reduction of the credit limit or a request for additional financial assurances. An event of default by one or more counterparties could subsequently result in termination-related settlement payments that reduce available liquidity if amounts are owed to the counterparties related to the derivative contracts or delays in receipts of expected settlements if the counterparties owe amounts to us.

Pension and Other Postretirement Employee Benefit (OPEB) Plans (Notes)

9 Months Ended

Sep. 30, 2018

Retirement Benefits [Abstract]

Pension and Other Postretirement Benefits Disclosure [Text Block]

PENSION AND OTHER POSTRETIREMENT EMPLOYEE BENEFIT (OPEB) PLANS

Vistra Energy is the plan sponsor of the Vistra Energy Retirement Plan, which provides benefits to eligible employees of its subsidiaries. Eligible employees under the Vistra Energy Retirement Plan consist entirely of active and retired collective bargaining unit employees. Vistra Energy and our participating subsidiaries offer other postretirement benefits (OPEB) in the form of certain health care and life insurance benefits to eligible retirees and their eligible dependents.

Prior to the Merger, Dynegy provided pension and OPEB benefits to certain of its employees and retirees. At the Merger Date, Vistra Energy assumed these plans and the excess of the benefit obligations over the fair value of plan assets was recognized as a liability (see Note 2). Benefit obligations assumed totaled $539 million and the fair value of plan assets assumed totaled $459 million, and the net unfunded liability was recorded as $15 million to other noncurrent assets, $2 million to other current liabilities and $93 million to other noncurrent liabilities in the condensed consolidated balance sheets.

Components of Net Benefit Cost

For the three and nine months ended September 30, 2018, net periodic benefit costs consisted of the following:



	Pension Benefits										OPEB Benefits
	Three Months Ended September 30,					Nine Months Ended September 30,					Three Months Ended September 30,				Nine Months Ended September 30,
	2018			2017		2018			2017		2018		2017		2018		2017
Service cost	$	5		$	1	$	10		$	4	$	1	$	—	$	2	$	1
Other costs	(1		)	—		(1		)	—		1		1		3		3
Net periodic benefit cost	$	4		$	1	$	9		$	4	$	2	$	1	$	5	$	4

Stock-Based Compensation (Notes)

9 Months Ended

Sep. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

STOCK-BASED COMPENSATION

At the Merger Date, Dynegy stock options and equity-based awards outstanding immediately prior to the Merger Date were generally automatically converted upon completion of the Merger into stock options and equity-based awards, respectively, with respect to Vistra Energy's common stock, after giving effect to the Exchange Ratio.



Instrument Type	Dynegy Awards Prior to the Merger Date	Vistra Awards Converted at the Merger Date	Fair Value of Awards (a)
Stock Options	4,096,027	2,670,610	$	10
Restricted Stock Units	5,718,148	3,056,689	61
Performance Units	1,538,133	938,721	18
Total			$	89

____________

(a)

$26 million was attributable to pre-combination service and considered part of the purchase price (see Note 2). $33 million was recognized immediately as compensation expense due to accelerated vesting as a result of the Merger. $30 million will be amortized as compensation expense over the remaining service period and will be recorded in additional paid in capital in the condensed consolidated balance sheets.

Related Party Transactions (Notes)

9 Months Ended

Sep. 30, 2018

Related Party Transactions

RELATED PARTY TRANSACTIONS

In connection with Emergence, we entered into agreements with certain of our affiliates and with parties who received shares of common stock and TRA Rights in exchange for their claims.

Registration Rights Agreement

Pursuant to the Plan of Reorganization, on the Effective Date, we entered into a Registration Rights Agreement (the Registration Rights Agreement) with certain selling stockholders providing for registration of the resale of the Vistra Energy common stock held by such selling stockholders.

In December 2016, we filed a Form S-1 registration statement with the SEC to register for resale the shares of Vistra Energy common stock held by certain significant stockholders pursuant to the Registration Rights Agreement, which was declared effective by the SEC in May 2017. The registration statement was amended in March 2018. Pursuant to the Registration Rights Agreement, in June 2018, we filed a post-effective amendment to the Form S-1 registration statement on Form S-3, which was declared effective by the SEC in July 2018. Among other things, under the terms of the Registration Rights Agreement:

•

if we propose to file certain types of registration statements under the Securities Act of 1933, as amended, with respect to an offering of equity securities, we will be required to use our reasonable best efforts to offer the other parties to the Registration Rights Agreement the opportunity to register all or part of their shares on the terms and conditions set forth in the Registration Rights Agreement; and

•

the selling stockholders received the right, subject to certain conditions and exceptions, to request that we file registration statements or amend or supplement registration statements, with the SEC for an underwritten offering of all or part of their respective shares of Vistra Energy common stock (a Demand Registration), and the Company is required to cause any such registration statement or amendment or supplement (a) to be filed with the SEC promptly and, in any event, on or before the date that is 45 days, in the case of a registration statement on Form S-1, or 30 days, in the case of a registration statement on Form S-3, after we receive the written request from the relevant selling stockholders to effectuate the Demand Registration and (b) to become effective as promptly as reasonably practicable and in any event no later than 120 days after it is initially filed.

All expenses of registration under the Registration Rights Agreement, including the legal fees of one counsel retained by or on behalf of the selling stockholders, will be paid by us. Legal fee expenses paid or accrued by Vistra Energy on behalf of the selling stockholders totaled less than $1 million during both the three and nine months ended September 30, 2018 and 2017.

Tax Receivable Agreement

On the Effective Date, Vistra Energy entered into the TRA with a transfer agent on behalf of certain former first lien creditors of TCEH. See Note 8 for discussion of the TRA.

Segment Information (Notes)

9 Months Ended

Sep. 30, 2018

Segment Reporting [Abstract]

Segment Information

SEGMENT INFORMATION

The operations of Vistra Energy are aligned into six reportable business segments: (i) Retail, (ii) ERCOT, (iii) PJM, (iv) NY/NE, (v) MISO and (vi) Asset Closure. Our chief operating decision maker reviews the results of these segments separately and allocates resources to the respective segments as part of our strategic operations.

The Retail segment is engaged in retail sales of electricity and related services to residential, commercial and industrial customers. Substantially all of these activities are conducted by TXU Energy and Value Based Brands LLC in Texas, Dynegy Energy Services in Massachusetts, Ohio, Illinois and Pennsylvania and Homefield Energy in Illinois. Prior to the Merger, the Retail segment was referred to as the Retail Electricity segment.

The ERCOT, PJM, NY/NE (comprising NYISO and ISO-NE) and MISO segments are engaged in electricity generation, wholesale energy sales and purchases, commodity risk management activities, fuel production and fuel logistics management, all largely within their respective ISO market. The PJM, NY/NE and MISO segments were established on the Merger Date to reflect markets served by businesses acquired in the Merger. Prior to the Merger, the ERCOT segment was referred to as the Wholesale Generation segment.

As discussed in Note 1, the Asset Closure segment was established effective January 1, 2018. The Asset Closure segment is engaged in the decommissioning and reclamation of retired plants and mines. Separately reporting the Asset Closure segment provides management with better information related to the performance and earnings power of Vistra Energy's ongoing operations and facilitates management's focus on minimizing the cost associated with decommissioning and reclamation of retired plants and mines. We have recast prior period information to reflect this change in reportable segments. We have not allocated any unrealized gains or losses on commodity risk management activities to the Asset Closure segment for the generation plants that were retired in January, February and May 2018.

Corporate and Other represents the remaining non-segment operations consisting primarily of (i) general corporate expenses, interest, taxes and other expenses related to our support functions that provide shared services to our operating segments and (ii) CAISO operations.

Except as noted in Note 1, the accounting policies of the business segments are the same as those described in the summary of significant accounting policies in Note 1 to the Financial Statements in our 2017 Form 10-K. Our chief operating decision maker uses more than one measure to assess segment performance, including segment net income (loss), which is the measure most comparable to consolidated net income (loss) prepared based on GAAP. We account for intersegment sales and transfers as if the sales or transfers were to third parties, that is, at market prices. Certain shared services costs are allocated to the segments.



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Operating revenues (a)
Retail	$	1,813		$	1,286		$	4,239		$	3,136
ERCOT	1,396			891			2,190			1,994
PJM	620			—			1,104			—
NY/NE	301			—			487			—
MISO	230			—			488			—
Asset Closure	(1		)	312			48			763
Corporate and Other (b)	91			—			123			—
Eliminations	(1,207		)	(656		)	(2,098		)	(1,406		)
Consolidated operating revenues	$	3,243		$	1,833		$	6,581		$	4,487



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Depreciation and amortization
Retail	$	(80	)	$	(108	)	$	(237	)	$	(322	)
ERCOT	(122		)	(59		)	(295		)	(166		)
PJM	(141		)	—			(266		)	—
NY/NE	(55		)	—			(104		)	—
MISO	(3		)	—			(6		)	—
Asset Closure	—			(1		)	—			(1		)
Corporate and Other (b)	(25		)	(10		)	(60		)	(30		)
Eliminations	—			—			1			—
Consolidated depreciation and amortization	$	(426	)	$	(178	)	$	(967	)	$	(519	)
Operating income (loss)
Retail (c)	$	(83	)	$	(3	)	$	371		$	54
ERCOT	643			406			234			555
PJM	61			—			85			—
NY/NE	45			—			36			—
MISO	(2		)	—			30			—
Asset Closure	(4		)	63			(26		)	96
Corporate and Other (b)	(8		)	(15		)	(244		)	(47		)
Eliminations	(2		)	1			(1		)	—
Consolidated operating income	$	650		$	452		$	485		$	658
Net income (loss)
Retail (c)	$	(86	)	$	7		$	397		$	77
ERCOT	643			405			236			552
PJM	62			—			86			—
NY/NE	47			—			41			—
MISO	(3		)	—			29			—
Asset Closure	(4		)	64			(24		)	101
Corporate and Other (b)	(328		)	(203		)	(635		)	(405		)
Consolidated net income	$	331		$	273		$	130		$	325

____________


(a)	The following unrealized net gains (losses) from mark-to-market valuations of commodity positions are included in operating revenues:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Retail	$	(24	)	$	2		$	(11	)	$	11
ERCOT	192			226			(207		)	375
PJM	(28		)	—			(38		)	—
NY/NE	(7		)	—			(32		)	—
MISO	(34		)	—			(4		)	—
Corporate and Other (b)	3			—			4			—
Eliminations (1)	(130		)	(89		)	49			(171		)
Consolidated unrealized net gains (losses) from mark-to-market valuations of commodity positions included in operating revenues	$	(28	)	$	139		$	(239	)	$	215

____________


(1)	Amounts offset in fuel, purchased power costs and delivery fees in the Retail segment, with no impact to consolidated results.


(b)	Other includes CAISO operations. Income tax expense is not reflected in net income of the segments but is reflected entirely in Corporate net income.


(c)	Retail operating loss and net loss is driven by unrealized losses from mark-to-market valuations of commodity positions included in fuel, purchased power costs and delivery fees.



	September 30, 2018			December 31, 2017
Total assets
Retail	$	7,365		$	6,156
ERCOT	9,101			6,834
PJM	6,796			—
NY/NE	2,705			—
MISO	945			—
Asset Closure	237			235
Corporate and Other and Eliminations	(1,261		)	1,375
Consolidated total assets	$	25,888		$	14,600

Supplementary Financial Information (Notes)

9 Months Ended

Sep. 30, 2018

Supplementary Financial Information [Abstract]

Supplementary Financial Information

SUPPLEMENTARY FINANCIAL INFORMATION

Interest Expense and Related Charges



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Interest paid/accrued	$	164		$	52		$	380		$	157
Unrealized mark-to-market net (gains) losses on interest rate swaps	(38		)	(3		)	(123		)	3
Losses on extinguishment of debt and amortization of debt issuance costs, discounts and premiums	27			2			31			2
Reversal of debt extinguishment gain	—			21			—			—
Capitalized interest	(3		)	(1		)	(10		)	(5		)
Other	4			5			13			12
Total interest expense and related charges	$	154		$	76		$	291		$	169

The weighted average interest rate applicable to the Vistra Operations Credit Facilities, taking into account the interest rate swaps discussed in Note 11, was 4.18% at September 30, 2018.

Other Income and Deductions



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Other income:
Office space sublease rental income (a)	$	2	$	3	$	6	$	9
Mineral rights royalty income (b)	—		1		—		3
Sale of land (b)	—		1		1		4
Interest income	3		4		14		10
All other	1		1		4		3
Total other income	$	6	$	10	$	25	$	29
Other deductions:
Other	1		—		$	4	$	5
Total other deductions	$	1	$	—	$	4	$	5

____________


(a)	Reported in Corporate and Other non-segment.


(b)	Reported in ERCOT segment.

Restricted Cash



	September 30, 2018				December 31, 2017
	Current Assets		Noncurrent Assets		Current Assets		Noncurrent Assets
Amounts related to the Vistra Operations Credit Facilities (Note 11)	$	—	$	—	$	—	$	500
Amounts related to restructuring escrow accounts	59		—		59		—
Total restricted cash	$	59	$	—	$	59	$	500

Trade Accounts Receivable



	September 30, 2018			December 31, 2017
Wholesale and retail trade accounts receivable	$	1,268		$	596
Allowance for uncollectible accounts	(25		)	(14		)
Trade accounts receivable — net	$	1,243		$	582

Gross trade accounts receivable at September 30, 2018 and December 31, 2017 included unbilled retail revenues of $356 million and $251 million, respectively.

Allowance for Uncollectible Accounts Receivable



	Nine Months Ended September 30,
	2018			2017
Allowance for uncollectible accounts receivable at beginning of period	$	14		$	10
Increase for bad debt expense	41			35
Decrease for account write-offs	(30		)	(24		)
Allowance for uncollectible accounts receivable at end of period	$	25		$	21

Inventories by Major Category



	September 30, 2018		December 31, 2017
Materials and supplies	$	279	$	149
Fuel stock	108		83
Natural gas in storage	6		21
Total inventories	$	393	$	253

Investments



	September 30, 2018		December 31, 2017
Nuclear plant decommissioning trust	$	1,274	$	1,188
Assets related to employee benefit plans (Note 16)	34		—
Land	49		49
Miscellaneous other	—		3
Total investments	$	1,357	$	1,240

Investments in Unconsolidated Subsidiaries

On the Merger Date, we assumed Dynegy's 50% interest in Northeast Energy, LP (NELP), a joint venture with NextEra Energy, Inc., which indirectly owns the Bellingham NEA facility and the Sayreville facility. At September 30, 2018, our estimated investment in NELP totaled $133 million subject to any adjustments to our purchase price allocation. Our risk of loss related to our equity method investment is limited to our investment balance (see Note 2).

For the three and nine months ended September 30, 2018, equity earnings related to our investment in NELP totaled $7 million and $11 million, respectively, recorded in equity in earnings of unconsolidated investment in our condensed statements of consolidated net income (loss). For the three and nine months ended September 30, 2018, we received distributions totaling $7 million and $13 million, respectively.

Nuclear Decommissioning Trust

Investments in a trust that will be used to fund the costs to decommission the Comanche Peak nuclear generation plant are carried at fair value. Decommissioning costs are being recovered from Oncor Electric Delivery Company LLC's (Oncor) customers as a delivery fee surcharge over the life of the plant and deposited by Vistra Energy in the trust fund. Income and expense associated with the trust fund and the decommissioning liability are offset by a corresponding change in a regulatory asset/liability (currently a regulatory liability reported in other noncurrent liabilities and deferred credits) that will ultimately be settled through changes in Oncor's delivery fees rates. In the event that funds recovered from Oncor's customers that are held in the trust fund are determined to be inadequate to decommission the Comanche Peak nuclear generation plant, Oncor would be required to collect all additional amounts from its customers, with no obligation from Vistra Energy, provided that Vistra Energy complied with PUCT rules and regulations regarding decommissioning trusts. A summary of investments in the fund follows:



	September 30, 2018
	Cost (a)		Unrealized gain		Unrealized loss			Fair market value
Debt securities (b)	$	437	$	5	$	(9	)	$	433
Equity securities (c)	277		564		—			841
Total	$	714	$	569	$	(9	)	$	1,274



	December 31, 2017
	Cost (a)		Unrealized gain		Unrealized loss			Fair market value
Debt securities (b)	$	418	$	14	$	(2	)	$	430
Equity securities (c)	265		495		(2		)	758
Total	$	683	$	509	$	(4	)	$	1,188

____________


(a)	Includes realized gains and losses on securities sold.

(b)

The investment objective for debt securities is to invest in a diversified tax efficient portfolio with an overall portfolio rating of AA or above as graded by S&P or Aa2 by Moody's. The debt securities are heavily weighted with government and municipal bonds and investment grade corporate bonds. The debt securities had an average coupon rate of 3.73% and 3.55% at September 30, 2018 and December 31, 2017, respectively, and an average maturity of nine years at both September 30, 2018 and December 31, 2017.


(c)	The investment objective for equity securities is to invest tax efficiently and to match the performance of the S&P 500 Index for U.S. equity investments and the MSCI Inc. EAFE Index for non-U.S. equity investments.

Debt securities held at September 30, 2018 mature as follows: $146 million in one to five years, $96 million in five to 10 years and $191 million after 10 years.

The following table summarizes proceeds from sales of available-for-sale securities and the related realized gains and losses from such sales.



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Realized gains	$	(1	)	$	1		$	—		$	3
Realized losses	$	1		$	(1	)	$	(2	)	$	(3	)
Proceeds from sales of securities	$	118		$	56		$	211		$	154
Investments in securities	$	(124	)	$	(62	)	$	(227	)	$	(169	)

Property, Plant and Equipment

At September 30, 2018 and December 31, 2017, property, plant and equipment of $14.756 billion and $4.820 billion, respectively, is stated net of accumulated depreciation and amortization of $1.148 billion and $393 million, respectively.

Asset Retirement and Mining Reclamation Obligations (ARO)

These liabilities primarily relate to nuclear generation plant decommissioning, land reclamation related to lignite mining and removal of lignite/coal fueled plant ash treatment facilities. There is no earnings impact with respect to changes in the nuclear plant decommissioning liability, as all costs are recoverable through the regulatory process as part of delivery fees charged by Oncor.

At September 30, 2018, the carrying value of our ARO related to our nuclear generation plant decommissioning totaled $1.265 billion, which is less than the fair value of the assets contained in the nuclear decommissioning trust. Since the costs to ultimately decommission that plant are recoverable through the regulatory rate making process as part of Oncor's delivery fees, a corresponding regulatory liability has been recorded to our condensed consolidated balance sheet of $9 million in other noncurrent liabilities and deferred credits.

The following table summarizes the changes to these obligations, reported as asset retirement obligations (current and noncurrent liabilities) in our condensed consolidated balance sheets, for the nine months ended September 30, 2018:



	Nuclear Plant Decommissioning		Mining Land Reclamation			Coal Ash and Other			Total
Liability at December 31, 2017	$	1,233	$	438		$	265		$	1,936
Additions:
Accretion	32		16			20			68
Adjustment for change in estimates	—		7			(47		)	(40		)
Obligations assumed in the Merger	—		2			424			426
Reductions:
Payments	—		(57		)	(11		)	(68		)
Liability at September 30, 2018	1,265		406			651			2,322
Less amounts due currently	—		(124		)	(59		)	(183		)
Noncurrent liability at September 30, 2018	$	1,265	$	282		$	592		$	2,139

Other Noncurrent Liabilities and Deferred Credits

The balance of other noncurrent liabilities and deferred credits consists of the following:



	September 30, 2018		December 31, 2017
Uncertain tax positions, including accrued interest	$	12	$	—
Other, including retirement and other employee benefits	334		220
Total other noncurrent liabilities and deferred credits	$	346	$	220

Fair Value of Debt



		September 30, 2018				December 31, 2017
Debt:	Fair Value Hierarchy	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt under the Vistra Operations Credit Facilities (Note 11)	Level 2	$	5,823	$	5,836	$	4,323	$	4,334
Vistra Operations Senior Notes (Note 11)	Level 2	1,000		1,010		—		—
Vistra Energy Senior Notes (Note 11)	Level 2	3,954		3,945		—		—
7.000% Amortizing Notes (Note 11)	Level 2	31		32		—		—
Forward Capacity Agreements (Note 11)	Level 3	221		221		—		—
Equipment Financing Agreements (Note 11)	Level 3	119		119		—		—
Mandatorily redeemable subsidiary preferred stock (Note 11)	Level 2	70		70		70		70
Building Financing (Note 11)	Level 2	23		21		30		27

We determine fair value in accordance with accounting standards as discussed in Note 14. We obtain security pricing from an independent party who uses broker quotes and third-party pricing services to determine fair values. Where relevant, these prices are validated through subscription services, such as Bloomberg.

Cash Flow Information

The following table reconciles cash, cash equivalents and restricted cash reported in our condensed statements of consolidated cash flows to the amounts reported in our condensed balance sheets at September 30, 2018 and December 31, 2017:



	September 30, 2018		December 31, 2017
Cash and cash equivalents	$	811	$	1,487
Restricted cash included in current assets	59		59
Restricted cash included in noncurrent assets	—		500
Total cash, cash equivalents and restricted cash	$	870	$	2,046

The following table summarizes our supplemental cash flow information for the nine months ended September 30, 2018 and 2017:



	Nine Months Ended September 30,
	2018			2017
Cash payments related to:
Interest paid	$	662		$	197
Capitalized interest	(10		)	(5		)
Interest paid (net of capitalized interest)	$	652		$	192
Income taxes	$	66		$	51
Noncash investing and financing activities:
Construction expenditures (a)	$	58		$	16
Vistra Energy common stock issued in the Merger (Notes 2 and 13)	$	2,245		$	—

____________


(a)	Represents end-of-period accruals for ongoing construction projects.

Supplemental Condensed Consolidating Financial Information Supplemental Condensed Consolidating Financial Information (Notes)

9 Months Ended

Sep. 30, 2018

Supplemental Condensed Consolidating Financial Information [Abstract]

Supplemental Condensed Consolidating Financial Information [Text Block]

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION

Our senior notes are guaranteed by substantially all of our wholly owned subsidiaries. The following condensed consolidating financial statements present the financial information of (i) Vistra Energy Corp. (Parent), which is the ultimate parent company and issuer of the senior notes with effect as of the Merger Date, on a stand-alone, unconsolidated basis, (ii) the guarantor subsidiaries of Vistra Energy (Guarantor Subsidiaries), (iii) the non-guarantor subsidiaries of Vistra Energy (Non-Guarantor Subsidiaries) and (iv) the eliminations necessary to arrive at the information for Vistra Energy on a consolidated basis. The Guarantor Subsidiaries consist of the wholly-owned subsidiaries, which jointly, severally, fully and unconditionally, guarantee the payment obligations under the senior notes. See Note 11 for discussion of the senior notes.

These statements should be read in conjunction with the unaudited condensed consolidated financial statements and notes thereto of Vistra Energy. The supplemental condensed consolidating financial information has been prepared pursuant to the rules and regulations for condensed financial information and does not include all disclosures included in annual financial statements. The inclusion of Vistra Energy's subsidiaries as either Guarantor Subsidiaries or Non-Guarantor Subsidiaries in the condensed consolidating financial information is determined as of the most recent balance sheet date presented.

Condensed Statements of Consolidating Income (Loss) for the Three Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Operating revenues	$	—		$	3,208		$	59		$	(24	)	$	3,243
Fuel, purchased power costs and delivery fees	—			(1,590		)	(37		)	—			(1,627		)
Operating costs	—			(334		)	(12		)	—			(346		)
Depreciation and amortization	—			(402		)	(24		)	—			(426		)
Selling, general and administrative expenses	(23		)	(165		)	(30		)	24			(194		)
Operating income (loss)	(23		)	717			(44		)	—			650
Other income	1			7			—			(2		)	6
Other deductions	—			(1		)	—			—			(1		)
Interest expense and related charges	(110		)	(43		)	(3		)	2			(154		)
Impacts of Tax Receivable Agreement	17			—			—			—			17
Equity in earnings of unconsolidated investment	—			7			—			—			7
Income (loss) before income taxes	(115		)	687			(47		)	—			525
Income tax expense	42			(251		)	15			—			(194		)
Equity in earnings (loss) of subsidiaries, net of tax	403			(33		)	—			(370		)	—
Net income (loss)	330			403			(32		)	(370		)	331
Net loss attributable to noncontrolling interest	—			—			1			—			1
Net income (loss) attributable to Vistra Energy	$	330		$	403		$	(33	)	$	(370	)	$	330

Condensed Statements of Consolidating Income (Loss) for the Three Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Operating revenues	$	—		$	1,833		$	—	$	—		$	1,833
Fuel, purchased power costs and delivery fees	—			(838		)	—		—			(838		)
Operating costs	—			(218		)	—		—			(218		)
Depreciation and amortization	—			(178		)	—		—			(178		)
Selling, general and administrative expenses	(7		)	(140		)	—		—			(147		)
Operating income (loss)	(7		)	459			—		—			452
Other income	2			8			—		—			10
Other deductions	—			—			—		—			—
Interest expense and related charges	—			(76		)	—		—			(76		)
Impacts of Tax Receivable Agreement	138			—			—		—			138
Income before income taxes	133			391			—		—			524
Income tax expense	(62		)	(189		)	—		—			(251		)
Equity in loss of subsidiaries, net of tax	202			—			—		(202		)	—
Net income (loss)	$	273		$	202		$	—	$	(202	)	$	273

Condensed Statements of Consolidating Income (Loss) for the Nine Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Operating revenues	$	—		$	6,480		$	126		$	(25	)	$	6,581
Fuel, purchased power costs and delivery fees	—			(3,405		)	(89		)	2			(3,492		)
Operating costs	—			(898		)	(28		)	—			(926		)
Depreciation and amortization	—			(926		)	(41		)	—			(967		)
Selling, general and administrative expenses	(250		)	(452		)	(32		)	23			(711		)
Operating income (loss)	(250		)	799			(64		)	—			485
Other income	8			19			—			(2		)	25
Other deductions	—			(5		)	1			—			(4		)
Interest expense and related charges	(197		)	(92		)	(4		)	2			(291		)
Impacts of Tax Receivable Agreement	(65		)	—			—			—			(65		)
Equity in earnings of unconsolidated investment	—			11			—			—			11
Income (loss) before income taxes	(504		)	732			(67		)	—			161
Income tax expense	183			(235		)	21			—			(31		)
Equity in earnings (loss) of subsidiaries, net of tax	453			(44		)	—			(409		)	—
Net income (loss)	132			453			(46		)	(409		)	130
Net income attributable to noncontrolling interest	—			—			(2		)	—			(2		)
Net income (loss) attributable to Vistra Energy	$	132		$	453		$	(44	)	$	(409	)	$	132

Condensed Statements of Consolidating Income (Loss) for the Nine Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Operating revenues	$	—		$	4,487		$	—	$	—		$	4,487
Fuel, purchased power costs and delivery fees	—			(2,250		)	—		—			(2,250		)
Operating costs	—			(626		)	—		—			(626		)
Depreciation and amortization	—			(519		)	—		—			(519		)
Selling, general and administrative expenses	(20		)	(414		)	—		—			(434		)
Operating income (loss)	(20		)	678			—		—			658
Other income	2			27			—		—			29
Other deductions	—			(5		)	—		—			(5		)
Interest expense and related charges	—			(169		)	—		—			(169		)
Impacts of Tax Receivable Agreement	96			—			—		—			96
Income before income taxes	78			531			—		—			609
Income tax expense	(36		)	(248		)	—		—			(284		)
Equity in earnings of subsidiaries, net of tax	283			—			—		(283		)	—
Net income (loss)	$	325		$	283		$	—	$	(283	)	$	325

Condensed Statements of Consolidating Comprehensive Income (Loss) for the Three Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net income (loss)	$	330	$	403	$	(32	)	$	(370	)	$	331
Other comprehensive income (loss), net of tax effects:
Effect related to pension and other retirement benefit obligations	—		1		—			—			1
Total other comprehensive income	—		1		—			—			1
Comprehensive income (loss)	330		404		(32		)	(370		)	332
Comprehensive loss attributable to noncontrolling interest	—		—		1			—			1
Comprehensive income (loss) attributable to Vistra Energy	$	330	$	404	$	(33	)	$	(370	)	$	331

Condensed Statements of Consolidating Comprehensive Income (Loss) for the Three Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Net income (loss)	$	273	$	202	$	—	$	(202	)	$	273
Other comprehensive income (loss), net of tax effects:
Effect related to pension and other retirement benefit obligations	—		—		—		—			—
Total other comprehensive income	—		—		—		—			—
Comprehensive income (loss)	$	273	$	202	$	—	$	(202	)	$	273

Condensed Statements of Consolidating Comprehensive Income (Loss) for the Nine Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net income (loss)	$	132	$	453	$	(46	)	$	(409	)	$	130
Other comprehensive income (loss), net of tax effects:
Effect related to pension and other retirement benefit obligations	—		2		—			—			2
Total other comprehensive income	—		2		—			—			2
Comprehensive income (loss)	132		455		(46		)	(409		)	132
Comprehensive income attributable to noncontrolling interest	—		—		(2		)	—			(2		)
Comprehensive income (loss) attributable to Vistra Energy	$	132	$	455	$	(44	)	$	(409	)	$	134

Condensed Statements of Consolidating Comprehensive Income (Loss) for the Nine Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Net income (loss)	$	325	$	283	$	—	$	(283	)	$	325
Other comprehensive income (loss), net of tax effects:
Effect related to pension and other retirement benefit obligations	—		—		—		—			—
Total other comprehensive income	—		—		—		—			—
Comprehensive income (loss)	$	325	$	283	$	—	$	(283	)	$	325

Condensed Statements of Consolidating Cash Flows for the Nine Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Cash flows — operating activities:
Cash provided by (used in) operating activities	$	521		$	670		$	(328	)	$	—		$	863
Cash flows — financing activities:
Issuances of long-term debt	—			1,000			—			—			1,000
Repayments/repurchases of debt	(4,918		)	2,016			—			—			(2,902		)
Borrowings under accounts receivable securitization program	—			—			350						350
Cash dividend paid	—			(3,928		)	—			3,928			—
Stock repurchase	(414		)	—			—			—			(414		)
Debt tender offer and other financing fees	(173		)	(43		)	—			—			(216		)
Other, net	10			—			—			—			10
Cash provided by (used in) financing activities	(5,495		)	(955		)	350			3,928			(2,172		)
Cash flows — investing activities:
Capital expenditures	(12		)	(191		)	(6		)	—			(209		)
Nuclear fuel purchases	—			(66		)	—			—			(66		)
Cash acquired in the Merger	—			445			—			—			445
Solar development expenditures	—			(28		)	—			—			(28		)
Proceeds from sales of nuclear decommissioning trust fund securities	—			211			—			—			211
Investments in nuclear decommissioning trust fund securities	—			(227		)	—			—			(227		)
Dividend received from subsidiaries	3,928									(3,928		)	—
Other, net	—			10			(3		)	—			7
Cash provided by (used in) investing activities	3,916			154			(9		)	(3,928		)	133
Net change in cash, cash equivalents and restricted cash	(1,058		)	(131		)	13			—			(1,176		)
Cash, cash equivalents and restricted cash — beginning balance	1,183			863			—			—			2,046
Cash, cash equivalents and restricted cash — ending balance	$	125		$	732		$	13		$	—		$	870

Condensed Statements of Consolidating Cash Flows for the Nine Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Cash flows — operating activities:
Cash provided by (used in) operating activities	$	(39	)	$	884		$	—	$	—		$	845
Cash flows — financing activities:
Repayments/repurchases of debt	—			(32		)	—		—			(32		)
Cash dividend paid	—			(537		)	—		537			—
Debt financing fees	—			(5		)	—		—			(5		)
Cash provided by (used in) financing activities	—			(574		)	—		537			(37		)
Cash flows — investing activities:
Capital expenditures	—			(86		)	—		—			(86		)
Nuclear fuel purchases	—			(56		)	—		—			(56		)
Solar development expenditures	—			(129		)	—		—			(129		)
Odessa acquisition	—			(355		)	—		—			(355		)
Proceeds from sales of nuclear decommissioning trust fund securities	—			154			—		—			154
Investments in nuclear decommissioning trust fund securities	—			(169		)	—		—			(169		)
Dividend received from subsidiaries	537			—			—		(537		)	—
Other, net	—			10			—		—			10
Cash provided by (used in) investing activities	537			(631		)	—		(537		)	(631		)
Net change in cash, cash equivalents and restricted cash	498			(321		)	—		—			177
Cash, cash equivalents and restricted cash — beginning balance	26			1,562			—		—			1,588
Cash, cash equivalents and restricted cash — ending balance	$	524		$	1,241		$	—	$	—		$	1,765

Condensed Consolidating Balance Sheet as of September 30, 2018 (Millions of Dollars)

	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
ASSETS
Current assets:
Cash and cash equivalents	$	66	$	732	$	13	$	—		$	811
Restricted cash	59		—		—		—			59
Advances to affiliates	11		—		—		(11		)	—
Trade accounts receivable — net	9		875		359		—			1,243
Accounts receivable — affiliates	15		—		211		(226		)	—
Notes due from affiliates	—		101		—		(101		)	—
Income taxes receivable	12		—		—		—			12
Inventories	—		378		15		—			393
Commodity and other derivative contractual assets	—		458		—		—			458
Margin deposits related to commodity contracts	—		177		—		—			177
Prepaid expense and other current assets	2		117		4		—			123
Total current assets	174		2,838		602		(338		)	3,276
Investments	—		1,323		34		—			1,357
Investment in unconsolidated subsidiary	—		135		—		—			135
Investment in affiliated companies	11,631		362		—		(11,993		)	—
Property, plant and equipment — net	18		14,058		680		—			14,756
Goodwill	—		1,907		—		—			1,907
Identifiable intangible assets — net	—		2,711		—		—			2,711
Commodity and other derivative contractual assets	—		265		—		—			265
Accumulated deferred income taxes	955		239		—		(141		)	1,053
Other noncurrent assets	240		185		2		1			428
Total assets	$	13,018	$	24,023	$	1,318	$	(12,471	)	$	25,888
LIABILITIES AND EQUITY
Current liabilities:
Accounts receivable securitization program	$	—	$	—	$	350	$	—		$	350
Advances from affiliates	—		2		8		(10		)	—
Long-term debt due currently	31		145		5		—			181
Trade accounts payable	3		587		222		—			812
Accounts payable — affiliates	—		215		8		(223		)	—
Notes due to affiliates	—		—		101		(101		)	—
Commodity and other derivative contractual liabilities	—		981		—		—			981
Margin deposits related to commodity contracts	—		4		—		—			4
Accrued taxes other than income	—		138		1		—			139
Accrued interest	107		16		3		(3		)	123
Asset retirement obligations	—		183		—		—			183
Other current liabilities	96		231		2		—			329
Total current liabilities	237		2,502		700		(337		)	3,102

Condensed Consolidating Balance Sheet as of September 30, 2018 (Millions of Dollars)

	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Long-term debt, less amounts due currently	3,954		7,073		33		—			11,060
Commodity and other derivative contractual liabilities	—		254		—		—			254
Accumulated deferred income taxes	—		—		146		(141		)	5
Tax Receivable Agreement obligation	402		—		—		—			402
Asset retirement obligations	—		2,126		13		—			2,139
Identifiable intangible liabilities — net	—		132		43		—			175
Other noncurrent liabilities and deferred credits	26		305		15		—			346
Total liabilities	4,619		12,392		950		(478		)	17,483
Total stockholders' equity	8,399		11,631		362		(11,993		)	8,399
Noncontrolling interest in subsidiary	—		—		6		—			6
Total liabilities and equity	$	13,018	$	24,023	$	1,318	$	(12,471	)	$	25,888

Condensed Consolidating Balance Sheet as of December 31, 2017

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
ASSETS
Current assets:
Cash and cash equivalents	$	1,124	$	363	$	—	$	—		$	1,487
Restricted cash	59		—		—		—			59
Trade accounts receivable — net	4		578		—		—			582
Inventories	—		253		—		—			253
Commodity and other derivative contractual assets	—		190		—		—			190
Margin deposits related to commodity contracts	—		30		—		—			30
Prepaid expense and other current assets	—		72		—		—			72
Total current assets	1,187		1,486		—		—			2,673
Restricted cash	—		500		—		—			500
Investments	—		1,240		—		—			1,240
Investment in affiliated companies	5,632		—		—		(5,632		)	—
Property, plant and equipment — net	—		4,820		—		—			4,820
Goodwill	—		1,907		—		—			1,907
Identifiable intangible assets — net	—		2,530		—		—			2,530
Commodity and other derivative contractual assets	—		58		—		—			58
Accumulated deferred income taxes	5		705		—		—			710
Other noncurrent assets	6		156		—		—			162
Total assets	$	6,830	$	13,402	$	—	$	(5,632	)	$	14,600
LIABILITIES AND EQUITY
Current liabilities:
Long-term debt due currently	$	—	$	44	$	—	$	—		$	44
Trade accounts payable	11		462		—		—			473
Commodity and other derivative contractual liabilities	—		224		—		—			224
Margin deposits related to commodity contracts	—		4		—		—			4
Accrued taxes	58		—		—		—			58
Accrued taxes other than income	—		136		—		—			136
Accrued interest	—		16		—		—			16
Asset retirement obligations	—		99		—		—			99
Other current liabilities	86		211		—		—			297
Total current liabilities	155		1,196		—		—			1,351
Long-term debt, less amounts due currently	—		4,379		—		—			4,379
Commodity and other derivative contractual liabilities	—		102		—		—			102
Tax Receivable Agreement obligation	333		—		—		—			333
Asset retirement obligations	—		1,837		—		—			1,837
Identifiable intangible liabilities — net	—		36		—		—			36
Other noncurrent liabilities and deferred credits	—		220		—		—			220
Total liabilities	488		7,770		—		—			8,258
Total equity	6,342		5,632		—		(5,632		)	6,342
Total liabilities and equity	$	6,830	$	13,402	$	—	$	(5,632	)	$	14,600

Business And Significant Accounting Policies (Policies)	9 Months Ended
Business And Significant Accounting Policies (Policies)	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements have been prepared in accordance with U.S. GAAP and on the same basis as the audited financial statements included in our 2017 Form 10-K, with the exception of the changes in reportable segments as detailed above. Adjustments (consisting of normal recurring accruals) necessary for a fair presentation of the results of operations and financial position have been included therein. All intercompany items and transactions have been eliminated in consolidation. Certain information and footnote disclosures normally included in annual consolidated financial statements prepared in accordance with U.S. GAAP have been omitted pursuant to the rules and regulations of the SEC. Because the condensed consolidated interim financial statements do not include all of the information and footnotes required by U.S. GAAP, they should be read in conjunction with the audited financial statements and related notes contained in our 2017 Form 10-K. The results of operations for an interim period may not give a true indication of results for a full year. All dollar amounts in the financial statements and tables in the notes are stated in millions of U.S. dollars unless otherwise indicated.
Use of Estimates	Use of Estimates Preparation of financial statements requires estimates and assumptions about future events that affect the reporting of assets and liabilities at the balance sheet dates and the reported amounts of revenue and expense, including fair value measurements, estimates of expected obligations, judgment related to the potential timing of events and other estimates. In the event estimates and/or assumptions prove to be different from actual amounts, adjustments are made in subsequent periods to reflect more current information.
Unconsolidated Investments	Unconsolidated Investments We use the equity method of accounting for investments in affiliates over which we exercise significant influence. Our share of net income (loss) from these affiliates is recorded to equity in earnings (loss) of unconsolidated investment in the condensed statements of consolidated net income (loss). We use the cost method of accounting where we do not exercise significant influence. See Note 20.
Noncontrolling Interest	Noncontrolling Interest Noncontrolling interest is comprised of the 20% of Electric Energy, Inc. (EEI) that we do not own. EEI is our consolidated subsidiary that owns a coal facility in Joppa, Illinois. This noncontrolling interest is classified as a component of equity separate from stockholders' equity in the condensed consolidated balance sheets.
Treasury Stock	Treasury Stock Treasury stock purchases are accounted for under the cost method whereby the entire cost of the acquired stock is recorded as treasury stock, which is presented in our condensed consolidated balance sheets as a reduction to additional paid-in capital. See Note 13.

- Definition

Disclosure of accounting policy for investments in financial assets, including marketable securities (debt and equity securities with readily determinable fair values), investments accounted for under the equity method and cost method, securities borrowed and loaned, and repurchase and resale agreements. For marketable securities, the disclosure may include the entity's accounting treatment for transfers between investment categories and how the fair values for such securities are determined. Also, for all investments, an entity may describe its policy for assessing, recognizing and measuring impairment of the investment.

+ References + Details

Business And Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Schedule of new accounting pronouncements and changes in accounting principles

As of January 1, 2018, the cumulative effect of the changes made to our condensed consolidated balance sheet for the adoption of the new revenue standard was as follows:



	December 31, 2017			Adoption of New Revenue Standard			January 1, 2018
Impact on condensed consolidated balance sheet:
Assets
Prepaid expense and other current assets	$	72		$	5		$	77
Accumulated deferred income taxes	$	710		$	(4	)	$	706
Other noncurrent assets	$	162		$	16		$	178
Equity
Retained deficit	$	(1,410	)	$	17		$	(1,393	)

The disclosure of the impact of adoption on our condensed statement of consolidated income (loss) and condensed consolidated balance sheet was as follows:



	Three Months Ended September 30, 2018								Nine Months Ended September 30, 2018
	As Reported			Amount Without Adoption of New Revenue Standard			Effect of Change Higher (Lower)		As Reported			Amount Without Adoption of New Revenue Standard			Effect of Change Higher (Lower)
Impact on condensed statement of consolidated income (loss):
Operating revenues	$	3,243		$	3,242		$	1	$	6,581		$	6,578		$	3
Selling, general and administrative expenses	(194		)	(196		)	2		(711		)	(720		)	9
Net income (loss)	331			328			3		130			121			9



	September 30, 2018
	As Reported			Balances Without Adoption of New Revenue Standard			Effect of Change Higher (Lower)
Impact on condensed consolidated balance sheet:
Assets
Prepaid expense and other current assets	$	123		$	116		$	7
Accumulated deferred income taxes	1,053			1,057			(4		)
Other noncurrent assets	428			403			25
Equity
Retained deficit	$	(1,261	)	$	(1,287	)	$	26

Merger Transaction and Business Combination Accounting (Tables)

9 Months Ended

Sep. 30, 2018

Business Combinations [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]

The following table summarizes the consideration paid and the preliminary allocation of the purchase price to the fair value amounts recognized for the assets acquired and liabilities assumed related to the Merger as of the Merger Date. Based on the opening price of Vistra Energy common stock on the Merger Date, the preliminary purchase price was approximately $2.3 billion. The preliminary values included below represent our current best estimates for property plant and equipment, identifiable intangible assets and liabilities, inventories, asset retirement obligations and deferred taxes. The purchase price allocation is preliminary and each of these may change materially based upon the receipt of more detailed information, additional analyses and completed valuations. The purchase price allocation is ongoing and is dependent upon final valuation determinations, which have not been completed. During the three months ended September 30, 2018, we updated the initial purchase price allocation with revised valuation estimates by increasing property, plant and equipment by $44 million, increasing intangible assets by $76 million, decreasing inventory by $37 million, decreasing accumulated deferred tax asset by $19 million, decreasing other noncurrent assets by $106 million, decreasing other noncurrent liabilities by $47 million as well as other minor adjustments. The valuation revisions were a result of updated inputs used in determining the fair value of the acquired assets and liabilities. We currently expect the final purchase price allocation will be completed no later than the second quarter of 2019.



Dynegy shares outstanding as of April 9, 2018 (in millions)	173
Exchange Ratio	0.652
Vistra Energy shares issued for Dynegy shares outstanding (in millions)	113
Opening price of Vistra Energy common stock on April 9, 2018	$	19.87
Purchase price for common stock	$	2,245
Fair value of outstanding stock compensation awards attributable to pre-combination service	$	26
Fair value of outstanding warrants	$	2
Total purchase price	$	2,273



Preliminary Purchase Price Allocation
Cash and cash equivalents	$	445
Trade accounts receivables, inventories, prepaid expenses and other current assets	826
Property, plant and equipment	10,406
Accumulated deferred income taxes	372
Identifiable intangible assets	463
Other noncurrent assets	426
Total assets acquired	12,938
Trade accounts payable and other current liabilities	645
Commodity and other derivative contractual assets and liabilities, net	422
Asset retirement obligations, including amounts due currently	426
Long-term debt, including amounts due currently	8,920
Other noncurrent liabilities	245
Total liabilities assumed	10,658
Identifiable net assets acquired	2,280
Noncontrolling interest in subsidiary	7
Total purchase price	$	2,273

Unaudited Pro Forma Financial Information [Table Text Block]

Unaudited Pro Forma Financial Information — The following unaudited pro forma financial information for the nine months ended September 30, 2018 and 2017 assumes that the Merger occurred on January 1, 2017. The unaudited pro forma financial information is provided for information purposes only and is not necessarily indicative of the results of operations that would have occurred had the Merger been completed on January 1, 2017, nor is the unaudited pro forma financial information indicative of future results of operations, which may differ materially from the pro forma financial information presented here.



	Nine Months Ended September 30,
	2018			2017
Revenues	$	8,032		$	8,542
Net income (loss)	$	(64	)	$	316
Net income (loss) attributable to Vistra Energy	$	(61	)	$	318
Net income (loss) attributable to Vistra Energy per weighted average share of common stock outstanding — basic	$	(0.12	)	$	0.56
Net income (loss) attributable to Vistra Energy per weighted average share of common stock outstanding — diluted	$	(0.12	)	$	0.56

Retirement of Generation Facilities (Tables)

9 Months Ended

Sep. 30, 2018

Retirement of Generation Facilities [Abstract]

Retirements of generation capacity

Two of our non-operated, jointly held power plants acquired in the Merger, for which our proportional generation capacity was 883 MW, were retired in May 2018. These units were retired as previously scheduled. No gain or loss was recorded in conjunction with the retirement of these units, and the operational results of these facilities are included in our Asset Closure segment. The following table details the units retired.



Name	Location	Fuel Type	Net Generation Capacity (MW)	Ownership Interest	Date Units Taken Offline
Killen	Manchester, Ohio	Coal	204	33%	May 31, 2018
Stuart	Aberdeen, Ohio	Coal	679	39%	May 24, 2018
Total			883

In January and February 2018, we retired three power plants with a total installed nameplate generation capacity of 4,167 MW. We decided to retire these units because they were projected to be uneconomic based on then current market conditions and would have faced significant environmental costs associated with operating such units. In the case of the Sandow units, the decision also reflected the execution of a contract termination agreement pursuant to which the Company and Alcoa agreed to an early settlement of a long-standing power and mining agreement. Expected retirement expenses were accrued in the third and fourth quarter of 2017 and, as a result, no retirement expenses were recorded related to these facilities in both the three and nine months ended September 30, 2018. The operational results of these facilities are included in our Asset Closure segment. The following table details the units retired.



Name	Location (all in the state of Texas)	Fuel Type	Installed Nameplate Generation Capacity (MW)	Number of Units	Date Units Taken Offline
Monticello	Titus County	Lignite/Coal	1,880	3	January 4, 2018
Sandow	Milam County	Lignite	1,137	2	January 11, 2018
Big Brown	Freestone County	Lignite/Coal	1,150	2	February 12, 2018
Total			4,167	7

Revenue (Tables)

9 Months Ended

Sep. 30, 2018

Revenue Recognition and Deferred Revenue [Abstract]

Disaggregation of revenue

The following tables disaggregate our revenue by major source:



	Three Months Ended September 30, 2018
	Retail			ERCOT		PJM			NY/NE			MISO			Asset Closure			CAISO/Eliminations			Consolidated
Revenue from contracts with customers:
Retail energy charge in ERCOT	$	1,362		$	—	$	—		$	—		$	—		$	—		$	—		$	1,362
Retail energy charge in Northeast/Midwest	442			—		—			—			—			—			—			442
Wholesale generation revenue from ISO	—			393		502			244			255			1			81			1,476
Capacity revenue	—			—		164			79			15			(4		)	9			263
Revenue from other wholesale contracts	—			72		11			9			5			(2		)	3			98
Total revenue from contracts with customers	1,804			465		677			332			275			(5		)	93			3,641
Other revenues:
Intangible amortization	15			—		—			(4		)	(5		)	—			—			6
Hedging and other revenues (a)	(6		)	52		(275		)	(42		)	(136		)	5			(2		)	(404		)
Affiliate sales	—			879		218			15			96			(1		)	(1,207		)	—
Total other revenues	9			931		(57		)	(31		)	(45		)	4			(1,209		)	(398		)
Total revenues	$	1,813		$	1,396	$	620		$	301		$	230		$	(1	)	$	(1,116	)	$	3,243

____________


(a)	Includes $28 million of unrealized net losses from mark-to-market valuations of commodity positions. See Note 19 for unrealized net gains (losses) by segment.



	Nine Months Ended September 30, 2018
	Retail			ERCOT			PJM			NY/NE			MISO			Asset Closure			CAISO/Eliminations			Consolidated
Revenue from contracts with customers:
Retail energy charge in ERCOT	$	3,423		$	—		$	—		$	—		$	—		$	—		$	—		$	3,423
Retail energy charge in Northeast/Midwest	778			—			—			—			—			—			—			778
Wholesale generation revenue from ISO	—			775			869			362			436			52			95			2,589
Capacity revenue	—			—			283			162			44			6			20			515
Revenue from other wholesale contracts	—			175			18			14			16			(1		)	4			226
Total revenue from contracts with customers	4,201			950			1,170			538			496			57			119			7,531
Other revenues:
Retail contract amortization	(12		)	(1		)	—			(6		)	(12		)	—			—			(31		)
Hedging and other revenues (a)	50			(181		)	(436		)	(71		)	(256		)	(29		)	4			(919		)
Affiliate sales	—			1,422			370			26			260			20			(2,098		)	—
Total other revenues	38			1,240			(66		)	(51		)	(8		)	(9		)	(2,094		)	(950		)
Total revenues	$	4,239		$	2,190		$	1,104		$	487		$	488		$	48		$	(1,975	)	$	6,581

Performance obligations

Performance Obligations

As of September 30, 2018, we have future performance obligations that are unsatisfied, or partially unsatisfied, relating to capacity auction volumes awarded through capacity auctions held by the ISO or through bilateral sales. Therefore, an obligation exists as of the date of the results of the respective ISO capacity auction or the contract execution date for bilateral customers. The transaction price is also set by the results of the capacity auction and/or executed contract.

Accounts receivable, contracts with customers

Accounts Receivable

The following table presents trade accounts receivable relating to both contracts with customers and other activities:



	September 30, 2018
Trade accounts receivable from contracts with customers — net	$	1,135
Other trade accounts receivable — net	108
Total trade accounts receivable — net	$	1,243

Goodwill and Identifiable Intangible Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of identifiable intangible assets reported in the balance sheet

Identifiable intangible assets and liabilities are comprised of the following:



	September 30, 2018						December 31, 2017
Identifiable Intangible Asset	Gross Carrying Amount		Accumulated Amortization		Net		Gross Carrying Amount		Accumulated Amortization		Net
Retail customer relationship	$	1,681	$	799	$	882	$	1,648	$	572	$	1,076
Software and other technology-related assets	239		80		159		183		47		136
Retail and wholesale contracts	445		123		322		154		87		67
Contractual service agreements	72		—		72		—		—		—
Other identifiable intangible assets (a)	40		14		26		33		11		22
Total identifiable intangible assets subject to amortization	$	2,477	$	1,016	1,461		$	2,018	$	717	1,301
Retail trade names (not subject to amortization)					1,246						1,225
Mineral interests (not currently subject to amortization)					4						4
Total identifiable intangible assets					$	2,711					$	2,530
______________
(a) Includes mining development costs and environmental allowances and credits.

Identifiable Intangible Liability									September 30, 2018		December 31, 2017
Contractual service agreements									$93		$0
Purchase and sales contracts									46		36
Environmental allowances									36		—
Total identifiable intangible liabilities									$	175	$	36

Schedule of amortization expense related to intangible assets (including income statement line item)

Amortization expense related to finite-lived identifiable intangible assets and liabilities (including the classification in the condensed statements of consolidated income (loss)) consisted of:



Identifiable Intangible Assets and Liabilities	Condensed Statements of Consolidated Income (Loss) Line	Three Months Ended September 30,						Nine Months Ended September 30,
Identifiable Intangible Assets and Liabilities	Condensed Statements of Consolidated Income (Loss) Line	2018			2017			2018		2017
Retail customer relationship	Depreciation and amortization	$	77		$	105		$	227	$	315
Software and other technology-related assets	Depreciation and amortization	6			10			36		27
Retail and wholesale contracts/purchase and sales contracts	Operating revenues/fuel, purchased power costs and delivery fees	(5		)	(19		)	28		27
Other identifiable intangible assets	Operating revenues/fuel, purchased power costs and delivery fees/depreciation and amortization	10			5			14		14
Total amortization expense (a)		$	88		$	101		$	305	$	383

____________


(a)	Amounts recorded in depreciation and amortization totaled $84 million and $116 million for the three months ended September 30, 2018 and 2017, respectively, and $266 million and $347 million for the nine months ended September 30, 2018 and 2017, respectively.

Schedule of estimated amortization expense of identifiable intangible assets

As of September 30, 2018, the estimated aggregate amortization expense of identifiable intangible assets and liabilities for each of the next five fiscal years is as shown below.



Year	Estimated Amortization Expense
2018	$	402
2019	$	331
2020	$	250
2021	$	180
2022	$	111

Income Taxes (Tables)

9 Months Ended

Sep. 30, 2018

Income Tax Disclosure [Abstract]

Calculation of effective income tax rate

The calculation of our effective tax rate is as follows:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Income before income taxes	$	525		$	524		$	161		$	609
Income tax expense	$	(194	)	$	(251	)	$	(31	)	$	(284	)
Effective tax rate	37.0		%	47.9		%	19.3		%	46.6		%

Tax Receivable Agreement Obligation (Tables)

9 Months Ended

Sep. 30, 2018

Income Tax Disclosure [Abstract]

Tax receivable agreement obligation

The following table summarizes the changes to the TRA obligation, reported as other current liabilities and Tax Receivable Agreement obligation in our condensed consolidated balance sheets, for the nine months ended September 30, 2018 and 2017:



	Nine Months Ended September 30,
	2018			2017
TRA obligation at the beginning of the period	$	357		$	596
Accretion expense	51			64
Changes in tax assumptions impacting timing of payments	14			(160		)
TRA obligation at the end of the period	422			500
Less amounts due currently	(20		)	(24		)
Noncurrent TRA obligation at the end of the period	$	402		$	476

Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

Schedule of earnings per share, basic and diluted

Basic earnings per share available to common shareholders are based on the weighted average number of common shares outstanding during the period. Diluted earnings per share is calculated using the treasury stock method and includes the effect of all potential issuances of common shares under stock-based incentive compensation arrangements.



	Three Months Ended September 30, 2018					Three Months Ended September 30, 2017
	Net Income		Shares	Per Share Amount		Net Income		Shares	Per Share Amount
Net income available for common stock — basic (a)	$	330	533,142,189	$	0.62	$	273	427,591,426	$	0.64
Dilutive securities:
Stock-based incentive compensation plan	—		7,830,613	0.01		—		721,012	—
Net income available for common stock — diluted	$	330	540,972,802	$	0.61	$	273	428,312,438	$	0.64

	Nine Months Ended September 30, 2018					Nine Months Ended September 30, 2017
	Net Income		Shares	Per Share Amount		Net Income		Shares	Per Share Amount
Net income available for common stock — basic (a)	$	132	500,781,573	$	0.26	$	325	427,587,404	$	0.76
Dilutive securities:
Stock-based incentive compensation plan	—		7,347,415	—		—		414,465	—
Net income available for common stock — diluted	$	132	508,128,988	$	0.26	$	325	428,001,869	$	0.76

____________


(a)	The minimum settlement amount of tangible equity units, or 15,056,260 shares, are considered to be outstanding and are included in the computation of basic net income per share

Long-Term Debt (Tables)

9 Months Ended

Sep. 30, 2018

Debt Disclosure [Abstract]

Schedule of long-term debt instruments

Amounts in the table below represent the categories of long-term debt obligations incurred by the Company.



	September 30, 2018			December 31, 2017
Vistra Operations Credit Facilities	$	5,828		$	4,311
Vistra Operations 5.500% Senior Notes, due September 1, 2026	1,000			—
Vistra Energy Senior Notes:
7.375% Senior Notes, due November 1, 2022	1,750			—
5.875% Senior Notes, due June 1, 2023	500			—
7.625% Senior Notes, due November 1, 2024	1,224			—
8.034% Senior Notes, due February 2, 2024	25			—
8.000% Senior Notes, due January 15, 2025	81			—
8.125% Senior Notes, due January 30, 2026	166			—
Total Vistra Energy Senior Notes	3,746			—
Other:
7.000% Amortizing Notes, due July 1, 2019	31			—
Forward Capacity Agreements	238			—
Equipment Financing Agreements	136			—
Mandatorily redeemable subsidiary preferred stock (a)	70			70
8.82% Building Financing due semiannually through February 11, 2022 (b)	21			27
Total other long-term debt	496			97
Unamortized debt premiums, discounts and issuance costs	171			15
Total long-term debt including amounts due currently	11,241			4,423
Less amounts due currently	(181		)	(44		)
Total long-term debt less amounts due currently	$	11,060		$	4,379

____________


(a)	Shares of mandatorily redeemable preferred stock in PrefCo issued as part of the Plan of Reorganization. This subsidiary preferred stock is accounted for as a debt instrument under relevant accounting guidance.


(b)	Obligation related to a corporate office space capital lease. This obligation will be funded by amounts held in an escrow account that is reflected in other noncurrent assets in our condensed consolidated balance sheets.

Schedule of line of credit facilities

The Vistra Operations Credit Facilities and related available capacity at September 30, 2018 are presented below.



		September 30, 2018
Vistra Operations Credit Facilities	Maturity Date	Facility Limit		Cash Borrowings		Available Capacity
Revolving Credit Facility (a)	June 14, 2023	$	2,500	$	—	$	1,290
Term Loan B-1 Facility (b)	August 4, 2023	2,800		2,800		—
Term Loan B-2 Facility (b)	December 14, 2023	983		983		—
Term Loan B-3 Facility (b)	December 31, 2025	2,045		2,045		—
Total Vistra Operations Credit Facilities		$	8,328	$	5,828	$	1,290

___________


(a)	Facility to be used for general corporate purposes. Facility includes a $2.3 billion letter of credit sub-facility, of which $1.210 billion of letters of credit were outstanding at September 30, 2018 and which reduce our available capacity.


(b)	Cash borrowings under the Term Loan B Facility reflect required scheduled quarterly payment in annual amount equal to 1% of the original principal amount with the balance paid at maturity. Principal amounts paid cannot be reborrowed.

Schedule of maturities of long-term debt

Long-term debt maturities at September 30, 2018 are as follows:



	September 30, 2018
Remainder of 2018	$	54
2019	182
2020	204
2021	130
2022	1,824
Thereafter	8,676
Unamortized premiums, discounts and debt issuance costs	171
Total long-term debt, including amounts due currently	$	11,241

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
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-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Topic 505
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Equity (Tables)

9 Months Ended

Sep. 30, 2018

Stockholders' Equity Note [Abstract]

Schedule of stockholders equity

The following table presents the changes to shareholder's equity for the three months ended September 30, 2018:



	Common Stock (a)		Additional Paid-in Capital			Retained Earnings (Deficit)			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interest			Total Equity
Balance at June 30, 2018	$	5	$	10,015		$	(1,591	)	$	(16	)	$	7		$	8,420
Net income	—		—			330			—			—			330
Treasury stock	—		(349		)	—			—			—			(349		)
Effects of stock-based incentive compensation plans	—		6			—			—			—			6
Change in unrecognized losses related to pension and OPEB plans	—		—			—			1			—			1
Investment by noncontrolling interest	—		—			—			—			(1		)	(1		)
Other	—		(2		)	—			—			—			(2		)
Balance at September 30, 2018	$	5	$	9,670		$	(1,261	)	$	(15	)	$	6		$	8,405

The following table presents the changes to shareholder's equity for the nine months ended September 30, 2018:



	Common Stock (a)		Additional Paid-in Capital			Retained Earnings (Deficit)			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interest		Total Equity
Balance at December 31, 2017	$	4	$	7,765		$	(1,410	)	$	(17	)	$	—	$	6,342
Stock issued in connection with the Merger	1		1,891			—			—			—		1,892
Net income	—		—			132			—			—		132
Adoption of accounting standard (Note 1)	—		—			17			—			—		17
Treasury stock	—		(424		)	—			—			—		(424		)
Effects of stock-based incentive compensation plans	—		69			—			—			—		69
Tangible equity units acquired	—		369			—			—			—		369
Warrants acquired	—		2			—			—			—		2
Change in unrecognized losses related to pension and OPEB plans	—		—			—			2			—		2
Investment by noncontrolling interest	—		—			—			—			6		6
Other	—		(2		)	—			—			—		(2		)
Balance at September 30, 2018	$	5	$	9,670		$	(1,261	)	$	(15	)	$	6	$	8,405

________________


(a)	Authorized shares totaled 1,800,000,000 at September 30, 2018. Outstanding shares totaled 507,391,134 and 428,398,802 at September 30, 2018 and December 31, 2017, respectively.

The following table presents the changes to shareholder's equity for the three months ended September 30, 2017:



	Common Stock (a)		Additional Paid-in Capital		Retained Earnings (Deficit)			Accumulated Other Comprehensive Income (Loss)		Total Shareholders' Equity
Balance at June 30, 2017	$	4	$	7,750	$	(1,102	)	$	6	$	6,658
Net income	—		—		273			—		273
Effects of stock-based incentive compensation plans	—		5		—			—		5
Other	—		—		(1		)	—		(1		)
Balance at September 30, 2017	$	4	$	7,755	$	(830	)	$	6	$	6,935

The following table presents the changes to shareholder's equity for the nine months ended September 30, 2017:



	Common Stock (a)		Additional Paid-in Capital		Retained Earnings (Deficit)			Accumulated Other Comprehensive Income (Loss)		Total Shareholders' Equity
Balance at December 31, 2016	$	4	$	7,742	$	(1,155	)	$	6	$	6,597
Net income	—		—		325			—		325
Effects of stock-based incentive compensation plans	—		13		—			—		13
Balance at September 30, 2017	$	4	$	7,755	$	(830	)	$	6	$	6,935

________________


(a)	Authorized shares totaled 1,800,000,000 at September 30, 2017. Outstanding shares totaled 427,597,368 and 427,580,232 at September 30, 2017 and December 31, 2016, respectively.

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Schedule of assets and liabilities measured at fair value on a recurring basis

Assets and liabilities measured at fair value on a recurring basis consisted of the following at the respective balance sheet dates shown below:



September 30, 2018
	Level 1		Level 2		Level 3 (a)		Reclassification (b)		Total
Assets:
Commodity contracts	$	192	$	143	$	148	$	65	$	548
Interest rate swaps	—		175		—		—		175
Nuclear decommissioning trust – equity securities (c)	519		—		—		—		519
Nuclear decommissioning trust – debt securities (c)	—		433		—		—		433
Sub-total	$	711	$	751	$	148	$	65	1,675
Assets measured at net asset value (d):
Nuclear decommissioning trust – equity securities (c)									322
Total assets									$	1,997
Liabilities:
Commodity contracts	$	273	$	501	$	392	$	65	$	1,231
Interest rate swaps	—		4		—		—		4
Total liabilities	$	273	$	505	$	392	$	65	$	1,235



December 31, 2017
	Level 1		Level 2		Level 3 (a)		Reclassification (b)		Total
Assets:
Commodity contracts	$	47	$	98	$	75	$	2	$	222
Interest rate swaps	—		18		—		8		26
Nuclear decommissioning trust – equity securities (c)	468		—		—		—		468
Nuclear decommissioning trust – debt securities (c)	—		430		—		—		430
Sub-total	$	515	$	546	$	75	$	10	1,146
Assets measured at net asset value (d):
Nuclear decommissioning trust – equity securities (c)									290
Total assets									$	1,436
Liabilities:
Commodity contracts	$	45	$	143	$	128	$	2	$	318
Interest rate swaps	—		—		—		8		8
Total liabilities	$	45	$	143	$	128	$	10	$	326

____________


(a)	See table below for description of Level 3 assets and liabilities.


(b)	Fair values are determined on a contract basis, but certain contracts result in a current asset and a noncurrent liability, or vice versa, as presented in our condensed consolidated balance sheets.


(c)	The nuclear decommissioning trust investment is included in the other investments line in our condensed consolidated balance sheets. See Note 20.


(d)	The fair value amounts presented in this line are intended to permit reconciliation of the fair value hierarchy to the amounts presented in our condensed consolidated balance sheets. Certain investments measured at fair value using the net asset value per share (or its equivalent) have not been classified in the fair value hierarchy.

Schedule of fair value of the Level 3 assets and liabilities by major contract type (all related to commodity contracts) and the significant unobservable inputs used in the valuations

The following tables present the fair value of the Level 3 assets and liabilities by major contract type and the significant unobservable inputs used in the valuations at September 30, 2018 and December 31, 2017:



September 30, 2018
	Fair Value
Contract Type (a)	Assets		Liabilities			Total			Valuation Technique	Significant Unobservable Input	Range (b)
Electricity purchases and sales	$	11	$	(173	)	$	(162	)	Valuation Model	Hourly price curve shape (c)	$0 to $90/ MWh
										Illiquid delivery periods for ERCOT hub power prices and heat rates (d)	$20 to $120/ MWh
Electricity and weather options	15		(161		)	(146		)	Option Pricing Model	Gas to power correlation (e)	15% to 95%
										Power volatility (e)	5% to 435%
Financial transmission rights	86		(19		)	67			Market Approach (f)	Illiquid price differences between settlement points (g)	$(10) to $50/ MWh
Other (h)	36		(39		)	(3		)
Total	$	148	$	(392	)	$	(244	)



December 31, 2017
	Fair Value
Contract Type (a)	Assets		Liabilities			Total			Valuation Technique	Significant Unobservable Input	Range (b)
Electricity purchases and sales	$	12	$	(33	)	$	(21	)	Valuation Model	Hourly price curve shape (c)	$0 to $40/ MWh
										Illiquid delivery periods for ERCOT hub power prices and heat rates (d)	$20 to $70/ MWh
Electricity and weather options	10		(91		)	(81		)	Option Pricing Model	Gas to power correlation (e)	30% to 100%
										Power volatility (e)	5% to 180%
Financial transmission rights	45		(4		)	41			Market Approach (f)	Illiquid price differences between settlement points (g)	$0 to $15/ MWh
Other (h)	8		—			8
Total	$	75	$	(128	)	$	(53	)

____________

(a)

Electricity purchase and sales contracts include power and heat rate positions in ERCOT, PJM, NYISO, ISO-NE and MISO regions. The forward purchase contracts (swaps and options) used to hedge electricity price differences between settlement points are referred to as congestion revenue rights contracts in ERCOT and financial transmission rights in PJM, NYISO, ISO-NE and MISO regions. Electricity options consist of physical electricity options and spread options.


(b)	The range of the inputs may be influenced by factors such as time of day, delivery period, season and location.


(c)	Primarily based on the historical range of forward average hourly ERCOT North Hub prices.


(d)	Primarily based on historical forward ERCOT power price and heat rate variability.


(e)	Based on historical forward correlation and volatility within ERCOT.


(f)	While we use the market approach, there is insufficient market data to consider the valuation liquid.


(g)	Primarily based on the historical price differences between settlement points within ERCOT hubs and load zones.


(h)	Other includes contracts for natural gas, coal options and emissions.

Schedule of changes in fair value of the Level 3 assets and liabilities

The following table presents the changes in fair value of the Level 3 assets and liabilities for the three and nine months ended September 30, 2018 and 2017.



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Net asset (liability) balance at beginning of period	$	(222	)	$	75		$	(53	)	$	83
Total unrealized valuation gains (losses)	(102		)	132			(333		)	139
Purchases, issuances and settlements (a):
Purchases	41			16			99			51
Issuances	(14		)	(5		)	(22		)	(19		)
Settlements	58			(45		)	104			(87		)
Transfers into Level 3 (b)	1			—			3			4
Transfers out of Level 3 (b)	(6		)	—			(5		)	2
Net liabilities assumed in connection with the Merger (Note 2)	—			—			(37		)	—
Earn-out provision	—			(16		)	—			(16		)
Net change (c)	(22		)	82			(191		)	74
Net asset (liability) balance at end of period	$	(244	)	$	157		$	(244	)	$	157
Unrealized valuation gains (losses) relating to instruments held at end of period	$	(120	)	$	106		$	(273	)	$	110

____________


(a)	Settlements reflect reversals of unrealized mark-to-market valuations previously recognized in net income. Purchases and issuances reflect option premiums paid or received.


(b)	Includes transfers due to changes in the observability of significant inputs. All Level 3 transfers during the periods presented are in and out of Level 2.


(c)	Activity excludes change in fair value in the month positions settle. Substantially all changes in value of commodity contracts (excluding net liabilities assumed in connection with the Merger) are reported as operating revenues in our condensed statements of consolidated income (loss).

Commodity and Other Derivative Contractual Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of commodity and other derivative contractual assets and liabilities as reported in the balance sheets

Substantially all derivative contractual assets and liabilities are accounted for under mark-to-market accounting consistent with accounting standards related to derivative instruments and hedging activities. The following tables provide detail of derivative contractual assets and liabilities as reported in our condensed consolidated balance sheets at September 30, 2018 and December 31, 2017. Derivative asset and liability totals represent the net value of the contract, while the balance sheet totals represent the gross value of the contract.



	September 30, 2018
	Derivative Assets					Derivative Liabilities
	Commodity Contracts			Interest Rate Swaps		Commodity Contracts			Interest Rate Swaps			Total
Current assets	$	432		$	25	$	1		$	—		$	458
Noncurrent assets	67			150		48			—			265
Current liabilities	(6		)	—		(973		)	(2		)	(981		)
Noncurrent liabilities	(10		)	—		(242		)	(2		)	(254		)
Net assets (liabilities)	$	483		$	175	$	(1,166	)	$	(4	)	$	(512	)



	December 31, 2017
	Derivative Assets					Derivative Liabilities
	Commodity Contracts		Interest Rate Swaps			Commodity Contracts			Interest Rate Swaps			Total
Current assets	$	190	$	—		$	—		$	—		$	190
Noncurrent assets	30		22			2			4			58
Current liabilities	—		(4		)	(216		)	(4		)	(224		)
Noncurrent liabilities	—		—			(102		)	—			(102		)
Net assets (liabilities)	$	220	$	18		$	(316	)	$	—		$	(78	)

Schedule of pretax effect on net income of derivatives not under hedge accounting, including realized and unrealized effects

The following table presents the pretax effect of derivative gains (losses) on net income, including realized and unrealized effects. Amount represents changes in fair value of positions in the derivative portfolio during the period, as realized amounts related to positions settled are assumed to equal reversals of previously recorded unrealized amounts.



Derivative (condensed statements of consolidated income (loss) presentation)	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Commodity contracts (Operating revenues)	$	(278	)	$	166		$	(655	)	$	333
Commodity contracts (Fuel, purchased power costs and delivery fees)	21			9			32			3
Interest rate swaps (Interest expense and related charges)	38			(4		)	115			(24		)
Net gain (loss)	$	(219	)	$	171		$	(508	)	$	312

Offsetting assets and liabilities

The following tables reconcile our derivative assets and liabilities on a contract basis to net amounts after taking into consideration netting arrangements with counterparties and financial collateral:



	September 30, 2018												December 31, 2017
	Derivative Assets and Liabilities			Offsetting Instruments (a)			Cash Collateral (Received) Pledged (b)			Net Amounts			Derivative Assets and Liabilities			Offsetting Instruments (a)			Cash Collateral (Received) Pledged (b)			Net Amounts
Derivative assets:
Commodity contracts	$	483		$	(338	)	$	(1	)	$	144		$	220		$	(113	)	$	(1	)	$	106
Interest rate swaps	175			(4		)	—			171			18			—			—			18
Total derivative assets	658			(342		)	(1		)	315			238			(113		)	(1		)	124
Derivative liabilities:
Commodity contracts	(1,166		)	338			92			(736		)	(316		)	113			1			(202		)
Interest rate swaps	(4		)	4			—			—			—			—			—			—
Total derivative liabilities	(1,170		)	342			92			(736		)	(316		)	113			1			(202		)
Net amounts	$	(512	)	$	—		$	91		$	(421	)	$	(78	)	$	—		$	—		$	(78	)

____________


(a)	Amounts presented exclude trade accounts receivable and payable related to settled financial instruments.


(b)	Represents cash amounts received or pledged pursuant to a master netting arrangement, including fair value-based margin requirements and, to a lesser extent, initial margin requirements.

Schedule of gross notional amounts of derivative volumes

The following table presents the gross notional amounts of derivative volumes at September 30, 2018 and December 31, 2017:



	September 30, 2018		December 31, 2017
Derivative type	Notional Volume				Unit of Measure
Natural gas (a)	5,264		1,259		Million MMBtu
Electricity	246,262		114,129		GWh
Financial Transmission Rights (b)	176,207		110,913		GWh
Coal	47		2		Million U.S. tons
Fuel oil	4		5		Million gallons
Uranium	100		325		Thousand pounds
Emissions	25		—		Million tons
Interest rate swaps – floating/fixed (c)	$	7,718	$	3,000	Million U.S. dollars

____________


(a)	Represents gross notional forward sales, purchases and options transactions, locational basis swaps and other natural gas transactions.


(b)	Represents gross forward purchases associated with instruments used to hedge electricity price differences between settlement points within ISOs.


(c)	Includes notional amounts of interest rate swaps with maturity dates through July 2026.

The following table presents the commodity derivative liabilities subject to credit risk-related contingent features that are not fully collateralized:



	September 30, 2018			December 31, 2017
Fair value of derivative contract liabilities (a)	$	(629	)	$	(204	)
Offsetting fair value under netting arrangements (b)	161			103
Cash collateral and letters of credit	222			41
Liquidity exposure	$	(246	)	$	(60	)

____________


(a)	Excludes fair value of contracts that contain contingent features that do not provide specific amounts to be posted if features are triggered, including provisions that generally provide the right to request additional collateral (material adverse change, performance assurance and other clauses).


(b)	Amounts include the offsetting fair value of in-the-money derivative contracts and net accounts receivable under master netting arrangements.

Pension and Other Postretirement Employee Benefit (OPEB) Plans (Tables)

9 Months Ended

Sep. 30, 2018

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

For the three and nine months ended September 30, 2018, net periodic benefit costs consisted of the following:



	Pension Benefits										OPEB Benefits
	Three Months Ended September 30,					Nine Months Ended September 30,					Three Months Ended September 30,				Nine Months Ended September 30,
	2018			2017		2018			2017		2018		2017		2018		2017
Service cost	$	5		$	1	$	10		$	4	$	1	$	—	$	2	$	1
Other costs	(1		)	—		(1		)	—		1		1		3		3
Net periodic benefit cost	$	4		$	1	$	9		$	4	$	2	$	1	$	5	$	4

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation Awards Assumed In Merger [Table Text Block]

At the Merger Date, Dynegy stock options and equity-based awards outstanding immediately prior to the Merger Date were generally automatically converted upon completion of the Merger into stock options and equity-based awards, respectively, with respect to Vistra Energy's common stock, after giving effect to the Exchange Ratio.



Instrument Type	Dynegy Awards Prior to the Merger Date	Vistra Awards Converted at the Merger Date	Fair Value of Awards (a)
Stock Options	4,096,027	2,670,610	$	10
Restricted Stock Units	5,718,148	3,056,689	61
Performance Units	1,538,133	938,721	18
Total			$	89

____________

(a)

$26 million was attributable to pre-combination service and considered part of the purchase price (see Note 2). $33 million was recognized immediately as compensation expense due to accelerated vesting as a result of the Merger. $30 million will be amortized as compensation expense over the remaining service period and will be recorded in additional paid in capital in the condensed consolidated balance sheets.

Segment Information (Tables)

9 Months Ended

Sep. 30, 2018

Segment Reporting [Abstract]

Schedule of segment reporting information, by segment

.



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Operating revenues (a)
Retail	$	1,813		$	1,286		$	4,239		$	3,136
ERCOT	1,396			891			2,190			1,994
PJM	620			—			1,104			—
NY/NE	301			—			487			—
MISO	230			—			488			—
Asset Closure	(1		)	312			48			763
Corporate and Other (b)	91			—			123			—
Eliminations	(1,207		)	(656		)	(2,098		)	(1,406		)
Consolidated operating revenues	$	3,243		$	1,833		$	6,581		$	4,487



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Depreciation and amortization
Retail	$	(80	)	$	(108	)	$	(237	)	$	(322	)
ERCOT	(122		)	(59		)	(295		)	(166		)
PJM	(141		)	—			(266		)	—
NY/NE	(55		)	—			(104		)	—
MISO	(3		)	—			(6		)	—
Asset Closure	—			(1		)	—			(1		)
Corporate and Other (b)	(25		)	(10		)	(60		)	(30		)
Eliminations	—			—			1			—
Consolidated depreciation and amortization	$	(426	)	$	(178	)	$	(967	)	$	(519	)
Operating income (loss)
Retail (c)	$	(83	)	$	(3	)	$	371		$	54
ERCOT	643			406			234			555
PJM	61			—			85			—
NY/NE	45			—			36			—
MISO	(2		)	—			30			—
Asset Closure	(4		)	63			(26		)	96
Corporate and Other (b)	(8		)	(15		)	(244		)	(47		)
Eliminations	(2		)	1			(1		)	—
Consolidated operating income	$	650		$	452		$	485		$	658
Net income (loss)
Retail (c)	$	(86	)	$	7		$	397		$	77
ERCOT	643			405			236			552
PJM	62			—			86			—
NY/NE	47			—			41			—
MISO	(3		)	—			29			—
Asset Closure	(4		)	64			(24		)	101
Corporate and Other (b)	(328		)	(203		)	(635		)	(405		)
Consolidated net income	$	331		$	273		$	130		$	325

____________


(a)	The following unrealized net gains (losses) from mark-to-market valuations of commodity positions are included in operating revenues:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Retail	$	(24	)	$	2		$	(11	)	$	11
ERCOT	192			226			(207		)	375
PJM	(28		)	—			(38		)	—
NY/NE	(7		)	—			(32		)	—
MISO	(34		)	—			(4		)	—
Corporate and Other (b)	3			—			4			—
Eliminations (1)	(130		)	(89		)	49			(171		)
Consolidated unrealized net gains (losses) from mark-to-market valuations of commodity positions included in operating revenues	$	(28	)	$	139		$	(239	)	$	215

____________


(1)	Amounts offset in fuel, purchased power costs and delivery fees in the Retail segment, with no impact to consolidated results.


(b)	Other includes CAISO operations. Income tax expense is not reflected in net income of the segments but is reflected entirely in Corporate net income.


(c)	Retail operating loss and net loss is driven by unrealized losses from mark-to-market valuations of commodity positions included in fuel, purchased power costs and delivery fees.



	September 30, 2018			December 31, 2017
Total assets
Retail	$	7,365		$	6,156
ERCOT	9,101			6,834
PJM	6,796			—
NY/NE	2,705			—
MISO	945			—
Asset Closure	237			235
Corporate and Other and Eliminations	(1,261		)	1,375
Consolidated total assets	$	25,888		$	14,600

Supplementary Financial Information (Tables)

9 Months Ended

Sep. 30, 2018

Supplementary Financial Information [Abstract]

Schedule of interest expense and related charges

Interest Expense and Related Charges



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Interest paid/accrued	$	164		$	52		$	380		$	157
Unrealized mark-to-market net (gains) losses on interest rate swaps	(38		)	(3		)	(123		)	3
Losses on extinguishment of debt and amortization of debt issuance costs, discounts and premiums	27			2			31			2
Reversal of debt extinguishment gain	—			21			—			—
Capitalized interest	(3		)	(1		)	(10		)	(5		)
Other	4			5			13			12
Total interest expense and related charges	$	154		$	76		$	291		$	169

Schedule of other income and deductions

Other Income and Deductions



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Other income:
Office space sublease rental income (a)	$	2	$	3	$	6	$	9
Mineral rights royalty income (b)	—		1		—		3
Sale of land (b)	—		1		1		4
Interest income	3		4		14		10
All other	1		1		4		3
Total other income	$	6	$	10	$	25	$	29
Other deductions:
Other	1		—		$	4	$	5
Total other deductions	$	1	$	—	$	4	$	5

____________


(a)	Reported in Corporate and Other non-segment.


(b)	Reported in ERCOT segment.

Schedule of restricted cash

Restricted Cash



	September 30, 2018				December 31, 2017
	Current Assets		Noncurrent Assets		Current Assets		Noncurrent Assets
Amounts related to the Vistra Operations Credit Facilities (Note 11)	$	—	$	—	$	—	$	500
Amounts related to restructuring escrow accounts	59		—		59		—
Total restricted cash	$	59	$	—	$	59	$	500

Schedule of accounts, notes, loans and financing receivable

Trade Accounts Receivable



	September 30, 2018			December 31, 2017
Wholesale and retail trade accounts receivable	$	1,268		$	596
Allowance for uncollectible accounts	(25		)	(14		)
Trade accounts receivable — net	$	1,243		$	582

Allowance for Uncollectible Accounts Receivable



	Nine Months Ended September 30,
	2018			2017
Allowance for uncollectible accounts receivable at beginning of period	$	14		$	10
Increase for bad debt expense	41			35
Decrease for account write-offs	(30		)	(24		)
Allowance for uncollectible accounts receivable at end of period	$	25		$	21

Schedule of inventories by major category

Inventories by Major Category



	September 30, 2018		December 31, 2017
Materials and supplies	$	279	$	149
Fuel stock	108		83
Natural gas in storage	6		21
Total inventories	$	393	$	253

Summary of other investments

Investments



	September 30, 2018		December 31, 2017
Nuclear plant decommissioning trust	$	1,274	$	1,188
Assets related to employee benefit plans (Note 16)	34		—
Land	49		49
Miscellaneous other	—		3
Total investments	$	1,357	$	1,240

Summary of investments in the fund



	September 30, 2018
	Cost (a)		Unrealized gain		Unrealized loss			Fair market value
Debt securities (b)	$	437	$	5	$	(9	)	$	433
Equity securities (c)	277		564		—			841
Total	$	714	$	569	$	(9	)	$	1,274



	December 31, 2017
	Cost (a)		Unrealized gain		Unrealized loss			Fair market value
Debt securities (b)	$	418	$	14	$	(2	)	$	430
Equity securities (c)	265		495		(2		)	758
Total	$	683	$	509	$	(4	)	$	1,188

____________


(a)	Includes realized gains and losses on securities sold.

(b)

The investment objective for debt securities is to invest in a diversified tax efficient portfolio with an overall portfolio rating of AA or above as graded by S&P or Aa2 by Moody's. The debt securities are heavily weighted with government and municipal bonds and investment grade corporate bonds. The debt securities had an average coupon rate of 3.73% and 3.55% at September 30, 2018 and December 31, 2017, respectively, and an average maturity of nine years at both September 30, 2018 and December 31, 2017.


(c)	The investment objective for equity securities is to invest tax efficiently and to match the performance of the S&P 500 Index for U.S. equity investments and the MSCI Inc. EAFE Index for non-U.S. equity investments.

Summary of proceeds from sales of available-for-sale securities and the related realized gains and losses from such sales

The following table summarizes proceeds from sales of available-for-sale securities and the related realized gains and losses from such sales.



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Realized gains	$	(1	)	$	1		$	—		$	3
Realized losses	$	1		$	(1	)	$	(2	)	$	(3	)
Proceeds from sales of securities	$	118		$	56		$	211		$	154
Investments in securities	$	(124	)	$	(62	)	$	(227	)	$	(169	)

Schedule of asset retirement and mining reclamation obligations

The following table summarizes the changes to these obligations, reported as asset retirement obligations (current and noncurrent liabilities) in our condensed consolidated balance sheets, for the nine months ended September 30, 2018:



	Nuclear Plant Decommissioning		Mining Land Reclamation			Coal Ash and Other			Total
Liability at December 31, 2017	$	1,233	$	438		$	265		$	1,936
Additions:
Accretion	32		16			20			68
Adjustment for change in estimates	—		7			(47		)	(40		)
Obligations assumed in the Merger	—		2			424			426
Reductions:
Payments	—		(57		)	(11		)	(68		)
Liability at September 30, 2018	1,265		406			651			2,322
Less amounts due currently	—		(124		)	(59		)	(183		)
Noncurrent liability at September 30, 2018	$	1,265	$	282		$	592		$	2,139

Schedule of other noncurrent liabilities and deferred credits

Other Noncurrent Liabilities and Deferred Credits

The balance of other noncurrent liabilities and deferred credits consists of the following:



	September 30, 2018		December 31, 2017
Uncertain tax positions, including accrued interest	$	12	$	—
Other, including retirement and other employee benefits	334		220
Total other noncurrent liabilities and deferred credits	$	346	$	220

Schedule of fair value of debt

Fair Value of Debt



		September 30, 2018				December 31, 2017
Debt:	Fair Value Hierarchy	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt under the Vistra Operations Credit Facilities (Note 11)	Level 2	$	5,823	$	5,836	$	4,323	$	4,334
Vistra Operations Senior Notes (Note 11)	Level 2	1,000		1,010		—		—
Vistra Energy Senior Notes (Note 11)	Level 2	3,954		3,945		—		—
7.000% Amortizing Notes (Note 11)	Level 2	31		32		—		—
Forward Capacity Agreements (Note 11)	Level 3	221		221		—		—
Equipment Financing Agreements (Note 11)	Level 3	119		119		—		—
Mandatorily redeemable subsidiary preferred stock (Note 11)	Level 2	70		70		70		70
Building Financing (Note 11)	Level 2	23		21		30		27

Schedule of cash, cash equivalents and restricted cash

The following table reconciles cash, cash equivalents and restricted cash reported in our condensed statements of consolidated cash flows to the amounts reported in our condensed balance sheets at September 30, 2018 and December 31, 2017:



	September 30, 2018		December 31, 2017
Cash and cash equivalents	$	811	$	1,487
Restricted cash included in current assets	59		59
Restricted cash included in noncurrent assets	—		500
Total cash, cash equivalents and restricted cash	$	870	$	2,046

Schedule of supplemental cash flow information

The following table summarizes our supplemental cash flow information for the nine months ended September 30, 2018 and 2017:



	Nine Months Ended September 30,
	2018			2017
Cash payments related to:
Interest paid	$	662		$	197
Capitalized interest	(10		)	(5		)
Interest paid (net of capitalized interest)	$	652		$	192
Income taxes	$	66		$	51
Noncash investing and financing activities:
Construction expenditures (a)	$	58		$	16
Vistra Energy common stock issued in the Merger (Notes 2 and 13)	$	2,245		$	—

____________


(a)	Represents end-of-period accruals for ongoing construction projects.

Supplemental Condensed Consolidating Financial Information (Tables)

9 Months Ended

Sep. 30, 2018

Supplemental Condensed Consolidating Financial Information [Abstract]

Condensed Statements of Consolidating Income (Loss)

Condensed Statements of Consolidating Income (Loss) for the Three Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Operating revenues	$	—		$	3,208		$	59		$	(24	)	$	3,243
Fuel, purchased power costs and delivery fees	—			(1,590		)	(37		)	—			(1,627		)
Operating costs	—			(334		)	(12		)	—			(346		)
Depreciation and amortization	—			(402		)	(24		)	—			(426		)
Selling, general and administrative expenses	(23		)	(165		)	(30		)	24			(194		)
Operating income (loss)	(23		)	717			(44		)	—			650
Other income	1			7			—			(2		)	6
Other deductions	—			(1		)	—			—			(1		)
Interest expense and related charges	(110		)	(43		)	(3		)	2			(154		)
Impacts of Tax Receivable Agreement	17			—			—			—			17
Equity in earnings of unconsolidated investment	—			7			—			—			7
Income (loss) before income taxes	(115		)	687			(47		)	—			525
Income tax expense	42			(251		)	15			—			(194		)
Equity in earnings (loss) of subsidiaries, net of tax	403			(33		)	—			(370		)	—
Net income (loss)	330			403			(32		)	(370		)	331
Net loss attributable to noncontrolling interest	—			—			1			—			1
Net income (loss) attributable to Vistra Energy	$	330		$	403		$	(33	)	$	(370	)	$	330

Condensed Statements of Consolidating Income (Loss) for the Three Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Operating revenues	$	—		$	1,833		$	—	$	—		$	1,833
Fuel, purchased power costs and delivery fees	—			(838		)	—		—			(838		)
Operating costs	—			(218		)	—		—			(218		)
Depreciation and amortization	—			(178		)	—		—			(178		)
Selling, general and administrative expenses	(7		)	(140		)	—		—			(147		)
Operating income (loss)	(7		)	459			—		—			452
Other income	2			8			—		—			10
Other deductions	—			—			—		—			—
Interest expense and related charges	—			(76		)	—		—			(76		)
Impacts of Tax Receivable Agreement	138			—			—		—			138
Income before income taxes	133			391			—		—			524
Income tax expense	(62		)	(189		)	—		—			(251		)
Equity in loss of subsidiaries, net of tax	202			—			—		(202		)	—
Net income (loss)	$	273		$	202		$	—	$	(202	)	$	273

Condensed Statements of Consolidating Income (Loss) for the Nine Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Operating revenues	$	—		$	6,480		$	126		$	(25	)	$	6,581
Fuel, purchased power costs and delivery fees	—			(3,405		)	(89		)	2			(3,492		)
Operating costs	—			(898		)	(28		)	—			(926		)
Depreciation and amortization	—			(926		)	(41		)	—			(967		)
Selling, general and administrative expenses	(250		)	(452		)	(32		)	23			(711		)
Operating income (loss)	(250		)	799			(64		)	—			485
Other income	8			19			—			(2		)	25
Other deductions	—			(5		)	1			—			(4		)
Interest expense and related charges	(197		)	(92		)	(4		)	2			(291		)
Impacts of Tax Receivable Agreement	(65		)	—			—			—			(65		)
Equity in earnings of unconsolidated investment	—			11			—			—			11
Income (loss) before income taxes	(504		)	732			(67		)	—			161
Income tax expense	183			(235		)	21			—			(31		)
Equity in earnings (loss) of subsidiaries, net of tax	453			(44		)	—			(409		)	—
Net income (loss)	132			453			(46		)	(409		)	130
Net income attributable to noncontrolling interest	—			—			(2		)	—			(2		)
Net income (loss) attributable to Vistra Energy	$	132		$	453		$	(44	)	$	(409	)	$	132

Condensed Statements of Consolidating Income (Loss) for the Nine Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Operating revenues	$	—		$	4,487		$	—	$	—		$	4,487
Fuel, purchased power costs and delivery fees	—			(2,250		)	—		—			(2,250		)
Operating costs	—			(626		)	—		—			(626		)
Depreciation and amortization	—			(519		)	—		—			(519		)
Selling, general and administrative expenses	(20		)	(414		)	—		—			(434		)
Operating income (loss)	(20		)	678			—		—			658
Other income	2			27			—		—			29
Other deductions	—			(5		)	—		—			(5		)
Interest expense and related charges	—			(169		)	—		—			(169		)
Impacts of Tax Receivable Agreement	96			—			—		—			96
Income before income taxes	78			531			—		—			609
Income tax expense	(36		)	(248		)	—		—			(284		)
Equity in earnings of subsidiaries, net of tax	283			—			—		(283		)	—
Net income (loss)	$	325		$	283		$	—	$	(283	)	$	325

Condensed Statements of Consolidating Other Comprehensive Income (Loss)

Condensed Statements of Consolidating Comprehensive Income (Loss) for the Three Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net income (loss)	$	330	$	403	$	(32	)	$	(370	)	$	331
Other comprehensive income (loss), net of tax effects:
Effect related to pension and other retirement benefit obligations	—		1		—			—			1
Total other comprehensive income	—		1		—			—			1
Comprehensive income (loss)	330		404		(32		)	(370		)	332
Comprehensive loss attributable to noncontrolling interest	—		—		1			—			1
Comprehensive income (loss) attributable to Vistra Energy	$	330	$	404	$	(33	)	$	(370	)	$	331

Condensed Statements of Consolidating Comprehensive Income (Loss) for the Three Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Net income (loss)	$	273	$	202	$	—	$	(202	)	$	273
Other comprehensive income (loss), net of tax effects:
Effect related to pension and other retirement benefit obligations	—		—		—		—			—
Total other comprehensive income	—		—		—		—			—
Comprehensive income (loss)	$	273	$	202	$	—	$	(202	)	$	273

Condensed Statements of Consolidating Comprehensive Income (Loss) for the Nine Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net income (loss)	$	132	$	453	$	(46	)	$	(409	)	$	130
Other comprehensive income (loss), net of tax effects:
Effect related to pension and other retirement benefit obligations	—		2		—			—			2
Total other comprehensive income	—		2		—			—			2
Comprehensive income (loss)	132		455		(46		)	(409		)	132
Comprehensive income attributable to noncontrolling interest	—		—		(2		)	—			(2		)
Comprehensive income (loss) attributable to Vistra Energy	$	132	$	455	$	(44	)	$	(409	)	$	134

Condensed Statements of Consolidating Comprehensive Income (Loss) for the Nine Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Net income (loss)	$	325	$	283	$	—	$	(283	)	$	325
Other comprehensive income (loss), net of tax effects:
Effect related to pension and other retirement benefit obligations	—		—		—		—			—
Total other comprehensive income	—		—		—		—			—
Comprehensive income (loss)	$	325	$	283	$	—	$	(283	)	$	325

Condensed Statements of Consolidating Cash Flows

Condensed Statements of Consolidating Cash Flows for the Nine Months Ended September 30, 2018

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Cash flows — operating activities:
Cash provided by (used in) operating activities	$	521		$	670		$	(328	)	$	—		$	863
Cash flows — financing activities:
Issuances of long-term debt	—			1,000			—			—			1,000
Repayments/repurchases of debt	(4,918		)	2,016			—			—			(2,902		)
Borrowings under accounts receivable securitization program	—			—			350						350
Cash dividend paid	—			(3,928		)	—			3,928			—
Stock repurchase	(414		)	—			—			—			(414		)
Debt tender offer and other financing fees	(173		)	(43		)	—			—			(216		)
Other, net	10			—			—			—			10
Cash provided by (used in) financing activities	(5,495		)	(955		)	350			3,928			(2,172		)
Cash flows — investing activities:
Capital expenditures	(12		)	(191		)	(6		)	—			(209		)
Nuclear fuel purchases	—			(66		)	—			—			(66		)
Cash acquired in the Merger	—			445			—			—			445
Solar development expenditures	—			(28		)	—			—			(28		)
Proceeds from sales of nuclear decommissioning trust fund securities	—			211			—			—			211
Investments in nuclear decommissioning trust fund securities	—			(227		)	—			—			(227		)
Dividend received from subsidiaries	3,928									(3,928		)	—
Other, net	—			10			(3		)	—			7
Cash provided by (used in) investing activities	3,916			154			(9		)	(3,928		)	133
Net change in cash, cash equivalents and restricted cash	(1,058		)	(131		)	13			—			(1,176		)
Cash, cash equivalents and restricted cash — beginning balance	1,183			863			—			—			2,046
Cash, cash equivalents and restricted cash — ending balance	$	125		$	732		$	13		$	—		$	870

Condensed Statements of Consolidating Cash Flows for the Nine Months Ended September 30, 2017

(Millions of Dollars)



	Parent (Issuer)			Guarantor Subsidiaries			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Cash flows — operating activities:
Cash provided by (used in) operating activities	$	(39	)	$	884		$	—	$	—		$	845
Cash flows — financing activities:
Repayments/repurchases of debt	—			(32		)	—		—			(32		)
Cash dividend paid	—			(537		)	—		537			—
Debt financing fees	—			(5		)	—		—			(5		)
Cash provided by (used in) financing activities	—			(574		)	—		537			(37		)
Cash flows — investing activities:
Capital expenditures	—			(86		)	—		—			(86		)
Nuclear fuel purchases	—			(56		)	—		—			(56		)
Solar development expenditures	—			(129		)	—		—			(129		)
Odessa acquisition	—			(355		)	—		—			(355		)
Proceeds from sales of nuclear decommissioning trust fund securities	—			154			—		—			154
Investments in nuclear decommissioning trust fund securities	—			(169		)	—		—			(169		)
Dividend received from subsidiaries	537			—			—		(537		)	—
Other, net	—			10			—		—			10
Cash provided by (used in) investing activities	537			(631		)	—		(537		)	(631		)
Net change in cash, cash equivalents and restricted cash	498			(321		)	—		—			177
Cash, cash equivalents and restricted cash — beginning balance	26			1,562			—		—			1,588
Cash, cash equivalents and restricted cash — ending balance	$	524		$	1,241		$	—	$	—		$	1,765

Condensed Consolidating Balance Sheets

Condensed Consolidating Balance Sheet as of September 30, 2018 (Millions of Dollars)

	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
ASSETS
Current assets:
Cash and cash equivalents	$	66	$	732	$	13	$	—		$	811
Restricted cash	59		—		—		—			59
Advances to affiliates	11		—		—		(11		)	—
Trade accounts receivable — net	9		875		359		—			1,243
Accounts receivable — affiliates	15		—		211		(226		)	—
Notes due from affiliates	—		101		—		(101		)	—
Income taxes receivable	12		—		—		—			12
Inventories	—		378		15		—			393
Commodity and other derivative contractual assets	—		458		—		—			458
Margin deposits related to commodity contracts	—		177		—		—			177
Prepaid expense and other current assets	2		117		4		—			123
Total current assets	174		2,838		602		(338		)	3,276
Investments	—		1,323		34		—			1,357
Investment in unconsolidated subsidiary	—		135		—		—			135
Investment in affiliated companies	11,631		362		—		(11,993		)	—
Property, plant and equipment — net	18		14,058		680		—			14,756
Goodwill	—		1,907		—		—			1,907
Identifiable intangible assets — net	—		2,711		—		—			2,711
Commodity and other derivative contractual assets	—		265		—		—			265
Accumulated deferred income taxes	955		239		—		(141		)	1,053
Other noncurrent assets	240		185		2		1			428
Total assets	$	13,018	$	24,023	$	1,318	$	(12,471	)	$	25,888
LIABILITIES AND EQUITY
Current liabilities:
Accounts receivable securitization program	$	—	$	—	$	350	$	—		$	350
Advances from affiliates	—		2		8		(10		)	—
Long-term debt due currently	31		145		5		—			181
Trade accounts payable	3		587		222		—			812
Accounts payable — affiliates	—		215		8		(223		)	—
Notes due to affiliates	—		—		101		(101		)	—
Commodity and other derivative contractual liabilities	—		981		—		—			981
Margin deposits related to commodity contracts	—		4		—		—			4
Accrued taxes other than income	—		138		1		—			139
Accrued interest	107		16		3		(3		)	123
Asset retirement obligations	—		183		—		—			183
Other current liabilities	96		231		2		—			329
Total current liabilities	237		2,502		700		(337		)	3,102

Condensed Consolidating Balance Sheet as of September 30, 2018 (Millions of Dollars)

	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Long-term debt, less amounts due currently	3,954		7,073		33		—			11,060
Commodity and other derivative contractual liabilities	—		254		—		—			254
Accumulated deferred income taxes	—		—		146		(141		)	5
Tax Receivable Agreement obligation	402		—		—		—			402
Asset retirement obligations	—		2,126		13		—			2,139
Identifiable intangible liabilities — net	—		132		43		—			175
Other noncurrent liabilities and deferred credits	26		305		15		—			346
Total liabilities	4,619		12,392		950		(478		)	17,483
Total stockholders' equity	8,399		11,631		362		(11,993		)	8,399
Noncontrolling interest in subsidiary	—		—		6		—			6
Total liabilities and equity	$	13,018	$	24,023	$	1,318	$	(12,471	)	$	25,888

Condensed Consolidating Balance Sheet as of December 31, 2017

(Millions of Dollars)



	Parent (Issuer)		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated
ASSETS
Current assets:
Cash and cash equivalents	$	1,124	$	363	$	—	$	—		$	1,487
Restricted cash	59		—		—		—			59
Trade accounts receivable — net	4		578		—		—			582
Inventories	—		253		—		—			253
Commodity and other derivative contractual assets	—		190		—		—			190
Margin deposits related to commodity contracts	—		30		—		—			30
Prepaid expense and other current assets	—		72		—		—			72
Total current assets	1,187		1,486		—		—			2,673
Restricted cash	—		500		—		—			500
Investments	—		1,240		—		—			1,240
Investment in affiliated companies	5,632		—		—		(5,632		)	—
Property, plant and equipment — net	—		4,820		—		—			4,820
Goodwill	—		1,907		—		—			1,907
Identifiable intangible assets — net	—		2,530		—		—			2,530
Commodity and other derivative contractual assets	—		58		—		—			58
Accumulated deferred income taxes	5		705		—		—			710
Other noncurrent assets	6		156		—		—			162
Total assets	$	6,830	$	13,402	$	—	$	(5,632	)	$	14,600
LIABILITIES AND EQUITY
Current liabilities:
Long-term debt due currently	$	—	$	44	$	—	$	—		$	44
Trade accounts payable	11		462		—		—			473
Commodity and other derivative contractual liabilities	—		224		—		—			224
Margin deposits related to commodity contracts	—		4		—		—			4
Accrued taxes	58		—		—		—			58
Accrued taxes other than income	—		136		—		—			136
Accrued interest	—		16		—		—			16
Asset retirement obligations	—		99		—		—			99
Other current liabilities	86		211		—		—			297
Total current liabilities	155		1,196		—		—			1,351
Long-term debt, less amounts due currently	—		4,379		—		—			4,379
Commodity and other derivative contractual liabilities	—		102		—		—			102
Tax Receivable Agreement obligation	333		—		—		—			333
Asset retirement obligations	—		1,837		—		—			1,837
Identifiable intangible liabilities — net	—		36		—		—			36
Other noncurrent liabilities and deferred credits	—		220		—		—			220
Total liabilities	488		7,770		—		—			8,258
Total equity	6,342		5,632		—		(5,632		)	6,342
Total liabilities and equity	$	6,830	$	13,402	$	—	$	(5,632	)	$	14,600

Business And Significant Accounting Policies (Narrative) (Details)	9 Months Ended
	Sep. 30, 2018 Reportable_segment
Accounting Policies [Abstract]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	20.00%
Business and Significant Accounting Policies
Number of reportable segments (in reportable segments)	6

Business And Significant Accounting Policies (Adoption of New Accounting Standards) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Assets [Abstract]
Prepaid expense and other current assets	$ 123		$ 123		$ 77	$ 72
Accumulated deferred income taxes	1,053		1,053		706	710
Other noncurrent assets	428		428		178	162
Retained deficit	(1,261)		(1,261)		(1,393)	(1,410)
Income Statement [Abstract]
Revenues	3,243	$ 1,833	6,581	$ 4,487
Selling, general and administrative expense	(194)	(147)	(711)	(434)
Net income	331	$ 273	130	325
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Assets [Abstract]
Prepaid expense and other current assets	116		116			72
Accumulated deferred income taxes	1,057		1,057			710
Other noncurrent assets	403		403			162
Retained deficit	(1,287)		(1,287)			$ (1,410)
Income Statement [Abstract]
Revenues	3,242		6,578
Selling, general and administrative expense	(196)		(720)
Net income	328		121
Restricted Cash Previously Reported As Source (Use) Of Cash Now Reported In Changes In Cash, Cash Equivalents And Restricted Cash Per ASU 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (Decrease) in Restricted Cash				$ 34
Accounting Standards Update 2014-09 [Member] \| Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Assets [Abstract]
Prepaid expense and other current assets	7		7		5
Accumulated deferred income taxes	(4)		(4)		(4)
Other noncurrent assets	25		25		16
Retained deficit	26		26		$ 17
Income Statement [Abstract]
Revenues	1		3
Selling, general and administrative expense	2		9
Net income	$ 3		$ 9

Merger Transaction and Business Combination Accounting (Merger Summary) (Details) - $ / shares	Apr. 09, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Common stock, par or stated value per share		$ 0.01
Merger agreement, common stock conversion ratio	0.652
Stock issued during period, shares, new issues	94,409,573
Common stock, shares outstanding	522,932,453	507,391,134	428,398,802	427,597,368	427,580,232
Vistra Energy Corp. [Member]
Common stock, par or stated value per share	$ 0.01
Dynegy Inc. [Member]
Common stock, par or stated value per share	$ 0.01
Common stock, shares outstanding	173,000,000

Merger Transaction and Business Combination Accounting (Business Combination Narrative) (Details) - USD ($) $ in Millions		6 Months Ended	9 Months Ended
	Apr. 09, 2018	Sep. 30, 2018	Sep. 30, 2018
Business Combinations [Abstract]
Business Combination, Preliminary Purchase Price	$ 2,273
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment	44
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles	76
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory	(37)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Accumulated Deferred Income Taxes	(19)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Other Noncurrent Assets	(106)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Other Noncurrent Liabilities	$ (47)
Business Combination, Acquisition Related Costs			$ 25
Business Combination, Separately Recognized Transactions, Revenues and Gains Recognized		$ 2,684
Business Combination, Separately Recognized Transactions, Net Gains and Losses		$ 193

Merger Transaction and Business Combination Accounting (Preliminary Purchase Price Allocation) (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 09, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Common stock, shares outstanding	522,932,453	507,391,134	428,398,802	427,597,368	427,580,232
Merger agreement, common stock conversion ratio	0.652
Business Acquisition, Share Price	$ 19.87
Business Combination, Consideration Paid For Acquiree Outstanding Common Stock	$ 2,245
Business Combination, Fair Value Of Outstanding Compensation Awards Attributable To Pre-Combination Service	26
Business Combination, Fair Value Of Outstanding Warrants	2
Preliminary Purchase Price Allocation [Abstract]
Cash and cash equivalents	445
Trade accounts receivables, inventories, prepaid expenses and other current assets	826
Property, plant and equipment	10,406
Accumulated deferred income taxes	372
Identifiable intangible assets	463
Other noncurrent assets	426
Total assets acquired	12,938
Trade accounts payable and other current liabilities	645
Commodity and other derivative contractual assets and liabilities, net	422
Asset retirement obligations, including amounts due currently	426
Long-term debt, including amounts due currently	8,920
Other noncurrent liabilities	245
Total liabilities assumed	10,658
Identifiable net assets acquired	2,280
Noncontrolling interest in subsidiary	7
Total purchase price	2,273
Business Combination, Consideration Transferred	$ 2,273
Dynegy Inc. [Member]
Common stock, shares outstanding	173,000,000
Vistra Energy Corp. [Member]
Business Combination, Acquirer Common Shares Issued In Exchange For Acquireee Common Shares Outstanding	113,000,000

Merger Transaction and Business Combination Accounting (Unaudited Pro Form Financial Information) (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Business Combinations [Abstract]
Revenue	$ 8,032	$ 8,542
Net income (loss)	(64)	316
Net income (loss) attributable to Vistra Energy	$ (61)	$ 318
Net income (loss) attributable to Vistra Energy per weighted average share of common stock outstanding — basic	$ (0.12)	$ 0.56
Net income (loss) attributable to Vistra Energy per weighted average share of common stock outstanding — diluted	$ (0.12)	$ 0.56

Acquisition and Development of Generation Facilities (Odessa Acquisition) (Details) - Odessa-Ector Power Partners, L.P. [Member] - La Frontera Holdings, LLC [Member] $ in Millions	1 Months Ended
	Aug. 31, 2017 USD ($)	Aug. 01, 2017 Megawatt-hour
Electricity Generation Facility Capacity \| Megawatt-hour		1,054
Purchase And Sale Agreement, Aggregate Purchase Price	$ 355
Earn-Out Provision, Initial Fair Value Included In Purchase Price	$ 16

Acquisition and Development of Generation Facilities (Upton Solar Development) (Details) $ in Millions	9 Months Ended		17 Months Ended
	Sep. 30, 2018 USD ($) Megawatt-hour	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Megawatt-hour
Solar development expenditures \| $	$ (28)	$ (129)	$ (218)
Luminant Generation Company LLC [Member] \| Upton County 2 Solar Facility [Member]
Electricity Generation Facility Capacity \| Megawatt-hour	180		180

Acquisition and Development of Generation Facilities (Battery Energy Storage Projects) (Details) - Vistra Energy Corp. [Member] $ in Millions	1 Months Ended	3 Months Ended
	Jun. 30, 2018	Sep. 30, 2018 USD ($) Megawatt-hour
Upton County 2 Solar Facility (Battery Storage Project) [Member] [Member]
Texas Emissions Reduction Plan, Grant Awarded \| $		$ 1
Electricity Generation Facility Capacity		10
Moss Landing Power Plant (Battery Storage Project) [Member]
Electricity Generation Facility Capacity		300
Proposed Contract, Duration, Number Of Years	20 years

Retirement of Generation Facilities (Retirement of Generation Facilities) (Details)	Sep. 30, 2018 Megawatt-hour power_plant
Northeastern Power Cogeneration Facility [Member]
Electricity generation facility capacity retired	51
Killen Station [Member]
Electricity generation facility capacity retired	204
Jointly Owned Utility Plant, Proportionate Ownership Share	33.00%
J.M. Stuart Station [Member]
Electricity generation facility capacity retired	679
Jointly Owned Utility Plant, Proportionate Ownership Share	39.00%
Killen and J.M. Stuart Stations [Member]
Electricity generation facility capacity retired	883
Number Of Electric Generation Plants Retired \| power_plant	2
Monticello Steam Electric Station [Member]
Electricity generation facility capacity retired	1,880
Number of electric generation units retired	3
Sandow Steam Electric Station Units 4 and 5 [Member]
Electricity generation facility capacity retired	1,137
Number of electric generation units retired	2
Big Brown Steam Electric Station [Member]
Electricity generation facility capacity retired	1,150
Number of electric generation units retired	2
Monticello, Sandow and Big Brown Steam Electric Stations [Member]
Electricity generation facility capacity retired	4,167
Number Of Electric Generation Plants Retired \| power_plant	3
Number of electric generation units retired	7

Revenue (Revenue Disaggregated By Major Source) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 38	$ 3	$ 123	$ (3)
Revenue from Contract with Customer, Excluding Assessed Tax	3,641		7,531
Revenues	3,243	1,833	6,581	4,487
Energy Charge In EROCT [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,362		3,423
Energy Charge In Northeast/Midwest [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	442		778
Wholesale Generation Revenue From ISO [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,476		2,589
Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	263		515
Revenue From Other Wholesale Contracts [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	98		226
Retail Contract Amortization [Member]
Disaggregation of Revenue [Line Items]
Revenues	6		(31)
Hedging And Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(404)		(919)
Affiliate Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	0		0
Total Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(398)		(950)
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	93		119
Revenues	(1,116)		(1,975)
Intersegment Eliminations [Member] \| Energy Charge In EROCT [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Intersegment Eliminations [Member] \| Energy Charge In Northeast/Midwest [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Intersegment Eliminations [Member] \| Wholesale Generation Revenue From ISO [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	81		95
Intersegment Eliminations [Member] \| Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	9		20
Intersegment Eliminations [Member] \| Revenue From Other Wholesale Contracts [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3		4
Intersegment Eliminations [Member] \| Retail Contract Amortization [Member]
Disaggregation of Revenue [Line Items]
Revenues	0		0
Intersegment Eliminations [Member] \| Hedging And Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(2)		4
Intersegment Eliminations [Member] \| Affiliate Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	(1,207)	(656)	(2,098)	(1,406)
Intersegment Eliminations [Member] \| Total Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(1,209)		(2,094)
Retail Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,804		4,201
Revenues	1,813	1,286	4,239	3,136
Retail Segment [Member] \| Energy Charge In EROCT [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,362		3,423
Retail Segment [Member] \| Energy Charge In Northeast/Midwest [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	442		778
Retail Segment [Member] \| Wholesale Generation Revenue From ISO [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Retail Segment [Member] \| Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Retail Segment [Member] \| Revenue From Other Wholesale Contracts [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Retail Segment [Member] \| Retail Contract Amortization [Member]
Disaggregation of Revenue [Line Items]
Revenues	15		(12)
Retail Segment [Member] \| Hedging And Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(6)		50
Retail Segment [Member] \| Affiliate Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	0		0
Retail Segment [Member] \| Total Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	9		38
ERCOT Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	465		950
Revenues	1,396	891	2,190	1,994
ERCOT Segment [Member] \| Energy Charge In EROCT [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
ERCOT Segment [Member] \| Energy Charge In Northeast/Midwest [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
ERCOT Segment [Member] \| Wholesale Generation Revenue From ISO [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	393		775
ERCOT Segment [Member] \| Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
ERCOT Segment [Member] \| Revenue From Other Wholesale Contracts [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	72		175
ERCOT Segment [Member] \| Retail Contract Amortization [Member]
Disaggregation of Revenue [Line Items]
Revenues	0		(1)
ERCOT Segment [Member] \| Hedging And Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	52		(181)
ERCOT Segment [Member] \| Affiliate Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	879		1,422
ERCOT Segment [Member] \| Total Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	931		1,240
PJM Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	677		1,170
Revenues	620	0	1,104	0
PJM Segment [Member] \| Energy Charge In EROCT [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
PJM Segment [Member] \| Energy Charge In Northeast/Midwest [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
PJM Segment [Member] \| Wholesale Generation Revenue From ISO [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	502		869
PJM Segment [Member] \| Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	164		283
PJM Segment [Member] \| Revenue From Other Wholesale Contracts [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	11		18
PJM Segment [Member] \| Retail Contract Amortization [Member]
Disaggregation of Revenue [Line Items]
Revenues	0		0
PJM Segment [Member] \| Hedging And Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(275)		(436)
PJM Segment [Member] \| Affiliate Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	218		370
PJM Segment [Member] \| Total Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(57)		(66)
NY/NE Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	332		538
Revenues	301	0	487	0
NY/NE Segment [Member] \| Energy Charge In EROCT [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
NY/NE Segment [Member] \| Energy Charge In Northeast/Midwest [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
NY/NE Segment [Member] \| Wholesale Generation Revenue From ISO [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	244		362
NY/NE Segment [Member] \| Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	79		162
NY/NE Segment [Member] \| Revenue From Other Wholesale Contracts [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	9		14
NY/NE Segment [Member] \| Retail Contract Amortization [Member]
Disaggregation of Revenue [Line Items]
Revenues	(4)		(6)
NY/NE Segment [Member] \| Hedging And Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(42)		(71)
NY/NE Segment [Member] \| Affiliate Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	15		26
NY/NE Segment [Member] \| Total Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(31)		(51)
MISO Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	275		496
Revenues	230	0	488	0
MISO Segment [Member] \| Energy Charge In EROCT [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
MISO Segment [Member] \| Energy Charge In Northeast/Midwest [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
MISO Segment [Member] \| Wholesale Generation Revenue From ISO [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	255		436
MISO Segment [Member] \| Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	15		44
MISO Segment [Member] \| Revenue From Other Wholesale Contracts [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5		16
MISO Segment [Member] \| Retail Contract Amortization [Member]
Disaggregation of Revenue [Line Items]
Revenues	(5)		(12)
MISO Segment [Member] \| Hedging And Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(136)		(256)
MISO Segment [Member] \| Affiliate Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	96		260
MISO Segment [Member] \| Total Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	(45)		(8)
Asset Closure Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(5)		57
Revenues	(1)	312	48	763
Asset Closure Segment [Member] \| Energy Charge In EROCT [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Asset Closure Segment [Member] \| Energy Charge In Northeast/Midwest [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Asset Closure Segment [Member] \| Wholesale Generation Revenue From ISO [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1		52
Asset Closure Segment [Member] \| Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(4)		6
Asset Closure Segment [Member] \| Revenue From Other Wholesale Contracts [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(2)		(1)
Asset Closure Segment [Member] \| Retail Contract Amortization [Member]
Disaggregation of Revenue [Line Items]
Revenues	0		0
Asset Closure Segment [Member] \| Hedging And Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	5		(29)
Asset Closure Segment [Member] \| Affiliate Sales [Member]
Disaggregation of Revenue [Line Items]
Revenues	(1)		20
Asset Closure Segment [Member] \| Total Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues	4		(9)
Operating revenues [Member]
Disaggregation of Revenue [Line Items]
Unrealized Gain (Loss) on Derivatives	(28)	139	(239)	215
Operating revenues [Member] \| Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Unrealized Gain (Loss) on Derivatives	(130)	(89)	49	(171)
Operating revenues [Member] \| Retail Segment [Member]
Disaggregation of Revenue [Line Items]
Unrealized Gain (Loss) on Derivatives	(24)	2	(11)	11
Operating revenues [Member] \| ERCOT Segment [Member]
Disaggregation of Revenue [Line Items]
Unrealized Gain (Loss) on Derivatives	192	226	(207)	375
Operating revenues [Member] \| PJM Segment [Member]
Disaggregation of Revenue [Line Items]
Unrealized Gain (Loss) on Derivatives	(28)	0	(38)	0
Operating revenues [Member] \| NY/NE Segment [Member]
Disaggregation of Revenue [Line Items]
Unrealized Gain (Loss) on Derivatives	(7)	0	(32)	0
Operating revenues [Member] \| MISO Segment [Member]
Disaggregation of Revenue [Line Items]
Unrealized Gain (Loss) on Derivatives	$ (34)	$ 0	$ (4)	$ 0

Revenue (Contract and Other Customer Acquisition Costs) (Details) - Costs To Acquire Residential And Business Retail Customers [Member] - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Jan. 01, 2018
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net	$ 34	$ 34	$ 22
Selling, General and Administrative Expenses [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Amortization	3	7
Operating revenues [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Amortization	$ 2	$ 5

Revenue (Performance Obligations) (Details) $ in Millions	9 Months Ended
Revenue (Performance Obligations) (Details) $ in Millions	Sep. 30, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 311
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 966
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 718
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 720
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 342
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 103
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	5 years

Revenue (Accounts Receivable) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Trade accounts receivable — net	$ 1,243	$ 582
Trade Accounts Receivable From Contracts With Customers [Member]
Trade accounts receivable — net	1,135
Other Trade Accounts Receivables [Member]
Trade accounts receivable — net	$ 108

Goodwill and Identifiable Intangible Assets and Liabilities (Goodwill) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	$ 1,907	$ 1,907
Retail Electricity Segment [Member]
Goodwill [Line Items]
Goodwill	1,907	$ 1,907
Goodwill, Expected Tax Deductible Amount	$ 1,686
Business Acquisition, Goodwill, Expected Tax Deductible Term	15 years

Goodwill and Identifiable Intangible Assets and Liabilities (Identifiable Intangible Assets and Liabilities Reported in the Balance Sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Gross Carrying Amount (Assets)	$ 2,477	$ 2,018
Accumulated Amortization (Assets)	1,016	717
Total identifiable intangible assets subject to amortization, net	1,461	1,301
Total identifiable intangible assets	2,711	2,530
Total identifiable intangible liabilities	175	36
Retail trade names (not subject to amortization) [Member]
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Gross Carrying Amount, Unamortized Intangibles	1,246	1,225
Mineral interests (not currently subject to amortization) [Member]
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Gross Carrying Amount, Unamortized Intangibles	4	4
Retail customer relationship [Member]
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Gross Carrying Amount (Assets)	1,681	1,648
Accumulated Amortization (Assets)	799	572
Total identifiable intangible assets subject to amortization, net	882	1,076
Software and other technology-related assets [Member]
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Gross Carrying Amount (Assets)	239	183
Accumulated Amortization (Assets)	80	47
Total identifiable intangible assets subject to amortization, net	159	136
Retail and wholesale contracts [Member]
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Gross Carrying Amount (Assets)	445	154
Accumulated Amortization (Assets)	123	87
Total identifiable intangible assets subject to amortization, net	322	67
Contractual service agreements [Member]
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Gross Carrying Amount (Assets)	72	0
Accumulated Amortization (Assets)	0	0
Total identifiable intangible assets subject to amortization, net	72	0
Total identifiable intangible liabilities	93	0
Other Identifiable Intangible Assets [Member]
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Gross Carrying Amount (Assets)	40	33
Accumulated Amortization (Assets)	14	11
Total identifiable intangible assets subject to amortization, net	26	22
Purchase And sales contracts [Member]
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Total identifiable intangible liabilities	46	36
Environmental allowances and credits [Member]
Finite-Lived and Indefinite-Lived Intangible [Line Items]
Total identifiable intangible liabilities	$ 36	$ 0

Goodwill and Identifiable Intangible Assets and Liabilities (Amortization Expense Related to Identifiable Intangible Assets and Liabilities (including income statement line item)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets and Liabilities [Line Items]
Amortization of Intangible Assets And Liabilities	$ 88	$ 101	$ 305	$ 383
Depreciation and amortization [Member]
Finite-Lived Intangible Assets and Liabilities [Line Items]
Amortization of Intangible Assets	84	116	266	347
Retail customer relationship [Member] \| Depreciation and amortization [Member]
Finite-Lived Intangible Assets and Liabilities [Line Items]
Amortization of Intangible Assets And Liabilities	77	105	227	315
Software and other technology-related assets [Member] \| Depreciation and amortization [Member]
Finite-Lived Intangible Assets and Liabilities [Line Items]
Amortization of Intangible Assets And Liabilities	6	10	36	27
Retail and wholesale contracts/purchase and sales contracts [Member] \| Operating revenues, fuel, purchased power costs and delivery fees [Member]
Finite-Lived Intangible Assets and Liabilities [Line Items]
Amortization of Intangible Assets And Liabilities	(5)	(19)	28	27
Other Identifiable Intangible Assets [Member] \| Operating revenues, fuel, purchased power costs and delivery fees, depreciation and amortization [Member]
Finite-Lived Intangible Assets and Liabilities [Line Items]
Amortization of Intangible Assets And Liabilities	$ 10	$ 5	$ 14	$ 14

Goodwill and Identifiable Intangible Assets and Liabilities (Estimated Amortization of Identifiable Intangible Assets and Liabilities) (Details) $ in Millions	Sep. 30, 2018 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2018	$ 402
2019	331
2020	250
2021	180
2022	$ 111

Income Taxes (Calculation of Effective Tax Rate) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income before income taxes	$ 525	$ 524	$ 161	$ 609
Income tax expense	$ (194)	$ (251)	$ (31)	$ (284)
Effective tax rate	37.00%	47.90%	19.30%	46.60%
Effective tax rate at federal statutory rate	21.00%	35.00%	21.00%
Unrecognized Tax Benefits	$ 41		$ 41

Tax Receivable Agreement Obligation (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Percent of cash tax savings due Tax Receivable Agreement rights holders			85.00%
Changes in tax assumptions impacting timing of payments	$ (32)		$ 14	$ (160)
Effective tax rate at federal statutory rate	21.00%	35.00%	21.00%
Estimated undiscounted future payments under Tax Receivable Agreement			$ 1,400
Impacts of tax receivable agreement	$ 17	$ 138	(65)	96
Accretion expense	$ 15	$ 22	$ 51	$ 64

Tax Receivable Agreement Obligation (Summary of Tax Receivable Agreement Obligation) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
TRA obligation at the beginning of the period			$ 357	$ 596
Accretion expense	$ 15	$ 22	51	64
Changes in tax assumptions impacting timing of payments	(32)		14	(160)
TRA obligation at the end of the period	422	500	422	500
Less amounts due currently	(20)	(24)	(20)	(24)
Noncurrent TRA obligation at the end of the period	$ 402	$ 476	$ 402	$ 476	$ 333

Earnings Per Share (Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income available for common stock — basic	$ 330	$ 273	$ 132	$ 325
Weighted average shares of common stock outstanding - basic	533,142,189	427,591,426	500,781,573	427,587,404
Net income (loss) per weighted average share of common stock outstanding - basic	$ 0.62	$ 0.64	$ 0.26	$ 0.76
Incremental common shares attributable to dilutive effect of share-based payment arrangements	7,830,613	721,012	7,347,415	414,465
Incremental Earnings Per Share Attributable To Dilutive Effect Of Share-Based Payment Arrangements	$ 0.01		$ 0.00
Net income available for common stock — diluted	$ 330	$ 273	$ 132	$ 325
Weighted average shares of common stock outstanding - diluted	540,972,802	428,312,438	508,128,988	428,001,869
Net income (loss) per weighted average share of common stock outstanding - diluted	$ 0.61	$ 0.64	$ 0.26	$ 0.76
Antidilutive securities excluded from computation of earnings per share	7,094,687	85,393	5,651,527	490,345

Accounts Receivable Securitization Program (Details) $ in Millions	Sep. 30, 2018 USD ($)
Accounts Receivable Securitization Program [Abstract]
Accounts Receivable Securitization Program, Maximum Borrowing Capacity	$ 350
Accounts Receivable Securitization Program, Gross Trade Accounts Receivable Held By Special Purpose Subsidiary	$ 587

Long-Term Debt (Long-Term Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Apr. 09, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt, including amounts due currently	$ 11,241
Total other long-term debt	496		$ 97
Unamortized debt premiums, discounts and issuance costs	171		15
Less amounts due currently	181		44
Total long-term debt less amounts due currently	11,060		4,379
Line of Credit [Member] \| Vistra Operations Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt, including amounts due currently	$ 5,828		4,311
Vistra Operations Senior Notes [Member] \| 5.50% Senior Notes Due September 1, 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.50%
Long-term debt, including amounts due currently	$ 1,000		0
Vistra Energy Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, including amounts due currently	$ 3,746		0
Vistra Energy Senior Notes [Member] \| 7.375% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.375%
Long-term debt, including amounts due currently	$ 1,750		0
Vistra Energy Senior Notes [Member] \| 5.875% Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.875%
Long-term debt, including amounts due currently	$ 500		0
Vistra Energy Senior Notes [Member] \| 7.625% Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.625%
Long-term debt, including amounts due currently	$ 1,224		0
Vistra Energy Senior Notes [Member] \| 8.034% Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.034%
Long-term debt, including amounts due currently	$ 25		0
Vistra Energy Senior Notes [Member] \| 8.000% Senior Notes Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.00%
Long-term debt, including amounts due currently	$ 81		0
Vistra Energy Senior Notes [Member] \| 8.125% Senior Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.125%
Long-term debt, including amounts due currently	$ 166		0
Amortizing Notes Due 2019 (Tangible Equity Units) [Member] \| 7% Amortization note due 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.00%	7.00%
Long-term debt, including amounts due currently	$ 31		0
Total long-term debt less amounts due currently		$ 38
Secured Debt [Member] \| Forward Capacity Agreement [Member]
Debt Instrument [Line Items]
Long-term debt, including amounts due currently	238		0
Unsecured Debt [Member] \| Equipment Financing Agreement [Member]
Debt Instrument [Line Items]
Long-term debt, including amounts due currently	136		0
Mandatorily Redeemable Preferred Stock [Member] \| PrefCo Mandatorily Redeemable Preferred Stock [Member]
Debt Instrument [Line Items]
Long-term debt, including amounts due currently	$ 70		70
Construction Loans [Member] \| Building Financing 8.82% due semiannually through February 11, 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.82%
Long-term debt, including amounts due currently	$ 21		27
Long-Term Debt, Including Amounts Due Currently [Member]
Debt Instrument [Line Items]
Long-term debt, including amounts due currently	$ 11,241		$ 4,423

Long-Term Debt (Vistra Operations Credit Facilities) (Details) - Vistra Operations Company LLC [Member] - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Jun. 30, 2018	Sep. 30, 2018
Cash Released from Collateral Accounts [Member]
Line of Credit Facility [Line Items]
Cash Collateral for Borrowed Securities		$ 500
Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity		8,328
Line of Credit Facility, Maximum Borrowing Capacity		8,328
Line Of Credit Facility, Borrowings Outstanding		(5,828)
Line of Credit Facility, Remaining Borrowing Capacity		1,290
Debt Fees And Expenses, Total		42
Debt Fees And Expenses, Recorded As Interest Expense		23
Debt Fees And Expenses, Capitalized As Reduction Of Debt		9
Debt Fees And Expenses, Capitalized As Noncurrent Asset		10
Line of Credit [Member] \| Senior Secured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		2,500
Line Of Credit Facility, Borrowings Outstanding		0
Line of Credit Facility, Remaining Borrowing Capacity		$ 1,290
Line of Credit Facility, Increase (Decrease), Net	$ 1,640
Debt Instrument, Basis Spread on Variable Rate		1.75%
Debt Covenant, Outstanding Borrowings To Outstanding Commitments Threshold, Amount Of Letters Of Credit Excluded		$ 300
Debt Covenant, Outstanding Borrowings To Outstanding Commitments Threshold, Percent		30.00%
Line of Credit [Member] \| Senior Secured Revolving Credit Facility [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Debt Covenant, Net First Lien Debt To EBITDA Threshold		4.25
Line of Credit [Member] \| Senior Secured Revolving Credit Facility Letter Of Credit Sub-Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 2,300
Line of Credit Facility, Increase (Decrease), Net	1,585
Line Of Credit Facility, Letters Of Credit Outstanding		$ 1,210
Debt Instrument, Basis Spread on Variable Rate		1.75%
Line of Credit [Member] \| Senior Secured Term Loan B-1, Senior Secured Term Loan B-2 and Senior Secured Term Loan B-3 Facilities [Member]
Line of Credit Facility [Line Items]
Line Of Credit Facility, Percentage Of Debt Required To Be Repaid Annually		1.00%
Line of Credit [Member] \| Senior Secured Term Loan B-1 Facility [Member] [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 2,800
Line Of Credit Facility, Borrowings Outstanding		(2,800)
Line of Credit Facility, Remaining Borrowing Capacity		$ 0
Debt Instrument, Basis Spread on Variable Rate		2.00%
Line of Credit Facility, Interest Rate at Period End		4.24%
Line of Credit [Member] \| Senior Secured Term Loan B-2 Facility [Member] [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 983
Line Of Credit Facility, Borrowings Outstanding		(983)
Line of Credit Facility, Remaining Borrowing Capacity		$ 0
Debt Instrument, Basis Spread on Variable Rate		2.25%
Line of Credit Facility, Interest Rate at Period End		4.49%
Line of Credit [Member] \| Senior Secured Term Loan B-3 Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 2,045
Line Of Credit Facility, Borrowings Outstanding		(2,045)
Line of Credit Facility, Remaining Borrowing Capacity		$ 0
Line of Credit Facility, Increase (Decrease), Net	2,050
Debt Instrument, Basis Spread on Variable Rate		2.00%
Line of Credit Facility, Interest Rate at Period End		4.18%
Line of Credit [Member] \| Senior Secured Term Loan C Facility [Member] [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Increase (Decrease), Net	$ 500

Long-Term Debt (Interest Rate Swaps) (Details) $ in Millions	Sep. 30, 2018 USD ($)
Derivative Notional Amount	$ 4,718
Interest Rate Swap, Effective From January 2017 To July 2023 [Member] [Member]
Derivative Notional Amount	3,000
Interest Rate Swap, Effective From July 2023 To July 2026 [Member]
Derivative Notional Amount	3,000
Interest Rate Swaps, Effective Through February 2024 [Member]
Derivative Notional Amount	1,959
Derivative, Notional Amount, Expired	$ 238
Minimum [Member] \| Interest Rate Swaps, Effective From January 2017 To July 2023 and Legacy Swaps Effective Through 2024 [Member]
Effective Interest Rate Debt Fixed Based On Derivative Contracts	4.13%
Minimum [Member] \| Interest Rate Swap, Effective From July 2023 To July 2026 [Member]
Effective Interest Rate Debt Fixed Based On Derivative Contracts	4.97%
Maximum [Member] \| Interest Rate Swaps, Effective From January 2017 To July 2023 and Legacy Swaps Effective Through 2024 [Member]
Effective Interest Rate Debt Fixed Based On Derivative Contracts	4.38%
Maximum [Member] \| Interest Rate Swap, Effective From July 2023 To July 2026 [Member]
Effective Interest Rate Debt Fixed Based On Derivative Contracts	5.04%

Long-Term Debt (Vistra Operations Senior Notes) (Details) - Vistra Operations Senior Notes [Member] - 5.50% Senior Notes Due September 1, 2026 [Member] $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)
Proceeds from Issuance of Debt		$ 1,000
Debt Instrument, Interest Rate, Stated Percentage	5.50%	5.50%
Debt Fees And Expenses, Capitalized As Reduction Of Debt	$ 12
Proceeds from Issuance of Senior Long-term Debt		$ 990

Long-Term Debt (Vistra Energy Senior Notes) (Details) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended
	Aug. 31, 2018	May 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Apr. 09, 2018
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities					$ 2,902,000,000	$ 32,000,000
Gain (Loss) on Extinguishment of Debt			$ 0	$ (21,000,000)	$ 0	$ 0
6.75% Senior Notes Due 2019 [Member] \| Vistra Energy Senior Notes [Member]
Debt Instrument, Redemption Price, Percentage		101.688%
Vistra Energy Senior Notes [Member]
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	$ 1,542,000,000
Gain (Loss) on Extinguishment of Debt	27,000,000
Long-term Debt							$ 6,138,000,000
Debt Instrument Debt Covenant Borrowed Money Maximum Percent Of Total Assets			30.00%		30.00%
Customary Event Of Default, Minimum Aggregate Amount Threshold			$ 100,000,000		$ 100,000,000
Vistra Energy Senior Notes [Member] \| 7.625% Senior Notes Due 2024 [Member]
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	26,000,000
Debt Instrument, Interest Rate, Stated Percentage			7.625%		7.625%
Vistra Energy Senior Notes [Member] \| 8.034% Senior Notes Due 2024 [Member]
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	163,000,000
Debt Instrument, Interest Rate, Stated Percentage			8.034%		8.034%
Vistra Energy Senior Notes [Member] \| 8.000% Senior Notes Due 2025 [Member]
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	669,000,000
Debt Instrument, Interest Rate, Stated Percentage			8.00%		8.00%
Vistra Energy Senior Notes [Member] \| 8.125% Senior Notes Due 2026 [Member]
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	$ 684,000,000
Debt Instrument, Interest Rate, Stated Percentage			8.125%		8.125%
Vistra Energy Senior Notes [Member] \| 6.75% Senior Notes Due 2019 [Member]
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities		$ 850,000,000
Debt Instrument, Interest Rate, Stated Percentage			6.75%		6.75%		6.75%
Debt Fees And Expenses, Recorded As Interest Expense		$ 14,000,000

Long-Term Debt (Other Long-Term Debt) (Details) - USD ($) $ in Millions	1 Months Ended
	Jun. 30, 2018	Apr. 30, 2018	Sep. 30, 2018	Apr. 09, 2018	Dec. 31, 2017
Long-term debt, including amounts due currently			$ 11,241
Amortizing Notes Due 2019 (Tangible Equity Units) [Member] \| 7% Amortization note due 2019 [Member]
Customary Event Of Default, Minimum Aggregate Amount Threshold			100
Long-term debt, including amounts due currently			31		$ 0
Secured Debt [Member] \| Forward Capacity Agreement [Member]
Long-term debt, including amounts due currently			$ 238		$ 0
Debt Instrument, Interest Rate, Effective Percentage			4.90%
Secured Debt [Member] \| Forward Capacity Agreement [Member] \| PJM Capacity Sold For Planning Years 2018-2019 [Member]
Long-term debt, including amounts due currently			$ 7
Secured Debt [Member] \| Forward Capacity Agreement [Member] \| PJM Capacity Sold For Planning Years 2019-2020 [Member]
Long-term debt, including amounts due currently			121
Secured Debt [Member] \| Forward Capacity Agreement [Member] \| PJM Capacity Sold For Planning Years 2020-2021 [Member]
Long-term debt, including amounts due currently			$ 110
Dynegy Inc. [Member]
Long-term Debt				$ 3,563
Dynegy Inc. [Member] \| Borrowings [Member] \| Senior Secured Revolving Credit Facility [Member]
Line Of Credit Facility, Borrowings Outstanding				0
Dynegy Inc. [Member] \| Line of Credit [Member] \| Senior Secured Revolving Credit Facility [Member]
Line Of Credit Facility, Letters Of Credit Outstanding				656
Dynegy Inc. [Member] \| Senior Secured Term Loan [Member]
Long-term Debt				2,018
Repayments of Debt	$ 2,018
Dynegy Inc. [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity				$ 1,545
Dynegy Inc. [Member] \| Line of Credit [Member] \| Senior Secured Revolving Credit Facility [Member]
Repayments of Lines of Credit		$ 70

Long-Term Debt (Maturities) (Details) $ in Millions	Sep. 30, 2018 USD ($)
Maturities [Abstract]
Remainder of 2018	$ 54
2019	182
2020	204
2021	130
2022	1,824
Thereafter	8,676
Unamortized premiums, discounts and debt issuance costs	171
Long-term debt, including amounts due currently	$ 11,241

Commitments And Contingencies (Narrative) (Details)	9 Months Ended
Commitments And Contingencies (Narrative) (Details)	Sep. 30, 2018 USD ($) generating_unit
Gas Index Pricing Litigation [Member]
Commitments and Contingencies [Line Items]
Numbers Of States In Which Entity Operates	3
Advatech Dispute [Member]
Commitments and Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss	$ 81,000,000
Loss Contingency Contested Invoice Amount	$ 1,000,000
MISO 2015-2016 Planning Resource Auction [Member]
Commitments and Contingencies [Line Items]
Loss Contingency, Pending Claims, Number	3
Pending Litigation [Member] \| EPA Versus Luminant and Big Brown Power Company (Big Brown and Martin Lake Generation Facilities) [Member] \| Minimum [Member]
Commitments and Contingencies [Line Items]
Loss Contingency Damages Sought Value Per Day	$ 32,500
Pending Litigation [Member] \| EPA Versus Luminant and Big Brown Power Company (Big Brown and Martin Lake Generation Facilities) [Member] \| Maximum [Member]
Commitments and Contingencies [Line Items]
Loss Contingency Damages Sought Value Per Day	$ 37,500
Pending Litigation [Member] \| MISO 2015-2016 Planning Resource Auction [Member]
Commitments and Contingencies [Line Items]
Loss Contingency, Pending Claims, Number	1
United States Environmental Protection Agency [Member]
Commitments and Contingencies [Line Items]
Clear Air Act, Regional Haze Program, Reasonable Progress Program, Number Of Units In Texas Subject To New Scrubbers \| generating_unit	7
Clean Air Act, Regional Haze Program, Reasonable Progress Program, Number Of Units In Texas Subject To Upgrades to Existing Scrubbers \| generating_unit	7
Clean Air Act, Regional Haze Program, Best Available Retrofit Technology Alternative, Sulfur Dioxide Emissions, Number of Unit In Texas Subject To Rule, Total	39
Luminant Generation Company LLC [Member] \| United States Environmental Protection Agency [Member]
Commitments and Contingencies [Line Items]
Clean Air Act, Regional Haze Program, Best Available Retrofit Technology Alternative, Sulfur Dioxide Annual Emission Allowances Allocated To Units Covered By Program	100,279
Financial Standby Letter of Credit [Member] \| Vistra Operations Company LLC [Member]
Commitments and Contingencies [Line Items]
Letters of Credit	$ 1,210,000,000
Support Risk Management And Trading Margin Requirements Including Over The Counter Hedging Transactions And Collateral Postings With Electric Reliability Council Of Texas [Member] \| Financial Standby Letter of Credit [Member] \| Vistra Operations Company LLC [Member]
Commitments and Contingencies [Line Items]
Letters of Credit	1,030,000,000
Support Executory Contracts And Insurance Agreements [Member] \| Financial Standby Letter of Credit [Member] \| Vistra Operations Company LLC [Member]
Commitments and Contingencies [Line Items]
Letters of Credit	52,000,000
Support Retail Electric Provider's financial requirements with the Public Utility Commission of Texas [Member] \| Financial Standby Letter of Credit [Member] \| Vistra Operations Company LLC [Member]
Commitments and Contingencies [Line Items]
Letters of Credit	55,000,000
Miscellaneous credit support requirements [Member] \| Financial Standby Letter of Credit [Member] \| Vistra Operations Company LLC [Member]
Commitments and Contingencies [Line Items]
Letters of Credit	$ 73,000,000
Vermillion Facility Old East And North Sites [Member]
Commitments and Contingencies [Line Items]
Site Contingency Number of Sites with Regulatory Violations	2

Equity (Narrative) (Details)		1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended
Equity (Narrative) (Details)	Apr. 09, 2018 USD ($) equity_unit shares	Nov. 30, 2018 $ / shares	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) shares	Dec. 31, 2017 USD ($) shares	Nov. 01, 2018 USD ($)	Dec. 31, 2016 shares
Share Repurchase Program
Treasury stock			$ 349,000,000	$ 424,000,000
Dividends and Dividend Restrictions
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries				0	$ 0
Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries			$ 7,800,000,000	$ 7,800,000,000
Warrants
Class of Warrant or Right, Outstanding \| shares			9,000,000	9,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares			$ 35.00	$ 35.00
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right \| shares			0.652	0.652
Tangible Equity Units [Abstract]
Tangible Equity Units, Number Of Units Issued \| shares	4,600,000
Tangible Equity Units, Unit Price \| equity_unit	100.00
Long-term debt, less amounts due currently			$ 11,060,000,000	$ 11,060,000,000		$ 4,379,000,000
Shares of Common Stock Authorized and Outstanding
Common stock, shares authorized \| shares			1,800,000,000	1,800,000,000	1,800,000,000
Common stock, shares outstanding \| shares	522,932,453		507,391,134	507,391,134	427,597,368	428,398,802		427,580,232
Maximum [Member]
Tangible Equity Units [Abstract]
Prepaid Stock Purchase Contract, Number Of Common Shares Per Tangible Equity Unit \| shares	4.0421
Minimum [Member]
Tangible Equity Units [Abstract]
Prepaid Stock Purchase Contract, Number Of Common Shares Per Tangible Equity Unit \| shares	3.2731
Amortizing Notes Due 2019 (Tangible Equity Units) [Member]
Tangible Equity Units [Abstract]
Debt Instrument, Periodic Payment	$ 1.75
Amortizing Notes Due 2019 (Tangible Equity Units) [Member] \| 7% Amortization note due 2019 [Member]
Tangible Equity Units [Abstract]
Debt Instrument, Interest Rate, Stated Percentage	7.00%		7.00%	7.00%
Long-term debt, less amounts due currently	$ 38,000,000
Vistra Operations Company LLC [Member] \| Vistra Energy Corp. [Member]
Dividends and Dividend Restrictions
Maximum Allowable Distribution To Parent Company By Consolidated Subsidiary Without Consent			$ 9,200,000,000	$ 9,200,000,000
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries			1,900,000,000	3,928,000,000		$ 1,100,000,000
Cash Dividends Accrued To Be Paid To Parent By Consolidated Subsidiaries			400,000,000
Initial Share Repurchase Program [Member]
Share Repurchase Program
Stock Repurchase Program, Authorized Amount			500,000,000	$ 500,000,000
Treasury Stock, Shares, Acquired \| shares				18,271,105
Treasury stock				$ 424,000,000
Treasury Stock Acquired, Average Cost Per Share \| $ / shares				$ 23.18
Stock Repurchase Program, Remaining Authorized Repurchase Amount			$ 76,000,000	$ 76,000,000
Subsequent Event [Member]
Dividends and Dividend Restrictions
Common Stock, Dividends Per Share, Authorized \| $ / shares		$ 0.50
Subsequent Event [Member] \| Incremental Share Repurchase Program [Member]
Share Repurchase Program
Stock Repurchase Program, Authorized Amount							$ 1,250,000,000

Equity (Changes to Equity) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 8,420	$ 6,658	$ 6,342	$ 6,597
Stock issued in connection with the Merger			1,892
Net income (loss)	330	273	132	325
Adoption of accounting standard	17		17
Treasury stock	(349)		(424)
Effects of stock-based incentive compensation plans	6	5	69	13
Tangible equity units assumed			369
Warrants assumed			2
Effect related to pension and other retirement benefit obligations (net of tax benefit of $— in all periods)	1	0	2	0
Investment by noncontrolling interest	(1)		6
Other	(2)	(1)	(2)
Ending balance	8,405	6,935	8,405	6,935
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	5	4	4	4
Stock issued in connection with the Merger			1
Ending balance	5	4	5	4
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	10,015	7,750	7,765	7,742
Stock issued in connection with the Merger			1,891
Treasury stock	(349)		(424)
Effects of stock-based incentive compensation plans	6	5	69	13
Tangible equity units assumed			369
Warrants assumed			2
Other			(2)
Ending balance	9,670	7,755	9,670	7,755
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,591)	(1,102)	(1,410)	(1,155)
Net income (loss)	330	273	132	325
Adoption of accounting standard	17		17
Other		(1)
Ending balance	(1,261)	(830)	(1,261)	(830)
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(16)	6	(17)	6
Effect related to pension and other retirement benefit obligations (net of tax benefit of $— in all periods)	1		2
Ending balance	(15)	$ 6	(15)	$ 6
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	7		0
Investment by noncontrolling interest	(1)		6
Ending balance	6		$ 6
Vistra Energy Corp. [Member] \| Vistra Operations Company LLC [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other	$ 2

Fair Value Measurements (Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Assets:
Nuclear decommissioning trust	$ 1,274	$ 1,188
Equity Securities [Member]
Assets:
Nuclear decommissioning trust	841	758
Debt Securities [Member]
Assets:
Nuclear decommissioning trust	433	430
Fair Value, Measurements, Recurring [Member]
Assets:
Sub-total	65	10
Liabilities:
Total liabilities	65	10
Fair Value, Measurements, Recurring [Member] \| Equity Securities [Member]
Assets:
Assets measured at net asset value	322	290
Fair Value, Measurements, Recurring [Member] \| Commodity contracts [Member]
Assets:
Derivative Assets	65	2
Liabilities:
Derivative Liabilities	65	2
Fair Value, Measurements, Recurring [Member] \| Interest rate swap [Member]
Assets:
Derivative Assets		8
Liabilities:
Derivative Liabilities		8
Fair Value, Measurements, Recurring [Member] \| Total [Member]
Assets:
Sub-total	1,675	1,146
Total assets	1,997	1,436
Liabilities:
Total liabilities	1,235	326
Fair Value, Measurements, Recurring [Member] \| Total [Member] \| Equity Securities [Member]
Assets:
Nuclear decommissioning trust	519	468
Fair Value, Measurements, Recurring [Member] \| Total [Member] \| Debt Securities [Member]
Assets:
Nuclear decommissioning trust	433	430
Fair Value, Measurements, Recurring [Member] \| Total [Member] \| Commodity contracts [Member]
Assets:
Derivative Assets	548	222
Liabilities:
Derivative Liabilities	1,231	318
Fair Value, Measurements, Recurring [Member] \| Total [Member] \| Interest rate swap [Member]
Assets:
Derivative Assets	175	26
Liabilities:
Derivative Liabilities	4	8
Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Assets:
Sub-total	711	515
Liabilities:
Total liabilities	273	45
Level 1 [Member] \| Fair Value, Measurements, Recurring [Member] \| Equity Securities [Member]
Assets:
Nuclear decommissioning trust	519	468
Level 1 [Member] \| Fair Value, Measurements, Recurring [Member] \| Commodity contracts [Member]
Assets:
Derivative Assets	192	47
Liabilities:
Derivative Liabilities	273	45
Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Assets:
Sub-total	751	546
Liabilities:
Total liabilities	505	143
Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Debt Securities [Member]
Assets:
Nuclear decommissioning trust	433	430
Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Commodity contracts [Member]
Assets:
Derivative Assets	143	98
Liabilities:
Derivative Liabilities	501	143
Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Interest rate swap [Member]
Assets:
Derivative Assets	175	18
Liabilities:
Derivative Liabilities	4
Level 3 [Member]
Assets:
Sub-total	148	75
Liabilities:
Total liabilities	392	128
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Assets:
Sub-total	148	75
Liabilities:
Total liabilities	392	128
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member] \| Commodity contracts [Member]
Assets:
Derivative Assets	148	75
Liabilities:
Derivative Liabilities	$ 392	$ 128

Fair Value Measurements (Schedule of Fair Value of the Level 3 Assets and Liabilities by Major Contract Type (All Related to Commodity Contracts) and the Significant Unobservable Inputs Used in the Valuations) (Details) - Level 3 [Member] $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($) $ / Megawatt-hour	Dec. 31, 2017 USD ($) $ / Megawatt-hour
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets	$ 148	$ 75
Liabilities	(392)	(128)
Derivative Assets (Liabilities), at Fair Value, Net	(244)	(53)
Electricity purchases and sales [Member] \| Valuation Model [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets	11	12
Liabilities	(173)	(33)
Derivative Assets (Liabilities), at Fair Value, Net	(162)	(21)
Electricity And Weather Options [Member] \| Option Pricing Model Valuation Technique [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets	15	10
Liabilities	(161)	(91)
Derivative Assets (Liabilities), at Fair Value, Net	(146)	(81)
Financial Transmission Rights [Member] \| Market Approach [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets	86	45
Liabilities	(19)	(4)
Derivative Assets (Liabilities), at Fair Value, Net	67	41
Other [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets	36	8
Liabilities	(39)	0
Derivative Assets (Liabilities), at Fair Value, Net	$ (3)	$ 8
Minimum [Member] \| Electricity purchases and sales [Member] \| Valuation Model [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Hourly price curve shape (in usd per MWh) \| $ / Megawatt-hour	0	0
Fair Value Inputs Illiquid Delivery Periods For ERCOT Hub Power Prices And Heat Rates \| $ / Megawatt-hour	20	20
Minimum [Member] \| Electricity And Weather Options [Member] \| Option Pricing Model Valuation Technique [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Gas to power correlation	15.00%	30.00%
Fair Value Inputs, Power volatility	5.00%	5.00%
Minimum [Member] \| Financial Transmission Rights [Member] \| Market Approach [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Illiquid price differences between settlement points \| $ / Megawatt-hour	(10)	0
Maximum [Member] \| Electricity spread options [Member] \| Option Pricing Model Valuation Technique [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Gas to power correlation		100.00%
Fair Value Inputs, Power volatility		180.00%
Maximum [Member] \| Electricity purchases and sales [Member] \| Valuation Model [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Hourly price curve shape (in usd per MWh) \| $ / Megawatt-hour	90	40
Fair Value Inputs Illiquid Delivery Periods For ERCOT Hub Power Prices And Heat Rates \| $ / Megawatt-hour	120	70
Maximum [Member] \| Electricity And Weather Options [Member] \| Option Pricing Model Valuation Technique [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Gas to power correlation	95.00%
Fair Value Inputs, Power volatility	435.00%
Maximum [Member] \| Financial Transmission Rights [Member] \| Market Approach [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Illiquid price differences between settlement points \| $ / Megawatt-hour	50	15

Fair Value Measurements (Schedule of Changes in Fair Value of the Level 3 Assets and Liabilities (All Related to Commodity Contracts)) (Details) - Level 3 [Member] - Commodity Contract [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net asset (liability) balance at beginning of period	$ (222)	$ 75	$ (53)	$ 83
Total unrealized valuation gains (losses)	(102)	132	(333)	139
Purchases, issuances and settlements
Purchases	41	16	99	51
Issuances	(14)	(5)	(22)	(19)
Settlements	58	(45)	104	(87)
Transfers into Level 3	1	0	3	4
Transfers out of Level 3	(6)	0	(5)	2
Net liabilities assumed in connection with the Merger	0	0	(37)	0
Earn-out provision	0	16	0	16
Net change	(22)	82	(191)	74
Net asset (liability) balance at end of period	(244)	157	(244)	157
Unrealized valuation gains (losses) relating to instruments held at end of period	$ (120)	$ 106	$ (273)	$ 110

Commodity and Other Derivative Contractual Assets and Liabilities (Financial Statement Effects of Derivatives) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 658	$ 238
Derivative liabilities, Fair Value, Gross Liability	(1,170)	(316)
Derivative, Fair Value, Net	(512)	(78)
Current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets And Liability, Fair Value, Gross Assets	458	190
Noncurrent assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets And Liability, Fair Value, Gross Assets	265	58
Current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets And Liability, Fair Value, Gross Liability	(981)	(224)
Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets And Liability, Fair Value, Gross Liability	(254)	(102)
Commodity contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	483	220
Derivative liabilities, Fair Value, Gross Liability	(1,166)	(316)
Derivative asset, Fair Value, Net	483	220
Derivative liabilities, Fair Value, Net	(1,166)	(316)
Commodity contracts [Member] \| Current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	432	190
Derivative liabilities, Fair Value, Gross Asset	1	0
Commodity contracts [Member] \| Noncurrent assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	67	30
Derivative liabilities, Fair Value, Gross Asset	48	2
Commodity contracts [Member] \| Current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Fair Value, Gross Liability	(6)	0
Derivative liabilities, Fair Value, Gross Liability	(973)	(216)
Commodity contracts [Member] \| Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Fair Value, Gross Liability	(10)	0
Derivative liabilities, Fair Value, Gross Liability	(242)	(102)
Interest rate swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	175	18
Derivative liabilities, Fair Value, Gross Liability	(4)	0
Derivative asset, Fair Value, Net	175	18
Derivative liabilities, Fair Value, Net	(4)	0
Interest rate swap [Member] \| Current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	25	0
Derivative liabilities, Fair Value, Gross Asset	0	0
Interest rate swap [Member] \| Noncurrent assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	150	22
Derivative liabilities, Fair Value, Gross Asset	0	4
Interest rate swap [Member] \| Current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Fair Value, Gross Liability	0	(4)
Derivative liabilities, Fair Value, Gross Liability	(2)	(4)
Interest rate swap [Member] \| Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Fair Value, Gross Liability	0	0
Derivative liabilities, Fair Value, Gross Liability	$ (2)	$ 0

Commodity and Other Derivative Contractual Assets and Liabilities (Derivative (Income Statement Presentation) and Derivative type (Income Statement Presentation of Loss Reclassified from Accumulated OCI into Income)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss)	$ (219)	$ 171	$ (508)	$ 312
Operating revenues [Member] \| Commodity contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss)	(278)	166	(655)	333
Fuel, purchased power costs and delivery fees [Member] \| Commodity contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss)	21	9	32	3
Interest expense [Member] \| Interest rate swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss)	$ 38	$ (4)	$ 115	$ (24)

Commodity and Other Derivative Contractual Assets and Liabilities (Derivative Assets and Liabilities From Balance Sheet to Net Amounts After Consideration Netting Arrangements with Counterparties and Financial Collateral) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative assets: Amounts Presented in Balance Sheet	$ 658	$ 238
Derivative assets: Offsetting Financial Instruments	(342)	(113)
Derivative assets: Financial Collateral (Received) Pledged	(1)	(1)
Derivative assets: Net Amounts	315	124
Derivative liabilities: Amounts Presented in Balance Sheet	(1,170)	(316)
Derivative liabilities: Offsetting Financial Instruments	342	113
Derivative liabilities: Financial Collateral (Received) Pledged	92	1
Derivative liabilities: Net Amounts	(736)	(202)
Derivative, Fair Value, Net	(512)	(78)
Derivative (Assets) Liability, Fair Value of Collateral, Net	91	0
Derivative Assets (Liability), Fair Value, Amount Offset Against Collateral	(421)	(78)
Commodity contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative assets: Amounts Presented in Balance Sheet	483	220
Derivative assets: Offsetting Financial Instruments	(338)	(113)
Derivative assets: Financial Collateral (Received) Pledged	(1)	(1)
Derivative assets: Net Amounts	144	106
Derivative liabilities: Amounts Presented in Balance Sheet	(1,166)	(316)
Derivative liabilities: Offsetting Financial Instruments	338	113
Derivative liabilities: Financial Collateral (Received) Pledged	92	1
Derivative liabilities: Net Amounts	(736)	(202)
Interest rate swap [Member]
Derivatives, Fair Value [Line Items]
Derivative assets: Amounts Presented in Balance Sheet	175	18
Derivative assets: Offsetting Financial Instruments	(4)	0
Derivative assets: Financial Collateral (Received) Pledged	0	0
Derivative assets: Net Amounts	171	18
Derivative liabilities: Amounts Presented in Balance Sheet	(4)	0
Derivative liabilities: Offsetting Financial Instruments	4	0
Derivative liabilities: Financial Collateral (Received) Pledged	0	0
Derivative liabilities: Net Amounts	$ 0	$ 0

Commodity and Other Derivative Contractual Assets and Liabilities (Derivative Volumes) (Details) lb in Thousands, gal in Millions, T in Millions, MMBTU in Millions, $ in Millions	Sep. 30, 2018 USD ($) T MMBTU GWh gal lb	Dec. 31, 2017 USD ($) T MMBTU GWh gal lb
Natural Gas Derivative [Member]
Derivatives, Fair Value [Line Items]
Nonmonetary Notional Volume \| MMBTU	5,264	1,259
Electricity (in GWh) [Member]
Derivatives, Fair Value [Line Items]
Nonmonetary Notional Volume \| GWh	246,262	114,129
Financial Transmission Rights [Member]
Derivatives, Fair Value [Line Items]
Nonmonetary Notional Volume \| GWh	176,207	110,913
Coal (in tons) [Member]
Derivatives, Fair Value [Line Items]
Nonmonetary Notional Volume \| T	47	2
Fuel oil (in gallons) [Member]
Derivatives, Fair Value [Line Items]
Nonmonetary Notional Volume \| gal	4	5
Uranium (in pounds) [Member]
Derivatives, Fair Value [Line Items]
Nonmonetary Notional Volume \| lb	100	325
Emissions [Member]
Derivatives, Fair Value [Line Items]
Nonmonetary Notional Volume \| T	25	0
Interest rate swaps - Floating/fixed [Member]
Derivatives, Fair Value [Line Items]
Derivative Notional Amount \| $	$ 7,718	$ 3,000

Commodity and Other Derivative Contractual Assets and Liabilities (Credit Risk-Related Contingent Features of Derivatives) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Credit Derivatives [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value	$ (629)	$ (204)
Credit risk derivative with contingent feature [Member]
Credit Derivatives [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value	161	103
Collateral Already Posted, Aggregate Fair Value	222	41
Cross-default credit derivative [Member]
Credit Derivatives [Line Items]
Assets Needed for Immediate Settlement, Aggregate Fair Value	$ (246)	$ (60)

Commodity and Other Derivative Contractual Assets and Liabilities (Concentrations of Credit Risk Related to Derivatives) (Details) - Credit Risk Contract [Member] $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($)
Derivative [Line Items]
Total credit risk exposure to all counterparties related to derivative contracts	$ 858
Net exposure to those counterparties after taking into effect master netting arrangements, setoff provisions and collateral	397
Largest net exposure to single counterparty	$ 70
Credit risk exposure to Banking and financial sector percentage	57.00%
Net exposure to banking and financial sector percentage	47.00%

Pension and Other Postretirement Employee Benefit (OPEB) Plans (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Apr. 09, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Assets related to employee benefit plans	$ 34		$ 0
Pension And Other Postretirement Employee Benefit Plans Assumed In Merger [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation		$ 539
Defined Benefit Plan, Fair Value of Plan Assets		459
Assets related to employee benefit plans		15
Liability, Defined Benefit Plan, Current		2
Liability, Defined Benefit Plan, Noncurrent		$ 93

Pension and Other Postretirement Employee Benefit (OPEB) Plans (Components of Net Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5	$ 1	$ 10	$ 4
Other costs	(1)	0	(1)	0
Net periodic benefit cost	4	1	9	4
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	0	2	1
Other costs	1	1	3	3
Net periodic benefit cost	$ 2	$ 1	$ 5	$ 4

Stock-Based Compensation (Details) $ in Millions	Apr. 09, 2018 USD ($) shares
Share-Based Compensation Arrangement By Share-Based Payment Award Fair Value Of Awards At Merger Date	$ 89
Share-Based Compensation Arrangement By Share-Based Payment Award Fair Value Of Awards At Merger Date Considered Part Of Purchase Price	26
Share-Based Compensation Arrangement By Share-Based Payment Award Fair Value Of Awards At Merger Date Recognized As Compensation Expense	33
Share-Based Compensation Arrangement By Share-Based Payment Award Fair Value Of Awards At Merger Date To Be Amortized To Expense Over Remaining Service Period	30
Employee Stock Option [Member]
Share-Based Compensation Arrangement By Share-Based Payment Award Fair Value Of Awards At Merger Date	$ 10
Employee Stock Option [Member] \| Dynegy Inc. [Member]
Share-Based Compensation Arrangement By Share-Based Payment Awards Prior To Merger Date \| shares	4,096,027
Employee Stock Option [Member] \| Vistra Energy Corp. [Member]
Share-Based Compensation Arrangement By Share-Based Payment Awards Converted At Merger Date \| shares	2,670,610
Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Arrangement By Share-Based Payment Award Fair Value Of Awards At Merger Date	$ 61
Restricted Stock Units (RSUs) [Member] \| Dynegy Inc. [Member]
Share-Based Compensation Arrangement By Share-Based Payment Awards Prior To Merger Date \| shares	5,718,148
Restricted Stock Units (RSUs) [Member] \| Vistra Energy Corp. [Member]
Share-Based Compensation Arrangement By Share-Based Payment Awards Converted At Merger Date \| shares	3,056,689
Performance Shares [Member]
Share-Based Compensation Arrangement By Share-Based Payment Award Fair Value Of Awards At Merger Date	$ 18
Performance Shares [Member] \| Dynegy Inc. [Member]
Share-Based Compensation Arrangement By Share-Based Payment Awards Prior To Merger Date \| shares	1,538,133
Performance Shares [Member] \| Vistra Energy Corp. [Member]
Share-Based Compensation Arrangement By Share-Based Payment Awards Converted At Merger Date \| shares	938,721

Related Party Transactions (Narrrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Maximum [Member]
Related Party Transaction [Line Items]
Registration Rights Agreement, Demand Registration, Number Of Days To File S-1 Registration Statement			45 days
Registration Rights Agreement, Demand Registration, Number Of Days To File S-3 Registration Statement			30 days
Registration Rights Agreement, Demand Registration, Number Of Days Between Initial Registration And Effective Date			120 days
Legal Expenses Paid On Behalf of Selling Stockholders [Member]
Related Party Transaction [Line Items]
Legal fees	$ 1	$ 1	$ 1	$ 1

Segment Information (Segment Information) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Reportable_segment	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments (in reportable segments) \| Reportable_segment			6
Operating revenues	$ 3,243	$ 1,833	$ 6,581	$ 4,487
Depreciation and amortization	(426)	(178)	(967)	(519)
Operating income (loss)	650	452	485	658
Unrealized mark-to-market net losses on interest rate swaps	38	3	123	(3)
Net income	331	273	130	325
Total assets	25,888		25,888		$ 14,600
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	91	0	123	0
Depreciation and amortization	(25)	(10)	(60)	(30)
Operating income (loss)	(8)	(15)	(244)	(47)
Unrealized mark-to-market net losses on interest rate swaps	3	0	4	0
Net income	(328)	(203)	(635)	(405)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	(1,116)		(1,975)
Depreciation and amortization	0	0	1	0
Operating income (loss)	(2)	1	(1)	0
Total assets	(1,261)		(1,261)		1,375
Retail Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,813	1,286	4,239	3,136
Depreciation and amortization	(80)	(108)	(237)	(322)
Operating income (loss)	(83)	(3)	371	54
Net income	(86)	7	397	77
Retail Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	7,365		7,365		6,156
ERCOT Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,396	891	2,190	1,994
Depreciation and amortization	(122)	(59)	(295)	(166)
Operating income (loss)	643	406	234	555
Net income	643	405	236	552
ERCOT Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	9,101		9,101		6,834
PJM Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	620	0	1,104	0
Depreciation and amortization	(141)	0	(266)	0
Operating income (loss)	61	0	85	0
Net income	62	0	86	0
PJM Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	6,796		6,796		0
NY/NE Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	301	0	487	0
Depreciation and amortization	(55)	0	(104)	0
Operating income (loss)	45	0	36	0
Net income	47	0	41	0
NY/NE Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	2,705		2,705		0
MISO Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	230	0	488	0
Depreciation and amortization	(3)	0	(6)	0
Operating income (loss)	(2)	0	30	0
Net income	(3)	0	29	0
MISO Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	945		945		0
Asset Closure Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	(1)	312	48	763
Depreciation and amortization	0	1	0	1
Operating income (loss)	(4)	63	(26)	96
Net income	(4)	64	(24)	101
Asset Closure Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total assets	237		237		$ 235
Operating revenues [Member]
Segment Reporting Information [Line Items]
Unrealized mark-to-market net losses on interest rate swaps	(28)	139	(239)	215
Operating revenues [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Unrealized mark-to-market net losses on interest rate swaps	(130)	(89)	49	(171)
Operating revenues [Member] \| Retail Segment [Member]
Segment Reporting Information [Line Items]
Unrealized mark-to-market net losses on interest rate swaps	(24)	2	(11)	11
Operating revenues [Member] \| ERCOT Segment [Member]
Segment Reporting Information [Line Items]
Unrealized mark-to-market net losses on interest rate swaps	192	226	(207)	375
Operating revenues [Member] \| PJM Segment [Member]
Segment Reporting Information [Line Items]
Unrealized mark-to-market net losses on interest rate swaps	(28)	0	(38)	0
Operating revenues [Member] \| NY/NE Segment [Member]
Segment Reporting Information [Line Items]
Unrealized mark-to-market net losses on interest rate swaps	(7)	0	(32)	0
Operating revenues [Member] \| MISO Segment [Member]
Segment Reporting Information [Line Items]
Unrealized mark-to-market net losses on interest rate swaps	(34)	0	(4)	0
Affiliate Sales [Member]
Segment Reporting Information [Line Items]
Operating revenues	0		0
Affiliate Sales [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	(1,207)	$ (656)	(2,098)	$ (1,406)
Affiliate Sales [Member] \| Retail Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0		0
Affiliate Sales [Member] \| ERCOT Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	879		1,422
Affiliate Sales [Member] \| PJM Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	218		370
Affiliate Sales [Member] \| NY/NE Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	15		26
Affiliate Sales [Member] \| MISO Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	96		260
Affiliate Sales [Member] \| Asset Closure Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ (1)		$ 20

Supplementary Financial Information (Interest Expense and Related Charges) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest Expense and Related Charges [Line Items]
Interest paid/accrued	$ 164	$ 52	$ 380	$ 157
Unrealized mark-to-market net losses on interest rate swaps	(38)	(3)	(123)	3
Losses on extinguishment of debt and amortization of debt issuance costs, discounts and premiums	27	2	31	2
Reversal of debt extinguishment gain	0	21	0	0
Capitalized interest	(3)	(1)	(10)	(5)
Other	4	5	13	12
Interest expense and related charges	$ 154	$ 76	$ 291	$ 169
Vistra Operations Company LLC [Member] \| Line of Credit [Member]
Interest Expense and Related Charges [Line Items]
Debt Instrument, Interest Rate During Period			4.18%

Supplementary Financial Information (Other Income and Deductions) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other income:
Interest income	$ 3	$ 4	$ 14	$ 10
All other	1	1	4	3
Total other income	6	10	25	29
Other deductions:
Other	1	0	4	5
Total other deductions	1	0	4	5
Corporate and Other Nonsegment [Member]
Other income:
Office space sublease rental income	2	3	6	9
Royalty Revenue \| ERCOT Segment [Member]
Other income:
Revenue from contracts	0	1	0	3
Land Sales \| ERCOT Segment [Member]
Other income:
Revenue from contracts	$ 0	$ 1	$ 1	$ 4

Supplementary Financial Information (Restricted Cash) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Restricted cash included in current assets	$ 59	$ 59
Restricted cash included in noncurrent assets	0	500
Vistra Operations Credit Facility [Member]
Restricted cash included in current assets	0	0
Restricted cash included in noncurrent assets	0	500
Amounts related to restructuring escrow accounts [Member]
Restricted cash included in current assets	59	59
Restricted cash included in noncurrent assets	$ 0	$ 0

Supplementary Financial Information (Trade Accounts Receivable and Allowance for Doubtful Accounts) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Supplementary Financial Information [Abstract]
Wholesale and retail trade accounts receivable			$ 1,268	$ 596
Allowance for uncollectible accounts	$ (14)	$ (10)	(25)	(14)
Trade accounts receivable — net			1,243	582
Unbilled Receivables, Current			$ 356	$ 251
Allowance for Doubtful Accounts Receivable [Roll Forward]
Allowance for uncollectible accounts receivable at beginning of period	14	10
Increase for bad debt expense	41	35
Decrease for account write-offs	(30)	(24)
Allowance for uncollectible accounts receivable at end of period	$ 25	$ 21

Supplementary Financial Information (Inventories by Major Category and Other Investments) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Inventories by Major Category
Materials and supplies	$ 279	$ 149
Fuel stock	108	83
Natural gas in storage	6	21
Total inventories	393	253
Other Investments
Nuclear plant decommissioning trust	1,274	1,188
Assets related to employee benefit plans	34	0
Land	49	49
Miscellaneous other	0	3
Total investments	$ 1,357	$ 1,240

Supplementary Financial Information (Other Investments) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Investment in unconsolidated subsidiary	$ 135		$ 135		$ 0
Equity in earnings of unconsolidated investments	7	$ 0	11	$ 0
Proceeds from Equity Method Investment, Distribution, Return of Capital	7		13
Northeast Energy, LP [Member]
Investment in unconsolidated subsidiary	$ 133		$ 133

Supplementary Financial Information (Nuclear Decommissioning Trust) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Schedule of Schedule of Decommissioning Fund Investments [Line Items]
Cost	$ 714		$ 714		$ 683
Unrealized gain	569		569		509
Unrealized loss	(9)		(9)		(4)
Fair market value	1,274		1,274		1,188
Realized gains	1	$ 1	0	$ 3
Realized losses	(1)	(1)	(2)	(3)
Proceeds from sales of securities	118	56	211	154
Investments in securities	(124)	$ (62)	(227)	$ (169)
Debt Securities [Member]
Schedule of Schedule of Decommissioning Fund Investments [Line Items]
Cost	437		437		418
Unrealized gain	5		5		14
Unrealized loss	(9)		(9)		(2)
Fair market value	$ 433		$ 433		$ 430
Debt, Weighted Average Interest Rate	3.73%		3.73%		3.55%
Decommissioning Fund Investments, Debt securities, average maturity			9 years		9 years
Decommissioning Fund Investments, debt maturities, one through five years, fair value	$ 146		$ 146
Decommissioning Fund Investments, debt maturities, five through ten years, fair value	96		96
Decommissioning Fund Investments, debt maturities, after ten years, fair value	191		191
Equity Securities [Member]
Schedule of Schedule of Decommissioning Fund Investments [Line Items]
Cost	277		277		$ 265
Unrealized gain	564		564		495
Unrealized loss	0		0		(2)
Fair market value	$ 841		$ 841		$ 758

Supplementary Financial Information (Property, Plant and Equipment) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Supplementary Financial Information [Abstract]
Property, plant and equipment — net	$ 14,756	$ 4,820
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 1,148	$ 393

Supplementary Financial Information (Asset Retirement and Mining Reclamation Obligations) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance, Liability	$ 1,936
Additions:
Accretion	68
Adjustment for change in estimate	(40)
Obligations assumed in the Merger	426
Reductions:
Payments	(68)
Ending balance, Liability	1,936	$ 2,322	$ 1,936
Less amounts due currently		(183)	(99)
Noncurrent liability at end of period	2,139
Nuclear Plant Decommissioning [Member]
Asset Retirement Obligations [Line Items]
Regulatory Liabilities		(9)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance, Liability	1,233
Additions:
Accretion	32
Adjustment for change in estimate	0
Obligations assumed in the Merger	0
Reductions:
Payments	0
Ending balance, Liability	1,233	1,265	1,233
Less amounts due currently		0
Noncurrent liability at end of period	1,265
Mining Land Reclamation [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance, Liability	438
Additions:
Accretion	16
Adjustment for change in estimate	7
Obligations assumed in the Merger	2
Reductions:
Payments	(57)
Ending balance, Liability	438	406	438
Less amounts due currently		(124)
Noncurrent liability at end of period	282
Other Asset Retirement Obligations [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance, Liability	265
Additions:
Accretion	20
Adjustment for change in estimate	(47)
Obligations assumed in the Merger	424
Reductions:
Payments	(11)
Ending balance, Liability	265	651	$ 265
Less amounts due currently		$ (59)
Noncurrent liability at end of period	$ 592

Supplementary Financial Information (Other Noncurrent Liabilities and Deferred Credits) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Supplementary Financial Information [Abstract]
Uncertain tax positions, including accrued interest	$ 12	$ 0
Other, including retirement and other employee benefits	334	220
Total other noncurrent liabilities and deferred credits	$ 346	$ 220

Supplementary Financial Information (Fair Value of Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Vistra Operations Credit Facility [Member] \| Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	$ 5,823	$ 4,323
Vistra Operations Senior Notes [Member] \| Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	1,000	0
Vistra Energy Senior Notes [Member] \| Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	3,954	0
Amortizing Notes Due 2019 (Tangible Equity Units) [Member] \| Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	31	0
Secured Debt [Member] \| Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	221	0
Unsecured Debt [Member] \| Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	119	0
Mandatorily Redeemable Preferred Stock [Member] \| Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	70	70
Construction Loans [Member] \| Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	23	30
Fair Value, Inputs, Level 2 [Member] \| Vistra Operations Credit Facility [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	5,836	4,334
Fair Value, Inputs, Level 2 [Member] \| Vistra Operations Senior Notes [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	1,010	0
Fair Value, Inputs, Level 2 [Member] \| Vistra Energy Senior Notes [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	3,945	0
Fair Value, Inputs, Level 2 [Member] \| Amortizing Notes Due 2019 (Tangible Equity Units) [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	32	0
Fair Value, Inputs, Level 2 [Member] \| Mandatorily Redeemable Preferred Stock [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	70	70
Fair Value, Inputs, Level 2 [Member] \| Construction Loans [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	21	27
Level 3 [Member] \| Secured Debt [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	221	0
Level 3 [Member] \| Unsecured Debt [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	$ 119	$ 0

Supplementary Financial Information (Supplemental Cash Flow Information) (Details) - USD ($) shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Supplementary Financial Information [Abstract]
Cash and cash equivalents	$ 811		$ 1,487
Restricted cash included in current assets	59		59
Restricted cash included in noncurrent assets	0		500
Total cash, cash equivalents and restricted cash	870	$ 1,765	$ 2,046	$ 1,588
Cash payments related to:
Interest paid	662	197
Capitalized interest	(10)	(5)
Interest paid (net of capitalized interest)	652	192
Income taxes	66	51
Noncash investing and financing activities:
Construction expenditures	$ 58	$ 16
Vistra Energy common stock issued in the Merger	2,245	0

Supplemental Condensed Consolidating Financial Information (Condensed Consolidating Statements of Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Operating revenues	$ 3,243	$ 1,833	$ 6,581	$ 4,487
Fuel, purchased power costs and delivery fees	(1,627)	(838)	(3,492)	(2,250)
Operating costs	(346)	(218)	(926)	(626)
Depreciation and amortization	(426)	(178)	(967)	(519)
Selling, general and administrative expenses	(194)	(147)	(711)	(434)
Operating income	650	452	485	658
Other income	6	10	25	29
Other deductions	(1)	0	(4)	(5)
Interest expense and related charges	(154)	(76)	(291)	(169)
Impacts of tax receivable agreement	17	138	(65)	96
Equity in earnings of unconsolidated investments	7	0	11	0
Income before income taxes	525	524	161	609
Income tax expense	(194)	(251)	(31)	(284)
Equity in earnings (loss) of subsidiaries, net of tax	0	0	0	0
Net income	331	273	130	325
Less: Net (income) loss attributable to noncontrolling interest	1	0	(2)	0
Net income attributable to Vistra Energy	330	273	132	325
Reportable Legal Entities [Member] \| Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Operating revenues	0	0	0	0
Fuel, purchased power costs and delivery fees	0	0	0	0
Operating costs	0	0	0	0
Depreciation and amortization	0	0	0	0
Selling, general and administrative expenses	(23)	(7)	(250)	(20)
Operating income	(23)	(7)	(250)	(20)
Other income	1	2	8	2
Other deductions	0	0	0	0
Interest expense and related charges	(110)	0	(197)	0
Impacts of tax receivable agreement	17	138	(65)	96
Equity in earnings of unconsolidated investments	0		0
Income before income taxes	(115)	133	(504)	78
Income tax expense	42	(62)	183	(36)
Equity in earnings (loss) of subsidiaries, net of tax	403	202	453	283
Net income	330	273	132	325
Less: Net (income) loss attributable to noncontrolling interest	0		0
Net income attributable to Vistra Energy	330		132
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Operating revenues	3,208	1,833	6,480	4,487
Fuel, purchased power costs and delivery fees	(1,590)	(838)	(3,405)	(2,250)
Operating costs	(334)	(218)	(898)	(626)
Depreciation and amortization	(402)	(178)	(926)	(519)
Selling, general and administrative expenses	(165)	(140)	(452)	(414)
Operating income	717	459	799	678
Other income	7	8	19	27
Other deductions	(1)	0	(5)	(5)
Interest expense and related charges	(43)	(76)	(92)	(169)
Impacts of tax receivable agreement	0	0	0	0
Equity in earnings of unconsolidated investments	7		11
Income before income taxes	687	391	732	531
Income tax expense	(251)	(189)	(235)	(248)
Equity in earnings (loss) of subsidiaries, net of tax	(33)	0	(44)	0
Net income	403	202	453	283
Less: Net (income) loss attributable to noncontrolling interest	0		0
Net income attributable to Vistra Energy	403		453
Reportable Legal Entities [Member] \| Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Operating revenues	59	0	126	0
Fuel, purchased power costs and delivery fees	(37)	0	(89)	0
Operating costs	(12)	0	(28)	0
Depreciation and amortization	(24)	0	(41)	0
Selling, general and administrative expenses	(30)	0	(32)	0
Operating income	(44)	0	(64)	0
Other income	0	0	0	0
Other deductions	0	0	1	0
Interest expense and related charges	(3)	0	(4)	0
Impacts of tax receivable agreement	0	0	0	0
Equity in earnings of unconsolidated investments	0		0
Income before income taxes	(47)	0	(67)	0
Income tax expense	15	0	21	0
Equity in earnings (loss) of subsidiaries, net of tax	0	0	0	0
Net income	(32)	0	(46)	0
Less: Net (income) loss attributable to noncontrolling interest	1		(2)
Net income attributable to Vistra Energy	(33)		(44)
Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Operating revenues	(24)	0	(25)	0
Fuel, purchased power costs and delivery fees	0	0	2	0
Operating costs	0	0	0	0
Depreciation and amortization	0	0	0	0
Selling, general and administrative expenses	24	0	23	0
Operating income	0	0	0	0
Other income	(2)	0	(2)	0
Other deductions	0	0	0	0
Interest expense and related charges	2	0	2	0
Impacts of tax receivable agreement	0	0	0	0
Equity in earnings of unconsolidated investments	0		0
Income before income taxes	0	0	0	0
Income tax expense	0	0	0	0
Equity in earnings (loss) of subsidiaries, net of tax	(370)	(202)	(409)	(283)
Net income	(370)	$ (202)	(409)	$ (283)
Less: Net (income) loss attributable to noncontrolling interest	0		0
Net income attributable to Vistra Energy	$ (370)		$ (409)

Supplemental Condensed Consolidating Financial Information (Condensed Statements of Consolidating Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net income	$ 331	$ 273	$ 130	$ 325
Effect related to pension and other retirement benefit obligations (net of tax benefit of $— in all periods)	1	0	2	0
Total other comprehensive income	1	0	2	0
Comprehensive income	332	273	132	325
Comprehensive (income) loss attributable to noncontrolling interest	1	0	(2)	0
Comprehensive income attributable to Vistra Energy	331	273	134	325
Reportable Legal Entities [Member] \| Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	330	273	132	325
Effect related to pension and other retirement benefit obligations (net of tax benefit of $— in all periods)	0	0	0	0
Total other comprehensive income	0	0	0	0
Comprehensive income	330	273	132	325
Comprehensive (income) loss attributable to noncontrolling interest	0		0
Comprehensive income attributable to Vistra Energy	330		132
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	403	202	453	283
Effect related to pension and other retirement benefit obligations (net of tax benefit of $— in all periods)	1	0	2	0
Total other comprehensive income	1	0	2	0
Comprehensive income	404	202	455	283
Comprehensive (income) loss attributable to noncontrolling interest	0		0
Comprehensive income attributable to Vistra Energy	404		455
Reportable Legal Entities [Member] \| Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	(32)	0	(46)	0
Effect related to pension and other retirement benefit obligations (net of tax benefit of $— in all periods)	0	0	0	0
Total other comprehensive income	0	0	0	0
Comprehensive income	(32)	0	(46)	0
Comprehensive (income) loss attributable to noncontrolling interest	1		(2)
Comprehensive income attributable to Vistra Energy	(33)		(44)
Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	(370)	(202)	(409)	(283)
Effect related to pension and other retirement benefit obligations (net of tax benefit of $— in all periods)	0	0	0	0
Total other comprehensive income	0	0	0	0
Comprehensive income	(370)	$ (202)	(409)	$ (283)
Comprehensive (income) loss attributable to noncontrolling interest	0		0
Comprehensive income attributable to Vistra Energy	$ (370)		$ (409)

Supplemental Condensed Consolidating Financial Information (Condensed Statements of Consolidating Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended	17 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Sep. 30, 2018
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities			$ 863	$ 845
Cash flows — financing activities:
Issuances of long-term debt			1,000	0
Repayments/repurchases of debt			(2,902)	(32)
Borrowing under accounts receivable securitization program			350	0
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries			0	0
Payments for Repurchase of Common Stock			(414)	0
Debt tender offer and other financing fees			(216)	(5)
Other, net			10	0
Cash used in financing activities			(2,172)	(37)
Cash flows — investing activities:
Capital expenditures			(209)	(86)
Nuclear fuel purchases			(66)	(56)
Cash acquired in the Merger			445	0
Solar development expenditures			(28)	(129)		$ (218)
Odessa acquisition			0	(355)
Proceeds from sales of nuclear decommissioning trust fund securities	$ 118	$ 56	211	154
Investments in nuclear decommissioning trust fund securities	(124)	(62)	(227)	(169)
Proceeds from Dividends Received			0	0
Other, net			7	10
Cash provided by (used in) investing activities			133	(631)
Net change in cash, cash equivalents and restricted cash			(1,176)	177
Cash, cash equivalents and restricted cash — beginning balance			2,046	1,588	$ 1,588
Cash, cash equivalents and restricted cash — ending balance	870	1,765	870	1,765	2,046	870
Reportable Legal Entities [Member] \| Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities			521	(39)
Cash flows — financing activities:
Issuances of long-term debt			0
Repayments/repurchases of debt			(4,918)	0
Borrowing under accounts receivable securitization program			0
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries			0	0
Payments for Repurchase of Common Stock			(414)
Debt tender offer and other financing fees			(173)	0
Other, net			10
Cash used in financing activities			(5,495)	0
Cash flows — investing activities:
Capital expenditures			(12)	0
Nuclear fuel purchases			0	0
Cash acquired in the Merger			0
Solar development expenditures			0	0
Odessa acquisition				0
Proceeds from sales of nuclear decommissioning trust fund securities			0	0
Investments in nuclear decommissioning trust fund securities			0	0
Proceeds from Dividends Received			3,928	537
Other, net			0	0
Cash provided by (used in) investing activities			3,916	537
Net change in cash, cash equivalents and restricted cash			(1,058)	498
Cash, cash equivalents and restricted cash — beginning balance			1,183	26	26
Cash, cash equivalents and restricted cash — ending balance	125	524	125	524	1,183	125
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities			670	884
Cash flows — financing activities:
Issuances of long-term debt			1,000
Repayments/repurchases of debt			2,016	(32)
Borrowing under accounts receivable securitization program			0
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries			(3,928)	(537)
Payments for Repurchase of Common Stock			0
Debt tender offer and other financing fees			(43)	(5)
Other, net			0
Cash used in financing activities			(955)	(574)
Cash flows — investing activities:
Capital expenditures			(191)	(86)
Nuclear fuel purchases			(66)	(56)
Cash acquired in the Merger			445
Solar development expenditures			(28)	(129)
Odessa acquisition				(355)
Proceeds from sales of nuclear decommissioning trust fund securities			211	154
Investments in nuclear decommissioning trust fund securities			(227)	(169)
Proceeds from Dividends Received				0
Other, net			10	10
Cash provided by (used in) investing activities			154	(631)
Net change in cash, cash equivalents and restricted cash			(131)	(321)
Cash, cash equivalents and restricted cash — beginning balance			863	1,562	1,562
Cash, cash equivalents and restricted cash — ending balance	732	1,241	732	1,241	863	732
Reportable Legal Entities [Member] \| Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities			(328)	0
Cash flows — financing activities:
Issuances of long-term debt			0
Repayments/repurchases of debt			0	0
Borrowing under accounts receivable securitization program			350
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries			0	0
Payments for Repurchase of Common Stock			0
Debt tender offer and other financing fees			0	0
Other, net			0
Cash used in financing activities			350	0
Cash flows — investing activities:
Capital expenditures			(6)	0
Nuclear fuel purchases			0	0
Cash acquired in the Merger			0
Solar development expenditures			0	0
Odessa acquisition				0
Proceeds from sales of nuclear decommissioning trust fund securities			0	0
Investments in nuclear decommissioning trust fund securities			0	0
Proceeds from Dividends Received				0
Other, net			(3)	0
Cash provided by (used in) investing activities			(9)	0
Net change in cash, cash equivalents and restricted cash			13	0
Cash, cash equivalents and restricted cash — beginning balance			0	0	0
Cash, cash equivalents and restricted cash — ending balance	13	0	13	0	0	13
Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities			0	0
Cash flows — financing activities:
Issuances of long-term debt			0
Repayments/repurchases of debt			0	0
Borrowing under accounts receivable securitization program
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries			3,928	537
Payments for Repurchase of Common Stock			0
Debt tender offer and other financing fees			0	0
Other, net			0
Cash used in financing activities			3,928	537
Cash flows — investing activities:
Capital expenditures			0	0
Nuclear fuel purchases			0	0
Cash acquired in the Merger			0
Solar development expenditures			0	0
Odessa acquisition				0
Proceeds from sales of nuclear decommissioning trust fund securities			0	0
Investments in nuclear decommissioning trust fund securities			0	0
Proceeds from Dividends Received			(3,928)	(537)
Other, net			0	0
Cash provided by (used in) investing activities			(3,928)	(537)
Net change in cash, cash equivalents and restricted cash			0	0
Cash, cash equivalents and restricted cash — beginning balance			0	0	0
Cash, cash equivalents and restricted cash — ending balance	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0

Supplemental Condensed Consolidating Financial Information (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Sep. 30, 2017
Current assets:
Cash and cash equivalents	$ 811		$ 1,487
Restricted cash	59		59
Advances to affiliates	0
Trade accounts receivable — net	1,243		582
Accounts receivable — affiliates	0
Notes due from affiliates	0
Income taxes receivable	12		0
Inventories	393		253
Commodity and other derivative contractual assets	458		190
Margin deposits related to commodity contracts	177		30
Prepaid expense and other current assets	123	$ 77	72
Total current assets	3,276		2,673
Restricted cash	0		500
Investments	1,357		1,240
Investment in unconsolidated subsidiary	135		0
Investment in affiliated companies	0		0
Property, plant and equipment — net	14,756		4,820
Goodwill	1,907		1,907
Identifiable intangible assets — net	2,711		2,530
Commodity and other derivative contractual assets	265		58
Accumulated deferred income taxes	1,053	706	710
Other noncurrent assets	428	$ 178	162
Total assets	25,888		14,600
Current liabilities:
Accounts receivable securitization program	350		0
Advances from affiliates	0
Long-term debt due currently	181		44
Trade accounts payable	812		473
Accounts payable — affiliates	0
Notes due to affiliates	0
Commodity and other derivative contractual liabilities	981		224
Margin deposits related to commodity contracts	4		4
Accrued income taxes	0		58
Accrued taxes other than income	139		136
Accrued interest	123		16
Asset retirement obligations	183		99
Other current liabilities	329		297
Total current liabilities	3,102		1,351
Long-term debt, less amounts due currently	11,060		4,379
Commodity and other derivative contractual liabilities	254		102
Deferred Tax Liabilities, Net, Noncurrent	5		0
Tax Receivable Agreement obligation	402		333	$ 476
Asset retirement obligation	2,139		1,837
Identifiable intangible liabilities - net	175		36
Other noncurrent liabilities and deferred credits	346		220
Total liabilities	17,483		8,258
Total stockholders' equity	8,399		6,342
Noncontrolling interest in subsidiary	6		0
Total liabilities and equity	25,888		14,600
Reportable Legal Entities [Member] \| Parent Company [Member]
Current assets:
Cash and cash equivalents	66		1,124
Restricted cash	59		59
Advances to affiliates	11
Trade accounts receivable — net	9		4
Accounts receivable — affiliates	15
Notes due from affiliates	0
Income taxes receivable	12
Inventories	0		0
Commodity and other derivative contractual assets	0		0
Margin deposits related to commodity contracts	0		0
Prepaid expense and other current assets	2		0
Total current assets	174		1,187
Restricted cash			0
Investments	0		0
Investment in unconsolidated subsidiary	0
Investment in affiliated companies	11,631		5,632
Property, plant and equipment — net	18		0
Goodwill	0		0
Identifiable intangible assets — net	0		0
Commodity and other derivative contractual assets	0		0
Accumulated deferred income taxes	955		5
Other noncurrent assets	240		6
Total assets	13,018		6,830
Current liabilities:
Accounts receivable securitization program	0
Advances from affiliates	0
Long-term debt due currently	31		0
Trade accounts payable	3		11
Accounts payable — affiliates	0
Notes due to affiliates	0
Commodity and other derivative contractual liabilities	0		0
Margin deposits related to commodity contracts	0		0
Accrued income taxes			58
Accrued taxes other than income	0		0
Accrued interest	107		0
Asset retirement obligations	0		0
Other current liabilities	96		86
Total current liabilities	237		155
Long-term debt, less amounts due currently	3,954		0
Commodity and other derivative contractual liabilities	0		0
Deferred Tax Liabilities, Net, Noncurrent	0
Tax Receivable Agreement obligation	402		333
Asset retirement obligation	0		0
Identifiable intangible liabilities - net	0		0
Other noncurrent liabilities and deferred credits	26		0
Total liabilities	4,619		488
Total stockholders' equity	8,399		6,342
Noncontrolling interest in subsidiary	0
Total liabilities and equity	13,018		6,830
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	732		363
Restricted cash	0		0
Advances to affiliates	0
Trade accounts receivable — net	875		578
Accounts receivable — affiliates	0
Notes due from affiliates	101
Income taxes receivable	0
Inventories	378		253
Commodity and other derivative contractual assets	458		190
Margin deposits related to commodity contracts	177		30
Prepaid expense and other current assets	117		72
Total current assets	2,838		1,486
Restricted cash			500
Investments	1,323		1,240
Investment in unconsolidated subsidiary	135
Investment in affiliated companies	362		0
Property, plant and equipment — net	14,058		4,820
Goodwill	1,907		1,907
Identifiable intangible assets — net	2,711		2,530
Commodity and other derivative contractual assets	265		58
Accumulated deferred income taxes	239		705
Other noncurrent assets	185		156
Total assets	24,023		13,402
Current liabilities:
Accounts receivable securitization program	0
Advances from affiliates	2
Long-term debt due currently	145		44
Trade accounts payable	587		462
Accounts payable — affiliates	215
Notes due to affiliates	0
Commodity and other derivative contractual liabilities	981		224
Margin deposits related to commodity contracts	4		4
Accrued income taxes			0
Accrued taxes other than income	138		136
Accrued interest	16		16
Asset retirement obligations	183		99
Other current liabilities	231		211
Total current liabilities	2,502		1,196
Long-term debt, less amounts due currently	7,073		4,379
Commodity and other derivative contractual liabilities	254		102
Deferred Tax Liabilities, Net, Noncurrent	0
Tax Receivable Agreement obligation	0		0
Asset retirement obligation	2,126		1,837
Identifiable intangible liabilities - net	132		36
Other noncurrent liabilities and deferred credits	305		220
Total liabilities	12,392		7,770
Total stockholders' equity	11,631		5,632
Noncontrolling interest in subsidiary	0
Total liabilities and equity	24,023		13,402
Reportable Legal Entities [Member] \| Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	13		0
Restricted cash	0		0
Advances to affiliates	0
Trade accounts receivable — net	359		0
Accounts receivable — affiliates	211
Notes due from affiliates	0
Income taxes receivable	0
Inventories	15		0
Commodity and other derivative contractual assets	0		0
Margin deposits related to commodity contracts	0		0
Prepaid expense and other current assets	4		0
Total current assets	602		0
Restricted cash			0
Investments	34		0
Investment in unconsolidated subsidiary	0
Investment in affiliated companies	0		0
Property, plant and equipment — net	680		0
Goodwill	0		0
Identifiable intangible assets — net	0		0
Commodity and other derivative contractual assets	0		0
Accumulated deferred income taxes	0		0
Other noncurrent assets	2		0
Total assets	1,318		0
Current liabilities:
Accounts receivable securitization program	350
Advances from affiliates	8
Long-term debt due currently	5		0
Trade accounts payable	222		0
Accounts payable — affiliates	8
Notes due to affiliates	101
Commodity and other derivative contractual liabilities	0		0
Margin deposits related to commodity contracts	0		0
Accrued income taxes			0
Accrued taxes other than income	1		0
Accrued interest	3		0
Asset retirement obligations	0		0
Other current liabilities	2		0
Total current liabilities	700		0
Long-term debt, less amounts due currently	33		0
Commodity and other derivative contractual liabilities	0		0
Deferred Tax Liabilities, Net, Noncurrent	146
Tax Receivable Agreement obligation	0		0
Asset retirement obligation	13		0
Identifiable intangible liabilities - net	43		0
Other noncurrent liabilities and deferred credits	15		0
Total liabilities	950		0
Total stockholders' equity	362		0
Noncontrolling interest in subsidiary	6
Total liabilities and equity	1,318		0
Consolidation, Eliminations [Member]
Current assets:
Cash and cash equivalents	0		0
Restricted cash	0		0
Advances to affiliates	(11)
Trade accounts receivable — net	0		0
Accounts receivable — affiliates	(226)
Notes due from affiliates	(101)
Income taxes receivable	0
Inventories	0		0
Commodity and other derivative contractual assets	0		0
Margin deposits related to commodity contracts	0		0
Prepaid expense and other current assets	0		0
Total current assets	(338)		0
Restricted cash			0
Investments	0		0
Investment in unconsolidated subsidiary	0
Investment in affiliated companies	(11,993)		(5,632)
Property, plant and equipment — net	0		0
Goodwill	0		0
Identifiable intangible assets — net	0		0
Commodity and other derivative contractual assets	0		0
Accumulated deferred income taxes	(141)		0
Other noncurrent assets	1		0
Total assets	(12,471)		(5,632)
Current liabilities:
Accounts receivable securitization program	0
Advances from affiliates	(10)
Long-term debt due currently	0		0
Trade accounts payable	0		0
Accounts payable — affiliates	(223)
Notes due to affiliates	(101)
Commodity and other derivative contractual liabilities	0		0
Margin deposits related to commodity contracts	0		0
Accrued income taxes			0
Accrued taxes other than income	0		0
Accrued interest	(3)		0
Asset retirement obligations	0		0
Other current liabilities	0		0
Total current liabilities	(337)		0
Long-term debt, less amounts due currently	0		0
Commodity and other derivative contractual liabilities	0		0
Deferred Tax Liabilities, Net, Noncurrent	(141)
Tax Receivable Agreement obligation	0		0
Asset retirement obligation	0		0
Identifiable intangible liabilities - net	0		0
Other noncurrent liabilities and deferred credits	0		0
Total liabilities	(478)		0
Total stockholders' equity	(11,993)		(5,632)
Noncontrolling interest in subsidiary	0
Total liabilities and equity	$ (12,471)		$ (5,632)