Dyne Therapeutics 10-Q 1 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	DYNEGY INC.
Entity Central Index Key	1,379,895
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		131,378,891
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 613	$ 1,776
Restricted cash	0	62
Accounts receivable, net of allowance for doubtful accounts of $1 and $1, respectively	478	386
Inventory	429	445
Assets from risk management activities	50	130
Intangible assets	24	38
Prepayments and other current assets	110	150
Total Current Assets	1,704	2,987
Property, plant and equipment, net	8,929	7,121
Investment in unconsolidated affiliate	154	0
Restricted cash	0	2,000
Assets from risk management activities	49	16
Goodwill	772	799
Intangible assets	49	23
Assets held-for-sale	181	0
Other long-term assets	169	107
Total Assets	12,007	13,053
Current Liabilities
Accounts payable	288	332
Accrued interest	154	81
Intangible liabilities	18	21
Accrued taxes	57	45
Accrued liabilities and other current liabilities	136	88
Liabilities from risk management activities	58	97
Asset retirement obligations	57	51
Debt, current portion, net	99	201
Total Current Liabilities	867	916
Liabilities subject to compromise (Note 18)	0	832
Debt, long-term portion, net	8,648	8,778
Liabilities from risk management activities	20	43
Asset retirement obligations	268	236
Deferred income taxes	18	5
Intangible liabilities	36	34
Other long-term liabilities	166	170
Total Liabilities	10,023	11,014
Commitments and Contingencies (Note 13)
Stockholders’ Equity
Common stock, $0.01 par value, 420,000,000 shares authorized; 142,699,979 shares issued and 131,373,857 shares outstanding at September 30, 2017; 128,626,740 shares issued and 117,300,618 outstanding at December 31, 2016	1	1
Additional paid-in capital	3,320	3,547
Accumulated other comprehensive income, net of tax	26	21
Accumulated deficit	(1,758)	(1,927)
Total Dynegy Stockholders’ Equity	1,989	2,042
Noncontrolling interest	(5)	(3)
Total Equity	1,984	2,039
Total Liabilities and Equity	12,007	13,053
Series A 5.375% mandatory convertible preferred stock
Stockholders’ Equity
Preferred stock, $0.01 par value, 20,000,000 shares authorized: Series A 5.375% mandatory convertible preferred stock, $0.01 par value; 4,000,000 shares issued and outstanding, respectively	$ 400	$ 400

CONSOLIDATED BALANCE SHEETS (PA

CONSOLIDATED BALANCE SHEETS (PARENTHETICAL) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Allowance for doubtful accounts	$ 1	$ 1
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	420,000,000	420,000,000
Common stock, shares issued (in shares)	142,699,979	128,626,740
Common stock, shares outstanding (in shares)	131,373,857	117,300,618
Series A 5.375% mandatory convertible preferred stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, series A 5.375%	5.375%	5.375%
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	4,000,000	4,000,000
Preferred stock, shares outstanding (in shares)	4,000,000	4,000,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenues	$ 1,437,000,000	$ 1,184,000,000	$ 3,848,000,000	$ 3,211,000,000
Cost of sales, excluding depreciation expense	(787,000,000)	(660,000,000)	(2,225,000,000)	(1,698,000,000)
Gross margin	650,000,000	524,000,000	1,623,000,000	1,513,000,000
Operating and maintenance expense	(236,000,000)	(218,000,000)	(750,000,000)	(695,000,000)
Depreciation expense	(202,000,000)	(163,000,000)	(611,000,000)	(494,000,000)
Impairments	(29,000,000)	(212,000,000)	(148,000,000)	(857,000,000)
Loss on sale of assets, net	(78,000,000)	0	(107,000,000)	0
General and administrative expense	(44,000,000)	(41,000,000)	(126,000,000)	(117,000,000)
Acquisition and integration costs	(3,000,000)	(7,000,000)	(55,000,000)	(8,000,000)
Other	0	0	1,000,000	(16,000,000)
Operating income (loss)	58,000,000	(117,000,000)	(173,000,000)	(674,000,000)
Bankruptcy reorganization items (Note 18)	12,000,000	0	494,000,000	0
Earnings from unconsolidated investments	4,000,000	4,000,000	4,000,000	7,000,000
Interest expense	(161,000,000)	(166,000,000)	(478,000,000)	(449,000,000)
Loss on early extinguishment of debt (Note 12)	(66,000,000)	0	(75,000,000)	0
Other income and expense, net	19,000,000	29,000,000	65,000,000	60,000,000
Loss before income taxes	(134,000,000)	(250,000,000)	(163,000,000)	(1,056,000,000)
Income tax benefit (expense) (Note 14)	1,000,000	1,000,000	330,000,000	(6,000,000)
Net income (loss)	(133,000,000)	(249,000,000)	167,000,000	(1,062,000,000)
Less: Net loss attributable to noncontrolling interest	(1,000,000)	0	(2,000,000)	(2,000,000)
Net income (loss) attributable to Dynegy Inc.	(132,000,000)	(249,000,000)	169,000,000	(1,060,000,000)
Less: Dividends on preferred stock	5,000,000	5,000,000	16,000,000	16,000,000
Net income (loss) attributable to Dynegy Inc. common stockholders	$ (137,000,000)	$ (254,000,000)	$ 153,000,000	$ (1,076,000,000)
Earnings (Loss) Per Share (Note 16):
Basic earnings (loss) per share attributable to Dynegy Inc. common stockholders (in dollars per share)	$ (0.89)	$ (1.81)	$ 1.01	$ (8.54)
Diluted earnings (loss) per share attributable to Dynegy Inc. common stockholders (in dollars per share)	$ (0.89)	$ (1.81)	$ 0.96	$ (8.54)
Basic shares outstanding (in shares)	154	140	152	126
Diluted shares outstanding (in shares)	154	140	159	126

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (133)	$ (249)	$ 167	$ (1,062)
Other comprehensive income before reclassifications:
Actuarial gain and plan amendment (net of tax of zero, zero, $4, and zero for each respective period)	0	0	11	0
Amounts reclassified from accumulated other comprehensive income:
Amortization of unrecognized prior service credit (net of tax of zero for each respective period)	(2)	(2)	(6)	(4)
Other comprehensive income (loss), net of tax	(2)	(2)	5	(4)
Comprehensive income (loss)	(135)	(251)	172	(1,066)
Less: Comprehensive loss attributable to noncontrolling interest	(1)	0	(2)	(2)
Total comprehensive income (loss) attributable to Dynegy Inc.	$ (134)	$ (251)	$ 174	$ (1,064)

CONSOLIDATED STATEMENTS OF COM6

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (PARENTHETICAL) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Tax on actuarial loss	$ 0	$ 0	$ 4	$ 0
Tax on amortization of unrecognized prior service cost (credit) and actuarial loss (gain)	$ 0	$ 0	$ 0	$ 0

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 167	$ (1,062)
Adjustments to reconcile net income (loss) to net cash flows from operating activities:
Depreciation expense	611	494
Non-cash interest expense	36	37
Amortization of intangibles	13	17
Risk management activities	(38)	(75)
Loss on sale of assets, net	107	0
Loss on early extinguishment of debt	75	0
Earnings from unconsolidated investments	(4)	(7)
Deferred income taxes	(330)	6
Impairments	148	857
Change in value of common stock warrants	(16)	(5)
Bankruptcy reorganization items	(494)	0
Other	50	1
Changes in working capital:
Accounts receivable, net	(20)	32
Inventory	106	153
Prepayments and other current assets	81	179
Accounts payable and accrued liabilities	9	104
Distributions from unconsolidated investments	2	1
Changes in non-current assets	(2)	(16)
Changes in non-current liabilities	0	12
Net cash provided by operating activities	501	728
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(129)	(337)
Acquisitions, net of cash acquired	(3,249)	0
Distributions from unconsolidated investments	7	14
Proceeds received from asset sales, net	600	0
Other investing	0	10
Net cash used in investing activities	(2,771)	(313)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from long-term borrowings, net of debt issuance costs	1,747	2,277
Repayments of borrowings	(2,261)	(21)
Proceeds from issuance of equity, net of issuance costs	150	359
Payments of debt extinguishment costs	(50)	0
Preferred stock dividends paid	(16)	(16)
Interest rate swap settlement payments	(15)	(13)
Acquisition of noncontrolling interest	(375)	0
Payments related to bankruptcy settlement	(133)	0
Other financing	(2)	(2)
Net cash provided by (used in) financing activities	(955)	2,584
Net increase (decrease) in cash, cash equivalents and restricted cash	(3,225)	2,999
Cash, cash equivalents, and restricted cash beginning of period	3,838	544
Cash, cash equivalents, and restricted cash end of period	$ 613	$ 3,543

Basis of Presentation and Organ

Basis of Presentation and Organization	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Organization	Note 1—Basis of Presentation and Organization The accompanying unaudited consolidated financial statements have been prepared in accordance with the instructions to interim financial reporting as prescribed by the SEC. The year-end consolidated balance sheet data was derived from audited consolidated financial statements, but does not include all disclosures required by the Generally Accepted Accounting Principles of the United States of America (“GAAP”). The unaudited consolidated financial statements contained in this report include all material adjustments of a normal recurring nature that, in the opinion of management, are necessary for a fair presentation of the results for the interim periods. Certain prior period amounts in our unaudited consolidated financial statements have been reclassified to conform to current year presentation. These interim financial statements should be read together with the consolidated financial statements and notes thereto included in our annual report on Form 10-K for the year ended December 31, 2016 , filed with the SEC on February 24, 2017, which we refer to as our “Form 10-K.” Unless the context indicates otherwise, throughout this report, the terms “Dynegy,” “the Company,” “we,” “us,” “our,” and “ours” are used to refer to Dynegy Inc. and its direct and indirect subsidiaries. We sell electric energy, capacity and ancillary services primarily on a wholesale basis from our power generation facilities. We also serve residential, municipal, commercial and industrial customers primarily in MISO, PJM and NY/NE thro ugh our Homefield Energy and Dynegy Energy Services retail businesses. We report the results of our power generation business as six segments in our unaudited consolidated financial statements: (i) PJM, (ii) ISO-NE/NYISO (“NY/NE”), (iii) ERCOT, (iv) MISO, (v) IPH, and (vi) CAISO. Our consolidated financial results also reflect corporate-level expenses such as general and administrative expense, interest expense, and income tax benefit (expense). All significant intercompany transactions have been eliminated. Please read Note 19—Segment Information for further discussion. On February 2, 2017 (the “Emergence Date”), Illinois Power Generating Company (“Genco”) emerged from bankruptcy. Please read Note 18—Genco Chapter 11 Bankruptcy and Emergence for further discussion.

Accounting Policies

Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Accounting Policies	Note 2—Accounting Policies The accounting policies followed by the Company are set forth in Note 2—Summary of Significant Accounting Policies in our Form 10-K. The accompanying unaudited consolidated financial statements include our accounts and the accounts of our majority-owned or controlled subsidiaries. Accounting policies for all of our operations are in accordance with GAAP. Except for the adoption of new policies as described below, there have been no significant changes to our accounting policies during the nine months ended September 30, 2017 . Use of Estimates. The preparation of unaudited consolidated financial statements in conformity with GAAP requires management to make informed estimates and judgments that affect our reported financial position and results of operations based on currently available information. Actual results could differ materially from our estimates. The results of operations for the interim periods presented in this Form 10-Q are not necessarily indicative of the results to be expected for the full year or any other interim period due to seasonal fluctuations in demand for our energy products and services, changes in commodity prices, timing of maintenance and other expenditures, and other factors. Accounting Standards Adopted Statement of Cash Flows. In August 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-15-Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. To reduce current and future diversity in practice, the amendments in this ASU provide guidance for several cash flow classification issues identified where current GAAP is either unclear or does not include specific guidance. We adopted this ASU on January 1, 2017 and applied the amendments on a retrospective basis. The adoption of this ASU affected the classification of prepayments for future planned outage work performed under long-term service agreements. The majority of the cash prepayments required under these agreements will now be reflected as cash outflows from investing activities and the remainder will be classified as cash outflows from operating activities, based on whether they are anticipated to be expensed or capitalized. As a result of the retrospective application of this ASU, we reclassified approximately $80 million of cash prepayments from operating activities to investing activities in our unaudited consolidated statement of cash flows for the nine months ended September 30, 2016 . In November 2016, the FASB issued ASU 2016-18-Statement of Cash Flows (Topic 230): Restricted Cash. The amendments in this ASU require that a statement of cash flows explains the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. We adopted this ASU as of January 1, 2017 and applied the amendments on a retrospective basis. As a result of the retrospective application of this ASU, changes in restricted cash of $1 million and $2.045 billion previously reflected as cash flows from operating activities and investing activities, respectively, are now reflected in Net increase (decrease) in cash, cash equivalents, and restricted cash in our unaudited consolidated statement of cash flows for the nine months ended September 30, 2016 . Additionally, restricted cash of $39 million and $2.085 billion are now reflected in the beginning of period and end of period cash, cash equivalents and restricted cash line items, respectively, in our unaudited consolidated statement of cash flows for the nine months ended September 30, 2016 . Please read Note 7—Cash Flow Information for further discussion. Compensation. In March 2016, the FASB issued ASU 2016-09-Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The amendments in this ASU simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. We adopted this ASU on January 1, 2017 with no material impact on our unaudited consolidated financial statements. Goodwill. In January 2017, the FASB issued ASU 2017-04-Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. To simplify the subsequent measure of goodwill, the amendments in this ASU eliminate step two from the goodwill impairment test. An entity will no longer be required to calculate the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if the reporting unit had been acquired in a business combination to determine the impairment of goodwill. The amendments in this ASU will now require goodwill impairment to be measured by the amount by which the carrying value of the reporting unit exceeds its fair value. The guidance in this ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Upon adoption, an entity shall apply the guidance in this ASU prospectively with early adoption permitted for annual goodwill tests performed after January 1, 2017. We adopted this ASU on January 1, 2017 with no material impact on our unaudited consolidated financial statements. Accounting Standards Not Yet Adopted Business Combinations. In January 2017, the FASB issued ASU 2017-01-Business Combinations (Topic 805): Clarifying the Definition of a Business. The amendments in this ASU clarify the definition of a business. The amendments affect all companies and other reporting organizations that must determine whether they have acquired or sold a business. The guidance in this ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. We are currently evaluating this ASU and any potential impacts the adoption will have on our unaudited consolidated financial statements. Pensions. In March 2017, the FASB issued ASU No. 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendments of this ASU require an entity to report the service cost component of net benefit costs in the same line item as other compensation costs arising from services rendered by the related employees during the applicable service period. The other components of net benefit cost are required to be presented separately from the service cost component and below the subtotal of operating income. Additionally, only the service cost component of net benefit costs is eligible for capitalization. The guidance in this ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The adoption of this standard must be applied on a retrospective basis for the amendments concerning income statement presentation and on a prospective basis for the amendments regarding the capitalization of the service cost component. We are currently evaluating this ASU and any potential impacts the adoption will have on our unaudited consolidated financial statements. Leases. In February 2016, the FASB issued ASU 2016-02-Leases (Topic 842). The provisions in this ASU will require lessees to recognize lease assets and lease liabilities, for all leases, including operating leases, on the balance sheet. The lease assets recognized in the balance sheet will represent a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The lease liability recognized in the balance sheet will represent the lessee’s obligation to make lease payments arising from a lease, measured based on the present value of the minimum rental payments. Entities may make an accounting policy election to not recognize lease assets or lease liabilities for leases with a term of 12 months or less. The guidance in this ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. We are currently evaluating this ASU and any potential impacts the adoption will have on our unaudited consolidated financial statements. Revenue from Contracts with Customers. In May 2014, the FASB issued ASU 2014-09-Revenue from Contracts with Customers (Topic 606). This ASU supersedes current revenue recognition requirements and industry specific guidance and develops a common revenue recognition standard whereby an entity will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to in exchange for those goods or services. Additional disclosures will be required to describe the nature, amount, timing, and uncertainty of revenues and cash flows from contracts with customers. The guidance in this ASU and its amendments are effective for interim and annual periods beginning after December 15, 2017, with early adoption permitted for interim and annual periods beginning after December 15, 2016. We have established an implementation team to assess the impact the new accounting standard will have on our financial statements upon adoption and have not currently identified any material changes to the timing of our revenue recognition. We continue to assess the impact of the standard by reviewing our revenue contracts to determine if changes in our recognition policies or controls are necessary. We believe changes to our disclosures will primarily include a regional presentation of our revenues disaggregated by revenue type - energy, capacity, and ancillary services.

Acquisitions and Divestitures

Acquisitions and Divestitures	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Acquisitions and Divestitures	Note 3—Acquisitions and Divestitures Acquisition ENGIE Acquisition. On February 7, 2017 (the “ENGIE Acquisition Closing Date”), pursuant to the terms of the stock purchase agreement, as amended and restated on June 27, 2016, (the “ENGIE Acquisition Stock Purchase Agreement”), Dynegy acquired approximately 9,017 MW of generation from GDF SUEZ Energy North America, Inc. (“GSENA”) and International Power, S.A. (the “Seller”), including (i) 15 natural gas-fired facilities located in Illinois, Massachusetts, New Jersey, Ohio, Pennsylvania, Texas, Virginia, and West Virginia, (ii) one coal-fired facility in Texas, and (iii) one waste coal-fired facility in Pennsylvania for a base purchase price of approximately $3.3 billion in cash, subject to certain adjustments (the “ENGIE Acquisition”). Business Combination Accounting. The ENGIE Acquisition has been accounted for in accordance with ASC 805, Business Combinations, with identifiable assets acquired and liabilities assumed recorded at their estimated fair values on the acquisition date, February 7, 2017. A summary of the various techniques used to fair value the identifiable assets and liabilities, as well as their classification within the fair value hierarchy are listed below. • Working capital was valued using available market information (Level 2). • Acquired property, plant and equipment (“PP&E”), excluding those assets classified as held-for-sale, was valued using a discounted cash flow (“DCF”) analysis based upon a debt-free, free cash flow model (Level 3). The DCF model was created for each power generation facility based on its remaining useful life, and: ◦ for the years 2017 and 2018, included gross margin forecasts using quoted forward commodity market prices; ◦ for the years 2019 through 2026, we used gross margin forecasts based upon commodity and capacity price curves developed internally using forward New York Mercantile Exchange natural gas prices and supply and demand factors; ◦ for periods beyond 2026, we assumed a 2.5 percent growth rate. We also used management’s forecasts of operations and maintenance expense, general and administrative expense, as well as capital expenditures for the years 2017 through 2021, and for years thereafter assumed a 2.5 percent growth rate. These cash flows were discounted using discount rates of approximately 9 percent to 13 percent for gas-fired, and approximately 13 percent to 14 percent for coal-fired, generation facilities, based upon the plant’s age, efficiency, region, and years until retirement. • Acquired PP&E classified as held-for-sale was valued based upon the sale price of the assets (Level 3). • Acquired derivatives were valued using the methods described in Note 6—Fair Value Measurements (Level 2 or Level 3). • Contracts with terms that were not at current market prices were also valued using a DCF 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. • Asset retirement obligations (“AROs”) were recorded in accordance with ASC 410, Asset Retirement and Environmental Obligations (Level 3). The accounting for the ENGIE Acquisition is not complete because certain information and analysis that may impact our initial valuation is still being obtained or reviewed. Dynegy expects to finalize these amounts during the first quarter of 2018. The significant assets and liabilities for which provisional amounts are recognized are PP&E, deferred income taxes, and taxes other than deferred income taxes. Additionally, some taxes have not yet been finalized with the associated taxing jurisdictions, resulting in a potential change to their fair value at acquisition. These changes may also impact the fair value of the acquired PP&E or deferred tax liability. As such, the provisional amounts recognized are subject to revision until our valuation is completed, not to exceed one year from the ENGIE Acquisition Closing Date, and any material adjustments identified that existed as of the acquisition date will be recognized in the period in which they are identified. The following table summarizes the consideration paid and the provisional fair value amounts recognized for the assets acquired and liabilities assumed related to the ENGIE Acquisition, as of the acquisition date, February 7, 2017: (amounts in millions) Base purchase price $ 3,300 Working capital adjustments and other (31 ) Fair value of total consideration transferred $ 3,269 Cash $ 20 Accounts receivable 22 Inventory 101 Prepayments and other current assets 3 Assets from risk management activities (including current portion of $21 million) 25 Property, plant and equipment 2,716 Investment in unconsolidated affiliate 159 Intangible assets (including current portion of $7 million) 50 Assets held-for-sale 478 Other long-term assets 131 Total assets acquired 3,705 Accounts payable 28 Liabilities from risk management activities (including current portion of $13 million) 16 Asset retirement obligations 19 Intangible liabilities (including current portion of $16 million) 30 Deferred income taxes, net 342 Other long-term liabilities 1 Total liabilities assumed 436 Net assets acquired $ 3,269 The following table summarizes certain information related to the ENGIE Acquisition, which is included in our unaudited consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Acquisition costs $ — $ 3 $ 35 $ 5 Revenues $ 345 N/A $ 669 N/A Operating loss $ (36 ) N/A $ (32 ) N/A Pro Forma Results. The unaudited pro forma financial results for the nine months ended September 30, 2017 and 2016 assume the ENGIE Acquisition occurred on January 1, 2016. The unaudited pro forma financial results may not be indicative of the results that would have occurred had the acquisition been completed as of January 1, 2016, nor are they indicative of future results of operations. The unaudited pro forma financial results for the nine months ended September 30, 2017 and 2016 include adjustments of $35 million and $5 million , respectively, for non-recurring acquisition costs attributable to the ENGIE Acquisition. Nine Months Ended September 30, (amounts in millions) 2017 2016 Revenue $ 3,905 $ 3,942 Net income (loss) $ 169 $ (1,090 ) Net income (loss) attributable to Dynegy Inc. $ 171 $ (1,088 ) AER Acquisition. On April 12, 2017, we received approximately $25 million of cash related to the 2013 AER Acquisition. As a result, we have recorded $25 million in Other income and expense, net in our unaudited consolidated statement of operations for the nine months ended September 30, 2017 . Divestitures Troy and Armstrong. On July 11, 2017, Dynegy completed the sale of its equity ownership interests in two peaking facilities in PJM to LS Power (the “Troy and Armstrong Sale”) for approximately $480 million in cash, including adjustments for capital expenditures and working capital. The facilities sold were recently acquired in the ENGIE Acquisition and total 1,269 MW. Lee. On July 10, 2017, Dynegy signed a membership interest purchase agreement (the “Lee Sale Agreement”) with an affiliate of Rockland Capital for the sale of its equity ownership interest in the Lee facility, a natural gas-fueled peaking facility in PJM, for $180 million in cash, plus adjustments for working capital. On October 4, 2017, the FERC approved our sale of Lee, and we completed the sale on October 12, 2017. Our Lee facility, associated inventory, and allocated goodwill of $9 million are classified as long-term assets held-for-sale as of September 30, 2017 . Goodwill was allocated based on the relative fair values of the assets sold to the reporting unit. For the three and nine months ended September 30, 2017 , we wrote down the carrying value of the assets held-for-sale to the sales price and recognized an impairment of $15 million , which was recorded in Impairments in our unaudited consolidated statements of operations. Dighton and Milford-MA. On September 22, 2017, Dynegy completed the sale of its equity ownership interests in two intermediate natural gas-fueled facilities in NY/NE to Starwood Energy Group for approximately $125 million in cash, including $6 million in working capital adjustments. This sale has fulfilled the mitigation plan approved by FERC regarding the Company’s purchase of ENGIE’s US-based asset portfolio. For the three and nine months ended September 30, 2017 , we recognized a loss on sale of assets on our Dighton and Milford-MA facilities of $77 million , which includes $18 million of allocated goodwill. Goodwill was allocated based on the relative fair values of the assets sold to the reporting unit.

Unconsolidated Investments

Unconsolidated Investments	9 Months Ended
	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Unconsolidated Investments	Note 4—Unconsolidated Investments Equity Method Investments NELP. In connection with the ENGIE Acquisition, we acquired a 50 percent 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, 2017 , our equity method investment in NELP included in our unaudited consolidated balance sheets was $154 million . Upon the acquisition, we recognized basis differences in the net assets of approximately $14 million primarily related to PP&E. These basis differences are being amortized over their respective useful lives. Our risk of loss related to our equity method investment is limited to our investment balance. For the three and nine months ended September 30, 2017 , we recorded $4 million and $4 million , respectively, in equity earnings related to our investment in NELP which is reflected in Earnings from unconsolidated investments in our unaudited consolidated statements of operations. For the nine months ended September 30, 2017 , we received distributions of $9 million , of which $7 million was considered to be a return of investment using the cumulative earnings approach and reflected as Distributions from unconsolidated investments in our unaudited consolidated statements of cash flows. Elwood. On November 21, 2016, Dynegy sold its 50 percent equity interest in Elwood Energy, LLC, a limited liability company (“Elwood Energy”) and Elwood Expansion LLC, a limited liability company (and together with Elwood Energy “Elwood”), to J-Power USA Development Co. Ltd. for approximately $173 million (the “Elwood Sale”). As a result, we recorded an impairment charge of $9 million to Impairments in our unaudited consolidated statements of operations for the three and nine months ended September 30, 2016 , to write down our investment in Elwood to the sales price. For the three and nine months ended September 30, 2016 , we recorded $4 million and $7 million , respectively, in equity earnings related to our investment in Elwood, which is reflected in Earnings from unconsolidated investments in our unaudited consolidated statements of operations. For the nine months ended September 30, 2016 , we received distributions of $15 million , of which $14 million was considered to be a return of investment using the accumulated earnings approach and reflected as Distributions from unconsolidated investments in our unaudited consolidated statements of cash flows. Note 10—Joint Ownership of Generating Facilities We hold ownership interests in certain jointly owned generating facilities. We are entitled to the proportional share of the generating capacity and the output of each unit equal to our ownership interests. We pay our share of capital expenditures, fuel inventory purchases, and operating expenses, except in certain instances where agreements have been executed to limit certain joint owners’ maximum exposure to additional costs. Our share of revenues and operating costs of the jointly owned generating facilities is included within the corresponding financial statement line items in our unaudited consolidated statements of operations. The following tables present the ownership interests of the jointly owned facilities as of September 30, 2017 and December 31, 2016 included in our unaudited consolidated balance sheets. Each facility is co-owned with one or more other generation companies. September 30, 2017 (dollars in millions) Ownership Interest Property, Plant and Equipment Accumulated Depreciation Construction Work in Progress Total Miami Fort 64.0 % $ 208 $ (55 ) $ 4 $ 157 Stuart (1)(2) 39.0 % $ — $ — $ 1 $ 1 Zimmer 71.9 % $ 131 $ (37 ) $ 8 $ 102 Killen (1)(2) 33.0 % $ — $ — $ — $ — December 31, 2016 (dollars in millions) Ownership Interest Property, Plant and Equipment Accumulated Depreciation Construction Work in Progress Total Miami Fort 64.0 % $ 207 $ (39 ) $ 4 $ 172 Stuart (1) 39.0 % $ — $ — $ 4 $ 4 Conesville (1) 40.0 % $ 61 $ (3 ) $ 6 $ 64 Zimmer 46.5 % $ 115 $ (25 ) $ 6 $ 96 Killen (1) 33.0 % $ 19 $ (2 ) $ 3 $ 20 __________________________________________ (1) Facilities not operated by Dynegy. (2) Stuart Unit 1 was retired early on September 30, 2017, with remaining Stuart and Killen units scheduled to be retired by mid-2018. On May 9, 2017, Dynegy finalized the sale of its 40 percent ownership interest in Conesville to American Electric Power (“AEP”) in exchange for AEP’s 25.4 percent ownership interest in Zimmer. As a result, Dynegy now owns 71.9 percent of the Zimmer facility and no longer has an ownership interest in the Conesville facility. No cash was exchanged in the transaction and no additional debt was incurred by either party. AEP returned a previously issued letter of credit totaling $58 million to Dynegy. The acquisition of the additional interest in Zimmer has been accounted for as a business combination using similar fair value methodologies as described in Note 3—Acquisitions and Divestitures . The fair value of the additional Zimmer interest is $27 million and was allocated $14 million to Property, plant and equipment, $14 million to Inventory, and $1 million to ARO liability in our unaudited consolidated balance sheets. As a result of the Conesville sale, we recognized a loss of $31 million for the nine months ended September 30, 2017 , representing the difference between the $58 million book value of our transferred interest in Conesville and the $27 million fair value of the acquired interest in Zimmer. On April 21, 2017, Dynegy reached an agreement with AES Ohio Generation, LLC and The Dayton Power and Light Company (collectively, “AES”) under which Dynegy will purchase AES’ 28.1 percent interest in Zimmer and 36 percent interest in Miami Fort for $50 million in cash and the assumption of certain liabilities, subject to customary adjustments. The transaction is expected to close by the end of 2017.

Risk Management Activities, Der

Risk Management Activities, Derivatives and Financial Instruments	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Risk Management Activities, Derivatives and Financial Instruments	Note 5—Risk Management Activities, Derivatives and Financial Instruments The nature of our business involves commodity market and financial risks. Specifically, we are exposed to commodity price variability related to our power generation business. Our commercial team manages these commodity price risks with financially and physically settled contracts consistent with our commodity risk management policy. Our treasury team manages our interest rate risk. Our commodity risk management policy gives us the flexibility to sell energy and capacity and purchase fuel through a combination of spot market sales and near-term contractual arrangements (generally over a rolling one - to three -year time frame). Our commodity risk management goal is to protect cash flow in the near-term while keeping the ability to capture value longer-term. Many of our contractual arrangements are derivative instruments and are accounted for at fair value as part of Revenues in our unaudited consolidated statements of operations. We have other contractual arrangements such as capacity forward sales arrangements, tolling arrangements, fixed price coal purchases, and retail power sales, which do not receive recurring fair value accounting treatment because these arrangements do not meet the definition of a derivative or are designated as “normal purchase, normal sale,” in accordance with ASC 815, Derivatives and Hedging. As a result, the gains and losses with respect to these arrangements are not reflected in the unaudited consolidated statements of operations until the delivery occurs. Quantitative Disclosures Related to Financial Instruments and Derivatives As of September 30, 2017 , we had net purchases and sales of derivative contracts outstanding in the following quantities: Contract Type Quantity Unit of Measure Fair Value (1) (dollars and quantities in millions) Purchases (Sales) Asset (Liability) Commodity contracts: Electricity derivatives (2) (60 ) MWh $ 14 Electricity basis derivatives (3) (34 ) MWh $ (7 ) Natural gas derivatives (2) 380 MMBtu $ (1 ) Natural gas basis derivatives 108 MMBtu $ (14 ) Physical heat rate derivatives 125/(13) MMBtu/MWh $ 14 Emissions derivatives 17 Metric Ton $ 4 Interest rate swaps 1,963 U.S. Dollar $ (11 ) Common stock warrants (4) 25 Warrant $ (2 ) __________________________________________ (1) Includes both asset and liability risk management positions but excludes margin and collateral netting of $22 million . (2) Mainly comprised of swaps and physical forwards. (3) Comprised of FTRs and swaps. (4) Each warrant is convertible into one share of Dynegy common stock. Derivatives on the Balance Sheet. The following tables present the fair value and balance sheet classification of derivatives in our unaudited consolidated balance sheets as of September 30, 2017 and December 31, 2016 . As of September 30, 2017 and December 31, 2016 , there were no gross amounts available to be offset that were not offset in our unaudited consolidated balance sheets. September 30, 2017 Gross amounts offset in the balance sheet Contract Type Balance Sheet Location Gross Fair Value Contract Netting Collateral or Margin Received or Paid Net Fair Value (amounts in millions) Derivative assets: Commodity contracts Assets from risk management activities $ 204 $ (117 ) $ — $ 87 Interest rate contracts Assets from risk management activities 12 — — 12 Total derivative assets $ 216 $ (117 ) $ — $ 99 Derivative liabilities: Commodity contracts Liabilities from risk management activities $ (194 ) $ 117 $ 22 $ (55 ) Interest rate contracts Liabilities from risk management activities (23 ) — — (23 ) Common stock warrants Accrued liabilities and other current liabilities and other long-term liabilities (2 ) — — (2 ) Total derivative liabilities $ (219 ) $ 117 $ 22 $ (80 ) Total derivatives $ (3 ) $ — $ 22 $ 19 December 31, 2016 Gross amounts offset in the balance sheet Contract Type Balance Sheet Location Gross Fair Value Contract Netting Collateral or Margin Received or Paid Net Fair Value (amounts in millions) Derivative assets: Commodity contracts Assets from risk management activities $ 311 $ (165 ) $ — $ 146 Total derivative assets $ 311 $ (165 ) $ — $ 146 Derivative liabilities: Commodity contracts Liabilities from risk management activities $ (329 ) $ 165 $ 54 $ (110 ) Interest rate contracts Liabilities from risk management activities (30 ) — — (30 ) Common stock warrants Accrued liabilities and other current liabilities (1 ) — — (1 ) Total derivative liabilities $ (360 ) $ 165 $ 54 $ (141 ) Total derivatives $ (49 ) $ — $ 54 $ 5 Certain of our derivative instruments have credit limits that require us to post collateral. The amount of collateral required to be posted is a function of the net liability position of the derivative as well as our established credit limit with the respective counterparty. If our credit rating were to worsen, the counterparties could require us to post additional collateral. The amount of additional collateral that would be required to be posted would vary depending on the extent of change in our credit rating as well as the requirements of the individual counterparty. As of September 30, 2017 , the aggregate fair value of all commodity derivative instruments containing credit-risk-related contingent features, in a liability position and not fully collateralized, is $9 million for which we have posted no collateral. Transactions with our clearing brokers are excluded as they are fully collateralized. Our remaining derivative instruments do not have credit-related collateral contingencies as they are included within our first-lien collateral program. The following table summarizes our cash collateral posted as of September 30, 2017 and December 31, 2016 , within Prepayments and other current assets in our unaudited consolidated balance sheets and the amount applied against short-term risk management activities: Location on Balance Sheet September 30, 2017 December 31, 2016 (amounts in millions) Gross collateral posted with counterparties $ 54 $ 116 Less: Collateral netted against risk management liabilities 22 54 Net collateral within Prepayments and other current assets $ 32 $ 62 Impact of Derivatives on the Unaudited Consolidated Statements of Operations We elect not to designate derivatives related to our power generation business and interest rate instruments as cash flow or fair value hedges. Thus, we account for changes in the fair value of these derivatives within our unaudited consolidated statements of operations. Our unaudited consolidated statements of operations for the three and nine months ended September 30, 2017 and 2016 include the impact of derivative financial instruments as presented below: Derivatives Not Designated as Hedges Location of Gain (Loss) Recognized in Income on Derivatives Three Months Ended September 30, Nine Months Ended 2017 2016 2017 2016 (amounts in millions) Commodity contracts Revenues $ 29 $ (27 ) $ 242 $ 188 Interest rate contracts Interest expense $ 1 $ 1 $ 4 $ (11 ) Common stock warrants Other income and (expense), net $ 1 $ 4 $ 16 $ 5

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 6—Fair Value Measurements We apply the market approach for recurring fair value measurements, employing valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. We have consistently used the same valuation techniques for all periods presented. Please read Note 2 — Summary of Significant Accounting Policies — Fair Value Measurements in our Form 10-K for further discussion. The following tables set forth, by level within the fair value hierarchy, our financial assets and liabilities that were accounted for at fair value on a recurring basis as of September 30, 2017 and December 31, 2016 , and are presented on a gross basis before consideration of amounts netted under master netting agreements and the application of collateral and margin paid: Fair Value as of September 30, 2017 (amounts in millions) Level 1 Level 2 Level 3 Total Assets: Assets from commodity risk management activities: Electricity derivatives $ — $ 100 $ 21 $ 121 Natural gas derivatives — 45 6 51 Physical heat rate derivatives — 20 1 21 Emissions derivatives — 11 — 11 Total assets from commodity risk management activities — 176 28 204 Assets from interest rate contracts — 12 — 12 Total assets $ — $ 188 $ 28 $ 216 Liabilities: Liabilities from commodity risk management activities: Electricity derivatives $ — $ (94 ) $ (20 ) $ (114 ) Natural gas derivatives — (60 ) (6 ) (66 ) Physical heat rate derivatives — (7 ) — (7 ) Emissions derivatives — (7 ) — (7 ) Total liabilities from commodity risk management activities — (168 ) (26 ) (194 ) Liabilities from interest rate contracts — (23 ) — (23 ) Liabilities from outstanding common stock warrants (2 ) — — (2 ) Total liabilities $ (2 ) $ (191 ) $ (26 ) $ (219 ) Fair Value as of December 31, 2016 (amounts in millions) Level 1 Level 2 Level 3 Total Assets: Assets from commodity risk management activities: Electricity derivatives $ — $ 118 $ 20 $ 138 Natural gas derivatives — 169 4 173 Total assets from commodity risk management activities $ — $ 287 $ 24 $ 311 Liabilities: Liabilities from commodity risk management activities: Electricity derivatives $ — $ (245 ) $ (12 ) $ (257 ) Natural gas derivatives — (52 ) (10 ) (62 ) Emissions derivatives — (10 ) — (10 ) Total liabilities from commodity risk management activities — (307 ) (22 ) (329 ) Liabilities from interest rate contracts — (30 ) — (30 ) Liabilities from outstanding common stock warrants (1 ) — — (1 ) Total liabilities $ (1 ) $ (337 ) $ (22 ) $ (360 ) Level 3 Valuation Methods. The electricity derivatives classified within Level 3 include financial swaps executed in illiquid trading locations or on long dated contracts, capacity contracts and FTRs. The curves used to generate the fair value of the financial swaps are based on basis adjustments applied to forward curves for liquid trading points, while the curves for the capacity deals are based upon auction results in the marketplace, which are infrequently executed. The forward market price of FTRs is derived using historical congestion patterns within the marketplace and heat rate derivative valuations are derived using a DCF model, which uses modeled forward natural gas and power prices. The natural gas derivatives classified within Level 3 include financial swaps, basis swaps, and physical purchases executed in illiquid trading locations or on long dated contracts. Sensitivity to Changes in Significant Unobservable Inputs for Level 3 Valuations. The significant unobservable inputs used in the fair value measurement of our commodity instruments categorized within Level 3 of the fair value hierarchy include estimates of forward congestion, power price spreads, and natural gas pricing, and the difference between our plant locational prices to liquid hub prices. Power price spreads, and natural gas pricing, and the difference between our plant locational prices to liquid hub prices are generally based on observable markets where available, or derived from historical prices and forward market prices from similar observable markets when not available. Increases in the price of the spread on a buy or sell position in isolation would result in a higher/lower fair value measurement. The significant unobservable inputs used in the valuation of Dynegy’s contracts classified as Level 3 as of September 30, 2017 are as follows: Transaction Type Quantity Unit of Measure Net Fair Value Valuation Technique Significant Unobservable Input Significant Unobservable Input Range (dollars in millions) Electricity derivatives: Forward contracts—power (1) (14 ) Million MWh $ 4 Basis spread + liquid location Basis spread $4.25 - $6.25 FTRs (29 ) Million MWh $ (3 ) Historical congestion Forward price $0 - $6.00 Physical heat rate derivatives 23/(3) Million MMBtu/Million MWh $ 1 Discounted Cash Flow Forward price $2.40 - $3.30 / $20 - $24 Natural gas derivatives (1) 102 Million MMBtu $ — Illiquid location fixed price Forward price $1.75 - $2.15 __________________________________________ (1) Represents forward financial and physical transactions at illiquid pricing locations and long-dated contracts. The following tables set forth a reconciliation of changes in the fair value of financial instruments classified as Level 3 in the fair value hierarchy: Three Months Ended September 30, 2017 (amounts in millions) Electricity Derivatives Natural Gas Derivatives Heat Rate Derivatives Total Balance at June 30, 2017 $ (1 ) $ 1 $ (2 ) $ (2 ) Total gains (losses) included in earnings 6 (1 ) 3 8 Transfers out of level 3 (1) (2 ) — — (2 ) Settlements (2) (2 ) — — (2 ) Balance at September 30, 2017 $ 1 $ — $ 1 $ 2 Unrealized gains (losses) relating to instruments held as of September 30, 2017 $ 6 $ (1 ) $ 3 $ 8 Nine Months Ended September 30, 2017 (amounts in millions) Electricity Derivatives Natural Gas Derivatives Heat Rate Derivatives Total Balance at December 31, 2016 $ 8 $ (6 ) $ — $ 2 Acquired derivatives 1 — — 1 Total gains (losses) included in earnings (16 ) 10 1 (5 ) Settlements (2) 8 (4 ) — 4 Balance at September 30, 2017 $ 1 $ — $ 1 $ 2 Unrealized gains (losses) relating to instruments held as of September 30, 2017 $ (16 ) $ 10 $ 1 $ (5 ) Three Months Ended September 30, 2016 (amounts in millions) Electricity Derivatives Natural Gas Derivatives Coal Derivatives Total Balance at June 30, 2016 $ (24 ) $ (15 ) $ 1 $ (38 ) Total gains (losses) included in earnings 9 (4 ) 1 6 Settlements (2) 5 5 (1 ) 9 Balance at September 30, 2016 $ (10 ) $ (14 ) $ 1 $ (23 ) Unrealized gains (losses) relating to instruments held as of September 30, 2016 $ 9 $ (4 ) $ 1 $ 6 Nine Months Ended September 30, 2016 (amounts in millions) Electricity Derivatives Natural Gas Derivatives Coal Derivatives Total Balance at December 31, 2015 $ (18 ) $ (32 ) $ 2 $ (48 ) Total gains included in earnings 4 — — 4 Settlements (2) 4 18 (1 ) 21 Balance at September 30, 2016 $ (10 ) $ (14 ) $ 1 $ (23 ) Unrealized gains relating to instruments held as of September 30, 2016 $ 4 $ — $ — $ 4 _________________________________________ (1) During the three months ended September 30, 2017 , we had transfers from Level 3 to Level 2 due to changes in market liquidity. (2) For purposes of these tables, we define settlements as the beginning of period fair value of contracts that settled during the period. Gains and losses recognized for Level 3 recurring items are included in Revenues in our unaudited consolidated statements of operations for commodity derivatives. We believe an analysis of commodity instruments classified as Level 3 should be undertaken with the understanding that these items generally serve as economic hedges of our power generation portfolio. Nonfinancial Assets and Liabilities. Nonfinancial assets and liabilities that are measured at fair value on a nonrecurring basis are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of such assets and liabilities and their placement within the fair value hierarchy. Impairments. During the three and nine months ended September 30, 2017 and 2016 , we recorded impairment charges related to certain of our facilities , materials and supplies inventory and assets held-for-sale using fair value measurements. See Note 3—Acquisitions and Divestitures , Note 8—Inventory and Note 9—Property, Plant and Equipment for further discussion. Acquisitions. We fair valued the ENGIE Acquisition and our acquisition of additional joint ownership interest in the Zimmer facility using fair value measurements. See Note 3—Acquisitions and Divestitures and Note 10—Joint Ownership of Generating Facilities for further discussion of the fair value hierarchy classifications of valuations of acquired identifiable assets and liabilities. Fair Value of Financial Instruments. The following table discloses the fair value of financial instruments which are not recognized at fair value in our unaudited consolidated balance sheets. Unless otherwise noted, the fair value of debt as reflected in the table has been calculated based on the average of certain available broker quotes as of September 30, 2017 and December 31, 2016 , respectively. September 30, 2017 December 31, 2016 (amounts in millions) Fair Value Hierarchy Carrying Amount Fair Value Carrying Amount Fair Value Dynegy Inc.: Tranche C-1 Term Loan, due 2024 (1) Level 2 $ (1,940 ) $ (2,029 ) $ (1,994 ) $ (2,025 ) Tranche B-2 Term Loan, due 2020 (1) Level 2 $ — $ — $ (219 ) $ (225 ) Revolving Facility (1) Level 2 $ (300 ) $ (300 ) $ — $ — 6.75% Senior Notes, due 2019 (1) Level 2 $ (845 ) $ (881 ) $ (2,083 ) $ (2,137 ) 7.375% Senior Notes, due 2022 (1) Level 2 $ (1,733 ) $ (1,824 ) $ (1,731 ) $ (1,665 ) 5.875% Senior Notes, due 2023 (1) Level 2 $ (493 ) $ (498 ) $ (492 ) $ (431 ) 7.625% Senior Notes, due 2024 (1) Level 2 $ (1,237 ) $ (1,294 ) $ (1,237 ) $ (1,156 ) 8.034% Senior Notes, due 2024 (1) Level 2 $ (188 ) $ (190 ) $ — $ — 8.00% Senior Notes, due 2025 (1) Level 2 $ (739 ) $ (778 ) $ (738 ) $ (703 ) 8.125% Senior Notes, due 2026 (1) Level 2 $ (842 ) $ (880 ) $ — $ — 7.00% Amortizing Notes, due 2019 (TEUs) (1) Level 2 $ (58 ) $ (62 ) $ (78 ) $ (90 ) Forward capacity agreement (1) Level 3 $ (212 ) $ (212 ) $ (205 ) $ (205 ) Inventory financing agreements Level 3 $ (48 ) $ (48 ) $ (129 ) $ (127 ) Equipment financing agreements (1) Level 3 $ (112 ) $ (112 ) $ (73 ) $ (73 ) Genco: Liabilities subject to compromise (2) Level 3 $ — $ — $ (825 ) $ (366 ) __________________________________________ (1) Carrying amounts include unamortized discounts and debt issuance costs. Please read Note 12—Debt for further discussion. (2) Carrying amounts represent the Genco senior notes that were classified as liabilities subject to compromise as of December 31, 2016. The fair value of the senior notes was equal to the Genco Plan consideration and is a Level 3 valuation due to a lack of observable inputs that make up the consideration. Please read Note 22—Genco Chapter 11 Bankruptcy in our Form 10-K for further details.

Cash Flow Information

Cash Flow Information	9 Months Ended
	Sep. 30, 2017
Cash and Cash Equivalents [Abstract]
Cash Flow Information	Note 7—Cash Flow Information The supplemental disclosures of our non-cash investing and financing information are as follows: Nine Months Ended September 30, (amounts in millions) 2017 2016 Change in capital expenditures included in accounts payable $ 5 $ (10 ) Change in capital expenditures pursuant to an equipment financing agreement $ 34 $ 11 Issuance of 2017 Warrants $ 17 $ — Issuance of senior notes related to the Genco restructuring $ 188 $ — Sale of interest in Conesville facility $ (58 ) $ — Acquisition of interest in Zimmer facility $ 27 $ — The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within our unaudited consolidated balance sheets that sum to the total of the same such amounts shown in our unaudited consolidated statements of cash flows: (amounts in millions) September 30, 2017 September 30, 2016 Cash and cash equivalents $ 613 $ 1,458 Restricted cash included in current assets (1) — 85 Restricted cash included in long-term assets (2) — 2,000 Total cash, cash equivalents and restricted cash $ 613 $ 3,543 __________________________________________ (1) Includes $45 million placed in escrow for the issuance of the Tranche C Term Loan ( $25 million of pre-funded interest and interest income earned and $20 million of pre-funded original issue discount) and $40 million related to collateral. (2) Relates to amounts placed into escrow for the issuance of the Tranche C Term Loan.

Inventory

Inventory	9 Months Ended
	Sep. 30, 2017
Inventory Disclosure [Abstract]
Inventory	Note 8—Inventory A summary of our inventories is as follows: (amounts in millions) September 30, 2017 December 31, 2016 Materials and supplies $ 236 $ 182 Coal 165 238 Fuel oil 14 17 Natural gas 12 — Emissions allowances (1) 2 8 Total $ 429 $ 445 __________________________________________ (1) At September 30, 2017 and December 31, 2016 , a portion of this inventory was held as collateral by one of our counterparties as part of an inventory financing agreement. Please read Note 12—Debt — Emissions Repurchase Agreements for further discussion. As discussed in Note 10—Joint Ownership of Generating Facilities , Stuart Unit 1 was retired early on September 30, 2017, with remaining Stuart and Killen units scheduled to be retired by mid-2018. We determined that we would not be able to recover the carrying value of our Materials and supplies inventory at these facilities and, as a result, recognized a charge of $14 million in Impairments in our unaudited consolidated statements of operations for the three and nine months ended September 30, 2017 .

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Note 9—Property, Plant and Equipment A summary of our property, plant and equipment is as follows: (amounts in millions) September 30, 2017 December 31, 2016 Power generation $ 9,845 $ 7,537 Buildings and improvements 958 944 Office and other equipment 115 98 Property, plant and equipment 10,918 8,579 Accumulated depreciation (1,989 ) (1,458 ) Property, plant and equipment, net $ 8,929 $ 7,121 Impairments For the three and nine months ended September 30, 2017 and 2016 , we recognized the following PP&E impairments in our unaudited consolidated statements of operations (amounts in millions). Each valuation is classified as Level 3 within the fair value hierarchy and is presented as of the date of its impairment. Three Months Ended September 30, Nine Months Ended September 30, Facility Fair Value 2017 2016 2017 2016 Baldwin (1) $ 97 — — — 645 Stuart (2) $ — — 55 — 55 Newton FGD (3) $ — — 148 — 148 Killen (4) $ — — — 20 — Hennepin (1) $ 16 — — 10 — Havana (1) $ 37 — — 89 — Total (5) $ — $ 203 $ 119 $ 848 _________________________________________ (1) Units failed to recover their basic operating costs in the MISO capacity auctions. The impairment was measured using a DCF model. (2) We determined that the facility would experience recurring negative cash flows due to on-going required maintenance and environmental capital expenditures, combined with consistently poor reliability. The impairment was measured using a DCF model. (3) We terminated the flue gas desulfurization (“FGD”) systems construction project at our Newton generation facility. The capitalized cost of the project was used to determine the impairment amount. (4) In first quarter 2017, Dayton Power and Light Co., the partner and operator of Killen, announced the shutdown of the Killen generation facility by June 2018. The impairment charge was equal to the book value. (5) Excludes impairments related to Goodwill and Materials and supplies inventory. Brayton Point Retirement The Brayton Point facility officially retired on June 1, 2017. During the three and nine months ended September 30, 2017 , we recognized approximately $7 million and $12 million of severance costs, respectively, which were classified within Operating and maintenance expense in our unaudited consolidated statement of operations.

Joint Ownership of Generating F

Joint Ownership of Generating Facilities	9 Months Ended
	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Joint Ownership of Generating Facilities	Note 4—Unconsolidated Investments Equity Method Investments NELP. In connection with the ENGIE Acquisition, we acquired a 50 percent 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, 2017 , our equity method investment in NELP included in our unaudited consolidated balance sheets was $154 million . Upon the acquisition, we recognized basis differences in the net assets of approximately $14 million primarily related to PP&E. These basis differences are being amortized over their respective useful lives. Our risk of loss related to our equity method investment is limited to our investment balance. For the three and nine months ended September 30, 2017 , we recorded $4 million and $4 million , respectively, in equity earnings related to our investment in NELP which is reflected in Earnings from unconsolidated investments in our unaudited consolidated statements of operations. For the nine months ended September 30, 2017 , we received distributions of $9 million , of which $7 million was considered to be a return of investment using the cumulative earnings approach and reflected as Distributions from unconsolidated investments in our unaudited consolidated statements of cash flows. Elwood. On November 21, 2016, Dynegy sold its 50 percent equity interest in Elwood Energy, LLC, a limited liability company (“Elwood Energy”) and Elwood Expansion LLC, a limited liability company (and together with Elwood Energy “Elwood”), to J-Power USA Development Co. Ltd. for approximately $173 million (the “Elwood Sale”). As a result, we recorded an impairment charge of $9 million to Impairments in our unaudited consolidated statements of operations for the three and nine months ended September 30, 2016 , to write down our investment in Elwood to the sales price. For the three and nine months ended September 30, 2016 , we recorded $4 million and $7 million , respectively, in equity earnings related to our investment in Elwood, which is reflected in Earnings from unconsolidated investments in our unaudited consolidated statements of operations. For the nine months ended September 30, 2016 , we received distributions of $15 million , of which $14 million was considered to be a return of investment using the accumulated earnings approach and reflected as Distributions from unconsolidated investments in our unaudited consolidated statements of cash flows. Note 10—Joint Ownership of Generating Facilities We hold ownership interests in certain jointly owned generating facilities. We are entitled to the proportional share of the generating capacity and the output of each unit equal to our ownership interests. We pay our share of capital expenditures, fuel inventory purchases, and operating expenses, except in certain instances where agreements have been executed to limit certain joint owners’ maximum exposure to additional costs. Our share of revenues and operating costs of the jointly owned generating facilities is included within the corresponding financial statement line items in our unaudited consolidated statements of operations. The following tables present the ownership interests of the jointly owned facilities as of September 30, 2017 and December 31, 2016 included in our unaudited consolidated balance sheets. Each facility is co-owned with one or more other generation companies. September 30, 2017 (dollars in millions) Ownership Interest Property, Plant and Equipment Accumulated Depreciation Construction Work in Progress Total Miami Fort 64.0 % $ 208 $ (55 ) $ 4 $ 157 Stuart (1)(2) 39.0 % $ — $ — $ 1 $ 1 Zimmer 71.9 % $ 131 $ (37 ) $ 8 $ 102 Killen (1)(2) 33.0 % $ — $ — $ — $ — December 31, 2016 (dollars in millions) Ownership Interest Property, Plant and Equipment Accumulated Depreciation Construction Work in Progress Total Miami Fort 64.0 % $ 207 $ (39 ) $ 4 $ 172 Stuart (1) 39.0 % $ — $ — $ 4 $ 4 Conesville (1) 40.0 % $ 61 $ (3 ) $ 6 $ 64 Zimmer 46.5 % $ 115 $ (25 ) $ 6 $ 96 Killen (1) 33.0 % $ 19 $ (2 ) $ 3 $ 20 __________________________________________ (1) Facilities not operated by Dynegy. (2) Stuart Unit 1 was retired early on September 30, 2017, with remaining Stuart and Killen units scheduled to be retired by mid-2018. On May 9, 2017, Dynegy finalized the sale of its 40 percent ownership interest in Conesville to American Electric Power (“AEP”) in exchange for AEP’s 25.4 percent ownership interest in Zimmer. As a result, Dynegy now owns 71.9 percent of the Zimmer facility and no longer has an ownership interest in the Conesville facility. No cash was exchanged in the transaction and no additional debt was incurred by either party. AEP returned a previously issued letter of credit totaling $58 million to Dynegy. The acquisition of the additional interest in Zimmer has been accounted for as a business combination using similar fair value methodologies as described in Note 3—Acquisitions and Divestitures . The fair value of the additional Zimmer interest is $27 million and was allocated $14 million to Property, plant and equipment, $14 million to Inventory, and $1 million to ARO liability in our unaudited consolidated balance sheets. As a result of the Conesville sale, we recognized a loss of $31 million for the nine months ended September 30, 2017 , representing the difference between the $58 million book value of our transferred interest in Conesville and the $27 million fair value of the acquired interest in Zimmer. On April 21, 2017, Dynegy reached an agreement with AES Ohio Generation, LLC and The Dayton Power and Light Company (collectively, “AES”) under which Dynegy will purchase AES’ 28.1 percent interest in Zimmer and 36 percent interest in Miami Fort for $50 million in cash and the assumption of certain liabilities, subject to customary adjustments. The transaction is expected to close by the end of 2017.

Intangible Assets and Liabiliti

Intangible Assets and Liabilities	9 Months Ended
	Sep. 30, 2017
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets and Liabilities	Note 11—Intangible Assets and Liabilities The following table summarizes the components of our intangible assets and liabilities as of September 30, 2017 and December 31, 2016 : September 30, 2017 December 31, 2016 (amounts in millions) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Intangible Assets: Electricity contracts $ 230 $ (176 ) $ 54 $ 260 $ (206 ) $ 54 Gas transport contracts 30 (11 ) 19 13 (6 ) 7 Total intangible assets $ 260 $ (187 ) $ 73 $ 273 $ (212 ) $ 61 Intangible Liabilities: Electricity contracts $ (19 ) $ 17 $ (2 ) $ (28 ) $ 26 $ (2 ) Coal contracts (32 ) 32 — (49 ) 42 (7 ) Coal transport contracts (84 ) 78 (6 ) (86 ) 73 (13 ) Gas transport contracts (58 ) 13 (45 ) (41 ) 8 (33 ) Gas storage contracts (2 ) 1 (1 ) — — — Total intangible liabilities $ (195 ) $ 141 $ (54 ) $ (204 ) $ 149 $ (55 ) Intangible assets and liabilities, net $ 65 $ (46 ) $ 19 $ 69 $ (63 ) $ 6 The following table presents our amortization expense (revenue) of intangible assets and liabilities for the three and nine months ended September 30, 2017 and 2016 : Three Months Ended September 30, Nine Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Electricity contracts, net (1) $ 5 $ 19 $ 29 $ 52 Coal contracts, net (2) (1 ) (9 ) (4 ) (32 ) Coal transport contracts, net (2) (2 ) (7 ) (7 ) (21 ) Gas transport contracts, net (2) (3 ) 1 (4 ) 18 Gas storage contracts, net (2) — — (1 ) — Total $ (1 ) $ 4 $ 13 $ 17 __________________________________________ (1) The amortization of these contracts is recognized in Revenues or Cost of sales in our unaudited consolidated statements of operations. (2) The amortization of these contracts is recognized in Cost of sales in our unaudited consolidated statements of operations. The following table summarizes the components of our contract based intangible assets and liabilities recorded in connection with the ENGIE Acquisition in February 2017: (amounts in millions/months) Gross Carrying Amount Weighted-Average Amortization Period Intangible Assets: Electricity contracts $ 34 39 Gas transport contracts 16 47 Total intangible assets $ 50 41 Intangible Liabilities: Electricity contracts $ (11 ) 32 Gas contracts — 1 Gas transport contracts (17 ) 35 Gas storage contracts (2 ) 13 Total intangible liabilities $ (30 ) 33 Total intangible assets and liabilities, net $ 20 Amortization expense (revenue), net related to intangible assets and liabilities recorded in connection with the ENGIE Acquisition for the next five years as of September 30, 2017 is as follows: 2017 — $(3) million , 2018 — $11 million , 2019 — $17 million , 2020 — $4 million and 2021 — $(1) million .

Debt

Debt	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Debt	Note 12—Debt A summary of our long-term debt is as follows: (amounts in millions) September 30, 2017 December 31, 2016 Secured Obligations: Tranche C-1 Term Loan, due 2024 (1) $ 2,018 $ 2,000 Tranche B-2 Term Loan, due 2020 — 224 Revolving Facility 300 — Forward Capacity Agreements 241 219 Inventory Financing Agreements 48 129 Subtotal secured obligations 2,607 2,572 Unsecured Obligations: 7.00% Amortizing Notes, due 2019 (TEUs) 60 80 6.75% Senior Notes, due 2019 850 2,100 7.375% Senior Notes, due 2022 1,750 1,750 5.875% Senior Notes, due 2023 500 500 7.625% Senior Notes, due 2024 1,250 1,250 8.034% Senior Notes, due 2024 (2) 188 — 8.00% Senior Notes, due 2025 750 750 8.125% Senior Notes, due 2026 850 — Equipment Financing Agreements 139 97 Subtotal unsecured obligations 6,337 6,527 Total debt obligations 8,944 9,099 Unamortized debt discounts and issuance costs (197 ) (120 ) 8,747 8,979 Less: Current maturities, including unamortized debt discounts and issuance costs, net 99 201 Total long-term debt $ 8,648 $ 8,778 __________________________________________ (1) At December 31, 2016, the $2.0 billion Tranche C Term Loan was held by Dynegy Finance IV. Upon the close of the ENGIE Acquisition, this debt obligation became Dynegy Inc.’s secured obligation. (2) See Note 18—Genco Chapter 11 Bankruptcy and Emergence for further discussion. Credit Agreement As of September 30, 2017 , we had a $3.769 billion credit agreement, as amended, that consisted of (i) a $2.224 billion seven -year senior secured term loan facility (the “Tranche C-1 Term Loan”) and (ii) $1.545 billion in senior secured revolving credit facilities (the “Revolving Facility,” and collectively with the Tranche C-1 Term Loan the “Credit Agreement”). During the nine months ended September 30, 2017 , we made the following changes to the Credit Agreement: • On January 10, 2017, we amended the Credit Agreement (Fourth Amendment) to increase the revolver capacity by $45 million and to extend the maturity date on $450 million in revolver capacity to 2021, which was effective upon the ENGIE Acquisition Closing Date. • On the ENGIE Acquisition Closing Date, we amended the Credit Agreement (Fifth Amendment) to (i) reduce the interest rate applicable to the Tranche C Term Loan by 75 basis points and (ii) extend the maturity to 2024 of the existing Tranche B-2 Term Loan t hrough the exchange of the outstanding initial Tranche B-2 Term Loan for the $2.224 billion Tranche C-1 Term Loan. As a result of this exchange, we recorded a loss on early extinguishment of debt of approximately $9 million in our unaudited consolidated statements of operations in the first quarter of 2017, of which approximately $7 million was related to the write-off of unamortized deferred financing costs and approximately $2 million was related to the write-off of unamortized debt discount. • On August 22, 2017, we repaid $200 million of our Tranche C-1 term loan. As a result of this transaction, we recorded a loss on early extinguishment of debt of approximately $8 million in our unaudited consolidated statements of operations for the three and nine months ended September 30, 2017 , of which $6 million was related to the write-off of unamortized deferred financing costs and $2 million was related to the write-off of unamortized debt discount. At September 30, 2017 , there was $300 million drawn on the Revolving Facility. We also had outstanding letters of credit (“LCs”) of approximately $310 million , which reduce the amount available under the Revolving Facility. The Credit Agreement contains customary events of default and affirmative and negative covenants, subject to certain specified exceptions, including a Senior Secured Leverage Ratio (as defined in the Credit Agreement) calculated on a rolling four quarters basis. Under the Credit Agreement, if Dynegy utilizes 25 percent or more of its Revolving Facility, Dynegy must be in compliance with the Consolidated Senior Secured Net Debt to Consolidated Adjusted EBITDA ratio of 4.00 :1.00. Our revolver usage at September 30, 2017 was 39 percent of the aggregate revolver commitment due to outstanding LCs and revolver draws. Based on the calculation outlined in the Credit Agreement, we were in compliance with these covenants as of September 30, 2017 . In October 2017, we repaid the outstanding Revolving Facility balance of $300 million . Under the terms of the Credit Agreement, existing balances under our Forward Capacity Agreement, Inventory Financing Agreements, and Equipment Financing Agreements are excluded from Consolidated Senior Secured Net Debt, as defined in the Credit Agreement. Interest Rate Swaps. In March 2017, we amended our existing interest rate swaps to more closely match the terms of our Tranche C-1 Term Loan. The swaps have an aggregate notional value of approximately $763 million at an average fixed rate of 3.03 percent and expire between the second quarter of 2018 and the second quarter of 2020. In a previous extension to the existing interest rate swaps, in lieu of paying the breakage fees related to terminating the old swaps and issuing the new swaps, the costs were incorporated into the terms of the new swaps. As a result, any cash flows related to the settlement of the swaps are reflected as a financing activity in our unaudited consolidated statements of cash flows. Additionally, in May 2017, we entered into new interest rate swap agreements. The swaps have an aggregate notional value of approximately $1.2 billion at an average fixed rate of 1.97 percent , and expire in the first quarter of 2024. Any cash flows related to the settlement of these swaps are reflected as an operating activity in our unaudited consolidated statements of cash flows. Senior Notes The senior notes are unsecured and unsubordinated obligations of the Company and are guaranteed by each of the Company’s current and future wholly-owned domestic subsidiaries that from time to time are a borrower or guarantor under the Credit Agreement. The senior notes indentures 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 percent of total assets. On August 21, 2017, we issued $850 million of 8.125 percent senior notes due 2026 (the “2026 Senior Notes”) in a private placement transaction. Interest is payable semiannually in arrears on January 30 and July 30 of each year, beginning January 30, 2018. Dynegy used the proceeds of the offering, together with proceeds from the sale of certain facilities, and cash-on-hand to repurchase $1.25 billion of its 6.75 percent senior notes due 2019 and repay $200 million of its Tranche C-1 term loan, as noted above. In connection with the extinguishment of a portion of our 2019 senior notes, we recorded a loss on early extinguishment of debt of approximately $58 million in our unaudited consolidated statements of operations for the three and nine months ended September 30, 2017 , of which approximately $44 million related to a premium paid in excess of debt principal, approximately $8 million related to the write-off of unamortized deferred financing costs, and approximately $6 million related to fees. The Company, pursuant to a Registration Rights Agreement, has agreed to use commercially reasonable efforts to register the 2026 Senior Notes by August 16, 2018. Otherwise, the 2026 Senior Notes are generally identical in all material respects to Dynegy’s other outstanding senior notes. Amortizing Notes On June 21, 2016, in connection with the issuance of the tangible equity units (“TEUs”), Dynegy issued the Amortizing Notes with a principal amount of approximately $87 million . The Amortizing Notes mature on July 1, 2019. 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 percent . 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 limits, among other things, the ability of Dynegy to consolidate, merge, sell, or dispose all or substantially all of its assets. If a fundamental change occurs, or if Dynegy elects to settle the prepaid stock contracts (“SPCs”) early, then the holders of the Amortizing Notes will have the right to require Dynegy 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, the failure to satisfy covenants, and specified events of bankruptcy and insolvency. Letter of Credit Facilities Dynegy has a Letter of Credit Reimbursement Agreement with an issuing bank, for an LC in an amount not to exceed $55 million . In July 2017, the expiry date of the facility was extended one year, to September 19, 2018. As of September 30, 2017 , there was $55 million outstanding under this LC. Following the ENGIE Acquisition Closing Date, Dynegy entered into a Letter of Credit Reimbursement Agreement with an issuing bank, pursuant to which the issuing bank agreed to provide LCs in an amount not to exceed $50 million . The facility matures February 7, 2018 and may be extended at the Lender’s discretion for up to four additional one -year terms. As of September 30, 2017 , there was $40 million outstanding under this facility. Forward Capacity Agreement As of September 30, 2017, we have sold a portion of our PJM capacity that cleared for Planning Years 2018-2019, 2019-2 020 and 2020-2021 to a financial institution. Dynegy will continue to be subject to the performance obligations as well as any associated performance pe nalties and bonus payments for those planning years. As a result, this transaction is accounted for as a debt issuance of $241 million with an implied interest rate of 4.9 percent . On March 29, 2017, we replaced an existing Planning Year 2017-2018 contract in the amount of $110 million , with a Planning Year 2019-2020 contract in the amount of $121 million . On July 7, 2017, we replaced $99 million of $109 million of an existing Planning Year 2018-2019 contract with a Planning Year 2020-2021 contract in the amount of $110 million . Inventory Financing Agreements Brayton Point Inventory Financing. On May 31, 2017, the Brayton Point inventory financing agreement terminated and the remaining obligation was paid. The Brayton Point facility officially retired on June 1, 2017. Emissions Repurchase Agreements. In August 2015, we entered into two repurchase transactions with a third party in which we sold approximately $78 million of RGGI inventory and received cash. In February 2017, we repurchased approximately $30 million of the previously sold RGGI inventory. We are obligated to repurchase the remaining inventory in February 2018 at a specified price with an annualized carry cost of approximately 3.49 percent . As of September 30, 2017 , there was $48 million , in aggregate, outstanding under these agreements. 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 2017 to 2025. 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 unaudited consolidated statements of cash flows. The related assets were recorded at the net present value of the payments of $112 million . The $27 million discount is currently being amortized as interest expense over the life of the payments.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 13—Commitments and Contingencies Legal Proceedings Set forth below is a summary of our material ongoing legal proceedings. We record accruals for estimated losses from contingencies when available information indicates that a loss is probable and the amount of the loss, or range of loss, can be reasonably estimated. In addition, we disclose matters for which management believes a material loss is reasonably possible. In all instances, management has assessed the matters below based on current information and made judgments concerning their potential outcome, giving consideration to the nature of the claim, the amount, if any, the nature of damages sought, and the probability of success. Management regularly reviews all new information with respect to such contingencies and adjusts its assessments and estimates of such contingencies accordingly. Because litigation is subject to inherent uncertainties including unfavorable rulings or developments, it is possible that the ultimate resolution of our legal proceedings could involve amounts that are different from our currently recorded accruals, and that such differences could be material. In addition to the matters discussed below, we are party to other routine proceedings arising in the ordinary course of business. Any accruals or estimated losses related to these matters are not material. In management’s judgment, the ultimate resolution of these matters will not have a material effect on our financial condition, results of operations, or cash flows. 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 and false reporting of natural gas prices to various index publications 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. The cases are consolidated in a multi-district litigation proceeding pending in the United States District Court for Nevada. On March 30, 2017, the court denied Plaintiffs’ motion to certify a class action, which will be subject to an interlocutory appeal granted by the Ninth Circuit on June 13, 2017. At this time we cannot reasonably estimate a potential loss. Advatech Dispute. On September 2, 2016, our Genco subsidiary 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 issued Genco its final invoice on September 30, 2016 totaling $81 million . Genco contested the invoice on October 3, 2016 and believes the proper amount is less than $1 million . On October 27, 2016, Advatech initiated the dispute resolution process under the Contract and filed for arbitration on March 16, 2017. Settlement discussions required under the dispute resolution process have been unsuccessful. We believe the risk of a material loss related to this dispute to be remote. We dispute the allegations and will defend our position vigorously. Other Contingencies 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 may 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 order converting 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. Dynegy is participating in the investigation. We believe the risk of a material loss related to the investigation to be remote. 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. New Source Review and CAA Matters. New Source Review. Since 1999, the EPA has been engaged in a nationwide enforcement initiative to determine whether coal-fired power plants failed to comply with the requirements of the New Source Review and New Source Performance Standard provisions under the CAA when the plants implemented modifications. The EPA’s initiative focuses on whether projects performed at power plants triggered various permitting requirements, including the need to install pollution control equipment. In August 2012, the EPA issued a Notice of Violation (“NOV”) alleging that projects performed in 1997, 2006, and 2007 at the Newton facility violated Prevention of Significant Deterioration, Title V permitting, and other requirements. The NOV remains unresolved. We believe our defenses to the allegations described in the NOV are meritorious. A decision by the U.S. Court of Appeals for the Seventh Circuit in 2013 held that similar claims older than five years were barred by the statute of limitations. This decision may provide an additional defense to the allegations in the Newton facility NOV. In September 2016, we retired Newton Unit 2. Zimmer NOVs. In December 2014, the EPA issued an NOV alleging violation of opacity standards at the Zimmer facility, which we co-own and operate. 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 involving 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. Killen and Stuart NOVs/ Notices of Intent to Sue. The EPA issued NOVs in December 2014 for Killen and Stuart, and in February 2017 for Stuart, alleging violations of opacity standards. In May and June 2017, we received two letters from the Sierra Club providing notice of its intent to sue various Dynegy entities and the owner and operator of the Killen and Stuart facilities, respectively, alleging violations of opacity standards under the CAA. The Dayton Power and Light Company, the operator of Killen and Stuart, is expected to act on behalf of itself and the co-owners with respect to these matters. 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 IPH 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 District Court has scheduled the remedy phase trial for October 2018. We dispute the allegations and will defend the case vigorously. 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. At this time we are unable to make a reasonable estimate of the possible costs, or range of costs, that might be incurred to resolve these matters. Coal Combustion Residuals/ Groundwater. MISO Segment . In 2012, the Illinois EPA (“IEPA”) issued violation notices alleging violations of groundwater standards onsite at our Baldwin and Vermilion facilities’ Coal Combustion Residuals (“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 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 further analysis of closure options and riverbank stabilization options. IPH Segment. 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 CCR rule. If remediation measures concerning groundwater are necessary at any of our coal-fired MISO or IPH Segment 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, we cannot reasonably estimate the costs, or range of costs, of remediation, if any, that ultimately may be required. CCR surface impoundment and landfill closure costs are reflected in our AROs. Dam Safety Assessment Reports. The EPA initiated a nationwide investigation of the structural integrity of CCR surface impoundments in 2009. The EPA assessments found all of our surface impoundments to be in satisfactory or fair condition, with the exception of the surface impoundments at the Baldwin and Hennepin facilities. In response to the Hennepin report, we made capital improvements to the Hennepin east CCR surface impoundment berms and notified the EPA of our intent to close the Hennepin west CCR surface impoundment, which is reflected in our AROs. We performed further studies needed to support closure of the west CCR surface impoundment, submitted those studies to the IEPA in 2014 and await IEPA action. In response to the Baldwin report, we notified the EPA of our action plan, which included implementation of recommended operating practices, remedial measures and studies. At this time, to resolve the concerns raised in the EPA’s assessment report and as a result of the CCR rule, we plan to initiate closure of the Baldwin west fly ash CCR surface impoundment in the fourth quarter of 2017, which is reflected in our AROs. Other Commitments In conducting our operations, we routinely enter into long-term commodity purchase and sale commitments, as well as agreements that commit future cash flow to the lease or acquisition of assets used in our businesses. These commitments have been typically associated with commodity supply arrangements, capital projects, reservation charges associated with firm transmission, transportation, storage and leases for office space, equipment, design and construction, plant sites, and power generation assets. Indemnifications and Guarantees In the ordinary course of business, we routinely enter into contractual agreements that contain various representations, warranties, indemnifications and guarantees. Examples of such agreements include, but are not limited to, service agreements, equipment purchase agreements, engineering and technical service agreements, asset sales agreements, and procurement and construction contracts. Some agreements contain indemnities that cover the other party’s negligence or limit the other party’s liability with respect to third party claims, in which event we will effectively be indemnifying the other party. Virtually all such agreements contain representations or warranties that are covered by indemnifications against the losses incurred by the other parties in the event such representations and warranties are false. While there is always the possibility of a loss related to such representations, warranties, indemnifications, and guarantees in our contractual agreements, and such loss could be significant, in most cases management considers the probability of loss to be remote. We have accrued no amounts with respect to the indemnifications as of September 30, 2017 because none were probable of occurring, nor could they be reasonably estimated.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Note 14—Income Taxes Income Tax Benefit. We compute our quarterly taxes under the effective tax rate method based on applying an anticipated annual effective rate to our year-to-date income or loss, except for significant, unusual, or extraordinary transactions. Income taxes for significant, unusual, or extraordinary transactions are computed and recorded in the period that the specific transaction occurs. The income taxes related to income (loss) from continuing operations were as follows: Three Months Ended September 30, Nine Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Expected refund of AMT credits previously subject to a valuation allowance $ 2 $ — $ 9 $ — Release of valuation allowance for OCI transactions that impacted deferred income taxes (1 ) — 4 — Valuation allowance release as a result of the 2017 ENGIE Acquisition and the 2016 EquiPower Acquisition — — 317 3 Other state taxes — 1 — (9 ) Income tax benefit (expense) $ 1 $ 1 $ 330 $ (6 ) As of September 30, 2017 , we continued to maintain a valuation allowance against our net deferred tax assets in each jurisdiction as they arise as there was not sufficient evidence to overcome our historical cumulative losses to conclude that it is more-likely-than-not our net deferred tax assets can be realized in the future. Unrecognized Tax Benefits. During the first quarter of 2017, we increased our unrecognized tax benefits by $66 million as a result of the ENGIE Acquisition for uncertain tax positions included in GSENA’s tax returns prior to our ownership. The entire $66 million would impact our effective tax rate if recognized.

Pension and Other Post-Employme

Pension and Other Post-Employment Benefit Plans	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Pension and Other Post-Employment Benefit Plans	Note 15—Pension and Other Post-Employment Benefit Plans We sponsor and administer defined benefit plans and defined contribution plans for the benefit of our employees and also provide other post-employment benefits to retirees who meet age and service requirements, which are further described in Note 19—Employee Compensation, Savings, Pension and Other Post-Employment Benefit Plans in our Form 10-K. In the first quarter of 2017, the Dynegy pension and other post-employment plans were amended as a result of negotiations with former Duke Midwest union participants, IBEW Local 1347. As part of these amendments, the participants’ previous pension plan accrued benefits will be frozen as of December 31, 2017 and will begin accruing on January 1, 2018 with a minimum interest crediting rate of 4 percent . Other post-employment plans were amended to provide retiree medical plan benefits to only certain participants as of January 1, 2018. As a result of these amendments, we remeasured our benefit obligations and funded status of the affected plans and recorded a net-of-tax gain of approximately $15 million through accumulated other comprehensive income during the first quarter of 2017. Components of Net Periodic Benefit Cost (Gain). The components of net periodic benefit cost (gain) were as follows: Pension Benefits Other Benefits Three Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Service cost benefits earned during period $ 4 $ 4 $ — $ — Interest cost on projected benefit obligation 5 5 — 1 Expected return on plan assets (6 ) (5 ) — (1 ) Amortization of prior service credit (1 ) (1 ) (1 ) (1 ) Net periodic benefit cost (gain) $ 2 $ 3 $ (1 ) $ (1 ) Pension Benefits Other Benefits Nine Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Service cost benefits earned during period $ 13 $ 12 $ — $ — Interest cost on projected benefit obligation 15 15 1 3 Expected return on plan assets (19 ) (17 ) (1 ) (3 ) Amortization of prior service credit (2 ) (1 ) (4 ) (3 ) Net periodic benefit cost (gain) $ 7 $ 9 $ (4 ) $ (3 )

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	Note 16—Stockholders' Equity Preferred Stock We pay quarterly dividends on our mandatory convertible preferred stock on February 1, May 1, August 1, and November 1 of each year, if declared by our Board of Directors. For each of the nine months ended September 30, 2017 and 2016 , we paid $16 million in dividends. On October 2, 2017, our Board of Directors declared a dividend on our mandatory convertible preferred stock of $1.34 per share, or approximately $5 million in the aggregate. The dividend is for the period beginning on August 1, 2017 and ending on October 31, 2017. Such dividends were paid on November 1, 2017, to stockholders of record as of October 15, 2017. In addition, on November 1, 2017 (the “Mandatory Conversion Date”), each share of Preferred Stock converted at 3.2258 shares of Common Stock for a total issuance of approximately 12.9 million shares of Common Stock. Stock Purchase Agreement-Terawatt On February 24, 2016, Dynegy entered into a Stock Purchase Agreement with Terawatt Holdings, LP (“Terawatt”), an affiliate of the ECP Funds, pursuant to which, at the ENGIE Acquisition Closing Date, Dynegy issued to Terawatt 13,711,152 shares of Dynegy common stock for $150 million (the “PIPE Transaction”). ECP Buyout Dynegy settled its payment obligation to Energy Capital Partners (“ECP”) of $375 million on the ENGIE Acquisition Closing Date. This payment is recorded as a reduction in additional paid-in capital in our unaudited consolidated balance sheet and is reflected as a purchase of a noncontrolling interest in financing activities in our unaudited consolidated statement of cash flows as of September 30, 2017 . Warrants On October 2, 2017, the warrants to purchase up to 15.6 million shares of Common Stock for an exercise price of $40 per share expired. These warrants were issued to Legacy Dynegy stockholders upon our emergence from bankruptcy on October 1, 2012 and had a five -year term. Earnings (Loss) Per Share Basic earnings (loss) per share is based on the weighted average number of common shares outstanding during the period. Diluted earnings (loss) is based on the weighted average number of common shares used for the basic earnings (loss) per share computation, adjusted for the incremental issuance of shares of common stock assuming (i) our stock options and warrants are exercised under the treasury stock method, (ii) our restricted stock units and performance stock units are fully vested under the treasury stock method, and (iii) our mandatory convertible preferred stock and the SPCs are converted into common stock under the if-converted method. Please read Note 18—Capital Stock and Note 13—Tangible Equity Units in our Form 10-K for further discussion. The following table reflects significant components of our weighted-average shares outstanding used in the basic and diluted loss per share calculations for the three and nine months ended September 30, 2017 and 2016 : Three Months Ended September 30, Nine Months Ended September 30, (in millions) 2017 2016 2017 2016 Shares outstanding at the beginning of the period (1) 154 140 140 117 Weighted-average shares outstanding during the period of: Shares issued under long-term compensation plans — — 1 — Shares issued under the PIPE Transaction — — 11 — Prepaid stock purchase contract (TEUs) (1) — — — 9 Basic weighted-average shares outstanding 154 140 152 126 Dilution from potentially dilutive shares (2) — — 7 — Diluted weighted-average shares outstanding (3) 154 140 159 126 _________________________________________ (1) The minimum settlement amount of the TEUs, or 23,092,460 shares, is considered to be outstanding since the issuance date of June 21, 2016, and is included in the computation of basic earnings (loss) per share for the three and nine months ended September 30, 2017 and 2016 . Please read Note 13—Tangible Equity Units in our Form 10-K for further discussion. (2) Shares included in the computation of diluted earnings per share for the nine months ended September 30, 2017 consist of: • 5,425,700 additional shares upon settlement of the TEUs - which reflects the difference between the minimum settlement amount included in basic weighted-average shares outstanding and the maximum settlement amount ( 28,518,160 shares); and • 1,279,515 additional shares attributable to restricted stock units and performance stock units. (3) Entities with a net loss from continuing operations are prohibited from including potential common shares in the computation of diluted per share amounts. Accordingly, we have utilized the basic shares outstanding amount to calculate both basic and diluted loss per share for the three months ended September 30, 2017 and three and nine months ended September 30, 2016 . For the three and nine months ended September 30, 2017 and 2016 , the following potentially dilutive securities were not included in the computation of diluted per share amounts because the effect would be anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, (in millions of shares) 2017 2016 2017 2016 Stock options 4.2 2.8 2.8 2.8 Restricted stock units 1.3 1.3 — 1.3 Performance stock units 1.6 1.2 — 1.2 Warrants (1) 24.6 15.6 24.6 15.6 Series A 5.375% mandatory convertible preferred stock (2) 12.9 12.9 12.9 12.9 Prepaid stock purchase contract (TEUs) 5.4 5.4 — 5.4 Total 50.0 39.2 40.3 39.2 _________________________________________ (1) Warrants to purchase 15,606,936 shares of our Common Stock expired on October 2, 2017. (2) On November 1, 2017, our outstanding Preferred Stock was converted to approximately 12.9 million shares of Common Stock. Accumulated Other Comprehensive Income Changes in accumulated other comprehensive income, net of tax, by component, are as follows: Nine Months Ended September 30, (amounts in millions) 2017 2016 Beginning of period $ 21 $ 19 Other comprehensive income before reclassifications: Actuarial gain and plan amendments (net of tax of $4 and zero, respectively) 11 — Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit (net of tax of zero and zero, respectively) (1) (6 ) (4 ) Net current period other comprehensive income (loss), net of tax 5 (4 ) End of period $ 26 $ 15 __________________________________________ (1) Amounts are associated with our defined benefit pension and other post-employment benefit plans and are included in the computation of net periodic pension cost (gain). Please read Note 15—Pension and Other Post-Employment Benefit Plans for further discussion.

Condensed Consolidating Financi

Condensed Consolidating Financial Information	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Consolidating Financial Information	Note 17—Condensed Consolidating Financial Information Dynegy’s senior notes are guaranteed by certain, but not all, of our wholly owned subsidiaries. The following condensed consolidating financial statements present the financial information of (i) Dynegy (“Parent”), which is the parent and issuer of the senior notes, on a stand-alone, unconsolidated basis, (ii) the guarantor subsidiaries of Dynegy, (iii) the non-guarantor subsidiaries of Dynegy, and (iv) the eliminations necessary to arrive at the information for Dynegy on a consolidated basis. The 100 percent owned subsidiary guarantors, jointly, severally, fully, and unconditionally, guarantee the payment obligations under the senior notes. Please read Note 12—Debt for further discussion. These statements should be read in conjunction with the unaudited consolidated financial statements and notes thereto of Dynegy. 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 Dynegy’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. On February 2, 2017, upon Genco’s emergence from bankruptcy, IPH (excluding Electric Energy, Inc.) became a guarantor to the senior notes. Accordingly, condensed consolidating financial information previously reported has been retroactively adjusted to reflect the status of Dynegy’s subsidiaries as either guarantor subsidiaries or non-guarantor subsidiaries as of September 30, 2017 . For purposes of the unaudited condensed consolidating financial statements, a portion of our intercompany receivable, which we do not consider to be likely of settlement, has been classified as equity as of September 30, 2017 and December 31, 2016 . Condensed Consolidating Balance Sheet as of September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Current Assets Cash and cash equivalents $ 354 $ 252 $ 7 $ — $ 613 Accounts receivable, net 157 3,990 12 (3,681 ) 478 Inventory — 388 41 — 429 Other current assets 8 265 2 (91 ) 184 Total Current Assets 519 4,895 62 (3,772 ) 1,704 Property, plant and equipment, net — 8,621 308 — 8,929 Investment in affiliates 16,462 — — (16,462 ) — Investment in unconsolidated affiliates — 154 — — 154 Goodwill — 772 — — 772 Assets held-for-sale — 181 — — 181 Other long-term assets 17 214 36 — 267 Intercompany note receivable 46 — — (46 ) — Total Assets $ 17,044 $ 14,837 $ 406 $ (20,280 ) $ 12,007 Current Liabilities Accounts payable $ 3,310 $ 426 $ 233 $ (3,681 ) $ 288 Other current liabilities 226 342 102 (91 ) 579 Total Current Liabilities 3,536 768 335 (3,772 ) 867 Debt, long-term portion, net 8,347 268 33 — 8,648 Intercompany note payable 3,042 46 — (3,088 ) — Other long-term liabilities 130 331 47 — 508 Total Liabilities 15,055 1,413 415 (6,860 ) 10,023 Stockholders’ Equity Dynegy Stockholders’ Equity 1,989 16,471 (9 ) (16,462 ) 1,989 Intercompany note receivable — (3,042 ) — 3,042 — Total Dynegy Stockholders’ Equity 1,989 13,429 (9 ) (13,420 ) 1,989 Noncontrolling interest — (5 ) — — (5 ) Total Equity 1,989 13,424 (9 ) (13,420 ) 1,984 Total Liabilities and Equity $ 17,044 $ 14,837 $ 406 $ (20,280 ) $ 12,007 Condensed Consolidating Balance Sheet as of December 31, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Current Assets Cash and cash equivalents $ 1,529 $ 221 $ 26 $ — $ 1,776 Restricted cash 21 41 — — 62 Accounts receivable, net 141 2,604 39 (2,398 ) 386 Inventory — 326 119 — 445 Other current assets 12 408 2 (104 ) 318 Total Current Assets 1,703 3,600 186 (2,502 ) 2,987 Property, plant and equipment, net — 6,772 349 — 7,121 Investment in affiliates 12,175 — — (12,175 ) — Restricted cash 2,000 — — — 2,000 Goodwill — 799 — — 799 Other long-term assets 2 109 35 — 146 Intercompany note receivable — 8 — (8 ) — Total Assets $ 15,880 $ 11,288 $ 570 $ (14,685 ) $ 13,053 Current Liabilities Accounts payable $ 1,990 $ 443 $ 297 $ (2,398 ) $ 332 Other current liabilities 143 377 168 (104 ) 584 Total Current Liabilities 2,133 820 465 (2,502 ) 916 Liabilities subject to compromise — 832 — — 832 Debt, long-term portion, net 8,531 216 31 — 8,778 Intercompany note payable 3,042 — — (3,042 ) — Other long-term liabilities 132 313 51 (8 ) 488 Total Liabilities 13,838 2,181 547 (5,552 ) 11,014 Stockholders’ Equity Dynegy Stockholders’ Equity 2,042 12,152 23 (12,175 ) 2,042 Intercompany note receivable — (3,042 ) — 3,042 — Total Dynegy Stockholders’ Equity 2,042 9,110 23 (9,133 ) 2,042 Noncontrolling interest — (3 ) — — (3 ) Total Equity 2,042 9,107 23 (9,133 ) 2,039 Total Liabilities and Equity $ 15,880 $ 11,288 $ 570 $ (14,685 ) $ 13,053 Condensed Consolidating Statements of Operations for the Three Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Revenues $ — $ 1,380 $ 84 $ (27 ) $ 1,437 Cost of sales, excluding depreciation expense — (760 ) (54 ) 27 (787 ) Gross margin — 620 30 — 650 Operating and maintenance expense — (209 ) (27 ) — (236 ) Depreciation expense — (193 ) (9 ) — (202 ) Impairments — (29 ) — — (29 ) Loss on sale of assets, net — (78 ) — — (78 ) General and administrative expense 8 (50 ) (2 ) — (44 ) Acquisition and integration costs — (3 ) — — (3 ) Other — — — — — Operating income (loss) 8 58 (8 ) — 58 Bankruptcy reorganization items — 12 — — 12 Earnings from unconsolidated investments — 4 — — 4 Equity in losses from investments in affiliates 78 — — (78 ) — Interest expense (155 ) (6 ) (3 ) 3 (161 ) Loss on early extinguishment of debt (66 ) — — — (66 ) Other income and expense, net 3 19 — (3 ) 19 Income (loss) before income taxes (132 ) 87 (11 ) (78 ) (134 ) Income tax benefit — 1 — — 1 Net income (loss) (132 ) 88 (11 ) (78 ) (133 ) Less: Net loss attributable to noncontrolling interest — (1 ) — — (1 ) Net Income (loss) attributable to Dynegy Inc. $ (132 ) $ 89 $ (11 ) $ (78 ) $ (132 ) Condensed Consolidating Statements of Operations for the Nine Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Revenues $ — $ 3,616 $ 342 $ (110 ) $ 3,848 Cost of sales, excluding depreciation expense — (2,108 ) (227 ) 110 (2,225 ) Gross margin — 1,508 115 — 1,623 Operating and maintenance expense — (660 ) (90 ) — (750 ) Depreciation expense — (567 ) (44 ) — (611 ) Impairments — (148 ) — — (148 ) Gain (loss) on sale of assets, net — (108 ) 1 — (107 ) General and administrative expense — (121 ) (5 ) — (126 ) Acquisition and integration costs (51 ) (4 ) — — (55 ) Other — 1 — — 1 Operating loss (51 ) (99 ) (23 ) — (173 ) Bankruptcy reorganization items — 494 — — 494 Earnings from unconsolidated investments — 4 — — 4 Equity in earnings from investments in affiliates 730 — — (730 ) — Interest expense (461 ) (18 ) (9 ) 10 (478 ) Loss on early extinguishment of debt (75 ) — — — (75 ) Other income and expense, net 26 49 — (10 ) 65 Income (loss) before income taxes 169 430 (32 ) (730 ) (163 ) Income tax benefit — 330 — — 330 Net income (loss) 169 760 (32 ) (730 ) 167 Less: Net loss attributable to noncontrolling interest — (2 ) — — (2 ) Net income (loss) attributable to Dynegy Inc. $ 169 $ 762 $ (32 ) $ (730 ) $ 169 Condensed Consolidating Statements of Operations for the Three Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Revenues $ — $ 1,082 $ 128 $ (26 ) $ 1,184 Cost of sales, excluding depreciation expense — (609 ) (77 ) 26 (660 ) Gross margin — 473 51 — 524 Operating and maintenance expense — (189 ) (29 ) — (218 ) Depreciation expense — (146 ) (17 ) — (163 ) Impairments — (212 ) — — (212 ) General and administrative expense (2 ) (38 ) (1 ) — (41 ) Acquisition and integration costs (5 ) (2 ) — — (7 ) Other — (1 ) 1 — — Operating income (loss) (7 ) (115 ) 5 — (117 ) Earnings from unconsolidated investments — 4 — — 4 Equity in losses from investments in affiliates (136 ) — — 136 — Interest expense (138 ) (27 ) (2 ) 1 (166 ) Other income and expense, net 25 5 — (1 ) 29 Income (loss) before income taxes (256 ) (133 ) 3 136 (250 ) Income tax benefit (expense) 7 (6 ) — — 1 Net income (loss) attributable to Dynegy Inc. $ (249 ) $ (139 ) $ 3 $ 136 $ (249 ) Condensed Consolidating Statements of Operations for the Nine Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Revenues $ — $ 2,921 $ 355 $ (65 ) $ 3,211 Cost of sales, excluding depreciation expense — (1,570 ) (193 ) 65 (1,698 ) Gross margin — 1,351 162 — 1,513 Operating and maintenance expense — (595 ) (100 ) — (695 ) Depreciation expense — (436 ) (58 ) — (494 ) Impairments — (857 ) — — (857 ) General and administrative expense (5 ) (108 ) (4 ) — (117 ) Acquisition and integration costs (8 ) — — — (8 ) Other — (9 ) (7 ) — (16 ) Operating loss (13 ) (654 ) (7 ) — (674 ) Earnings from unconsolidated investments — 7 — — 7 Equity in losses from investments in affiliates (693 ) — — 693 — Interest expense (382 ) (65 ) (6 ) 4 (449 ) Other income and expense, net 28 36 — (4 ) 60 Loss before income taxes (1,060 ) (676 ) (13 ) 693 (1,056 ) Income tax expense — (6 ) — — (6 ) Net loss (1,060 ) (682 ) (13 ) 693 (1,062 ) Less: Net loss attributable to noncontrolling interest — (2 ) — — (2 ) Net loss attributable to Dynegy Inc. $ (1,060 ) $ (680 ) $ (13 ) $ 693 $ (1,060 ) Condensed Consolidating Statements of Comprehensive Income (Loss) for the Three Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Net income (loss) $ (132 ) $ 88 $ (11 ) $ (78 ) $ (133 ) Other comprehensive income before reclassifications: Actuarial gain and plan amendments, net of tax of zero — — — — — Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit, net of tax of zero (2 ) — — — (2 ) Other comprehensive loss, net of tax (2 ) — — — (2 ) Comprehensive income (loss) (134 ) 88 (11 ) (78 ) (135 ) Less: Comprehensive loss attributable to noncontrolling interest — (1 ) — — (1 ) Total comprehensive income (loss) attributable to Dynegy Inc. $ (134 ) $ 89 $ (11 ) $ (78 ) $ (134 ) Condensed Consolidating Statements of Comprehensive Income (Loss) for the Nine Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Net income (loss) $ 169 $ 760 $ (32 ) $ (730 ) $ 167 Other comprehensive income before reclassifications: Actuarial gain and plan amendments, net of tax of $4 11 — — — 11 Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit, net of tax of zero (5 ) — (1 ) — (6 ) Other comprehensive loss from investment in affiliates (1 ) — — 1 — Other comprehensive income (loss), net of tax 5 — (1 ) 1 5 Comprehensive income (loss) 174 760 (33 ) (729 ) 172 Less: Comprehensive loss attributable to noncontrolling interest — (2 ) — — (2 ) Total comprehensive income (loss) attributable to Dynegy Inc. $ 174 $ 762 $ (33 ) $ (729 ) $ 174 Condensed Consolidating Statements of Comprehensive Income (Loss) for the Three Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Net income (loss) $ (249 ) $ (139 ) $ 3 $ 136 $ (249 ) Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit and actuarial gain, net of tax of zero (1 ) (1 ) — — (2 ) Other comprehensive loss from investment in affiliates (1 ) — — 1 — Other comprehensive loss, net of tax (2 ) (1 ) — 1 (2 ) Comprehensive income (loss) (251 ) (140 ) 3 137 (251 ) Less: Comprehensive income attributable to noncontrolling interest — — — — — Total comprehensive income (loss) attributable to Dynegy Inc. $ (251 ) $ (140 ) $ 3 $ 137 $ (251 ) Condensed Consolidating Statements of Comprehensive Income (Loss) for the Nine Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Net loss $ (1,060 ) $ (682 ) $ (13 ) $ 693 $ (1,062 ) Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit and actuarial gain, net of tax of zero (3 ) (1 ) — — (4 ) Other comprehensive loss from investment in affiliates (1 ) — — 1 — Other comprehensive loss, net of tax (4 ) (1 ) — 1 (4 ) Comprehensive loss (1,064 ) (683 ) (13 ) 694 (1,066 ) Less: Comprehensive loss attributable to noncontrolling interest — (2 ) — — (2 ) Total comprehensive loss attributable to Dynegy Inc. $ (1,064 ) $ (681 ) $ (13 ) $ 694 $ (1,064 ) Condensed Consolidating Statements of Cash Flows for the Nine Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES: Net cash provided by (used in) operating activities $ (455 ) $ 877 $ 79 $ — $ 501 CASH FLOWS FROM INVESTING ACTIVITIES: Capital expenditures — (123 ) (6 ) — (129 ) Acquisitions, net of cash acquired (3,244 ) (5 ) — — (3,249 ) Distributions from unconsolidated investments — 7 — — 7 Net intercompany transfers 726 — — (726 ) — Proceeds received from asset sales, net 599 — 1 — 600 Net cash used in investing activities (1,919 ) (121 ) (5 ) (726 ) (2,771 ) CASH FLOWS FROM FINANCING ACTIVITIES: Proceeds from long-term borrowings, net of debt issuance costs 1,747 — — — 1,747 Repayments of borrowings (2,180 ) (30 ) (51 ) — (2,261 ) Proceeds from issuance of equity, net of issuance costs 150 — — — 150 Payments of debt extinguishment costs (50 ) — — — (50 ) Preferred stock dividends paid (16 ) — — — (16 ) Interest rate swap settlement payments (15 ) — — — (15 ) Acquisition of noncontrolling interest (375 ) — — — (375 ) Payments related to bankruptcy settlement (126 ) (7 ) — — (133 ) Net intercompany transfers — (684 ) (42 ) 726 — Intercompany borrowings, net of repayments 45 (45 ) — — — Other financing (2 ) — — — (2 ) Net cash used in financing activities (822 ) (766 ) (93 ) 726 (955 ) Net decrease in cash, cash equivalents and restricted cash (3,196 ) (10 ) (19 ) — (3,225 ) Cash, cash equivalents, and restricted cash beginning of period 3,550 262 26 — 3,838 Cash, cash equivalents, and restricted cash end of period $ 354 $ 252 $ 7 $ — $ 613 Condensed Consolidating Statements of Cash Flows for the Nine Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES: Net cash provided by (used in) operating activities $ (236 ) $ 977 $ (13 ) $ — $ 728 CASH FLOWS FROM INVESTING ACTIVITIES: Capital expenditures — (271 ) (66 ) — (337 ) Distributions from unconsolidated investments — 14 — — 14 Net intercompany transfers 801 — — (801 ) — Other investing — 10 — — 10 Net cash provided by (used in) investing activities 801 (247 ) (66 ) (801 ) (313 ) CASH FLOWS FROM FINANCING ACTIVITIES: Proceeds from long-term borrowings, net of debt issuance costs 2,079 198 — — 2,277 Repayments of borrowings (6 ) (15 ) — — (21 ) Proceeds from issuance of equity, net of issuance costs 359 — — — 359 Preferred stock dividends paid (16 ) — — — (16 ) Interest rate swap settlement payments (13 ) — — — (13 ) Net intercompany transfers — (837 ) 36 801 — Other financing (2 ) — — — (2 ) Net cash provided by (used in) financing activities 2,401 (654 ) 36 801 2,584 Net increase (decrease) in cash, cash equivalents and restricted cash 2,966 76 (43 ) — 2,999 Cash, cash equivalents and restricted cash, beginning of period 327 133 84 — 544 Cash, cash equivalents and restricted cash, end of period $ 3,293 $ 209 $ 41 $ — $ 3,543

Genco Chapter 11 Bankruptcy and

Genco Chapter 11 Bankruptcy and Emergence	9 Months Ended
	Sep. 30, 2017
Reorganizations [Abstract]
Genco Chapter 11 Bankruptcy and Emergence	Note 18—Genco Chapter 11 Bankruptcy and Emergence On December 9, 2016, Genco filed a petition (the “Bankruptcy Petition”) under title 11 of the United States Code (the “Bankruptcy Code”) in the United States Bankruptcy Court for the Southern District of Texas (the “Bankruptcy Court”). On January 25, 2017, the Bankruptcy Court confirmed the Genco Plan and Genco emerged from bankruptcy on February 2, 2017. As a result, we eliminated $825 million of Genco senior notes and $7 million of accrued interest in exchange for: • On the Emergence Date, approximately $113 million of cash, $182 million of new Dynegy seven -year unsecured notes, and warrants (the “2017 Warrants”) to purchase up to 8.7 million shares of common stock with a fair value of $17 million . • On April 18, 2017, approximately $3 million of cash, $3 million of new Dynegy seven -year unsecured notes, and 0.1 million 2017 Warrants with a fair value of less than $1 million . • On August 1, 2017, approximately $6 million of cash, $4 million of new Dynegy seven -year unsecured notes, and 0.2 million 2017 Warrants with a fair value of less than $1 million were issued to remaining eligible holders of Genco senior notes and represented the final payment in the Genco restructuring. The 2017 Warrants, which have an exercise price of $35 per share of common stock, have a seven -year term expiring on February 2, 2024 and are recorded as Other long-term liabilities in our unaudited consolidated balance sheet as of September 30, 2017 . The following table summarizes the Company’s gain from the termination of the Genco senior notes, which is recognized in Bankruptcy reorganization items in our unaudited consolidated statement of operations for the nine months ended September 30, 2017 : (amounts in millions) Liabilities subject to compromise, which were terminated $ 832 Less: Seven-year unsecured notes 188 Cash consideration 122 2017 Warrants, at fair value 17 Legal and consulting fees 11 Bankruptcy reorganization items $ 494 Included in the table above is an approximate $12 million gain to Bankruptcy reorganization items recognized for the three months ended September 30, 2017 upon the final payment under the Genco restructuring. For income tax purposes, the income from cancellation of debt is excluded from taxable income in the current year and will instead reduce Genco’s tax attributes.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Information	Note 19—Segment Information We report the results of our operations in six segments: (i) PJM, (ii) NY/NE, (iii) ERCOT, (iv) MISO, (v) IPH, and (vi) CAISO. PJM also includes our Dynegy Energy Services retail business in Ohio and Pennsylvania. NY/NE also includes our Dynegy Energy Services retail business in Massachusetts. IPH also includes our Homefield Energy reta il business in Illinois. Our unaudited consolidated financial results also reflect corporate-level expenses such as general and administrative expense, interest expense, and income tax benefit (expense). Reportable segment information, including intercompany transactions accounted for at prevailing market rates, for the three and nine months ended September 30, 2017 and 2016 is presented below: Segment Data as of and for the Three Months Ended September 30, 2017 (amounts in millions) PJM NY/NE ERCOT MISO IPH CAISO Other and Eliminations Total Domestic: Unaffiliated revenues $ 628 $ 269 $ 210 $ 98 $ 182 $ 50 $ — $ 1,437 Intercompany and affiliate revenues (25 ) (1 ) (1 ) 6 21 — — — Total revenues $ 603 $ 268 $ 209 $ 104 $ 203 $ 50 $ — $ 1,437 Depreciation expense $ (94 ) $ (52 ) $ (20 ) $ (9 ) $ (11 ) $ (14 ) $ (2 ) $ (202 ) Impairments (29 ) — — — — — — (29 ) Loss on sale of assets, net (1 ) (77 ) — — — — — (78 ) General and administrative expense — — — — — — (44 ) (44 ) Acquisition and integration costs — — — — — — (3 ) (3 ) Operating income (loss) $ 86 $ (30 ) $ 50 $ (9 ) $ 11 $ — $ (50 ) $ 58 Bankruptcy reorganization items — — — — 12 — — 12 Earnings from unconsolidated investments 2 2 — — — — — 4 Interest expense — — — — — — (161 ) (161 ) Loss on early extinguishment of debt — — — — — — (66 ) (66 ) Other income and expense, net 16 — — — — — 3 19 Loss before income taxes (134 ) Income tax benefit — — — — — — 1 1 Net loss (133 ) Less: Net loss attributable to noncontrolling interest (1 ) Net loss attributable to Dynegy Inc. $ (132 ) Total assets—domestic $ 5,158 $ 3,401 $ 1,564 $ 232 $ 581 $ 461 $ 610 $ 12,007 Investment in unconsolidated affiliate $ 77 $ 77 $ — $ — $ — $ — $ — $ 154 Capital expenditures $ (6 ) $ (6 ) $ (3 ) $ — $ (4 ) $ (3 ) $ (2 ) $ (24 ) Segment Data as of and for the Nine Months Ended September 30, 2017 (amounts in millions) PJM NY/NE ERCOT MISO IPH CAISO Other and Eliminations Total Domestic: Unaffiliated revenues $ 1,806 $ 817 $ 322 $ 276 $ 538 $ 89 $ — $ 3,848 Intercompany and affiliate revenues (47 ) (2 ) (1 ) 16 34 — — — Total revenues $ 1,759 $ 815 $ 321 $ 292 $ 572 $ 89 $ — $ 3,848 Depreciation expense $ (283 ) $ (171 ) $ (54 ) $ (22 ) $ (35 ) $ (40 ) $ (6 ) $ (611 ) Impairments (49 ) — — (99 ) — — — (148 ) Gain (loss) on sale of assets, net (31 ) (77 ) — — 1 — — (107 ) General and administrative expense — — — — — — (126 ) (126 ) Acquisition and integration costs — — — — — — (55 ) (55 ) Operating income (loss) $ 178 $ (72 ) $ (8 ) $ (90 ) $ 40 $ (33 ) $ (188 ) $ (173 ) Bankruptcy reorganization items — — — — 494 — — 494 Earnings from unconsolidated investments 2 2 — — — — — 4 Interest expense — — — — — — (478 ) (478 ) Loss on early extinguishment of debt — — — — — — (75 ) (75 ) Other income and expense, net 16 — — — 26 — 23 65 Loss before income taxes 0 — 0 — — — 0 (163 ) Income tax benefit — — — — — — 330 330 Net income 167 Less: Net loss attributable to noncontrolling interest (2 ) Net income attributable to Dynegy Inc. $ 169 Total assets—domestic $ 5,158 $ 3,401 $ 1,564 $ 232 $ 581 $ 461 $ 610 $ 12,007 Investment in unconsolidated affiliate $ 77 $ 77 $ — $ — $ — $ — $ — $ 154 Capital expenditures $ (74 ) $ (46 ) $ (20 ) $ (3 ) $ (10 ) $ (34 ) $ (5 ) $ (192 ) Segment Data as of and for the Three Months Ended September 30, 2016 (amounts in millions) PJM NY/NE MISO IPH CAISO Other and Eliminations Total Domestic: Unaffiliated revenues $ 551 $ 200 $ 130 $ 241 $ 46 $ — $ 1,168 Intercompany revenues 17 (5 ) 3 1 — — 16 Total revenues $ 568 $ 195 $ 133 $ 242 $ 46 $ — $ 1,184 Depreciation expense $ (88 ) $ (53 ) $ (3 ) $ (7 ) $ (11 ) $ (1 ) $ (163 ) Impairments (64 ) — — (148 ) — — (212 ) General and administrative expense — — — — — (41 ) (41 ) Acquisition and integration costs — — — — — (7 ) (7 ) Operating income (loss) $ 29 $ (15 ) $ 13 $ (104 ) $ 10 $ (50 ) $ (117 ) Earnings from unconsolidated investments 4 — — — — — 4 Interest expense — — — — — (166 ) (166 ) Other income and expense, net 3 — — 1 — 25 29 Loss before income taxes (250 ) Income tax benefit — — — — — 1 1 Net loss (249 ) Less: Net loss attributable to noncontrolling interest — Net loss attributable to Dynegy Inc. $ (249 ) Total assets—domestic $ 5,208 $ 2,807 $ 371 $ 746 $ 499 $ 3,393 $ 13,024 Investment in unconsolidated affiliate $ 173 $ — $ — $ — $ — $ — $ 173 Capital expenditures $ (13 ) $ (10 ) $ (1 ) $ (9 ) $ (1 ) $ (1 ) $ (35 ) Segment Data as of and for the Nine Months Ended September 30, 2016 (amounts in millions) PJM NY/NE MISO IPH CAISO Other and Eliminations Total Domestic: Unaffiliated revenues $ 1,559 $ 630 $ 315 $ 575 $ 105 $ — $ 3,184 Intercompany revenues 45 (2 ) (15 ) (1 ) — — 27 Total revenues $ 1,604 $ 628 $ 300 $ 574 $ 105 $ — $ 3,211 Depreciation expense $ (257 ) $ (167 ) $ (19 ) $ (21 ) $ (26 ) $ (4 ) $ (494 ) Impairments (64 ) — (645 ) (148 ) — — (857 ) General and administrative expense — — — — — (117 ) (117 ) Acquisition and integration costs — — — 8 — (16 ) (8 ) Operating income (loss) $ 277 $ (22 ) $ (703 ) $ (87 ) $ — $ (139 ) $ (674 ) Earnings from unconsolidated investments 7 — — — — — 7 Interest expense — — — — — (449 ) (449 ) Other income and expense, net 9 — — 15 12 24 60 Loss before income taxes (1,056 ) Income tax expense — — — — — (6 ) (6 ) Net loss (1,062 ) Less: Net loss attributable to noncontrolling interest (2 ) Net loss attributable to Dynegy Inc. $ (1,060 ) Total assets—domestic $ 5,208 $ 2,807 $ 371 $ 746 $ 499 $ 3,393 $ 13,024 Investment in unconsolidated affiliate $ 173 $ — $ — $ — $ — $ — $ 173 Capital expenditures $ (124 ) $ (84 ) $ (9 ) $ (30 ) $ (4 ) $ (9 ) $ (260 )

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	Note 20—Subsequent Events On October 29, 2017, Dynegy and Vistra Energy Corp., a Delaware corporation (“Vistra Energy”), entered into an Agreement and Plan of Merger (the “Merger Agreement”). Under the Merger Agreement, which has been approved by the boards of directors of both companies, Dynegy will merge with and into Vistra Energy in a tax-free, all-stock transaction, with Vistra Energy continuing as the surviving corporation (the “Merger”). Under the terms of the agreement, Dynegy stockholders will receive 0.652 shares of Vistra Energy common stock for each share of Dynegy common stock they own, resulting in Vistra Energy stockholders and Dynegy stockholders owning approximately 79 percent and 21 percent , respectively, of the combined company. Completion of the Merger is subject to various customary conditions, including, among others, (a) approval by Vistra Energy’s stockholders of the issuance of the Vistra Energy common stock in the Merger, (b) adoption of the Merger Agreement by Dynegy ’s stockholders and Vistra Energy’s stockholders, (c) receipt of all requisite regulatory approvals, which includes, among others, approvals of the FERC, the Public Utility Commission of Texas and the New York Public Service Commission, and the expiration or termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, and (d) effectiveness of the registration statement for the shares of Vistra Energy common stock to be issued in the Merger, and the approval of the listing of such shares on the New York Stock Exchange. Each party’s obligation to consummate the Merger is also subject to certain additional customary conditions. The Merger Agreement contains customary representations, warranties and covenants of Dynegy and Vistra Energy, and contains certain termination rights for both Dynegy and Vistra Energy.

Accounting Policies (Policies)

Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	The accompanying unaudited consolidated financial statements have been prepared in accordance with the instructions to interim financial reporting as prescribed by the SEC. The year-end consolidated balance sheet data was derived from audited consolidated financial statements, but does not include all disclosures required by the Generally Accepted Accounting Principles of the United States of America (“GAAP”). The unaudited consolidated financial statements contained in this report include all material adjustments of a normal recurring nature that, in the opinion of management, are necessary for a fair presentation of the results for the interim periods. Certain prior period amounts in our unaudited consolidated financial statements have been reclassified to conform to current year presentation. These interim financial statements should be read together with the consolidated financial statements and notes thereto included in our annual report on Form 10-K for the year ended December 31, 2016 , filed with the SEC on February 24, 2017, which we refer to as our “Form 10-K.” Unless the context indicates otherwise, throughout this report, the terms “Dynegy,” “the Company,” “we,” “us,” “our,” and “ours” are used to refer to Dynegy Inc. and its direct and indirect subsidiaries. We sell electric energy, capacity and ancillary services primarily on a wholesale basis from our power generation facilities. We also serve residential, municipal, commercial and industrial customers primarily in MISO, PJM and NY/NE thro ugh our Homefield Energy and Dynegy Energy Services retail businesses. We report the results of our power generation business as six segments in our unaudited consolidated financial statements: (i) PJM, (ii) ISO-NE/NYISO (“NY/NE”), (iii) ERCOT, (iv) MISO, (v) IPH, and (vi) CAISO. Our consolidated financial results also reflect corporate-level expenses such as general and administrative expense, interest expense, and income tax benefit (expense). All significant intercompany transactions have been eliminated. Please read Note 19—Segment Information for further discussion. On February 2, 2017 (the “Emergence Date”), Illinois Power Generating Company (“Genco”) emerged from bankruptcy. Please read Note 18—Genco Chapter 11 Bankruptcy and Emergence for further discussion.
Use of Estimates	Use of Estimates. The preparation of unaudited consolidated financial statements in conformity with GAAP requires management to make informed estimates and judgments that affect our reported financial position and results of operations based on currently available information. Actual results could differ materially from our estimates. The results of operations for the interim periods presented in this Form 10-Q are not necessarily indicative of the results to be expected for the full year or any other interim period due to seasonal fluctuations in demand for our energy products and services, changes in commodity prices, timing of maintenance and other expenditures, and other factors.
Accounting Standards Adopted During the Current Period	Accounting Standards Adopted Statement of Cash Flows. In August 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-15-Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. To reduce current and future diversity in practice, the amendments in this ASU provide guidance for several cash flow classification issues identified where current GAAP is either unclear or does not include specific guidance. We adopted this ASU on January 1, 2017 and applied the amendments on a retrospective basis. The adoption of this ASU affected the classification of prepayments for future planned outage work performed under long-term service agreements. The majority of the cash prepayments required under these agreements will now be reflected as cash outflows from investing activities and the remainder will be classified as cash outflows from operating activities, based on whether they are anticipated to be expensed or capitalized. As a result of the retrospective application of this ASU, we reclassified approximately $80 million of cash prepayments from operating activities to investing activities in our unaudited consolidated statement of cash flows for the nine months ended September 30, 2016 . In November 2016, the FASB issued ASU 2016-18-Statement of Cash Flows (Topic 230): Restricted Cash. The amendments in this ASU require that a statement of cash flows explains the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. We adopted this ASU as of January 1, 2017 and applied the amendments on a retrospective basis. As a result of the retrospective application of this ASU, changes in restricted cash of $1 million and $2.045 billion previously reflected as cash flows from operating activities and investing activities, respectively, are now reflected in Net increase (decrease) in cash, cash equivalents, and restricted cash in our unaudited consolidated statement of cash flows for the nine months ended September 30, 2016 . Additionally, restricted cash of $39 million and $2.085 billion are now reflected in the beginning of period and end of period cash, cash equivalents and restricted cash line items, respectively, in our unaudited consolidated statement of cash flows for the nine months ended September 30, 2016 . Please read Note 7—Cash Flow Information for further discussion. Compensation. In March 2016, the FASB issued ASU 2016-09-Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The amendments in this ASU simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. We adopted this ASU on January 1, 2017 with no material impact on our unaudited consolidated financial statements. Goodwill. In January 2017, the FASB issued ASU 2017-04-Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. To simplify the subsequent measure of goodwill, the amendments in this ASU eliminate step two from the goodwill impairment test. An entity will no longer be required to calculate the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if the reporting unit had been acquired in a business combination to determine the impairment of goodwill. The amendments in this ASU will now require goodwill impairment to be measured by the amount by which the carrying value of the reporting unit exceeds its fair value. The guidance in this ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Upon adoption, an entity shall apply the guidance in this ASU prospectively with early adoption permitted for annual goodwill tests performed after January 1, 2017. We adopted this ASU on January 1, 2017 with no material impact on our unaudited consolidated financial statements. Accounting Standards Not Yet Adopted Business Combinations. In January 2017, the FASB issued ASU 2017-01-Business Combinations (Topic 805): Clarifying the Definition of a Business. The amendments in this ASU clarify the definition of a business. The amendments affect all companies and other reporting organizations that must determine whether they have acquired or sold a business. The guidance in this ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. We are currently evaluating this ASU and any potential impacts the adoption will have on our unaudited consolidated financial statements. Pensions. In March 2017, the FASB issued ASU No. 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendments of this ASU require an entity to report the service cost component of net benefit costs in the same line item as other compensation costs arising from services rendered by the related employees during the applicable service period. The other components of net benefit cost are required to be presented separately from the service cost component and below the subtotal of operating income. Additionally, only the service cost component of net benefit costs is eligible for capitalization. The guidance in this ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The adoption of this standard must be applied on a retrospective basis for the amendments concerning income statement presentation and on a prospective basis for the amendments regarding the capitalization of the service cost component. We are currently evaluating this ASU and any potential impacts the adoption will have on our unaudited consolidated financial statements. Leases. In February 2016, the FASB issued ASU 2016-02-Leases (Topic 842). The provisions in this ASU will require lessees to recognize lease assets and lease liabilities, for all leases, including operating leases, on the balance sheet. The lease assets recognized in the balance sheet will represent a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The lease liability recognized in the balance sheet will represent the lessee’s obligation to make lease payments arising from a lease, measured based on the present value of the minimum rental payments. Entities may make an accounting policy election to not recognize lease assets or lease liabilities for leases with a term of 12 months or less. The guidance in this ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. We are currently evaluating this ASU and any potential impacts the adoption will have on our unaudited consolidated financial statements. Revenue from Contracts with Customers. In May 2014, the FASB issued ASU 2014-09-Revenue from Contracts with Customers (Topic 606). This ASU supersedes current revenue recognition requirements and industry specific guidance and develops a common revenue recognition standard whereby an entity will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to in exchange for those goods or services. Additional disclosures will be required to describe the nature, amount, timing, and uncertainty of revenues and cash flows from contracts with customers. The guidance in this ASU and its amendments are effective for interim and annual periods beginning after December 15, 2017, with early adoption permitted for interim and annual periods beginning after December 15, 2016. We have established an implementation team to assess the impact the new accounting standard will have on our financial statements upon adoption and have not currently identified any material changes to the timing of our revenue recognition. We continue to assess the impact of the standard by reviewing our revenue contracts to determine if changes in our recognition policies or controls are necessary. We believe changes to our disclosures will primarily include a regional presentation of our revenues disaggregated by revenue type - energy, capacity, and ancillary services.

Acquisitions and Divestitures (

Acquisitions and Divestitures (Tables)	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the consideration paid and the provisional fair value amounts recognized for the assets acquired and liabilities assumed related to the ENGIE Acquisition, as of the acquisition date, February 7, 2017: (amounts in millions) Base purchase price $ 3,300 Working capital adjustments and other (31 ) Fair value of total consideration transferred $ 3,269 Cash $ 20 Accounts receivable 22 Inventory 101 Prepayments and other current assets 3 Assets from risk management activities (including current portion of $21 million) 25 Property, plant and equipment 2,716 Investment in unconsolidated affiliate 159 Intangible assets (including current portion of $7 million) 50 Assets held-for-sale 478 Other long-term assets 131 Total assets acquired 3,705 Accounts payable 28 Liabilities from risk management activities (including current portion of $13 million) 16 Asset retirement obligations 19 Intangible liabilities (including current portion of $16 million) 30 Deferred income taxes, net 342 Other long-term liabilities 1 Total liabilities assumed 436 Net assets acquired $ 3,269
Business Acquisition, Pro Forma Information	The unaudited pro forma financial results for the nine months ended September 30, 2017 and 2016 assume the ENGIE Acquisition occurred on January 1, 2016. The unaudited pro forma financial results may not be indicative of the results that would have occurred had the acquisition been completed as of January 1, 2016, nor are they indicative of future results of operations. The unaudited pro forma financial results for the nine months ended September 30, 2017 and 2016 include adjustments of $35 million and $5 million , respectively, for non-recurring acquisition costs attributable to the ENGIE Acquisition. Nine Months Ended September 30, (amounts in millions) 2017 2016 Revenue $ 3,905 $ 3,942 Net income (loss) $ 169 $ (1,090 ) Net income (loss) attributable to Dynegy Inc. $ 171 $ (1,088 ) The following table summarizes certain information related to the ENGIE Acquisition, which is included in our unaudited consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Acquisition costs $ — $ 3 $ 35 $ 5 Revenues $ 345 N/A $ 669 N/A Operating loss $ (36 ) N/A $ (32 ) N/A

Risk Management Activities, D30

Risk Management Activities, Derivatives and Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Contracts and Interest Rate Swaps	As of September 30, 2017 , we had net purchases and sales of derivative contracts outstanding in the following quantities: Contract Type Quantity Unit of Measure Fair Value (1) (dollars and quantities in millions) Purchases (Sales) Asset (Liability) Commodity contracts: Electricity derivatives (2) (60 ) MWh $ 14 Electricity basis derivatives (3) (34 ) MWh $ (7 ) Natural gas derivatives (2) 380 MMBtu $ (1 ) Natural gas basis derivatives 108 MMBtu $ (14 ) Physical heat rate derivatives 125/(13) MMBtu/MWh $ 14 Emissions derivatives 17 Metric Ton $ 4 Interest rate swaps 1,963 U.S. Dollar $ (11 ) Common stock warrants (4) 25 Warrant $ (2 ) __________________________________________ (1) Includes both asset and liability risk management positions but excludes margin and collateral netting of $22 million . (2) Mainly comprised of swaps and physical forwards. (3) Comprised of FTRs and swaps. (4) Each warrant is convertible into one share of Dynegy common stock.
Schedule of Derivative Instruments in the Balance Sheet, Fair Value	The following tables present the fair value and balance sheet classification of derivatives in our unaudited consolidated balance sheets as of September 30, 2017 and December 31, 2016 . As of September 30, 2017 and December 31, 2016 , there were no gross amounts available to be offset that were not offset in our unaudited consolidated balance sheets. September 30, 2017 Gross amounts offset in the balance sheet Contract Type Balance Sheet Location Gross Fair Value Contract Netting Collateral or Margin Received or Paid Net Fair Value (amounts in millions) Derivative assets: Commodity contracts Assets from risk management activities $ 204 $ (117 ) $ — $ 87 Interest rate contracts Assets from risk management activities 12 — — 12 Total derivative assets $ 216 $ (117 ) $ — $ 99 Derivative liabilities: Commodity contracts Liabilities from risk management activities $ (194 ) $ 117 $ 22 $ (55 ) Interest rate contracts Liabilities from risk management activities (23 ) — — (23 ) Common stock warrants Accrued liabilities and other current liabilities and other long-term liabilities (2 ) — — (2 ) Total derivative liabilities $ (219 ) $ 117 $ 22 $ (80 ) Total derivatives $ (3 ) $ — $ 22 $ 19 December 31, 2016 Gross amounts offset in the balance sheet Contract Type Balance Sheet Location Gross Fair Value Contract Netting Collateral or Margin Received or Paid Net Fair Value (amounts in millions) Derivative assets: Commodity contracts Assets from risk management activities $ 311 $ (165 ) $ — $ 146 Total derivative assets $ 311 $ (165 ) $ — $ 146 Derivative liabilities: Commodity contracts Liabilities from risk management activities $ (329 ) $ 165 $ 54 $ (110 ) Interest rate contracts Liabilities from risk management activities (30 ) — — (30 ) Common stock warrants Accrued liabilities and other current liabilities (1 ) — — (1 ) Total derivative liabilities $ (360 ) $ 165 $ 54 $ (141 ) Total derivatives $ (49 ) $ — $ 54 $ 5
Schedule of Derivative Collateral Posted and Location on Balance Sheet	The following table summarizes our cash collateral posted as of September 30, 2017 and December 31, 2016 , within Prepayments and other current assets in our unaudited consolidated balance sheets and the amount applied against short-term risk management activities: Location on Balance Sheet September 30, 2017 December 31, 2016 (amounts in millions) Gross collateral posted with counterparties $ 54 $ 116 Less: Collateral netted against risk management liabilities 22 54 Net collateral within Prepayments and other current assets $ 32 $ 62
Schedule of Derivative Instruments, Gain (Loss) in the Statement of Operations	Our unaudited consolidated statements of operations for the three and nine months ended September 30, 2017 and 2016 include the impact of derivative financial instruments as presented below: Derivatives Not Designated as Hedges Location of Gain (Loss) Recognized in Income on Derivatives Three Months Ended September 30, Nine Months Ended 2017 2016 2017 2016 (amounts in millions) Commodity contracts Revenues $ 29 $ (27 ) $ 242 $ 188 Interest rate contracts Interest expense $ 1 $ 1 $ 4 $ (11 ) Common stock warrants Other income and (expense), net $ 1 $ 4 $ 16 $ 5

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables set forth, by level within the fair value hierarchy, our financial assets and liabilities that were accounted for at fair value on a recurring basis as of September 30, 2017 and December 31, 2016 , and are presented on a gross basis before consideration of amounts netted under master netting agreements and the application of collateral and margin paid: Fair Value as of September 30, 2017 (amounts in millions) Level 1 Level 2 Level 3 Total Assets: Assets from commodity risk management activities: Electricity derivatives $ — $ 100 $ 21 $ 121 Natural gas derivatives — 45 6 51 Physical heat rate derivatives — 20 1 21 Emissions derivatives — 11 — 11 Total assets from commodity risk management activities — 176 28 204 Assets from interest rate contracts — 12 — 12 Total assets $ — $ 188 $ 28 $ 216 Liabilities: Liabilities from commodity risk management activities: Electricity derivatives $ — $ (94 ) $ (20 ) $ (114 ) Natural gas derivatives — (60 ) (6 ) (66 ) Physical heat rate derivatives — (7 ) — (7 ) Emissions derivatives — (7 ) — (7 ) Total liabilities from commodity risk management activities — (168 ) (26 ) (194 ) Liabilities from interest rate contracts — (23 ) — (23 ) Liabilities from outstanding common stock warrants (2 ) — — (2 ) Total liabilities $ (2 ) $ (191 ) $ (26 ) $ (219 ) Fair Value as of December 31, 2016 (amounts in millions) Level 1 Level 2 Level 3 Total Assets: Assets from commodity risk management activities: Electricity derivatives $ — $ 118 $ 20 $ 138 Natural gas derivatives — 169 4 173 Total assets from commodity risk management activities $ — $ 287 $ 24 $ 311 Liabilities: Liabilities from commodity risk management activities: Electricity derivatives $ — $ (245 ) $ (12 ) $ (257 ) Natural gas derivatives — (52 ) (10 ) (62 ) Emissions derivatives — (10 ) — (10 ) Total liabilities from commodity risk management activities — (307 ) (22 ) (329 ) Liabilities from interest rate contracts — (30 ) — (30 ) Liabilities from outstanding common stock warrants (1 ) — — (1 ) Total liabilities $ (1 ) $ (337 ) $ (22 ) $ (360 )
Sensitivity to Changes in Significant Unobservable Inputs for Level 3 Valuations	The significant unobservable inputs used in the valuation of Dynegy’s contracts classified as Level 3 as of September 30, 2017 are as follows: Transaction Type Quantity Unit of Measure Net Fair Value Valuation Technique Significant Unobservable Input Significant Unobservable Input Range (dollars in millions) Electricity derivatives: Forward contracts—power (1) (14 ) Million MWh $ 4 Basis spread + liquid location Basis spread $4.25 - $6.25 FTRs (29 ) Million MWh $ (3 ) Historical congestion Forward price $0 - $6.00 Physical heat rate derivatives 23/(3) Million MMBtu/Million MWh $ 1 Discounted Cash Flow Forward price $2.40 - $3.30 / $20 - $24 Natural gas derivatives (1) 102 Million MMBtu $ — Illiquid location fixed price Forward price $1.75 - $2.15 __________________________________________ (1) Represents forward financial and physical transactions at illiquid pricing locations and long-dated contracts.
Schedule of Changes in Fair Value of Financial Instruments	The following tables set forth a reconciliation of changes in the fair value of financial instruments classified as Level 3 in the fair value hierarchy: Three Months Ended September 30, 2017 (amounts in millions) Electricity Derivatives Natural Gas Derivatives Heat Rate Derivatives Total Balance at June 30, 2017 $ (1 ) $ 1 $ (2 ) $ (2 ) Total gains (losses) included in earnings 6 (1 ) 3 8 Transfers out of level 3 (1) (2 ) — — (2 ) Settlements (2) (2 ) — — (2 ) Balance at September 30, 2017 $ 1 $ — $ 1 $ 2 Unrealized gains (losses) relating to instruments held as of September 30, 2017 $ 6 $ (1 ) $ 3 $ 8 Nine Months Ended September 30, 2017 (amounts in millions) Electricity Derivatives Natural Gas Derivatives Heat Rate Derivatives Total Balance at December 31, 2016 $ 8 $ (6 ) $ — $ 2 Acquired derivatives 1 — — 1 Total gains (losses) included in earnings (16 ) 10 1 (5 ) Settlements (2) 8 (4 ) — 4 Balance at September 30, 2017 $ 1 $ — $ 1 $ 2 Unrealized gains (losses) relating to instruments held as of September 30, 2017 $ (16 ) $ 10 $ 1 $ (5 ) Three Months Ended September 30, 2016 (amounts in millions) Electricity Derivatives Natural Gas Derivatives Coal Derivatives Total Balance at June 30, 2016 $ (24 ) $ (15 ) $ 1 $ (38 ) Total gains (losses) included in earnings 9 (4 ) 1 6 Settlements (2) 5 5 (1 ) 9 Balance at September 30, 2016 $ (10 ) $ (14 ) $ 1 $ (23 ) Unrealized gains (losses) relating to instruments held as of September 30, 2016 $ 9 $ (4 ) $ 1 $ 6 Nine Months Ended September 30, 2016 (amounts in millions) Electricity Derivatives Natural Gas Derivatives Coal Derivatives Total Balance at December 31, 2015 $ (18 ) $ (32 ) $ 2 $ (48 ) Total gains included in earnings 4 — — 4 Settlements (2) 4 18 (1 ) 21 Balance at September 30, 2016 $ (10 ) $ (14 ) $ 1 $ (23 ) Unrealized gains relating to instruments held as of September 30, 2016 $ 4 $ — $ — $ 4 _________________________________________ (1) During the three months ended September 30, 2017 , we had transfers from Level 3 to Level 2 due to changes in market liquidity. (2) For purposes of these tables, we define settlements as the beginning of period fair value of contracts that settled during the period.
Fair Value of Financial Assets and Liabilities	The following table discloses the fair value of financial instruments which are not recognized at fair value in our unaudited consolidated balance sheets. Unless otherwise noted, the fair value of debt as reflected in the table has been calculated based on the average of certain available broker quotes as of September 30, 2017 and December 31, 2016 , respectively. September 30, 2017 December 31, 2016 (amounts in millions) Fair Value Hierarchy Carrying Amount Fair Value Carrying Amount Fair Value Dynegy Inc.: Tranche C-1 Term Loan, due 2024 (1) Level 2 $ (1,940 ) $ (2,029 ) $ (1,994 ) $ (2,025 ) Tranche B-2 Term Loan, due 2020 (1) Level 2 $ — $ — $ (219 ) $ (225 ) Revolving Facility (1) Level 2 $ (300 ) $ (300 ) $ — $ — 6.75% Senior Notes, due 2019 (1) Level 2 $ (845 ) $ (881 ) $ (2,083 ) $ (2,137 ) 7.375% Senior Notes, due 2022 (1) Level 2 $ (1,733 ) $ (1,824 ) $ (1,731 ) $ (1,665 ) 5.875% Senior Notes, due 2023 (1) Level 2 $ (493 ) $ (498 ) $ (492 ) $ (431 ) 7.625% Senior Notes, due 2024 (1) Level 2 $ (1,237 ) $ (1,294 ) $ (1,237 ) $ (1,156 ) 8.034% Senior Notes, due 2024 (1) Level 2 $ (188 ) $ (190 ) $ — $ — 8.00% Senior Notes, due 2025 (1) Level 2 $ (739 ) $ (778 ) $ (738 ) $ (703 ) 8.125% Senior Notes, due 2026 (1) Level 2 $ (842 ) $ (880 ) $ — $ — 7.00% Amortizing Notes, due 2019 (TEUs) (1) Level 2 $ (58 ) $ (62 ) $ (78 ) $ (90 ) Forward capacity agreement (1) Level 3 $ (212 ) $ (212 ) $ (205 ) $ (205 ) Inventory financing agreements Level 3 $ (48 ) $ (48 ) $ (129 ) $ (127 ) Equipment financing agreements (1) Level 3 $ (112 ) $ (112 ) $ (73 ) $ (73 ) Genco: Liabilities subject to compromise (2) Level 3 $ — $ — $ (825 ) $ (366 ) __________________________________________ (1) Carrying amounts include unamortized discounts and debt issuance costs. Please read Note 12—Debt for further discussion. (2) Carrying amounts represent the Genco senior notes that were classified as liabilities subject to compromise as of December 31, 2016. The fair value of the senior notes was equal to the Genco Plan consideration and is a Level 3 valuation due to a lack of observable inputs that make up the consideration. Please read Note 22—Genco Chapter 11 Bankruptcy in our Form 10-K for further details.

Cash Flow Information (Tables)

Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2017
Cash and Cash Equivalents [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	The supplemental disclosures of our non-cash investing and financing information are as follows: Nine Months Ended September 30, (amounts in millions) 2017 2016 Change in capital expenditures included in accounts payable $ 5 $ (10 ) Change in capital expenditures pursuant to an equipment financing agreement $ 34 $ 11 Issuance of 2017 Warrants $ 17 $ — Issuance of senior notes related to the Genco restructuring $ 188 $ — Sale of interest in Conesville facility $ (58 ) $ — Acquisition of interest in Zimmer facility $ 27 $ —
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within our unaudited consolidated balance sheets that sum to the total of the same such amounts shown in our unaudited consolidated statements of cash flows: (amounts in millions) September 30, 2017 September 30, 2016 Cash and cash equivalents $ 613 $ 1,458 Restricted cash included in current assets (1) — 85 Restricted cash included in long-term assets (2) — 2,000 Total cash, cash equivalents and restricted cash $ 613 $ 3,543 __________________________________________ (1) Includes $45 million placed in escrow for the issuance of the Tranche C Term Loan ( $25 million of pre-funded interest and interest income earned and $20 million of pre-funded original issue discount) and $40 million related to collateral. (2) Relates to amounts placed into escrow for the issuance of the Tranche C Term Loan.

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2017
Inventory Disclosure [Abstract]
Summary of Inventories	A summary of our inventories is as follows: (amounts in millions) September 30, 2017 December 31, 2016 Materials and supplies $ 236 $ 182 Coal 165 238 Fuel oil 14 17 Natural gas 12 — Emissions allowances (1) 2 8 Total $ 429 $ 445 __________________________________________ (1) At September 30, 2017 and December 31, 2016 , a portion of this inventory was held as collateral by one of our counterparties as part of an inventory financing agreement. Please read Note 12—Debt — Emissions Repurchase Agreements for further discussion.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	A summary of our property, plant and equipment is as follows: (amounts in millions) September 30, 2017 December 31, 2016 Power generation $ 9,845 $ 7,537 Buildings and improvements 958 944 Office and other equipment 115 98 Property, plant and equipment 10,918 8,579 Accumulated depreciation (1,989 ) (1,458 ) Property, plant and equipment, net $ 8,929 $ 7,121
Property, Plant and Equipment Impairment	For the three and nine months ended September 30, 2017 and 2016 , we recognized the following PP&E impairments in our unaudited consolidated statements of operations (amounts in millions). Each valuation is classified as Level 3 within the fair value hierarchy and is presented as of the date of its impairment. Three Months Ended September 30, Nine Months Ended September 30, Facility Fair Value 2017 2016 2017 2016 Baldwin (1) $ 97 — — — 645 Stuart (2) $ — — 55 — 55 Newton FGD (3) $ — — 148 — 148 Killen (4) $ — — — 20 — Hennepin (1) $ 16 — — 10 — Havana (1) $ 37 — — 89 — Total (5) $ — $ 203 $ 119 $ 848 _________________________________________ (1) Units failed to recover their basic operating costs in the MISO capacity auctions. The impairment was measured using a DCF model. (2) We determined that the facility would experience recurring negative cash flows due to on-going required maintenance and environmental capital expenditures, combined with consistently poor reliability. The impairment was measured using a DCF model. (3) We terminated the flue gas desulfurization (“FGD”) systems construction project at our Newton generation facility. The capitalized cost of the project was used to determine the impairment amount. (4) In first quarter 2017, Dayton Power and Light Co., the partner and operator of Killen, announced the shutdown of the Killen generation facility by June 2018. The impairment charge was equal to the book value. (5) Excludes impairments related to Goodwill and Materials and supplies inventory.

Joint Ownership of Generating35

Joint Ownership of Generating Facilities (Tables)	9 Months Ended
	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	The following tables present the ownership interests of the jointly owned facilities as of September 30, 2017 and December 31, 2016 included in our unaudited consolidated balance sheets. Each facility is co-owned with one or more other generation companies. September 30, 2017 (dollars in millions) Ownership Interest Property, Plant and Equipment Accumulated Depreciation Construction Work in Progress Total Miami Fort 64.0 % $ 208 $ (55 ) $ 4 $ 157 Stuart (1)(2) 39.0 % $ — $ — $ 1 $ 1 Zimmer 71.9 % $ 131 $ (37 ) $ 8 $ 102 Killen (1)(2) 33.0 % $ — $ — $ — $ — December 31, 2016 (dollars in millions) Ownership Interest Property, Plant and Equipment Accumulated Depreciation Construction Work in Progress Total Miami Fort 64.0 % $ 207 $ (39 ) $ 4 $ 172 Stuart (1) 39.0 % $ — $ — $ 4 $ 4 Conesville (1) 40.0 % $ 61 $ (3 ) $ 6 $ 64 Zimmer 46.5 % $ 115 $ (25 ) $ 6 $ 96 Killen (1) 33.0 % $ 19 $ (2 ) $ 3 $ 20 __________________________________________ (1) Facilities not operated by Dynegy. (2) Stuart Unit 1 was retired early on September 30, 2017, with remaining Stuart and Killen units scheduled to be retired by mid-2018.

Intangible Assets and Liabili36

Intangible Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2017
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets and Liabilities	The following table summarizes the components of our intangible assets and liabilities as of September 30, 2017 and December 31, 2016 : September 30, 2017 December 31, 2016 (amounts in millions) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Intangible Assets: Electricity contracts $ 230 $ (176 ) $ 54 $ 260 $ (206 ) $ 54 Gas transport contracts 30 (11 ) 19 13 (6 ) 7 Total intangible assets $ 260 $ (187 ) $ 73 $ 273 $ (212 ) $ 61 Intangible Liabilities: Electricity contracts $ (19 ) $ 17 $ (2 ) $ (28 ) $ 26 $ (2 ) Coal contracts (32 ) 32 — (49 ) 42 (7 ) Coal transport contracts (84 ) 78 (6 ) (86 ) 73 (13 ) Gas transport contracts (58 ) 13 (45 ) (41 ) 8 (33 ) Gas storage contracts (2 ) 1 (1 ) — — — Total intangible liabilities $ (195 ) $ 141 $ (54 ) $ (204 ) $ 149 $ (55 ) Intangible assets and liabilities, net $ 65 $ (46 ) $ 19 $ 69 $ (63 ) $ 6 The following table presents our amortization expense (revenue) of intangible assets and liabilities for the three and nine months ended September 30, 2017 and 2016 : Three Months Ended September 30, Nine Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Electricity contracts, net (1) $ 5 $ 19 $ 29 $ 52 Coal contracts, net (2) (1 ) (9 ) (4 ) (32 ) Coal transport contracts, net (2) (2 ) (7 ) (7 ) (21 ) Gas transport contracts, net (2) (3 ) 1 (4 ) 18 Gas storage contracts, net (2) — — (1 ) — Total $ (1 ) $ 4 $ 13 $ 17 __________________________________________ (1) The amortization of these contracts is recognized in Revenues or Cost of sales in our unaudited consolidated statements of operations. (2) The amortization of these contracts is recognized in Cost of sales in our unaudited consolidated statements of operations. The following table summarizes the components of our contract based intangible assets and liabilities recorded in connection with the ENGIE Acquisition in February 2017: (amounts in millions/months) Gross Carrying Amount Weighted-Average Amortization Period Intangible Assets: Electricity contracts $ 34 39 Gas transport contracts 16 47 Total intangible assets $ 50 41 Intangible Liabilities: Electricity contracts $ (11 ) 32 Gas contracts — 1 Gas transport contracts (17 ) 35 Gas storage contracts (2 ) 13 Total intangible liabilities $ (30 ) 33 Total intangible assets and liabilities, net $ 20

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	A summary of our long-term debt is as follows: (amounts in millions) September 30, 2017 December 31, 2016 Secured Obligations: Tranche C-1 Term Loan, due 2024 (1) $ 2,018 $ 2,000 Tranche B-2 Term Loan, due 2020 — 224 Revolving Facility 300 — Forward Capacity Agreements 241 219 Inventory Financing Agreements 48 129 Subtotal secured obligations 2,607 2,572 Unsecured Obligations: 7.00% Amortizing Notes, due 2019 (TEUs) 60 80 6.75% Senior Notes, due 2019 850 2,100 7.375% Senior Notes, due 2022 1,750 1,750 5.875% Senior Notes, due 2023 500 500 7.625% Senior Notes, due 2024 1,250 1,250 8.034% Senior Notes, due 2024 (2) 188 — 8.00% Senior Notes, due 2025 750 750 8.125% Senior Notes, due 2026 850 — Equipment Financing Agreements 139 97 Subtotal unsecured obligations 6,337 6,527 Total debt obligations 8,944 9,099 Unamortized debt discounts and issuance costs (197 ) (120 ) 8,747 8,979 Less: Current maturities, including unamortized debt discounts and issuance costs, net 99 201 Total long-term debt $ 8,648 $ 8,778 __________________________________________ (1) At December 31, 2016, the $2.0 billion Tranche C Term Loan was held by Dynegy Finance IV. Upon the close of the ENGIE Acquisition, this debt obligation became Dynegy Inc.’s secured obligation. (2) See Note 18—Genco Chapter 11 Bankruptcy and Emergence for further discussion.

Income Taxes Income Taxes (Tabl

Income Taxes Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The income taxes related to income (loss) from continuing operations were as follows: Three Months Ended September 30, Nine Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Expected refund of AMT credits previously subject to a valuation allowance $ 2 $ — $ 9 $ — Release of valuation allowance for OCI transactions that impacted deferred income taxes (1 ) — 4 — Valuation allowance release as a result of the 2017 ENGIE Acquisition and the 2016 EquiPower Acquisition — — 317 3 Other state taxes — 1 — (9 ) Income tax benefit (expense) $ 1 $ 1 $ 330 $ (6 )

Pension and Other Post-Employ39

Pension and Other Post-Employment Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Schedule of Net Benefit Costs	The components of net periodic benefit cost (gain) were as follows: Pension Benefits Other Benefits Three Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Service cost benefits earned during period $ 4 $ 4 $ — $ — Interest cost on projected benefit obligation 5 5 — 1 Expected return on plan assets (6 ) (5 ) — (1 ) Amortization of prior service credit (1 ) (1 ) (1 ) (1 ) Net periodic benefit cost (gain) $ 2 $ 3 $ (1 ) $ (1 ) Pension Benefits Other Benefits Nine Months Ended September 30, (amounts in millions) 2017 2016 2017 2016 Service cost benefits earned during period $ 13 $ 12 $ — $ — Interest cost on projected benefit obligation 15 15 1 3 Expected return on plan assets (19 ) (17 ) (1 ) (3 ) Amortization of prior service credit (2 ) (1 ) (4 ) (3 ) Net periodic benefit cost (gain) $ 7 $ 9 $ (4 ) $ (3 )

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table reflects significant components of our weighted-average shares outstanding used in the basic and diluted loss per share calculations for the three and nine months ended September 30, 2017 and 2016 : Three Months Ended September 30, Nine Months Ended September 30, (in millions) 2017 2016 2017 2016 Shares outstanding at the beginning of the period (1) 154 140 140 117 Weighted-average shares outstanding during the period of: Shares issued under long-term compensation plans — — 1 — Shares issued under the PIPE Transaction — — 11 — Prepaid stock purchase contract (TEUs) (1) — — — 9 Basic weighted-average shares outstanding 154 140 152 126 Dilution from potentially dilutive shares (2) — — 7 — Diluted weighted-average shares outstanding (3) 154 140 159 126 _________________________________________ (1) The minimum settlement amount of the TEUs, or 23,092,460 shares, is considered to be outstanding since the issuance date of June 21, 2016, and is included in the computation of basic earnings (loss) per share for the three and nine months ended September 30, 2017 and 2016 . Please read Note 13—Tangible Equity Units in our Form 10-K for further discussion. (2) Shares included in the computation of diluted earnings per share for the nine months ended September 30, 2017 consist of: • 5,425,700 additional shares upon settlement of the TEUs - which reflects the difference between the minimum settlement amount included in basic weighted-average shares outstanding and the maximum settlement amount ( 28,518,160 shares); and • 1,279,515 additional shares attributable to restricted stock units and performance stock units. (3) Entities with a net loss from continuing operations are prohibited from including potential common shares in the computation of diluted per share amounts. Accordingly, we have utilized the basic shares outstanding amount to calculate both basic and diluted loss per share for the three months ended September 30, 2017 and three and nine months ended September 30, 2016 .
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	For the three and nine months ended September 30, 2017 and 2016 , the following potentially dilutive securities were not included in the computation of diluted per share amounts because the effect would be anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, (in millions of shares) 2017 2016 2017 2016 Stock options 4.2 2.8 2.8 2.8 Restricted stock units 1.3 1.3 — 1.3 Performance stock units 1.6 1.2 — 1.2 Warrants (1) 24.6 15.6 24.6 15.6 Series A 5.375% mandatory convertible preferred stock (2) 12.9 12.9 12.9 12.9 Prepaid stock purchase contract (TEUs) 5.4 5.4 — 5.4 Total 50.0 39.2 40.3 39.2 _________________________________________ (1) Warrants to purchase 15,606,936 shares of our Common Stock expired on October 2, 2017. (2) On November 1, 2017, our outstanding Preferred Stock was converted to approximately 12.9 million shares of Common Stock.
Schedule of Accumulated Other Comprehensive Income (Loss)	Changes in accumulated other comprehensive income, net of tax, by component, are as follows: Nine Months Ended September 30, (amounts in millions) 2017 2016 Beginning of period $ 21 $ 19 Other comprehensive income before reclassifications: Actuarial gain and plan amendments (net of tax of $4 and zero, respectively) 11 — Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit (net of tax of zero and zero, respectively) (1) (6 ) (4 ) Net current period other comprehensive income (loss), net of tax 5 (4 ) End of period $ 26 $ 15 __________________________________________ (1) Amounts are associated with our defined benefit pension and other post-employment benefit plans and are included in the computation of net periodic pension cost (gain). Please read Note 15—Pension and Other Post-Employment Benefit Plans for further discussion.

Condensed Consolidating Finan41

Condensed Consolidating Financial Information (Tables)	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheet as of September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Current Assets Cash and cash equivalents $ 354 $ 252 $ 7 $ — $ 613 Accounts receivable, net 157 3,990 12 (3,681 ) 478 Inventory — 388 41 — 429 Other current assets 8 265 2 (91 ) 184 Total Current Assets 519 4,895 62 (3,772 ) 1,704 Property, plant and equipment, net — 8,621 308 — 8,929 Investment in affiliates 16,462 — — (16,462 ) — Investment in unconsolidated affiliates — 154 — — 154 Goodwill — 772 — — 772 Assets held-for-sale — 181 — — 181 Other long-term assets 17 214 36 — 267 Intercompany note receivable 46 — — (46 ) — Total Assets $ 17,044 $ 14,837 $ 406 $ (20,280 ) $ 12,007 Current Liabilities Accounts payable $ 3,310 $ 426 $ 233 $ (3,681 ) $ 288 Other current liabilities 226 342 102 (91 ) 579 Total Current Liabilities 3,536 768 335 (3,772 ) 867 Debt, long-term portion, net 8,347 268 33 — 8,648 Intercompany note payable 3,042 46 — (3,088 ) — Other long-term liabilities 130 331 47 — 508 Total Liabilities 15,055 1,413 415 (6,860 ) 10,023 Stockholders’ Equity Dynegy Stockholders’ Equity 1,989 16,471 (9 ) (16,462 ) 1,989 Intercompany note receivable — (3,042 ) — 3,042 — Total Dynegy Stockholders’ Equity 1,989 13,429 (9 ) (13,420 ) 1,989 Noncontrolling interest — (5 ) — — (5 ) Total Equity 1,989 13,424 (9 ) (13,420 ) 1,984 Total Liabilities and Equity $ 17,044 $ 14,837 $ 406 $ (20,280 ) $ 12,007 Condensed Consolidating Balance Sheet as of December 31, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Current Assets Cash and cash equivalents $ 1,529 $ 221 $ 26 $ — $ 1,776 Restricted cash 21 41 — — 62 Accounts receivable, net 141 2,604 39 (2,398 ) 386 Inventory — 326 119 — 445 Other current assets 12 408 2 (104 ) 318 Total Current Assets 1,703 3,600 186 (2,502 ) 2,987 Property, plant and equipment, net — 6,772 349 — 7,121 Investment in affiliates 12,175 — — (12,175 ) — Restricted cash 2,000 — — — 2,000 Goodwill — 799 — — 799 Other long-term assets 2 109 35 — 146 Intercompany note receivable — 8 — (8 ) — Total Assets $ 15,880 $ 11,288 $ 570 $ (14,685 ) $ 13,053 Current Liabilities Accounts payable $ 1,990 $ 443 $ 297 $ (2,398 ) $ 332 Other current liabilities 143 377 168 (104 ) 584 Total Current Liabilities 2,133 820 465 (2,502 ) 916 Liabilities subject to compromise — 832 — — 832 Debt, long-term portion, net 8,531 216 31 — 8,778 Intercompany note payable 3,042 — — (3,042 ) — Other long-term liabilities 132 313 51 (8 ) 488 Total Liabilities 13,838 2,181 547 (5,552 ) 11,014 Stockholders’ Equity Dynegy Stockholders’ Equity 2,042 12,152 23 (12,175 ) 2,042 Intercompany note receivable — (3,042 ) — 3,042 — Total Dynegy Stockholders’ Equity 2,042 9,110 23 (9,133 ) 2,042 Noncontrolling interest — (3 ) — — (3 ) Total Equity 2,042 9,107 23 (9,133 ) 2,039 Total Liabilities and Equity $ 15,880 $ 11,288 $ 570 $ (14,685 ) $ 13,053
Condensed Consolidating Statements of Operations	Condensed Consolidating Statements of Operations for the Three Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Revenues $ — $ 1,380 $ 84 $ (27 ) $ 1,437 Cost of sales, excluding depreciation expense — (760 ) (54 ) 27 (787 ) Gross margin — 620 30 — 650 Operating and maintenance expense — (209 ) (27 ) — (236 ) Depreciation expense — (193 ) (9 ) — (202 ) Impairments — (29 ) — — (29 ) Loss on sale of assets, net — (78 ) — — (78 ) General and administrative expense 8 (50 ) (2 ) — (44 ) Acquisition and integration costs — (3 ) — — (3 ) Other — — — — — Operating income (loss) 8 58 (8 ) — 58 Bankruptcy reorganization items — 12 — — 12 Earnings from unconsolidated investments — 4 — — 4 Equity in losses from investments in affiliates 78 — — (78 ) — Interest expense (155 ) (6 ) (3 ) 3 (161 ) Loss on early extinguishment of debt (66 ) — — — (66 ) Other income and expense, net 3 19 — (3 ) 19 Income (loss) before income taxes (132 ) 87 (11 ) (78 ) (134 ) Income tax benefit — 1 — — 1 Net income (loss) (132 ) 88 (11 ) (78 ) (133 ) Less: Net loss attributable to noncontrolling interest — (1 ) — — (1 ) Net Income (loss) attributable to Dynegy Inc. $ (132 ) $ 89 $ (11 ) $ (78 ) $ (132 ) Condensed Consolidating Statements of Operations for the Nine Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Revenues $ — $ 3,616 $ 342 $ (110 ) $ 3,848 Cost of sales, excluding depreciation expense — (2,108 ) (227 ) 110 (2,225 ) Gross margin — 1,508 115 — 1,623 Operating and maintenance expense — (660 ) (90 ) — (750 ) Depreciation expense — (567 ) (44 ) — (611 ) Impairments — (148 ) — — (148 ) Gain (loss) on sale of assets, net — (108 ) 1 — (107 ) General and administrative expense — (121 ) (5 ) — (126 ) Acquisition and integration costs (51 ) (4 ) — — (55 ) Other — 1 — — 1 Operating loss (51 ) (99 ) (23 ) — (173 ) Bankruptcy reorganization items — 494 — — 494 Earnings from unconsolidated investments — 4 — — 4 Equity in earnings from investments in affiliates 730 — — (730 ) — Interest expense (461 ) (18 ) (9 ) 10 (478 ) Loss on early extinguishment of debt (75 ) — — — (75 ) Other income and expense, net 26 49 — (10 ) 65 Income (loss) before income taxes 169 430 (32 ) (730 ) (163 ) Income tax benefit — 330 — — 330 Net income (loss) 169 760 (32 ) (730 ) 167 Less: Net loss attributable to noncontrolling interest — (2 ) — — (2 ) Net income (loss) attributable to Dynegy Inc. $ 169 $ 762 $ (32 ) $ (730 ) $ 169 Condensed Consolidating Statements of Operations for the Three Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Revenues $ — $ 1,082 $ 128 $ (26 ) $ 1,184 Cost of sales, excluding depreciation expense — (609 ) (77 ) 26 (660 ) Gross margin — 473 51 — 524 Operating and maintenance expense — (189 ) (29 ) — (218 ) Depreciation expense — (146 ) (17 ) — (163 ) Impairments — (212 ) — — (212 ) General and administrative expense (2 ) (38 ) (1 ) — (41 ) Acquisition and integration costs (5 ) (2 ) — — (7 ) Other — (1 ) 1 — — Operating income (loss) (7 ) (115 ) 5 — (117 ) Earnings from unconsolidated investments — 4 — — 4 Equity in losses from investments in affiliates (136 ) — — 136 — Interest expense (138 ) (27 ) (2 ) 1 (166 ) Other income and expense, net 25 5 — (1 ) 29 Income (loss) before income taxes (256 ) (133 ) 3 136 (250 ) Income tax benefit (expense) 7 (6 ) — — 1 Net income (loss) attributable to Dynegy Inc. $ (249 ) $ (139 ) $ 3 $ 136 $ (249 ) Condensed Consolidating Statements of Operations for the Nine Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Revenues $ — $ 2,921 $ 355 $ (65 ) $ 3,211 Cost of sales, excluding depreciation expense — (1,570 ) (193 ) 65 (1,698 ) Gross margin — 1,351 162 — 1,513 Operating and maintenance expense — (595 ) (100 ) — (695 ) Depreciation expense — (436 ) (58 ) — (494 ) Impairments — (857 ) — — (857 ) General and administrative expense (5 ) (108 ) (4 ) — (117 ) Acquisition and integration costs (8 ) — — — (8 ) Other — (9 ) (7 ) — (16 ) Operating loss (13 ) (654 ) (7 ) — (674 ) Earnings from unconsolidated investments — 7 — — 7 Equity in losses from investments in affiliates (693 ) — — 693 — Interest expense (382 ) (65 ) (6 ) 4 (449 ) Other income and expense, net 28 36 — (4 ) 60 Loss before income taxes (1,060 ) (676 ) (13 ) 693 (1,056 ) Income tax expense — (6 ) — — (6 ) Net loss (1,060 ) (682 ) (13 ) 693 (1,062 ) Less: Net loss attributable to noncontrolling interest — (2 ) — — (2 ) Net loss attributable to Dynegy Inc. $ (1,060 ) $ (680 ) $ (13 ) $ 693 $ (1,060 )
Condensed Consolidating Statements of Comprehensive Income (Loss)	Condensed Consolidating Statements of Comprehensive Income (Loss) for the Three Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Net income (loss) $ (132 ) $ 88 $ (11 ) $ (78 ) $ (133 ) Other comprehensive income before reclassifications: Actuarial gain and plan amendments, net of tax of zero — — — — — Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit, net of tax of zero (2 ) — — — (2 ) Other comprehensive loss, net of tax (2 ) — — — (2 ) Comprehensive income (loss) (134 ) 88 (11 ) (78 ) (135 ) Less: Comprehensive loss attributable to noncontrolling interest — (1 ) — — (1 ) Total comprehensive income (loss) attributable to Dynegy Inc. $ (134 ) $ 89 $ (11 ) $ (78 ) $ (134 ) Condensed Consolidating Statements of Comprehensive Income (Loss) for the Nine Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Net income (loss) $ 169 $ 760 $ (32 ) $ (730 ) $ 167 Other comprehensive income before reclassifications: Actuarial gain and plan amendments, net of tax of $4 11 — — — 11 Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit, net of tax of zero (5 ) — (1 ) — (6 ) Other comprehensive loss from investment in affiliates (1 ) — — 1 — Other comprehensive income (loss), net of tax 5 — (1 ) 1 5 Comprehensive income (loss) 174 760 (33 ) (729 ) 172 Less: Comprehensive loss attributable to noncontrolling interest — (2 ) — — (2 ) Total comprehensive income (loss) attributable to Dynegy Inc. $ 174 $ 762 $ (33 ) $ (729 ) $ 174 Condensed Consolidating Statements of Comprehensive Income (Loss) for the Three Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Net income (loss) $ (249 ) $ (139 ) $ 3 $ 136 $ (249 ) Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit and actuarial gain, net of tax of zero (1 ) (1 ) — — (2 ) Other comprehensive loss from investment in affiliates (1 ) — — 1 — Other comprehensive loss, net of tax (2 ) (1 ) — 1 (2 ) Comprehensive income (loss) (251 ) (140 ) 3 137 (251 ) Less: Comprehensive income attributable to noncontrolling interest — — — — — Total comprehensive income (loss) attributable to Dynegy Inc. $ (251 ) $ (140 ) $ 3 $ 137 $ (251 ) Condensed Consolidating Statements of Comprehensive Income (Loss) for the Nine Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated Net loss $ (1,060 ) $ (682 ) $ (13 ) $ 693 $ (1,062 ) Amounts reclassified from accumulated other comprehensive income: Amortization of unrecognized prior service credit and actuarial gain, net of tax of zero (3 ) (1 ) — — (4 ) Other comprehensive loss from investment in affiliates (1 ) — — 1 — Other comprehensive loss, net of tax (4 ) (1 ) — 1 (4 ) Comprehensive loss (1,064 ) (683 ) (13 ) 694 (1,066 ) Less: Comprehensive loss attributable to noncontrolling interest — (2 ) — — (2 ) Total comprehensive loss attributable to Dynegy Inc. $ (1,064 ) $ (681 ) $ (13 ) $ 694 $ (1,064 )
Condensed Consolidating Statements of Cash Flow	Condensed Consolidating Statements of Cash Flows for the Nine Months Ended September 30, 2017 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES: Net cash provided by (used in) operating activities $ (455 ) $ 877 $ 79 $ — $ 501 CASH FLOWS FROM INVESTING ACTIVITIES: Capital expenditures — (123 ) (6 ) — (129 ) Acquisitions, net of cash acquired (3,244 ) (5 ) — — (3,249 ) Distributions from unconsolidated investments — 7 — — 7 Net intercompany transfers 726 — — (726 ) — Proceeds received from asset sales, net 599 — 1 — 600 Net cash used in investing activities (1,919 ) (121 ) (5 ) (726 ) (2,771 ) CASH FLOWS FROM FINANCING ACTIVITIES: Proceeds from long-term borrowings, net of debt issuance costs 1,747 — — — 1,747 Repayments of borrowings (2,180 ) (30 ) (51 ) — (2,261 ) Proceeds from issuance of equity, net of issuance costs 150 — — — 150 Payments of debt extinguishment costs (50 ) — — — (50 ) Preferred stock dividends paid (16 ) — — — (16 ) Interest rate swap settlement payments (15 ) — — — (15 ) Acquisition of noncontrolling interest (375 ) — — — (375 ) Payments related to bankruptcy settlement (126 ) (7 ) — — (133 ) Net intercompany transfers — (684 ) (42 ) 726 — Intercompany borrowings, net of repayments 45 (45 ) — — — Other financing (2 ) — — — (2 ) Net cash used in financing activities (822 ) (766 ) (93 ) 726 (955 ) Net decrease in cash, cash equivalents and restricted cash (3,196 ) (10 ) (19 ) — (3,225 ) Cash, cash equivalents, and restricted cash beginning of period 3,550 262 26 — 3,838 Cash, cash equivalents, and restricted cash end of period $ 354 $ 252 $ 7 $ — $ 613 Condensed Consolidating Statements of Cash Flows for the Nine Months Ended September 30, 2016 (amounts in millions) Parent Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES: Net cash provided by (used in) operating activities $ (236 ) $ 977 $ (13 ) $ — $ 728 CASH FLOWS FROM INVESTING ACTIVITIES: Capital expenditures — (271 ) (66 ) — (337 ) Distributions from unconsolidated investments — 14 — — 14 Net intercompany transfers 801 — — (801 ) — Other investing — 10 — — 10 Net cash provided by (used in) investing activities 801 (247 ) (66 ) (801 ) (313 ) CASH FLOWS FROM FINANCING ACTIVITIES: Proceeds from long-term borrowings, net of debt issuance costs 2,079 198 — — 2,277 Repayments of borrowings (6 ) (15 ) — — (21 ) Proceeds from issuance of equity, net of issuance costs 359 — — — 359 Preferred stock dividends paid (16 ) — — — (16 ) Interest rate swap settlement payments (13 ) — — — (13 ) Net intercompany transfers — (837 ) 36 801 — Other financing (2 ) — — — (2 ) Net cash provided by (used in) financing activities 2,401 (654 ) 36 801 2,584 Net increase (decrease) in cash, cash equivalents and restricted cash 2,966 76 (43 ) — 2,999 Cash, cash equivalents and restricted cash, beginning of period 327 133 84 — 544 Cash, cash equivalents and restricted cash, end of period $ 3,293 $ 209 $ 41 $ — $ 3,543

Genco Chapter 11 Bankruptcy a42

Genco Chapter 11 Bankruptcy and Emergence (Tables)	9 Months Ended
	Sep. 30, 2017
Reorganizations [Abstract]
Schedule of Reorganization Items	The following table summarizes the Company’s gain from the termination of the Genco senior notes, which is recognized in Bankruptcy reorganization items in our unaudited consolidated statement of operations for the nine months ended September 30, 2017 : (amounts in millions) Liabilities subject to compromise, which were terminated $ 832 Less: Seven-year unsecured notes 188 Cash consideration 122 2017 Warrants, at fair value 17 Legal and consulting fees 11 Bankruptcy reorganization items $ 494

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Reportable segment information, including intercompany transactions accounted for at prevailing market rates, for the three and nine months ended September 30, 2017 and 2016 is presented below: Segment Data as of and for the Three Months Ended September 30, 2017 (amounts in millions) PJM NY/NE ERCOT MISO IPH CAISO Other and Eliminations Total Domestic: Unaffiliated revenues $ 628 $ 269 $ 210 $ 98 $ 182 $ 50 $ — $ 1,437 Intercompany and affiliate revenues (25 ) (1 ) (1 ) 6 21 — — — Total revenues $ 603 $ 268 $ 209 $ 104 $ 203 $ 50 $ — $ 1,437 Depreciation expense $ (94 ) $ (52 ) $ (20 ) $ (9 ) $ (11 ) $ (14 ) $ (2 ) $ (202 ) Impairments (29 ) — — — — — — (29 ) Loss on sale of assets, net (1 ) (77 ) — — — — — (78 ) General and administrative expense — — — — — — (44 ) (44 ) Acquisition and integration costs — — — — — — (3 ) (3 ) Operating income (loss) $ 86 $ (30 ) $ 50 $ (9 ) $ 11 $ — $ (50 ) $ 58 Bankruptcy reorganization items — — — — 12 — — 12 Earnings from unconsolidated investments 2 2 — — — — — 4 Interest expense — — — — — — (161 ) (161 ) Loss on early extinguishment of debt — — — — — — (66 ) (66 ) Other income and expense, net 16 — — — — — 3 19 Loss before income taxes (134 ) Income tax benefit — — — — — — 1 1 Net loss (133 ) Less: Net loss attributable to noncontrolling interest (1 ) Net loss attributable to Dynegy Inc. $ (132 ) Total assets—domestic $ 5,158 $ 3,401 $ 1,564 $ 232 $ 581 $ 461 $ 610 $ 12,007 Investment in unconsolidated affiliate $ 77 $ 77 $ — $ — $ — $ — $ — $ 154 Capital expenditures $ (6 ) $ (6 ) $ (3 ) $ — $ (4 ) $ (3 ) $ (2 ) $ (24 ) Segment Data as of and for the Nine Months Ended September 30, 2017 (amounts in millions) PJM NY/NE ERCOT MISO IPH CAISO Other and Eliminations Total Domestic: Unaffiliated revenues $ 1,806 $ 817 $ 322 $ 276 $ 538 $ 89 $ — $ 3,848 Intercompany and affiliate revenues (47 ) (2 ) (1 ) 16 34 — — — Total revenues $ 1,759 $ 815 $ 321 $ 292 $ 572 $ 89 $ — $ 3,848 Depreciation expense $ (283 ) $ (171 ) $ (54 ) $ (22 ) $ (35 ) $ (40 ) $ (6 ) $ (611 ) Impairments (49 ) — — (99 ) — — — (148 ) Gain (loss) on sale of assets, net (31 ) (77 ) — — 1 — — (107 ) General and administrative expense — — — — — — (126 ) (126 ) Acquisition and integration costs — — — — — — (55 ) (55 ) Operating income (loss) $ 178 $ (72 ) $ (8 ) $ (90 ) $ 40 $ (33 ) $ (188 ) $ (173 ) Bankruptcy reorganization items — — — — 494 — — 494 Earnings from unconsolidated investments 2 2 — — — — — 4 Interest expense — — — — — — (478 ) (478 ) Loss on early extinguishment of debt — — — — — — (75 ) (75 ) Other income and expense, net 16 — — — 26 — 23 65 Loss before income taxes 0 — 0 — — — 0 (163 ) Income tax benefit — — — — — — 330 330 Net income 167 Less: Net loss attributable to noncontrolling interest (2 ) Net income attributable to Dynegy Inc. $ 169 Total assets—domestic $ 5,158 $ 3,401 $ 1,564 $ 232 $ 581 $ 461 $ 610 $ 12,007 Investment in unconsolidated affiliate $ 77 $ 77 $ — $ — $ — $ — $ — $ 154 Capital expenditures $ (74 ) $ (46 ) $ (20 ) $ (3 ) $ (10 ) $ (34 ) $ (5 ) $ (192 ) Segment Data as of and for the Three Months Ended September 30, 2016 (amounts in millions) PJM NY/NE MISO IPH CAISO Other and Eliminations Total Domestic: Unaffiliated revenues $ 551 $ 200 $ 130 $ 241 $ 46 $ — $ 1,168 Intercompany revenues 17 (5 ) 3 1 — — 16 Total revenues $ 568 $ 195 $ 133 $ 242 $ 46 $ — $ 1,184 Depreciation expense $ (88 ) $ (53 ) $ (3 ) $ (7 ) $ (11 ) $ (1 ) $ (163 ) Impairments (64 ) — — (148 ) — — (212 ) General and administrative expense — — — — — (41 ) (41 ) Acquisition and integration costs — — — — — (7 ) (7 ) Operating income (loss) $ 29 $ (15 ) $ 13 $ (104 ) $ 10 $ (50 ) $ (117 ) Earnings from unconsolidated investments 4 — — — — — 4 Interest expense — — — — — (166 ) (166 ) Other income and expense, net 3 — — 1 — 25 29 Loss before income taxes (250 ) Income tax benefit — — — — — 1 1 Net loss (249 ) Less: Net loss attributable to noncontrolling interest — Net loss attributable to Dynegy Inc. $ (249 ) Total assets—domestic $ 5,208 $ 2,807 $ 371 $ 746 $ 499 $ 3,393 $ 13,024 Investment in unconsolidated affiliate $ 173 $ — $ — $ — $ — $ — $ 173 Capital expenditures $ (13 ) $ (10 ) $ (1 ) $ (9 ) $ (1 ) $ (1 ) $ (35 ) Segment Data as of and for the Nine Months Ended September 30, 2016 (amounts in millions) PJM NY/NE MISO IPH CAISO Other and Eliminations Total Domestic: Unaffiliated revenues $ 1,559 $ 630 $ 315 $ 575 $ 105 $ — $ 3,184 Intercompany revenues 45 (2 ) (15 ) (1 ) — — 27 Total revenues $ 1,604 $ 628 $ 300 $ 574 $ 105 $ — $ 3,211 Depreciation expense $ (257 ) $ (167 ) $ (19 ) $ (21 ) $ (26 ) $ (4 ) $ (494 ) Impairments (64 ) — (645 ) (148 ) — — (857 ) General and administrative expense — — — — — (117 ) (117 ) Acquisition and integration costs — — — 8 — (16 ) (8 ) Operating income (loss) $ 277 $ (22 ) $ (703 ) $ (87 ) $ — $ (139 ) $ (674 ) Earnings from unconsolidated investments 7 — — — — — 7 Interest expense — — — — — (449 ) (449 ) Other income and expense, net 9 — — 15 12 24 60 Loss before income taxes (1,056 ) Income tax expense — — — — — (6 ) (6 ) Net loss (1,062 ) Less: Net loss attributable to noncontrolling interest (2 ) Net loss attributable to Dynegy Inc. $ (1,060 ) Total assets—domestic $ 5,208 $ 2,807 $ 371 $ 746 $ 499 $ 3,393 $ 13,024 Investment in unconsolidated affiliate $ 173 $ — $ — $ — $ — $ — $ 173 Capital expenditures $ (124 ) $ (84 ) $ (9 ) $ (30 ) $ (4 ) $ (9 ) $ (260 )

Basis of Presentation and Org44

Basis of Presentation and Organization (Details)	9 Months Ended
	Sep. 30, 2017segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	6

Accounting Policies (Details)

Accounting Policies (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities	$ 501	$ 728
Net cash provided by (used in) investing activities	$ 2,771	313
Accounting Standards Update 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities		80
Net cash provided by (used in) investing activities		80
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities		(1)
Net cash provided by (used in) investing activities		2,045
Restricted cash		$ 2,085	$ 39

Acquisitions and Divestitures -

Acquisitions and Divestitures - Engie Acquisition (Details) - Engie Acquisition $ in Millions	Feb. 07, 2017USD ($)facilityMW
Business Acquisition [Line Items]
Capacity of power facilities acquired (in MW) | MW	9,017
Number of natural gas power facilities acquired	15
Base purchase price | $	$ 3,300
TEXAS
Business Acquisition [Line Items]
Number of coal-fired power facilities	1
PENNSYLVANIA
Business Acquisition [Line Items]
Number of coal-fired power facilities	1

Acquisitions and Divestitures47

Acquisitions and Divestitures - Business Combination Accounting (Details) - Engie Acquisition	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2027
Business Acquisition [Line Items]
Operations, maintenance and capital expenditures, growth rate after year five	2.50%
Minimum | Gas
Business Acquisition [Line Items]
Discount rate	9.00%
Minimum | Coal
Business Acquisition [Line Items]
Discount rate	13.00%
Maximum | Gas
Business Acquisition [Line Items]
Discount rate	13.00%
Maximum | Coal
Business Acquisition [Line Items]
Discount rate	14.00%
Scenario, Forecast
Business Acquisition [Line Items]
Long-term growth rate		2.50%

Acquisitions and Divestitures48

Acquisitions and Divestitures - Schedule of Assets Acquired and Liabilities Assumed (Details) - Engie Acquisition $ in Millions	Feb. 07, 2017USD ($)
Business Acquisition [Line Items]
Base purchase price	$ 3,300
Working capital adjustments and other	(31)
Fair value of total consideration transferred	3,269
Cash	20
Accounts receivable	22
Inventory	101
Prepayments and other current assets	3
Assets from risk management activities (including current portion of $21 million)	25
Current assets from risk management activities	21
Property, plant and equipment	2,716
Investment in unconsolidated affiliate	159
Intangible assets (including current portion of $7 million)	50
Intangible assets, current, other than goodwill	7
Assets held-for-sale	478
Other long-term assets	131
Total assets acquired	3,705
Accounts payable	28
Liabilities from risk management activities (including current portion of $13 million)	16
Current liabilities from risk management activities	13
Asset retirement obligations	19
Intangible liabilities (including current portion of $16 million)	30
Intangible liabilities, current	16
Deferred income taxes, net	342
Other long-term liabilities	1
Total liabilities assumed	436
Net assets acquired	$ 3,269

Acquisitions and Divestitures49

Acquisitions and Divestitures - Results Since Acquisition (Details) - Engie Acquisition - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Acquisition costs	$ 0	$ 3	$ 35	$ 5
Revenues	345		669
Operating loss	$ (36)		$ (32)

Acquisitions and Divestitures50

Acquisitions and Divestitures - Pro Forma Results (Details) - Engie Acquisition - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Acquisition costs	$ 0	$ 3	$ 35	$ 5
Revenue			3,905	3,942
Net income (loss)			169	(1,090)
Parent
Business Acquisition [Line Items]
Net income (loss)			$ 171	$ (1,088)

Acquisitions and Divestitures51

Acquisitions and Divestitures - AER Acquisition (Details) - USD ($) $ in Millions	Apr. 12, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Other income and expense, net		$ 19	$ 29	$ 65	$ 60
AER Acquisition
Business Acquisition [Line Items]
Contingent consideration, liability	$ 25
Other income and expense, net	$ 25

Acquisitions and Divestitures52

Acquisitions and Divestitures - Divestitures (Details) $ in Millions	Oct. 12, 2017USD ($)	Sep. 22, 2017USD ($)facility	Jul. 11, 2017USD ($)facilityMW	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of assets, net				$ 78	$ 0	$ 107	$ 0
Troy and Armstrong | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of facilities sold in divestiture agreement | facility			2
Proceeds from divestiture of businesses			$ 480
Power output of facilities sold in divestiture agreement (in MW) | MW			1,269
Lee Facility | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of property, plant, and equipment	$ 180
Lee Facility | Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill				9		9
Impairments				15		15
Dighton and Milford, Massachusetts Facilities | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of property, plant, and equipment		$ 125
Number of properties sold | facility		2
Working capital adjustment		$ 6
Loss on sale of assets, net				77		77
Goodwill, written off related to sale of business unit				$ 18		$ 18

Unconsolidated Investments (Det

Unconsolidated Investments (Details) - USD ($) $ in Millions	Nov. 21, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Feb. 07, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated affiliate		$ 154		$ 154			$ 0
Earnings from unconsolidated investments				4	$ 7
Distributions from unconsolidated investments				2	1
Return of investment				7	14
Northeast Energy LP
Schedule of Equity Method Investments [Line Items]
Percent of voting interests acquired (as a percentage)						50.00%
Investment in unconsolidated affiliate		154		154
Identifiable net assets acquired						$ (14)
Earnings from unconsolidated investments		$ 4		4
Distributions from unconsolidated investments				9
Return of investment				$ 7
Elwood Energy LLC and Elwood Expansion LLC
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated investments			$ 4		7
Distributions from unconsolidated investments					15
Return of investment					14
Percent divested	50.00%
Proceeds from sale of investment	$ 173
Other than temporary impairment			$ 9		$ 9

Risk Management Activities, D54

Risk Management Activities, Derivatives and Financial Instruments - Narratives (Details)	9 Months Ended
	Sep. 30, 2017USD ($)
Commodity Contract
Derivative [Line Items]
Credit risk derivative liabilities at fair value	$ 9,000,000
Fair value of collateral	$ 0
Minimum
Derivative [Line Items]
Rolling time period over which the entity can sell energy and capacity through near-term contractual arrangements	1 year
Maximum
Derivative [Line Items]
Rolling time period over which the entity can sell energy and capacity through near-term contractual arrangements	3 years

Risk Management Activities, D55

Risk Management Activities, Derivatives and Financial Instruments - Schedule of Derivative Contracts and Interest Rate Swaps (Details) t in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)MMBTUMWhtshares	Dec. 31, 2016USD ($)
Derivative [Line Items]
Number of securities called by each warrant or right (in shares) | shares	1
Commodity Contract | Prepayments and Other Current Assets
Derivative [Line Items]
Margin and collateral netting	$ 22	$ 54
Not Designated as Hedging Instrument
Derivative [Line Items]
Margin and collateral netting	22	$ 54
Not Designated as Hedging Instrument | Long
Derivative [Line Items]
Derivative, notional amount	1,963
Fair value, asset (liability)	$ (11)
Not Designated as Hedging Instrument | Electricity derivatives | Short
Derivative [Line Items]
Nonmonetary notional amount, energy | MWh	(60)
Fair value, asset (liability)	$ 14
Not Designated as Hedging Instrument | Electricity basis derivatives | Short
Derivative [Line Items]
Nonmonetary notional amount, energy | MWh	(34)
Fair value, asset (liability)	$ (7)
Not Designated as Hedging Instrument | Natural gas derivatives | Long
Derivative [Line Items]
Nonmonetary notional amount, energy | MMBTU	(380)
Fair value, asset (liability)	$ (1)
Not Designated as Hedging Instrument | Natural gas basis derivatives | Long
Derivative [Line Items]
Nonmonetary notional amount, energy | MMBTU	(108)
Fair value, asset (liability)	$ (14)
Not Designated as Hedging Instrument | Physical heat rate derivatives
Derivative [Line Items]
Fair value, asset (liability)	$ 14
Not Designated as Hedging Instrument | Physical heat rate derivatives | Short
Derivative [Line Items]
Nonmonetary notional amount, energy | MWh	(13)
Not Designated as Hedging Instrument | Physical heat rate derivatives | Long
Derivative [Line Items]
Nonmonetary notional amount, energy | MMBTU	(125)
Not Designated as Hedging Instrument | Emissions derivatives | Long
Derivative [Line Items]
Nonmonetary notional amount, mass | t	17
Fair value, asset (liability)	$ 4
Not Designated as Hedging Instrument | Warrants | Long
Derivative [Line Items]
Nonmonetary notional amount, equity award (in shares) | shares	25,000,000
Fair value, asset (liability)	$ (2)

Risk Management Activities, D56

Risk Management Activities, Derivatives and Financial Instruments - Schedule of Derivative Instruments in the Balance Sheet (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Risk Management Activities, Derivatives and Financial Instruments
Derivative Asset, Gross Fair Value	$ 216	$ 311
Derivative Asset, Contract Netting	(117)	(165)
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0	0
Derivative Assets, Net Fair Value	99	146
Derivative Liabilities, Gross Fair Value	(219)	(360)
Derivative Liability, Contract Netting	117	165
Margin and collateral netting	22	54
Derivative Liabilities, Net Fair Value	(80)	(141)
Derivative Assets (Liabilities), Gross Fair Value	(3)	(49)
Derivative Asset and Liability Contract Netting	0	0
Derivative Asset And Liability, Collateral, Obligation to Return Cash, Offset	22	54
Derivative Assets (Liabilities), Net Fair Value	19	5
Commodity Contract | Assets from Risk Management Activities
Risk Management Activities, Derivatives and Financial Instruments
Derivative Asset, Gross Fair Value	204	311
Derivative Asset, Contract Netting	(117)	(165)
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0	0
Derivative Assets, Net Fair Value	87	146
Commodity Contract | Liabilities from Risk Management Activities
Risk Management Activities, Derivatives and Financial Instruments
Derivative Liabilities, Gross Fair Value	(194)	(329)
Derivative Liability, Contract Netting	117	165
Margin and collateral netting	22	54
Derivative Liabilities, Net Fair Value	(55)	(110)
Interest Rate Contracts | Assets from Risk Management Activities
Risk Management Activities, Derivatives and Financial Instruments
Derivative Asset, Gross Fair Value	12
Derivative Asset, Contract Netting	0
Derivative Asset, Collateral, Obligation to Return Cash, Offset	0
Derivative Assets, Net Fair Value	12
Interest Rate Contracts | Liabilities from Risk Management Activities
Risk Management Activities, Derivatives and Financial Instruments
Derivative Liabilities, Gross Fair Value	(23)	(30)
Derivative Liability, Contract Netting	0	0
Margin and collateral netting	0	0
Derivative Liabilities, Net Fair Value	(23)	(30)
Warrants | Other Liabilities
Risk Management Activities, Derivatives and Financial Instruments
Derivative Liabilities, Gross Fair Value	(2)	(1)
Derivative Liability, Contract Netting	0	0
Margin and collateral netting	0	0
Derivative Liabilities, Net Fair Value	$ (2)	$ (1)

Risk Management Activities, D57

Risk Management Activities, Derivatives and Financial Instruments - Schedule of Collateral Posted and Balance Sheet Location (Details) - Commodity Contract - Prepayments and Other Current Assets - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Gross collateral posted with counterparties	$ 54	$ 116
Less: Collateral netted against risk management liabilities	22	54
Net collateral within Prepayments and other current assets	$ 32	$ 62

Risk Management Activities, D58

Risk Management Activities, Derivatives and Financial Instruments - Schedule of Derivative Instruments, Gain (Loss) in the Statement of Operations (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Commodity Contract | Revenues
Derivative Instruments, Gain (Loss) [Line Items]
Recognized gain (loss) on derivatives	$ 29	$ (27)	$ 242	$ 188
Interest Rate Contracts | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Recognized gain (loss) on derivatives	1	1	4	(11)
Warrants | Other Income and (Expense), Net
Derivative Instruments, Gain (Loss) [Line Items]
Recognized gain (loss) on derivatives	$ 1	$ 4	$ 16	$ 5

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Assets:
Assets from commodity risk management activities:	$ 204	$ 311
Assets from interest rate contracts	12
Total assets	216
Liabilities:
Liabilities from commodity risk management activities:	(194)	(329)
Liabilities from interest rate contracts	(23)	(30)
Total liabilities	(219)	(360)
Electricity derivatives
Assets:
Assets from commodity risk management activities:	121	138
Liabilities:
Liabilities from commodity risk management activities:	(114)	(257)
Natural gas derivatives
Assets:
Assets from commodity risk management activities:	51	173
Liabilities:
Liabilities from commodity risk management activities:	(66)	(62)
Physical heat rate derivatives
Assets:
Assets from commodity risk management activities:	21
Liabilities:
Liabilities from commodity risk management activities:	(7)
Emissions derivatives
Assets:
Assets from commodity risk management activities:	11
Liabilities:
Liabilities from commodity risk management activities:	(7)	(10)
Liabilities from outstanding common stock warrants
Liabilities:
Liabilities from outstanding common stock warrants	(2)	(1)
Level 1
Assets:
Assets from commodity risk management activities:	0	0
Assets from interest rate contracts	0
Total assets	0
Liabilities:
Liabilities from commodity risk management activities:	0	0
Liabilities from interest rate contracts	0	0
Total liabilities	(2)	(1)
Level 1 | Electricity derivatives
Assets:
Assets from commodity risk management activities:	0	0
Liabilities:
Liabilities from commodity risk management activities:	0	0
Level 1 | Natural gas derivatives
Assets:
Assets from commodity risk management activities:	0	0
Liabilities:
Liabilities from commodity risk management activities:	0	0
Level 1 | Physical heat rate derivatives
Assets:
Assets from commodity risk management activities:	0
Liabilities:
Liabilities from commodity risk management activities:	0
Level 1 | Emissions derivatives
Assets:
Assets from commodity risk management activities:	0
Liabilities:
Liabilities from commodity risk management activities:	0	0
Level 1 | Liabilities from outstanding common stock warrants
Liabilities:
Liabilities from outstanding common stock warrants	(2)	(1)
Level 2
Assets:
Assets from commodity risk management activities:	176	287
Assets from interest rate contracts	12
Total assets	188
Liabilities:
Liabilities from commodity risk management activities:	(168)	(307)
Liabilities from interest rate contracts	(23)	(30)
Total liabilities	(191)	(337)
Level 2 | Electricity derivatives
Assets:
Assets from commodity risk management activities:	100	118
Liabilities:
Liabilities from commodity risk management activities:	(94)	(245)
Level 2 | Natural gas derivatives
Assets:
Assets from commodity risk management activities:	45	169
Liabilities:
Liabilities from commodity risk management activities:	(60)	(52)
Level 2 | Physical heat rate derivatives
Assets:
Assets from commodity risk management activities:	20
Liabilities:
Liabilities from commodity risk management activities:	(7)
Level 2 | Emissions derivatives
Assets:
Assets from commodity risk management activities:	11
Liabilities:
Liabilities from commodity risk management activities:	(7)	(10)
Level 2 | Liabilities from outstanding common stock warrants
Liabilities:
Liabilities from outstanding common stock warrants	0	0
Level 3
Assets:
Assets from commodity risk management activities:	28	24
Assets from interest rate contracts	0
Total assets	28
Liabilities:
Liabilities from commodity risk management activities:	(26)	(22)
Liabilities from interest rate contracts	0	0
Total liabilities	(26)	(22)
Level 3 | Electricity derivatives
Assets:
Assets from commodity risk management activities:	21	20
Liabilities:
Liabilities from commodity risk management activities:	(20)	(12)
Level 3 | Natural gas derivatives
Assets:
Assets from commodity risk management activities:	6	4
Liabilities:
Liabilities from commodity risk management activities:	(6)	(10)
Level 3 | Physical heat rate derivatives
Assets:
Assets from commodity risk management activities:	1
Liabilities:
Liabilities from commodity risk management activities:	0
Level 3 | Emissions derivatives
Assets:
Assets from commodity risk management activities:	0
Liabilities:
Liabilities from commodity risk management activities:	0	0
Level 3 | Liabilities from outstanding common stock warrants
Liabilities:
Liabilities from outstanding common stock warrants	$ 0	$ 0

Fair Value Measurements - Sensi

Fair Value Measurements - Sensitivity to Changes in Significant Unobservable Inputs for Level 3 Valuations (Details) - Market Approach Valuation Technique - Level 3 - Fair Value, Measurements, Recurring MWh in Millions, MMBTU in Millions, BTU in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)MMBTUMWhBTU$ / MWh$ / MMBTU
Forward contracts - power
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Nonmonetary notional amount, energy | MWh	(14)
Fair value of derivatives held | $	$ 4
Forward contracts - power | Minimum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Basis spread (usd per MWh)	4.25
Forward contracts - power | Maximum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Basis spread (usd per MWh)	6.25
FTRs
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Nonmonetary notional amount, energy | MWh	(29)
Fair value of derivatives held | $	$ (3)
FTRs | Minimum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Forward price (usd per MMBtu)	0
FTRs | Maximum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Forward price (usd per MMBtu)	6
Physical heat rate derivatives
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Fair value of derivatives held | $	$ 1
Physical heat rate derivatives | Long
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Nonmonetary notional amount, energy | BTU	(23)
Physical heat rate derivatives | Short
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Nonmonetary notional amount, energy | MWh	(3)
Physical Heat Rate Derivative - MMBtu | Minimum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Forward price (usd per MMBtu) | $ / MMBTU	2.40
Physical Heat Rate Derivative - MMBtu | Maximum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Forward price (usd per MMBtu) | $ / MMBTU	3.30
Physical Heat Rate Derivative - MWh | Minimum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Forward price (usd per MMBtu)	20
Physical Heat Rate Derivative - MWh | Maximum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Forward price (usd per MMBtu)	24
Natural gas derivatives
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Nonmonetary notional amount, energy | MMBTU	(102)
Fair value of derivatives held | $	$ 0
Natural gas derivatives | Minimum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Forward price (usd per MMBtu) | $ / MMBTU	1.75
Natural gas derivatives | Maximum
Fair Value Inputs, Equity, Quantitative Information [Line Items]
Forward price (usd per MMBtu) | $ / MMBTU	2.15

Fair Value Measurements - Sch61

Fair Value Measurements - Schedule of Changes in Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Unrealized gain (loss) relating to instruments held at the end of the period			$ 38	$ 75
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of the period	$ (2)	$ (38)	2	(48)
Acquired derivatives			1
Total gains (losses) included in earnings	8	6	(5)	4
Transfers out of level 3	(2)
Settlements	(2)	(9)	4	(21)
Balance at the end of the period	2	(23)	2	(23)
Unrealized gain (loss) relating to instruments held at the end of the period	8	6	(5)	4
Level 3 | Electricity Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of the period	(1)	(24)	8	(18)
Acquired derivatives			1
Total gains (losses) included in earnings	6	9	(16)	4
Transfers out of level 3	(2)
Settlements	(2)	(5)	8	(4)
Balance at the end of the period	1	(10)	1	(10)
Unrealized gain (loss) relating to instruments held at the end of the period	6	9	(16)	4
Level 3 | Natural gas derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of the period	1	(15)	(6)	(32)
Acquired derivatives			0
Total gains (losses) included in earnings	(1)	(4)	10	0
Transfers out of level 3	0
Settlements	0	(5)	(4)	(18)
Balance at the end of the period	0	(14)	0	(14)
Unrealized gain (loss) relating to instruments held at the end of the period	(1)	(4)	10	0
Level 3 | Heat Rate Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of the period	(2)		0
Acquired derivatives			0
Total gains (losses) included in earnings	3		1
Transfers out of level 3	0
Settlements	0		0
Balance at the end of the period	1		1
Unrealized gain (loss) relating to instruments held at the end of the period	$ 3		$ 1
Level 3 | Coal Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of the period		1		2
Total gains (losses) included in earnings		1		0
Settlements		1		1
Balance at the end of the period		1		1
Unrealized gain (loss) relating to instruments held at the end of the period		$ 1		$ 0

Fair Value Measurements - Sch62

Fair Value Measurements - Schedule of Financial Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Dynegy, Inc. | 6.75% Senior Notes, due 2019
Fair value of Financial Instruments
Stated interest rate	6.75%
Dynegy, Inc. | 7.375% Senior Notes, due 2022
Fair value of Financial Instruments
Stated interest rate	7.375%
Dynegy, Inc. | 5.875% Senior Notes, due 2023
Fair value of Financial Instruments
Stated interest rate	5.875%
Dynegy, Inc. | 7.625% Senior Notes, due 2024
Fair value of Financial Instruments
Stated interest rate	7.625%
Dynegy, Inc. | 8.034% Senior Notes, due 2024
Fair value of Financial Instruments
Stated interest rate	8.034%
Dynegy, Inc. | 8.00% Senior Notes, due 2025
Fair value of Financial Instruments
Stated interest rate	8.00%
Dynegy, Inc. | 8.125% Senior Notes, due 2026
Fair value of Financial Instruments
Stated interest rate	8.125%
Dynegy, Inc. | 7.00% Amortizing Notes, due 2019 (TEUs)
Fair value of Financial Instruments
Stated interest rate	7.00%
Level 2 | Carrying Amount | Term Facilities Tranche C-1, due 2024
Fair value of Financial Instruments
Long-term debt, gross	$ (1,940)	$ (1,994)
Level 2 | Carrying Amount | Term Facilities Tranche B-2, due 2020
Fair value of Financial Instruments
Long-term debt, gross	0	(219)
Level 2 | Carrying Amount | Revolving Facility
Fair value of Financial Instruments
Long-term debt, gross	(300)	0
Level 2 | Carrying Amount | 6.75% Senior Notes, due 2019
Fair value of Financial Instruments
Long-term debt, gross	(845)	(2,083)
Level 2 | Carrying Amount | 7.375% Senior Notes, due 2022
Fair value of Financial Instruments
Long-term debt, gross	(1,733)	(1,731)
Level 2 | Carrying Amount | 5.875% Senior Notes, due 2023
Fair value of Financial Instruments
Long-term debt, gross	(493)	(492)
Level 2 | Carrying Amount | 7.625% Senior Notes, due 2024
Fair value of Financial Instruments
Long-term debt, gross	(1,237)	(1,237)
Level 2 | Carrying Amount | 8.034% Senior Notes, due 2024
Fair value of Financial Instruments
Long-term debt, gross	(188)	0
Level 2 | Carrying Amount | 8.00% Senior Notes, due 2025
Fair value of Financial Instruments
Long-term debt, gross	(739)	(738)
Level 2 | Carrying Amount | 8.125% Senior Notes, due 2026
Fair value of Financial Instruments
Long-term debt, gross	(842)	0
Level 2 | Carrying Amount | 7.00% Amortizing Notes, due 2019 (TEUs)
Fair value of Financial Instruments
Long-term debt, gross	(58)	(78)
Level 2 | Fair Value | Term Facilities Tranche C-1, due 2024
Fair value of Financial Instruments
Long-term debt, gross	(2,029)	(2,025)
Level 2 | Fair Value | Term Facilities Tranche B-2, due 2020
Fair value of Financial Instruments
Long-term debt, gross	0	(225)
Level 2 | Fair Value | Revolving Facility
Fair value of Financial Instruments
Long-term debt, gross	(300)	0
Level 2 | Fair Value | 6.75% Senior Notes, due 2019
Fair value of Financial Instruments
Long-term debt, gross	(881)	(2,137)
Level 2 | Fair Value | 7.375% Senior Notes, due 2022
Fair value of Financial Instruments
Long-term debt, gross	(1,824)	(1,665)
Level 2 | Fair Value | 5.875% Senior Notes, due 2023
Fair value of Financial Instruments
Long-term debt, gross	(498)	(431)
Level 2 | Fair Value | 7.625% Senior Notes, due 2024
Fair value of Financial Instruments
Long-term debt, gross	(1,294)	(1,156)
Level 2 | Fair Value | 8.034% Senior Notes, due 2024
Fair value of Financial Instruments
Long-term debt, gross	(190)	0
Level 2 | Fair Value | 8.00% Senior Notes, due 2025
Fair value of Financial Instruments
Long-term debt, gross	(778)	(703)
Level 2 | Fair Value | 8.125% Senior Notes, due 2026
Fair value of Financial Instruments
Long-term debt, gross	(880)	0
Level 2 | Fair Value | 7.00% Amortizing Notes, due 2019 (TEUs)
Fair value of Financial Instruments
Long-term debt, gross	(62)	(90)
Level 3 | Carrying Amount | Forward capacity agreement
Fair value of Financial Instruments
Long-term debt, gross	(212)	(205)
Level 3 | Carrying Amount | Inventory financing agreements
Fair value of Financial Instruments
Long-term debt, gross	(48)	(129)
Level 3 | Carrying Amount | Equipment financing agreements
Fair value of Financial Instruments
Long-term debt, gross	(112)	(73)
Level 3 | Carrying Amount | Genco | Liabilities subject to compromise
Fair value of Financial Instruments
Long-term debt, gross	0	(825)
Level 3 | Fair Value | Forward capacity agreement
Fair value of Financial Instruments
Long-term debt, gross	(212)	(205)
Level 3 | Fair Value | Inventory financing agreements
Fair value of Financial Instruments
Long-term debt, gross	(48)	(127)
Level 3 | Fair Value | Equipment financing agreements
Fair value of Financial Instruments
Long-term debt, gross	(112)	(73)
Level 3 | Fair Value | Genco | Liabilities subject to compromise
Fair value of Financial Instruments
Long-term debt, gross	$ 0	$ (366)

Cash Flow Information - Supplem

Cash Flow Information - Supplemental Disclosures of Non-cash Investing and Financing Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash and Cash Equivalents [Abstract]
Change in capital expenditures included in accounts payable	$ 5	$ (10)
Change in capital expenditures pursuant to an equipment financing agreement	34	11
Issuance of 2017 Warrants	17	0
Issuance of senior notes related to the Genco restructuring	188	0
Sale of interest in Conesville facility	(58)	0
Acquisition of interest in Zimmer facility	$ 27	$ 0

Cash Flow Information - Reconci

Cash Flow Information - Reconciliation of Cash and Cash Equivalents (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 613	$ 1,776	$ 1,458
Restricted cash included in current assets	0	62	85
Restricted cash included in long-term assets	0	2,000	2,000
Total cash, cash equivalents and restricted cash	$ 613	$ 3,838	3,543	$ 544
Escrow			45
Escrow, pre-funded interest			25
Escrow, pre-funded original issue discount			20
Cash collateral for borrowed securities			$ 40

Inventory - Summary of Inventor

Inventory - Summary of Inventories (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Materials and supplies	$ 236	$ 236	$ 182
Coal	165	165	238
Fuel oil	14	14	17
Natural gas	12	12	0
Emissions allowances	2	2	8
Total	429	429	$ 445
Inventory impairment	$ 14	$ 14

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Property, Plant, and Equipment (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment, Net, by Type [Abstract]
Property, plant and equipment	$ 10,918	$ 8,579
Accumulated depreciation	(1,989)	(1,458)
Property, plant and equipment, net	8,929	7,121
Power generation
Property, Plant and Equipment, Net, by Type [Abstract]
Property, plant and equipment	9,845	7,537
Buildings and improvements
Property, Plant and Equipment, Net, by Type [Abstract]
Property, plant and equipment	958	944
Office and other equipment
Property, Plant and Equipment, Net, by Type [Abstract]
Property, plant and equipment	$ 115	$ 98

Property, Plant and Equipment67

Property, Plant and Equipment - Schedule of Property, Plant and Equipment Impairment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Line Items]
Impairments	$ 0	$ 203	$ 119	$ 848
Baldwin
Property, Plant and Equipment [Line Items]
Fair Value	97		97
Impairments	0	0	0	645
Stuart Facility
Property, Plant and Equipment [Line Items]
Fair Value	0		0
Impairments	0	55	0	55
Newton FGD Facility
Property, Plant and Equipment [Line Items]
Fair Value	0		0
Impairments	0	148	0	148
Killen
Property, Plant and Equipment [Line Items]
Fair Value	0		0
Impairments	0	0	20	0
Hennepin
Property, Plant and Equipment [Line Items]
Fair Value	16		16
Impairments	0	0	10	0
Havana
Property, Plant and Equipment [Line Items]
Fair Value	37		37
Impairments	$ 0	$ 0	$ 89	$ 0

Property, Plant and Equipment68

Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Brayton Point Facility
Property, Plant and Equipment [Line Items]
Severance costs	$ 7	$ 12

Joint Ownership of Generating69

Joint Ownership of Generating Facilities (Details) - USD ($) $ in Millions	May 09, 2017	Apr. 21, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Property, Plant and Equipment			$ 10,918		$ 10,918		$ 8,579
Accumulated Depreciation			(1,989)		(1,989)		(1,458)
Property, plant and equipment, net			8,929		8,929		$ 7,121
Fair value of assets acquired					27	$ 0
Increase to inventory					(106)	(153)
Loss on sale of assets, net			$ 78	$ 0	107	0
Carrying value of sold asset					$ 58	$ 0
Miami Fort
Schedule of Equity Method Investments [Line Items]
Ownership Interest		36.00%	64.00%		64.00%		64.00%
Property, Plant and Equipment			$ 208		$ 208		$ 207
Accumulated Depreciation			(55)		(55)		(39)
Construction Work in Progress			4		4		4
Property, plant and equipment, net			$ 157		$ 157		$ 172
Stuart
Schedule of Equity Method Investments [Line Items]
Ownership Interest			39.00%		39.00%		39.00%
Property, Plant and Equipment			$ 0		$ 0		$ 0
Accumulated Depreciation			0		0		0
Construction Work in Progress			1		1		4
Property, plant and equipment, net			$ 1		1		$ 4
Conesville
Schedule of Equity Method Investments [Line Items]
Ownership Interest	40.00%						40.00%
Property, Plant and Equipment							$ 61
Accumulated Depreciation							(3)
Construction Work in Progress							6
Property, plant and equipment, net							$ 64
Loss on sale of assets, net					31
Carrying value of sold asset					$ 58
Zimmer
Schedule of Equity Method Investments [Line Items]
Ownership Interest		28.10%	71.90%		71.90%		46.50%
Property, Plant and Equipment			$ 131		$ 131		$ 115
Accumulated Depreciation			(37)		(37)		(25)
Construction Work in Progress			8		8		6
Property, plant and equipment, net			$ 102		$ 102		$ 96
Ownership percentage by parent			71.90%		71.90%
Fair value of assets acquired					$ 27
PPE additions	$ 14
Increase to inventory	14
Asset retirement obligation	$ 1
Zimmer | American Electric Power
Schedule of Equity Method Investments [Line Items]
Ownership Interest	25.40%
Letters of credit outstanding, amount	$ 58
Killen
Schedule of Equity Method Investments [Line Items]
Ownership Interest			33.00%		33.00%		33.00%
Property, Plant and Equipment			$ 0		$ 0		$ 19
Accumulated Depreciation			0		0		(2)
Construction Work in Progress			0		0		3
Property, plant and equipment, net			$ 0		$ 0		$ 20
Zimmer and Miami Fort
Schedule of Equity Method Investments [Line Items]
Payments to acquire interest in joint venture		$ 50

Intangible Assets and Liabili70

Intangible Assets and Liabilities - Schedule of Intangible Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Intangible Assets:
Gross Carrying Amount	$ 260	$ 273
Accumulated Amortization	(187)	(212)
Net Carrying Amount	73	61
Intangible Liabilities:
Gross Carrying Amount	(195)	(204)
Accumulated Amortization	141	149
Net Carrying Amount	(54)	(55)
Gross Carrying Amount	65	69
Accumulated Amortization	(46)	(63)
Net Carrying Amount	19	6
Electricity derivatives
Intangible Liabilities:
Gross Carrying Amount	(19)	(28)
Accumulated Amortization	17	26
Net Carrying Amount	(2)	(2)
Coal contracts
Intangible Liabilities:
Gross Carrying Amount	(32)	(49)
Accumulated Amortization	32	42
Net Carrying Amount	0	(7)
Coal transport contracts
Intangible Liabilities:
Gross Carrying Amount	(84)	(86)
Accumulated Amortization	78	73
Net Carrying Amount	(6)	(13)
Gas transport contracts
Intangible Liabilities:
Gross Carrying Amount	(58)	(41)
Accumulated Amortization	13	8
Net Carrying Amount	(45)	(33)
Gas storage contracts
Intangible Liabilities:
Gross Carrying Amount	(2)	0
Accumulated Amortization	1	0
Net Carrying Amount	(1)	0
Electricity derivatives
Intangible Assets:
Gross Carrying Amount	230	260
Accumulated Amortization	(176)	(206)
Net Carrying Amount	54	54
Gas transport contracts
Intangible Assets:
Gross Carrying Amount	30	13
Accumulated Amortization	(11)	(6)
Net Carrying Amount	$ 19	$ 7

Intangible Assets and Liabili71

Intangible Assets and Liabilities - Amortization of Intangible Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Intangible Assets and Liabilities [Line Items]
Amortization of intangibles	$ (1)	$ 4	$ 13	$ 17
Electricity derivatives
Intangible Assets and Liabilities [Line Items]
Amortization of intangibles	5	19	29	52
Coal contracts
Intangible Assets and Liabilities [Line Items]
Amortization of intangibles	(1)	(9)	(4)	(32)
Coal transport contracts
Intangible Assets and Liabilities [Line Items]
Amortization of intangibles	(2)	(7)	(7)	(21)
Gas transport contracts
Intangible Assets and Liabilities [Line Items]
Amortization of intangibles	(3)	1	(4)	18
Gas storage contracts
Intangible Assets and Liabilities [Line Items]
Amortization of intangibles	$ 0	$ 0	$ (1)	$ 0

Intangible Assets and Liabili72

Intangible Assets and Liabilities - Schedule of Intangible Assets and Liabilities Related to Acquisition (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Intangible Assets:
Gross Carrying Amount	$ 260	$ 273
Intangible Liabilities:
Gross Carrying Amount	(195)	(204)
Gross Carrying Amount	65	69
Electricity derivatives
Intangible Liabilities:
Gross Carrying Amount	(19)	(28)
Gas transport contracts
Intangible Liabilities:
Gross Carrying Amount	(58)	(41)
Gas storage contracts
Intangible Liabilities:
Gross Carrying Amount	(2)	0
Electricity derivatives
Intangible Assets:
Gross Carrying Amount	230	260
Gas transport contracts
Intangible Assets:
Gross Carrying Amount	30	$ 13
Engie Acquisition
Intangible Assets:
Gross Carrying Amount	$ 50
Weighted-Average Amortization Period (in years)	41 months
Intangible Liabilities:
Gross Carrying Amount	$ (30)
Weighted-Average Amortization Period (in years)	33 months
Gross Carrying Amount	$ 20
Engie Acquisition | Electricity derivatives
Intangible Liabilities:
Gross Carrying Amount	$ (11)
Weighted-Average Amortization Period (in years)	32 months
Engie Acquisition | Gas Contracts
Intangible Liabilities:
Gross Carrying Amount	$ 0
Weighted-Average Amortization Period (in years)	1 month
Engie Acquisition | Gas transport contracts
Intangible Liabilities:
Gross Carrying Amount	$ (17)
Weighted-Average Amortization Period (in years)	35 months
Engie Acquisition | Gas storage contracts
Intangible Liabilities:
Gross Carrying Amount	$ (2)
Weighted-Average Amortization Period (in years)	13 months
Engie Acquisition | Electricity derivatives
Intangible Assets:
Gross Carrying Amount	$ 34
Weighted-Average Amortization Period (in years)	39 months
Engie Acquisition | Gas transport contracts
Intangible Assets:
Gross Carrying Amount	$ 16
Weighted-Average Amortization Period (in years)	47 months

Intangible Assets and Liabili73

Intangible Assets and Liabilities - Additional Information (Details) $ in Millions	Sep. 30, 2017USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense (revenue), 2017	$ (3)
Amortization expense (revenue), 2018	11
Amortization expense (revenue), 2019	17
Amortization expense (revenue), 2020	4
Amortization expense (revenue), 2021	$ (1)

Debt - Schedule of Long-term De

Debt - Schedule of Long-term Debt (Details) - USD ($)	Sep. 30, 2017	Aug. 21, 2017	Aug. 01, 2017	Apr. 18, 2017	Feb. 02, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Carrying amount	$ 8,944,000,000					$ 9,099,000,000
Unamortized debt discounts and issuance costs	(197,000,000)					(120,000,000)
Total Debt	8,747,000,000					8,979,000,000
Less: Current maturities, including unamortized debt discounts and issuance costs, net	99,000,000					201,000,000
Debt, long-term portion, net	8,648,000,000					8,778,000,000
Forward capacity agreement
Debt Instrument [Line Items]
Carrying amount	241,000,000
Term Facilities Tranche C-1 | Reported Value Measurement
Debt Instrument [Line Items]
Debt instrument, face amount						2,000,000,000
Secured Debt
Debt Instrument [Line Items]
Carrying amount	2,607,000,000					2,572,000,000
Secured Debt | Tranche C-1 Term Loan, due 2024
Debt Instrument [Line Items]
Carrying amount	2,018,000,000					2,000,000,000
Secured Debt | Tranche B-2 Term Loan, Due 2020
Debt Instrument [Line Items]
Carrying amount	0					224,000,000
Secured Debt | Revolving Facility
Debt Instrument [Line Items]
Carrying amount	300,000,000					0
Secured Debt | Forward capacity agreement
Debt Instrument [Line Items]
Carrying amount	241,000,000					219,000,000
Secured Debt | Inventory financing agreements
Debt Instrument [Line Items]
Carrying amount	48,000,000					129,000,000
Unsecured Debt
Debt Instrument [Line Items]
Carrying amount	6,337,000,000					6,527,000,000
Unsecured Debt | 7.00% Amortizing Notes, due 2019 (TEUs)
Debt Instrument [Line Items]
Carrying amount	$ 60,000,000					80,000,000
Stated interest rate	7.00%
Unsecured Debt | 6.75% Senior Notes, due 2019
Debt Instrument [Line Items]
Carrying amount	$ 850,000,000					2,100,000,000
Stated interest rate		6.75%
Unsecured Debt | 7.375% Senior Notes, due 2022
Debt Instrument [Line Items]
Carrying amount	$ 1,750,000,000					1,750,000,000
Stated interest rate	7.375%
Unsecured Debt | 5.875% Senior Notes, due 2023
Debt Instrument [Line Items]
Carrying amount	$ 500,000,000					500,000,000
Stated interest rate	5.875%
Unsecured Debt | 7.625% Senior Notes, due 2024
Debt Instrument [Line Items]
Carrying amount	$ 1,250,000,000					1,250,000,000
Stated interest rate	7.625%
Unsecured Debt | 8.034% Senior Notes, due 2024
Debt Instrument [Line Items]
Carrying amount	$ 188,000,000		$ 4,000,000	$ 3,000,000	$ 182,000,000	0
Stated interest rate	8.034%
Unsecured Debt | 8.00% Senior Notes, due 2025
Debt Instrument [Line Items]
Carrying amount	$ 750,000,000					750,000,000
Stated interest rate	8.00%
Unsecured Debt | 8.125% Senior Notes, due 2026
Debt Instrument [Line Items]
Carrying amount	$ 850,000,000	$ 850,000,000				0
Stated interest rate		8.125%
Unsecured Debt | Equipment financing agreements
Debt Instrument [Line Items]
Carrying amount	$ 139,000,000					$ 97,000,000

Debt - Narratives (Details)

Debt - Narratives (Details)	Aug. 22, 2017USD ($)	Aug. 21, 2017USD ($)	Jul. 07, 2017USD ($)	Mar. 29, 2017USD ($)	Jun. 21, 2016USD ($)	Feb. 28, 2017USD ($)	Sep. 30, 2017USD ($)extension	Mar. 31, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)extension	Sep. 30, 2016USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	May 31, 2017USD ($)	Jan. 10, 2017USD ($)	Dec. 31, 2016USD ($)	Aug. 31, 2015USD ($)agreement
Debt Instrument [Line Items]
Loss on early extinguishment of debt							$ 66,000,000		$ 0	$ 75,000,000	$ 0
Debt to consolidated adjusted EBITDA ratio										4
Carrying amount							8,944,000,000			$ 8,944,000,000							$ 9,099,000,000
RGGI Repurchase Agreement
Debt Instrument [Line Items]
Number of repurchase agreements | agreement																		2
Assets sold under agreements to repurchase, carrying amount							$ 48,000,000			$ 48,000,000								$ 78,000,000
Assets sold under agreements to repurchase, repurchases						$ 30,000,000
Assets sold under agreements to repurchase, carry rate																		3.49%
Amortizing Note
Debt Instrument [Line Items]
Gross proceeds					$ 87,000,000
Tangible Equity Units
Debt Instrument [Line Items]
Stated interest rate					7.00%
Senior Notes
Debt Instrument [Line Items]
Borrowed money maximum, percent of total assets							30.00%			30.00%
Unsecured Debt
Debt Instrument [Line Items]
Carrying amount							$ 6,337,000,000			$ 6,337,000,000							6,527,000,000
Interest rate swaps
Debt Instrument [Line Items]
Derivative, notional amount															$ 1,200,000,000
Derivative, average fixed interest rate (as a percentage)															1.97%
Term Facilities and Revolving Facility, (The Credit Agreement)
Debt Instrument [Line Items]
Maximum borrowing capacity							3,769,000,000			3,769,000,000
Term Facilities Tranche C-1
Debt Instrument [Line Items]
Maximum borrowing capacity							2,224,000,000			$ 2,224,000,000
Debt instrument term (in years)										7 years
Loss on early extinguishment of debt							8,000,000	$ 9,000,000		$ 8,000,000
Write off of deferred debt issuance cost							6,000,000	7,000,000		6,000,000
Write-off of unamortized debt discount							2,000,000	2,000,000		2,000,000
Extinguishment of debt, amount	$ 200,000,000
Line of Credit | Revolving Facility
Debt Instrument [Line Items]
Maximum borrowing capacity							1,545,000,000			1,545,000,000
Line of credit facility, amount outstanding							$ 300,000,000			$ 300,000,000
Usage percentage							39.00%			39.00%
Revolving Credit Facility, Tranche B
Debt Instrument [Line Items]
Line of credit facility, amount outstanding																$ 45,000,000
Revolver Tranche due 2021 | Revolving Facility
Debt Instrument [Line Items]
Maximum borrowing capacity																$ 450,000,000
Tranche C Term Loan, Due 2024
Debt Instrument [Line Items]
Interest rate decrease										0.75%
Letter of Credit
Debt Instrument [Line Items]
Letters of credit outstanding, amount							$ 55,000,000			$ 55,000,000
Letter of Credit | Revolving Facility
Debt Instrument [Line Items]
Letters of credit outstanding, amount							310,000,000			310,000,000
Term Facilities Tranche B-2 | Interest rate swaps
Debt Instrument [Line Items]
Derivative, notional amount								$ 763,000,000
Derivative, average fixed interest rate (as a percentage)								3.03%
8.125% Senior Notes, due 2026 | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount		$ 850,000,000					850,000,000			850,000,000							0
Stated interest rate		8.125%
6.75% Senior Notes, due 2019 | Unsecured Debt
Debt Instrument [Line Items]
Loss on early extinguishment of debt							58,000,000			58,000,000
Write off of deferred debt issuance cost							8,000,000
Write-off of unamortized debt discount										8,000,000
Extinguishment of debt, amount		$ 1,250,000,000
Carrying amount							850,000,000			850,000,000							2,100,000,000
Stated interest rate		6.75%
Write off of premiums							(44,000,000)
Debt extinguishment fees							6,000,000			6,000,000
Amortization of debt premium										44,000,000
Letter of Credit Reimbursement Agreement | Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity							50,000,000			50,000,000
Letters of credit outstanding, amount							$ 40,000,000			$ 40,000,000
Number of discretionary extensions, maximum | extension							4			4
Expiration period, optional extension										1 year
Forward capacity agreement
Debt Instrument [Line Items]
Carrying amount							$ 241,000,000			$ 241,000,000
Effective interest rate							4.90%			4.90%
Repayments of debt			$ 99,000,000	$ 110,000,000
Forward capacity agreement | Forecasted repayments
Debt Instrument [Line Items]
Repayments of debt												$ 110,000,000	$ 121,000,000	$ 109,000,000
Equipment financing agreements
Debt Instrument [Line Items]
Unamortized discount							$ 27,000,000			$ 27,000,000
Equipment financing agreements | Carrying Amount
Debt Instrument [Line Items]
Net present value of the payments							112,000,000			112,000,000
Equipment financing agreements | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount							$ 139,000,000			$ 139,000,000							$ 97,000,000

Commitments and Contingencies -

Commitments and Contingencies - Legal Proceedings (Details) - Pending Litigation $ in Millions	Sep. 30, 2017state	Sep. 30, 2016USD ($)
Gas Index Pricing Litigation
Loss Contingencies [Line Items]
Number of States with pending litigation | state	3
Advatech Dispute
Loss Contingencies [Line Items]
Estimate of possible loss		$ 81
Contested invoice amount (less than)		$ 1

Commitments and Contingencies77

Commitments and Contingencies - Other Commitments and Contingencies (Details)	12 Months Ended
	Dec. 31, 2012surface_impoundment	May 31, 2015complaint
Vermillion Facility, Old East and North Sites
Loss Contingencies [Line Items]
Number of localized areas where groundwater standards were exceeded | surface_impoundment	2
MISO 2015-2016 Planning Resource Auction
Loss Contingencies [Line Items]
Number of complaints		3
MISO 2015-2016 Planning Resource Auction | Pending Litigation
Loss Contingencies [Line Items]
Number of complaints		1

Commitments and Contingencies78

Commitments and Contingencies - Indemnifications and Guarantees (Details)	Sep. 30, 2017USD ($)
LS Power Indemnities
Loss Contingencies [Line Items]
Number of claims and amount of accrued indemnifications, if any	$ 0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating Loss Carryforwards [Line Items]
Expected refund of AMT credits previously subject to a valuation allowance	$ 2		$ 0	$ 9	$ 0
Release of valuation allowance for OCI transactions that impacted deferred income taxes	(1)		0	4	0
Valuation allowance release as a result of the 2017 ENGIE Acquisition and the 2016 EquiPower Acquisition	0		0	317	3
Other state taxes	0		1	0	(9)
Income tax benefit (expense)	$ 1		$ 1	$ 330	$ (6)
Engie Acquisition
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, increase resulting from acquisition		$ 66
Unrecognized tax benefits		$ 66

Pension and Other Post-Employ80

Pension and Other Post-Employment Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Interest crediting rate		4.00%
Gain recognized in OCI from remeasurement		$ 15
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost benefits earned during period	$ 4		$ 4	$ 13	$ 12
Interest cost on projected benefit obligation	5		5	15	15
Expected return on plan assets	(6)		(5)	(19)	(17)
Amortization of prior service credit	(1)		(1)	(2)	(1)
Net periodic benefit cost (gain)	2		3	7	9
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost benefits earned during period	0		0	0	0
Interest cost on projected benefit obligation	0		1	1	3
Expected return on plan assets	0		(1)	(1)	(3)
Amortization of prior service credit	(1)		(1)	(4)	(3)
Net periodic benefit cost (gain)	$ (1)		$ (1)	$ (4)	$ (3)

Stockholders' Equity - Stockhol

Stockholders' Equity - Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Nov. 01, 2017	Oct. 02, 2017	Feb. 07, 2017	Feb. 24, 2016	Sep. 30, 2017	Sep. 30, 2016
Class of Stock [Line Items]
Payments of dividends					$ 16	$ 16
Payment for contingent consideration liability, financing activities					375	0
Minimum
Class of Stock [Line Items]
Payment for contingent consideration liability, financing activities			$ 375
Subsequent Event
Class of Stock [Line Items]
Preferred stock conversion ratio (in shares)	3.2258
Shares issued in conversion (in shares)	12,900,000
Number of uncalled shares expired (in shares)		15,606,936
Warrants, exercise price (in dollars per share)		$ 40
Term of warrant (in years)		5 years
Convertible preferred stock
Class of Stock [Line Items]
Dividends					$ 16	$ 16
Convertible preferred stock | Subsequent Event
Class of Stock [Line Items]
Dividends		$ 5
Dividends (in dollars per share)	$ 1.34
Dividends per share, declared (in dollars per share)		$ 1.34
Payments of dividends	$ 5
Common Stock | PIPE Stock Purchase Agreement | Parent
Class of Stock [Line Items]
Stock issued during the period for acquisitions (in shares)				13,711,152
Stock issued during the period, value				$ 150

Stockholders' Equity - Shares U

Stockholders' Equity - Shares Used in Basic and Diluted Loss per Share Calculations (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares outstanding at the beginning of the period (in shares)					154,000,000	140,000,000	140,000,000	117,000,000
Prepaid stock purchase contract (TEUs) (in shares)	0	0	0	9,000,000
Basic weighted-average shares outstanding (in shares)	154,000,000	140,000,000	152,000,000	126,000,000
Dilution from potentially dilutive shares (in shares)	0	0	7,000,000	0
Diluted weighted-average shares outstanding (in shares)	154,000,000	140,000,000	159,000,000	126,000,000
TEU settlement, shares outstanding (in shares)	23,092,460	23,092,460	23,092,460	23,092,460
TEU settlement, additional number of shares (in shares)	5,425,700		5,425,700
TEU settlement, maximum number of shares (in shares)	28,518,160		28,518,160
Restricted stock units and performance stock units (in shares)			1,279,515
PIPE
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issued (in shares)	0	0	11,000,000	0
Stock Compensation Plan
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issued (in shares)	0	0	1,000,000	0

Stockholders' Equity - Anti-Dil

Stockholders' Equity - Anti-Dilutive Shares - Potentially Dilutive in the Future (Details) - shares	Nov. 01, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Oct. 02, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		50,000,000	39,200,000	40,300,000	39,200,000
Subsequent Event
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of uncalled shares expired (in shares)						15,606,936
Shares issued in conversion (in shares)	12,900,000
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		4,200,000	2,800,000	2,800,000	2,800,000
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		1,300,000	1,300,000	0	1,300,000
Performance stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		1,600,000	1,200,000	0	1,200,000
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		24,600,000	15,600,000	24,600,000	15,600,000
Series A 5.375% mandatory convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		12,900,000	12,900,000	12,900,000	12,900,000
Series A 5.375% mandatory convertible preferred stock | Series A Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred stock dividend rate				5.375%
Prepaid stock purchase contract (TEUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		5,400,000	5,400,000	0	5,400,000

Stockholders' Equity - Accumula

Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Amounts reclassified from accumulated other comprehensive income:
Beginning of period			$ 2,039
Actuarial gain and plan amendments (net of tax of $4 and zero, respectively)			11	$ 0
Amortization of unrecognized prior service credit (net of tax of zero and zero, respectively) (1)			(6)	(4)
Other comprehensive income (loss), net of tax	$ (2)	$ (2)	5	(4)
End of period	1,984		1,984
AOCI Including Portion Attributable to Noncontrolling Interest
Amounts reclassified from accumulated other comprehensive income:
Beginning of period			21	19
End of period	26	15	26	15
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest
Amounts reclassified from accumulated other comprehensive income:
AOCI, tax	4	0	4	0
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Including Portion Attributable to Noncontrolling Interest
Amounts reclassified from accumulated other comprehensive income:
AOCI, tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidating Finan85

Condensed Consolidating Financial Information - Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Current Assets
Cash and cash equivalents	$ 613	$ 1,776	$ 1,458
Restricted cash	0	62	85
Accounts receivable, net	478	386
Inventory	429	445
Other current assets	184	318
Total Current Assets	1,704	2,987
Property, plant and equipment, net	8,929	7,121
Investment in affiliates	0	0
Restricted cash	0	2,000	2,000
Investment in unconsolidated affiliate	154	0
Goodwill	772	799
Assets held-for-sale	181	0
Other long-term assets	267	146
Intercompany note receivable	0	0
Total Assets	12,007	13,053	$ 13,024
Current Liabilities
Accounts payable	288	332
Other current liabilities	579	584
Total Current Liabilities	867	916
Liabilities subject to compromise (Note 18)	0	832
Debt, long-term portion, net	8,648	8,778
Intercompany note payable	0	0
Other long-term liabilities	508	488
Total Liabilities	10,023	11,014
Stockholders’ Equity
Dynegy Stockholders’ Equity	1,989	2,042
Intercompany note receivable	0	0
Total Dynegy Stockholders’ Equity	1,989	2,042
Noncontrolling interest	(5)	(3)
Total Equity	1,984	2,039
Total Liabilities and Equity	12,007	13,053
Eliminations
Current Assets
Cash and cash equivalents	0	0
Restricted cash		0
Accounts receivable, net	(3,681)	(2,398)
Inventory	0	0
Other current assets	(91)	(104)
Total Current Assets	(3,772)	(2,502)
Property, plant and equipment, net	0	0
Investment in affiliates	(16,462)	(12,175)
Restricted cash		0
Investment in unconsolidated affiliate	0
Goodwill	0	0
Assets held-for-sale	0
Other long-term assets	0	0
Intercompany note receivable	(46)	(8)
Total Assets	(20,280)	(14,685)
Current Liabilities
Accounts payable	(3,681)	(2,398)
Other current liabilities	(91)	(104)
Total Current Liabilities	(3,772)	(2,502)
Liabilities subject to compromise (Note 18)		0
Debt, long-term portion, net	0	0
Intercompany note payable	(3,088)	(3,042)
Other long-term liabilities	0	(8)
Total Liabilities	(6,860)	(5,552)
Stockholders’ Equity
Dynegy Stockholders’ Equity	(16,462)	(12,175)
Intercompany note receivable	3,042	3,042
Total Dynegy Stockholders’ Equity	(13,420)	(9,133)
Noncontrolling interest	0	0
Total Equity	(13,420)	(9,133)
Total Liabilities and Equity	(20,280)	(14,685)
Parent | Reportable Legal Entities
Current Assets
Cash and cash equivalents	354	1,529
Restricted cash		21
Accounts receivable, net	157	141
Inventory	0	0
Other current assets	8	12
Total Current Assets	519	1,703
Property, plant and equipment, net	0	0
Investment in affiliates	16,462	12,175
Restricted cash		2,000
Investment in unconsolidated affiliate	0
Goodwill	0	0
Assets held-for-sale	0
Other long-term assets	17	2
Intercompany note receivable	46	0
Total Assets	17,044	15,880
Current Liabilities
Accounts payable	3,310	1,990
Other current liabilities	226	143
Total Current Liabilities	3,536	2,133
Liabilities subject to compromise (Note 18)		0
Debt, long-term portion, net	8,347	8,531
Intercompany note payable	3,042	3,042
Other long-term liabilities	130	132
Total Liabilities	15,055	13,838
Stockholders’ Equity
Dynegy Stockholders’ Equity	1,989	2,042
Intercompany note receivable	0	0
Total Dynegy Stockholders’ Equity	1,989	2,042
Noncontrolling interest	0	0
Total Equity	1,989	2,042
Total Liabilities and Equity	17,044	15,880
Guarantor Subsidiaries | Reportable Legal Entities
Current Assets
Cash and cash equivalents	252	221
Restricted cash		41
Accounts receivable, net	3,990	2,604
Inventory	388	326
Other current assets	265	408
Total Current Assets	4,895	3,600
Property, plant and equipment, net	8,621	6,772
Investment in affiliates	0	0
Restricted cash		0
Investment in unconsolidated affiliate	154
Goodwill	772	799
Assets held-for-sale	181
Other long-term assets	214	109
Intercompany note receivable	0	8
Total Assets	14,837	11,288
Current Liabilities
Accounts payable	426	443
Other current liabilities	342	377
Total Current Liabilities	768	820
Liabilities subject to compromise (Note 18)		832
Debt, long-term portion, net	268	216
Intercompany note payable	46	0
Other long-term liabilities	331	313
Total Liabilities	1,413	2,181
Stockholders’ Equity
Dynegy Stockholders’ Equity	16,471	12,152
Intercompany note receivable	(3,042)	(3,042)
Total Dynegy Stockholders’ Equity	13,429	9,110
Noncontrolling interest	(5)	(3)
Total Equity	13,424	9,107
Total Liabilities and Equity	14,837	11,288
Non-Guarantor Subsidiaries | Reportable Legal Entities
Current Assets
Cash and cash equivalents	7	26
Restricted cash		0
Accounts receivable, net	12	39
Inventory	41	119
Other current assets	2	2
Total Current Assets	62	186
Property, plant and equipment, net	308	349
Investment in affiliates	0	0
Restricted cash		0
Investment in unconsolidated affiliate	0
Goodwill	0	0
Assets held-for-sale	0
Other long-term assets	36	35
Intercompany note receivable	0	0
Total Assets	406	570
Current Liabilities
Accounts payable	233	297
Other current liabilities	102	168
Total Current Liabilities	335	465
Liabilities subject to compromise (Note 18)		0
Debt, long-term portion, net	33	31
Intercompany note payable	0	0
Other long-term liabilities	47	51
Total Liabilities	415	547
Stockholders’ Equity
Dynegy Stockholders’ Equity	(9)	23
Intercompany note receivable	0	0
Total Dynegy Stockholders’ Equity	(9)	23
Noncontrolling interest	0	0
Total Equity	(9)	23
Total Liabilities and Equity	$ 406	$ 570

Condensed Consolidating Finan86

Condensed Consolidating Financial Information - Operations (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 1,437,000,000	$ 1,184,000,000	$ 3,848,000,000	$ 3,211,000,000
Cost of sales, excluding depreciation expense	(787,000,000)	(660,000,000)	(2,225,000,000)	(1,698,000,000)
Gross margin	650,000,000	524,000,000	1,623,000,000	1,513,000,000
Operating and maintenance expense	(236,000,000)	(218,000,000)	(750,000,000)	(695,000,000)
Depreciation expense	(202,000,000)	(163,000,000)	(611,000,000)	(494,000,000)
Impairments	(29,000,000)	(212,000,000)	(148,000,000)	(857,000,000)
Loss on sale of assets, net	(78,000,000)	0	(107,000,000)	0
General and administrative expense	(44,000,000)	(41,000,000)	(126,000,000)	(117,000,000)
Acquisition and integration costs	(3,000,000)	(7,000,000)	(55,000,000)	(8,000,000)
Other	0	0	1,000,000	(16,000,000)
Operating income (loss)	58,000,000	(117,000,000)	(173,000,000)	(674,000,000)
Bankruptcy reorganization items (Note 18)	12,000,000	0	494,000,000	0
Earnings from unconsolidated investments	4,000,000	4,000,000	4,000,000	7,000,000
Equity in earnings from investments in affiliates	0	0	0	0
Interest expense	(161,000,000)	(166,000,000)	(478,000,000)	(449,000,000)
Loss on early extinguishment of debt	(66,000,000)	0	(75,000,000)	0
Other income and expense, net	19,000,000	29,000,000	65,000,000	60,000,000
Loss before income taxes	(134,000,000)	(250,000,000)	(163,000,000)	(1,056,000,000)
Income tax benefit	1,000,000	1,000,000	330,000,000	(6,000,000)
Net income (loss)	(133,000,000)	(249,000,000)	167,000,000	(1,062,000,000)
Less: Net loss attributable to noncontrolling interest	(1,000,000)	0	(2,000,000)	(2,000,000)
Net income (loss) attributable to Dynegy Inc.	(132,000,000)	(249,000,000)	169,000,000	(1,060,000,000)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Revenues	(27,000,000)	(26,000,000)	(110,000,000)	(65,000,000)
Cost of sales, excluding depreciation expense	27,000,000	26,000,000	110,000,000	65,000,000
Gross margin	0	0	0	0
Operating and maintenance expense	0	0	0	0
Depreciation expense	0	0	0	0
Impairments	0	0	0	0
Loss on sale of assets, net	0		0
General and administrative expense	0	0	0	0
Acquisition and integration costs	0	0	0	0
Other	0	0	0	0
Operating income (loss)	0	0	0	0
Bankruptcy reorganization items (Note 18)	0		0
Earnings from unconsolidated investments	0	0	0	0
Equity in earnings from investments in affiliates	(78,000,000)	136,000,000	(730,000,000)	693,000,000
Interest expense	3,000,000	1,000,000	10,000,000	4,000,000
Loss on early extinguishment of debt	0		0
Other income and expense, net	(3,000,000)	(1,000,000)	(10,000,000)	(4,000,000)
Loss before income taxes	(78,000,000)	136,000,000	(730,000,000)	693,000,000
Income tax benefit	0	0	0	0
Net income (loss)	(78,000,000)	136,000,000	(730,000,000)	693,000,000
Less: Net loss attributable to noncontrolling interest	0		0	0
Net income (loss) attributable to Dynegy Inc.	(78,000,000)	136,000,000	(730,000,000)	693,000,000
Parent | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Revenues	0	0	0	0
Cost of sales, excluding depreciation expense	0	0	0	0
Gross margin	0	0	0	0
Operating and maintenance expense	0	0	0	0
Depreciation expense	0	0	0	0
Impairments	0	0	0	0
Loss on sale of assets, net	0		0
General and administrative expense	8,000,000	(2,000,000)	0	(5,000,000)
Acquisition and integration costs	0	(5,000,000)	(51,000,000)	(8,000,000)
Other	0	0	0	0
Operating income (loss)	8,000,000	(7,000,000)	(51,000,000)	(13,000,000)
Bankruptcy reorganization items (Note 18)	0		0
Earnings from unconsolidated investments	0	0	0	0
Equity in earnings from investments in affiliates	78,000,000	(136,000,000)	730,000,000	(693,000,000)
Interest expense	(155,000,000)	(138,000,000)	(461,000,000)	(382,000,000)
Loss on early extinguishment of debt	(66,000,000)		(75,000,000)
Other income and expense, net	3,000,000	25,000,000	26,000,000	28,000,000
Loss before income taxes	(132,000,000)	(256,000,000)	169,000,000	(1,060,000,000)
Income tax benefit	0	7,000,000	0	0
Net income (loss)	(132,000,000)	(249,000,000)	169,000,000	(1,060,000,000)
Less: Net loss attributable to noncontrolling interest	0		0	0
Net income (loss) attributable to Dynegy Inc.	(132,000,000)	(249,000,000)	169,000,000	(1,060,000,000)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Revenues	1,380,000,000	1,082,000,000	3,616,000,000	2,921,000,000
Cost of sales, excluding depreciation expense	(760,000,000)	(609,000,000)	(2,108,000,000)	(1,570,000,000)
Gross margin	620,000,000	473,000,000	1,508,000,000	1,351,000,000
Operating and maintenance expense	(209,000,000)	(189,000,000)	(660,000,000)	(595,000,000)
Depreciation expense	(193,000,000)	(146,000,000)	(567,000,000)	(436,000,000)
Impairments	(29,000,000)	(212,000,000)	(148,000,000)	(857,000,000)
Loss on sale of assets, net	(78,000,000)		(108,000,000)
General and administrative expense	(50,000,000)	(38,000,000)	(121,000,000)	(108,000,000)
Acquisition and integration costs	(3,000,000)	(2,000,000)	(4,000,000)	0
Other	0	(1,000,000)	1,000,000	(9,000,000)
Operating income (loss)	58,000,000	(115,000,000)	(99,000,000)	(654,000,000)
Bankruptcy reorganization items (Note 18)	12,000,000		494,000,000
Earnings from unconsolidated investments	4,000,000	4,000,000	4,000,000	7,000,000
Equity in earnings from investments in affiliates	0	0	0	0
Interest expense	(6,000,000)	(27,000,000)	(18,000,000)	(65,000,000)
Loss on early extinguishment of debt	0		0
Other income and expense, net	19,000,000	5,000,000	49,000,000	36,000,000
Loss before income taxes	87,000,000	(133,000,000)	430,000,000	(676,000,000)
Income tax benefit	1,000,000	(6,000,000)	330,000,000	(6,000,000)
Net income (loss)	88,000,000	(139,000,000)	760,000,000	(682,000,000)
Less: Net loss attributable to noncontrolling interest	(1,000,000)		(2,000,000)	(2,000,000)
Net income (loss) attributable to Dynegy Inc.	89,000,000	(139,000,000)	762,000,000	(680,000,000)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Revenues	84,000,000	128,000,000	342,000,000	355,000,000
Cost of sales, excluding depreciation expense	(54,000,000)	(77,000,000)	(227,000,000)	(193,000,000)
Gross margin	30,000,000	51,000,000	115,000,000	162,000,000
Operating and maintenance expense	(27,000,000)	(29,000,000)	(90,000,000)	(100,000,000)
Depreciation expense	(9,000,000)	(17,000,000)	(44,000,000)	(58,000,000)
Impairments	0	0	0	0
Loss on sale of assets, net	0		1,000,000
General and administrative expense	(2,000,000)	(1,000,000)	(5,000,000)	(4,000,000)
Acquisition and integration costs	0	0	0	0
Other	0	1,000,000	0	(7,000,000)
Operating income (loss)	(8,000,000)	5,000,000	(23,000,000)	(7,000,000)
Bankruptcy reorganization items (Note 18)	0		0
Earnings from unconsolidated investments	0	0	0	0
Equity in earnings from investments in affiliates	0	0	0	0
Interest expense	(3,000,000)	(2,000,000)	(9,000,000)	(6,000,000)
Loss on early extinguishment of debt	0		0
Other income and expense, net	0	0	0	0
Loss before income taxes	(11,000,000)	3,000,000	(32,000,000)	(13,000,000)
Income tax benefit	0	0	0	0
Net income (loss)	(11,000,000)	3,000,000	(32,000,000)	(13,000,000)
Less: Net loss attributable to noncontrolling interest	0		0	0
Net income (loss) attributable to Dynegy Inc.	$ (11,000,000)	$ 3,000,000	$ (32,000,000)	$ (13,000,000)

Condensed Consolidating Finan87

Condensed Consolidating Financial Information - Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ (133)	$ (249)	$ 167	$ (1,062)
Actuarial gain and plan amendment (net of tax of zero, zero, $4, and zero for each respective period)	0	0	11	0
Amortization of unrecognized prior service credit (net of tax of zero for each respective period)	(2)	(2)	(6)	(4)
Other Comprehensive Income (Loss) From Subsidiaries, Net of Tax		0	0	0
Other comprehensive income (loss), net of tax	(2)	(2)	5	(4)
Comprehensive income (loss)	(135)	(251)	172	(1,066)
Comprehensive income (loss) attributable to noncontrolling interest	(1)	0	(2)	(2)
Total comprehensive income (loss) attributable to Dynegy Inc.	(134)	(251)	174	(1,064)
Tax on actuarial loss	0	0	4	0
Tax on amortization of unrecognized prior service cost (credit) and actuarial loss (gain)	0	0	0	0
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(78)	136	(730)	693
Actuarial gain and plan amendment (net of tax of zero, zero, $4, and zero for each respective period)	0		0
Amortization of unrecognized prior service credit (net of tax of zero for each respective period)	0	0	0	0
Other Comprehensive Income (Loss) From Subsidiaries, Net of Tax		1	1	1
Other comprehensive income (loss), net of tax	0	1	1	1
Comprehensive income (loss)	(78)	137	(729)	694
Comprehensive income (loss) attributable to noncontrolling interest	0	0	0	0
Total comprehensive income (loss) attributable to Dynegy Inc.	(78)	137	(729)	694
Parent | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(132)	(249)	169	(1,060)
Actuarial gain and plan amendment (net of tax of zero, zero, $4, and zero for each respective period)	0		11
Amortization of unrecognized prior service credit (net of tax of zero for each respective period)	(2)	(1)	(5)	(3)
Other Comprehensive Income (Loss) From Subsidiaries, Net of Tax		(1)	(1)	(1)
Other comprehensive income (loss), net of tax	(2)	(2)	5	(4)
Comprehensive income (loss)	(134)	(251)	174	(1,064)
Comprehensive income (loss) attributable to noncontrolling interest	0	0	0	0
Total comprehensive income (loss) attributable to Dynegy Inc.	(134)	(251)	174	(1,064)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	88	(139)	760	(682)
Actuarial gain and plan amendment (net of tax of zero, zero, $4, and zero for each respective period)	0		0
Amortization of unrecognized prior service credit (net of tax of zero for each respective period)	0	(1)	0	(1)
Other Comprehensive Income (Loss) From Subsidiaries, Net of Tax		0	0	0
Other comprehensive income (loss), net of tax	0	(1)	0	(1)
Comprehensive income (loss)	88	(140)	760	(683)
Comprehensive income (loss) attributable to noncontrolling interest	(1)	0	(2)	(2)
Total comprehensive income (loss) attributable to Dynegy Inc.	89	(140)	762	(681)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(11)	3	(32)	(13)
Actuarial gain and plan amendment (net of tax of zero, zero, $4, and zero for each respective period)	0		0
Amortization of unrecognized prior service credit (net of tax of zero for each respective period)	0	0	(1)	0
Other Comprehensive Income (Loss) From Subsidiaries, Net of Tax		0	0	0
Other comprehensive income (loss), net of tax	0	0	(1)	0
Comprehensive income (loss)	(11)	3	(33)	(13)
Comprehensive income (loss) attributable to noncontrolling interest	0	0	0	0
Total comprehensive income (loss) attributable to Dynegy Inc.	$ (11)	$ 3	$ (33)	$ (13)

Condensed Consolidating Finan88

Condensed Consolidating Financial Information - Cash Flow (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	$ 501	$ 728
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(129)	(337)
Acquisitions, net of cash acquired	(3,249)	0
Distributions from unconsolidated investments	7	14
Net intercompany transfers	0	0
Other investing	0	10
Proceeds received from asset sales, net	600	0
Net cash used in investing activities	(2,771)	(313)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from long-term borrowings, net of debt issuance costs	1,747	2,277
Repayments of borrowings	(2,261)	(21)
Proceeds from issuance of equity, net of issuance costs	150	359
Payments of debt extinguishment costs	(50)	0
Preferred stock dividends paid	(16)	(16)
Interest rate swap settlement payments	(15)	(13)
Acquisition of noncontrolling interest	(375)	0
Payments related to bankruptcy settlement	(133)	0
Net intercompany transfers	0	0
Intercompany borrowings, net of repayments	0
Other financing	(2)	(2)
Net cash provided by (used in) financing activities	(955)	2,584
Net increase (decrease) in cash, cash equivalents and restricted cash	(3,225)	2,999
Cash, cash equivalents, and restricted cash beginning of period	3,838	544
Cash, cash equivalents, and restricted cash end of period	613	3,543
Eliminations
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	0	0
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	0	0
Acquisitions, net of cash acquired	0
Distributions from unconsolidated investments	0	0
Net intercompany transfers	(726)	(801)
Other investing		0
Proceeds received from asset sales, net	0
Net cash used in investing activities	(726)	(801)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from long-term borrowings, net of debt issuance costs	0	0
Repayments of borrowings	0	0
Proceeds from issuance of equity, net of issuance costs	0	0
Payments of debt extinguishment costs	0
Preferred stock dividends paid	0	0
Interest rate swap settlement payments	0	0
Acquisition of noncontrolling interest	0
Payments related to bankruptcy settlement	0
Net intercompany transfers	726	801
Intercompany borrowings, net of repayments	0
Other financing	0	0
Net cash provided by (used in) financing activities	726	801
Net increase (decrease) in cash, cash equivalents and restricted cash	0	0
Cash, cash equivalents, and restricted cash beginning of period	0	0
Cash, cash equivalents, and restricted cash end of period	0	0
Parent | Reportable Legal Entities
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	(455)	(236)
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	0	0
Acquisitions, net of cash acquired	(3,244)
Distributions from unconsolidated investments	0	0
Net intercompany transfers	726	801
Other investing		0
Proceeds received from asset sales, net	599
Net cash used in investing activities	(1,919)	801
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from long-term borrowings, net of debt issuance costs	1,747	2,079
Repayments of borrowings	(2,180)	(6)
Proceeds from issuance of equity, net of issuance costs	150	359
Payments of debt extinguishment costs	(50)
Preferred stock dividends paid	(16)	(16)
Interest rate swap settlement payments	(15)	(13)
Acquisition of noncontrolling interest	(375)
Payments related to bankruptcy settlement	(126)
Net intercompany transfers	0	0
Intercompany borrowings, net of repayments	45
Other financing	(2)	(2)
Net cash provided by (used in) financing activities	(822)	2,401
Net increase (decrease) in cash, cash equivalents and restricted cash	(3,196)	2,966
Cash, cash equivalents, and restricted cash beginning of period	3,550	327
Cash, cash equivalents, and restricted cash end of period	354	3,293
Guarantor Subsidiaries | Reportable Legal Entities
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	877	977
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(123)	(271)
Acquisitions, net of cash acquired	(5)
Distributions from unconsolidated investments	7	14
Net intercompany transfers	0	0
Other investing		10
Proceeds received from asset sales, net	0
Net cash used in investing activities	(121)	(247)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from long-term borrowings, net of debt issuance costs	0	198
Repayments of borrowings	(30)	(15)
Proceeds from issuance of equity, net of issuance costs	0	0
Payments of debt extinguishment costs	0
Preferred stock dividends paid	0	0
Interest rate swap settlement payments	0	0
Acquisition of noncontrolling interest	0
Payments related to bankruptcy settlement	(7)
Net intercompany transfers	(684)	(837)
Intercompany borrowings, net of repayments	(45)
Other financing	0	0
Net cash provided by (used in) financing activities	(766)	(654)
Net increase (decrease) in cash, cash equivalents and restricted cash	(10)	76
Cash, cash equivalents, and restricted cash beginning of period	262	133
Cash, cash equivalents, and restricted cash end of period	252	209
Non-Guarantor Subsidiaries | Reportable Legal Entities
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	79	(13)
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(6)	(66)
Acquisitions, net of cash acquired	0
Distributions from unconsolidated investments	0	0
Net intercompany transfers	0	0
Other investing		0
Proceeds received from asset sales, net	1
Net cash used in investing activities	(5)	(66)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from long-term borrowings, net of debt issuance costs	0	0
Repayments of borrowings	(51)	0
Proceeds from issuance of equity, net of issuance costs	0	0
Payments of debt extinguishment costs	0
Preferred stock dividends paid	0	0
Interest rate swap settlement payments	0	0
Acquisition of noncontrolling interest	0
Payments related to bankruptcy settlement	0
Net intercompany transfers	(42)	36
Intercompany borrowings, net of repayments	0
Other financing	0	0
Net cash provided by (used in) financing activities	(93)	36
Net increase (decrease) in cash, cash equivalents and restricted cash	(19)	(43)
Cash, cash equivalents, and restricted cash beginning of period	26	84
Cash, cash equivalents, and restricted cash end of period	$ 7	$ 41

Genco Chapter 11 Bankruptcy a89

Genco Chapter 11 Bankruptcy and Emergence - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Aug. 01, 2017	Apr. 18, 2017	Feb. 02, 2017	Jan. 25, 2017	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2016
Chapter 11 Reorganization [Line Items]
Carrying amount					$ 8,944	$ 8,944	$ 9,099
Gain on bankruptcy reorganization items					$ 12
Affiliate | Restructuring Support Agreement | Genco and Ad Hock Group of Shareholders
Chapter 11 Reorganization [Line Items]
Payments of debt restructuring costs	$ 6	$ 3	$ 113
Warrants and rights outstanding (in shares)	0.2	0.1	8.7
Warrants and rights outstanding	$ 1	$ 1	$ 17
Warrants, exercise price (in dollars per share)					$ 35	$ 35
Plan of reorganization, term of warrants (in years)						7 years
Affiliate | Restructuring Support Agreement | Genco and Ad Hock Group of Shareholders | Seven-year Unsecured Notes
Chapter 11 Reorganization [Line Items]
Debt instrument term (in years)	7 years	7 years	7 years
Senior Notes | Affiliate | Restructuring Support Agreement | Genco and Ad Hock Group of Shareholders
Chapter 11 Reorganization [Line Items]
Write-off of senior notes, amount				$ 825
Write-off of senior notes, accrued interest, amount				$ 7
Unsecured Debt
Chapter 11 Reorganization [Line Items]
Carrying amount					$ 6,337	$ 6,337	6,527
Unsecured Debt | 8.034% Senior Notes, due 2024
Chapter 11 Reorganization [Line Items]
Carrying amount	$ 4	$ 3	$ 182		$ 188	$ 188	$ 0

Genco Chapter 11 Bankruptcy a90

Genco Chapter 11 Bankruptcy and Emergence - Schedule of Reorganization Items (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reorganizations [Abstract]
Liabilities subject to compromise, which were terminated			$ 832
Seven-year unsecured notes			188
Cash consideration			122
2017 Warrants, at fair value			17
Legal and consulting fees			11
Bankruptcy reorganization items	$ 12	$ 0	$ 494	$ 0

Segment Information - Narrative

Segment Information - Narrative (Details)	9 Months Ended
	Sep. 30, 2017segment
Segment Reporting [Abstract]
Number of reportable segments	6

Segment Information - Reportabl

Segment Information - Reportable Segment Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Information
Unaffiliated revenues	$ 1,437,000,000	$ 1,168,000,000	$ 3,848,000,000	$ 3,184,000,000
Intercompany and affiliate revenues	0	16,000,000	0	27,000,000
Revenues	1,437,000,000	1,184,000,000	3,848,000,000	3,211,000,000
Depreciation expense	(202,000,000)	(163,000,000)	(611,000,000)	(494,000,000)
Impairments	(29,000,000)	(212,000,000)	(148,000,000)	(857,000,000)
Loss on sale of assets, net	(78,000,000)	0	(107,000,000)	0
General and administrative expense	(44,000,000)	(41,000,000)	(126,000,000)	(117,000,000)
Acquisition and integration costs	(3,000,000)	(7,000,000)	(55,000,000)	(8,000,000)
Operating income (loss)	58,000,000	(117,000,000)	(173,000,000)	(674,000,000)
Bankruptcy reorganization items (Note 18)	12,000,000	0	494,000,000	0
Earnings from unconsolidated investments	4,000,000	4,000,000	4,000,000	7,000,000
Interest expense	(161,000,000)	(166,000,000)	(478,000,000)	(449,000,000)
Loss on early extinguishment of debt	(66,000,000)	0	(75,000,000)	0
Other items, net	19,000,000	29,000,000	65,000,000	60,000,000
Loss before income taxes	(134,000,000)	(250,000,000)	(163,000,000)	(1,056,000,000)
Income tax benefit	1,000,000	1,000,000	330,000,000	(6,000,000)
Net income (loss)	(133,000,000)	(249,000,000)	167,000,000	(1,062,000,000)
Less: Net loss attributable to noncontrolling interest	(1,000,000)	0	(2,000,000)	(2,000,000)
Net income (loss) attributable to Dynegy Inc.	(132,000,000)	(249,000,000)	169,000,000	(1,060,000,000)
Identifiable assets (domestic)	12,007,000,000	13,024,000,000	12,007,000,000	13,024,000,000	$ 13,053,000,000
Investment in unconsolidated affiliate	154,000,000	173,000,000	154,000,000	173,000,000
Capital expenditures	(24,000,000)	(35,000,000)	(192,000,000)	(260,000,000)
Operating segments | PJM
Segment Information
Unaffiliated revenues	628,000,000	551,000,000	1,806,000,000	1,559,000,000
Intercompany and affiliate revenues	(25,000,000)	17,000,000	(47,000,000)	45,000,000
Revenues	603,000,000	568,000,000	1,759,000,000	1,604,000,000
Depreciation expense	(94,000,000)	(88,000,000)	(283,000,000)	(257,000,000)
Impairments	(29,000,000)	(64,000,000)	(49,000,000)	(64,000,000)
Loss on sale of assets, net	(1,000,000)		(31,000,000)
General and administrative expense	0	0	0	0
Acquisition and integration costs	0	0	0	0
Operating income (loss)	86,000,000	29,000,000	178,000,000	277,000,000
Bankruptcy reorganization items (Note 18)	0		0
Earnings from unconsolidated investments	2,000,000	4,000,000	2,000,000	7,000,000
Interest expense	0	0	0	0
Loss on early extinguishment of debt	0		0
Other items, net	16,000,000	3,000,000	16,000,000	9,000,000
Income tax benefit	0	0	0	0
Identifiable assets (domestic)	5,158,000,000	5,208,000,000	5,158,000,000	5,208,000,000
Investment in unconsolidated affiliate	77,000,000	173,000,000	77,000,000	173,000,000
Capital expenditures	(6,000,000)	(13,000,000)	(74,000,000)	(124,000,000)
Operating segments | NY/NE
Segment Information
Unaffiliated revenues	269,000,000	200,000,000	817,000,000	630,000,000
Intercompany and affiliate revenues	(1,000,000)	(5,000,000)	(2,000,000)	(2,000,000)
Revenues	268,000,000	195,000,000	815,000,000	628,000,000
Depreciation expense	(52,000,000)	(53,000,000)	(171,000,000)	(167,000,000)
Impairments	0	0	0	0
Loss on sale of assets, net	(77,000,000)		(77,000,000)
General and administrative expense	0	0	0	0
Acquisition and integration costs	0	0	0	0
Operating income (loss)	(30,000,000)	(15,000,000)	(72,000,000)	(22,000,000)
Bankruptcy reorganization items (Note 18)	0		0
Earnings from unconsolidated investments	2,000,000	0	2,000,000	0
Interest expense	0	0	0	0
Loss on early extinguishment of debt	0		0
Other items, net	0	0	0	0
Income tax benefit	0	0	0	0
Identifiable assets (domestic)	3,401,000,000	2,807,000,000	3,401,000,000	2,807,000,000
Investment in unconsolidated affiliate	77,000,000	0	77,000,000	0
Capital expenditures	(6,000,000)	(10,000,000)	(46,000,000)	(84,000,000)
Operating segments | ERCOT
Segment Information
Unaffiliated revenues	210,000,000		322,000,000
Intercompany and affiliate revenues	(1,000,000)		(1,000,000)
Revenues	209,000,000		321,000,000
Depreciation expense	(20,000,000)		(54,000,000)
Impairments	0		0
Loss on sale of assets, net	0		0
General and administrative expense	0		0
Acquisition and integration costs	0		0
Operating income (loss)	50,000,000		(8,000,000)
Bankruptcy reorganization items (Note 18)	0		0
Earnings from unconsolidated investments	0		0
Interest expense	0		0
Loss on early extinguishment of debt	0		0
Other items, net	0		0
Income tax benefit	0		0
Identifiable assets (domestic)	1,564,000,000		1,564,000,000
Investment in unconsolidated affiliate	0		0
Capital expenditures	(3,000,000)		(20,000,000)
Operating segments | MISO
Segment Information
Unaffiliated revenues	98,000,000	130,000,000	276,000,000	315,000,000
Intercompany and affiliate revenues	6,000,000	3,000,000	16,000,000	(15,000,000)
Revenues	104,000,000	133,000,000	292,000,000	300,000,000
Depreciation expense	(9,000,000)	(3,000,000)	(22,000,000)	(19,000,000)
Impairments	0	0	(99,000,000)	(645,000,000)
Loss on sale of assets, net	0		0
General and administrative expense	0	0	0	0
Acquisition and integration costs	0	0	0	0
Operating income (loss)	(9,000,000)	13,000,000	(90,000,000)	(703,000,000)
Bankruptcy reorganization items (Note 18)	0		0
Earnings from unconsolidated investments	0	0	0	0
Interest expense	0	0	0	0
Loss on early extinguishment of debt	0		0
Other items, net	0	0	0	0
Income tax benefit	0	0	0	0
Identifiable assets (domestic)	232,000,000	371,000,000	232,000,000	371,000,000
Investment in unconsolidated affiliate	0	0	0	0
Capital expenditures	0	(1,000,000)	(3,000,000)	(9,000,000)
Operating segments | IPH
Segment Information
Unaffiliated revenues	182,000,000	241,000,000	538,000,000	575,000,000
Intercompany and affiliate revenues	21,000,000	1,000,000	34,000,000	(1,000,000)
Revenues	203,000,000	242,000,000	572,000,000	574,000,000
Depreciation expense	(11,000,000)	(7,000,000)	(35,000,000)	(21,000,000)
Impairments	0	(148,000,000)	0	(148,000,000)
Loss on sale of assets, net	0		1,000,000
General and administrative expense	0	0	0	0
Acquisition and integration costs	0	0	0	8,000,000
Operating income (loss)	11,000,000	(104,000,000)	40,000,000	(87,000,000)
Bankruptcy reorganization items (Note 18)	12,000,000		494,000,000
Earnings from unconsolidated investments	0	0	0	0
Interest expense	0	0	0	0
Loss on early extinguishment of debt	0		0
Other items, net	0	1,000,000	26,000,000	15,000,000
Income tax benefit	0	0	0	0
Identifiable assets (domestic)	581,000,000	746,000,000	581,000,000	746,000,000
Investment in unconsolidated affiliate	0	0	0	0
Capital expenditures	(4,000,000)	(9,000,000)	(10,000,000)	(30,000,000)
Operating segments | CAISO
Segment Information
Unaffiliated revenues	50,000,000	46,000,000	89,000,000	105,000,000
Intercompany and affiliate revenues	0	0	0	0
Revenues	50,000,000	46,000,000	89,000,000	105,000,000
Depreciation expense	(14,000,000)	(11,000,000)	(40,000,000)	(26,000,000)
Impairments	0	0	0	0
Loss on sale of assets, net	0		0
General and administrative expense	0	0	0	0
Acquisition and integration costs	0	0	0	0
Operating income (loss)	0	10,000,000	(33,000,000)	0
Bankruptcy reorganization items (Note 18)	0		0
Earnings from unconsolidated investments	0	0	0	0
Interest expense	0	0	0	0
Loss on early extinguishment of debt	0		0
Other items, net	0	0	0	12,000,000
Income tax benefit	0	0	0	0
Identifiable assets (domestic)	461,000,000	499,000,000	461,000,000	499,000,000
Investment in unconsolidated affiliate	0	0	0	0
Capital expenditures	(3,000,000)	(1,000,000)	(34,000,000)	(4,000,000)
Other and Eliminations
Segment Information
Unaffiliated revenues	0	0	0	0
Intercompany and affiliate revenues	0	0	0	0
Revenues	0	0	0	0
Depreciation expense	(2,000,000)	(1,000,000)	(6,000,000)	(4,000,000)
Impairments	0	0	0	0
Loss on sale of assets, net	0		0
General and administrative expense	(44,000,000)	(41,000,000)	(126,000,000)	(117,000,000)
Acquisition and integration costs	(3,000,000)	(7,000,000)	(55,000,000)	(16,000,000)
Operating income (loss)	(50,000,000)	(50,000,000)	(188,000,000)	(139,000,000)
Bankruptcy reorganization items (Note 18)	0		0
Earnings from unconsolidated investments	0	0	0	0
Interest expense	(161,000,000)	166,000,000	(478,000,000)	(449,000,000)
Loss on early extinguishment of debt	(66,000,000)		(75,000,000)
Other items, net	3,000,000	25,000,000	23,000,000	24,000,000
Income tax benefit	1,000,000	1,000,000	330,000,000	(6,000,000)
Identifiable assets (domestic)	610,000,000	3,393,000,000	610,000,000	3,393,000,000
Investment in unconsolidated affiliate	0	0	0	0
Capital expenditures	$ (2,000,000)	$ (1,000,000)	$ (5,000,000)	$ (9,000,000)

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - Vistra Energy Merger	Oct. 29, 2017
Subsequent Event [Line Items]
Ratio of acquiring entity shares to be received	0.652
Vistra Energy Corp. | Vistra Energy Shareholders
Subsequent Event [Line Items]
Percentage of ownership after transaction	79.00%
Vistra Energy Corp. | Dynegy Shareholders
Subsequent Event [Line Items]
Percentage of ownership after transaction	21.00%