Southwestern Energy (SWN) 10-Q 29 Oct 20 2020 Q3 Quarterly report Financial data

COVER PAGE

COVER PAGE - shares	9 Months Ended
	Sep. 30, 2020	Oct. 27, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-08246
Entity Registrant Name	Southwestern Energy Company
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Central Index Key	0000007332
Current Fiscal Year End Date	--12-31
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	71-0205415
Entity Address, Address Line One	10000 Energy Drive
Entity Address, City or Town	Spring
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77389
City Area Code	832
Local Phone Number	796-1000
Title of 12(b) Security	Common Stock, Par Value $0.01
Trading Symbol	SWN
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		605,559,524

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating Revenues:
Total operating revenues	$ 527	$ 636	$ 1,529	$ 2,293
Operating Costs and Expenses:
Operating expenses	202	189	577	523
General and administrative expenses	31	42	89	119
Montage acquisition-related expenses	3	0	3	0
Restructuring charges	0	4	12	9
Loss on sale of operating assets	0	0	0	3
Depreciation, depletion and amortization	70	125	267	352
Impairments	361	2	2,495	8
Taxes, other than income taxes	15	15	38	51
Total operating costs and expense	908	665	4,156	2,087
Operating Income (Loss)	(381)	(29)	(2,627)	206
Interest Expense:
Interest on debt	43	42	123	125
Other interest charges	2	2	7	5
Interest capitalized	(23)	(27)	(67)	(84)
Total Interest Expense	22	17	63	46
Gain (Loss) on Derivatives	(192)	100	38	220
Gain on Early Extinguishment of Debt	0	7	35	7
Other Income (Loss), Net	2	(2)	3	(7)
Income (Loss) Before Income Taxes	(593)	59	(2,614)	380
Provision (Benefit) for Income Taxes:
Current	0	(1)	(2)	(1)
Deferred	0	11	408	(400)
Total Provision (Benefit) from Income Taxes	0	10	406	(401)
Net Income (Loss)	$ (593)	$ 49	$ (3,020)	$ 781
Earnings (Loss) Per Common Share:
Basic (in dollars per share)	$ (1.04)	$ 0.09	$ (5.48)	$ 1.45
Diluted (in dollars per share)	$ (1.04)	$ 0.09	$ (5.48)	$ 1.44
Weighted Average Common Shares Outstanding:
Basic (in shares)	571,872,413	539,221,101	551,162,559	539,315,170
Diluted (in shares)	571,872,413	540,038,187	551,162,559	540,442,649
Gas sales
Operating Revenues:
Total operating revenues	$ 199	$ 238	$ 611	$ 943
Oil sales
Operating Revenues:
Total operating revenues	40	67	111	153
NGL sales
Operating Revenues:
Total operating revenues	68	52	158	191
Marketing
Operating Revenues:
Total operating revenues	219	279	645	1,004
Other
Operating Revenues:
Total operating revenues	1	0	4	2
Marketing purchases
Operating Costs and Expenses:
Marketing purchases	$ 226	$ 288	$ 675	$ 1,022

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ (593)	$ 49	$ (3,020)	$ 781
Change in value of pension and other postretirement liabilities:
Amortization of prior service cost and net loss included in net periodic pension cost	[1]	1	1	1	5
Comprehensive income (loss)		$ (592)	$ 50	$ (3,019)	$ 786
[1]	Tax benefits for the three months ended September 30, 2020 were immaterial. Net of less than

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Defined benefit plan, tax	$ 1	$ 1	$ 2

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 95	$ 5
Accounts receivable, net	239	345
Derivative assets	238	278
Other current assets	41	51
Total current assets	613	679
Natural gas and oil properties, using the full cost method, including $1,379 million as of September 30, 2020 and $1,506 million as of December 31, 2019 excluded from amortization	25,969	25,250
Other	500	520
Less: Accumulated depreciation, depletion and amortization	(23,247)	(20,503)
Total property and equipment, net	3,222	5,267
Operating lease assets	145	159
Deferred tax assets	0	407
Other long-term assets	177	205
Total long-term assets	322	771
TOTAL ASSETS	4,157	6,717
Current liabilities:
Accounts payable	416	525
Taxes payable	47	59
Interest payable	56	51
Derivative liabilities	287	125
Current operating lease liabilities	33	34
Other current liabilities	30	54
Total current liabilities	869	848
Long-term debt	2,450	2,242
Long-term operating lease liabilities	107	119
Long-term derivative liabilities	188	111
Pension and other postretirement liabilities	35	43
Other long-term liabilities	124	108
Total long-term liabilities	2,904	2,623
Commitments and contingencies (Note 12)
Equity:
Common stock, $0.01 par value; 1,250,000,000 shares authorized; issued 649,899,653 shares as of September 30, 2020 and 585,555,923 shares as of December 31, 2019	7	6
Additional paid-in capital	4,882	4,726
Accumulated deficit	(4,271)	(1,251)
Accumulated other comprehensive loss	(32)	(33)
Common stock in treasury, 44,353,224 shares as of September 30, 2020 and December 31, 2019	(202)	(202)
Total equity	384	3,246
TOTAL LIABILITIES AND EQUITY	$ 4,157	$ 6,717

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Natural gas and oil properties, using the full cost method, costs excluded from amortization	$ 1,379	$ 1,506
Common stock, par value (in dollars per shares)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,250,000,000	1,250,000,000
Common stock, shares issued (in shares)	649,899,653	585,555,923
Treasury stock, shares (in shares)	44,353,224	44,353,224

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Cash Flows From Operating Activities:
Net income (loss)	$ (593)	$ 49	$ (3,020)	$ 781
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	70	125	267	352
Amortization of debt issuance costs			6	5
Impairments	361	2	2,495	8
Deferred income taxes	0	11	408	(400)
(Gain) loss on derivatives, unsettled			272	(108)
Stock-based compensation	0	2	2	6
Gain on early extinguishment of debt	0	(7)	(35)	(7)
Loss on sale of assets	0	0	0	3
Other			3	11
Change in assets and liabilities:
Accounts receivable			106	257
Accounts payable			(129)	(124)
Taxes payable			(12)	(3)
Interest payable			3	2
Inventories			3	(2)
Other assets and liabilities			38	(42)
Net cash provided by operating activities			407	739
Cash Flows From Investing Activities:
Capital investments			(700)	(877)
Proceeds from sale of property and equipment			2	42
Net cash used in investing activities			(698)	(835)
Cash Flows From Financing Activities:
Payments on long-term debt			(72)	(43)
Payments on revolving credit facility			(1,449)	0
Borrowings under revolving credit facility			1,415	0
Change in bank drafts outstanding			(9)	(11)
Proceeds from issuance of long-term debt			350	0
Debt issuance costs			(5)	0
Purchase of treasury stock			0	(21)
Proceeds from issuance of common stock, net			152	0
Cash paid for tax withholding			(1)	(1)
Net cash provided by (used in) financing activities			381	(76)
Increase (decrease) in cash and cash equivalents			90	(172)
Cash and cash equivalents at beginning of year			5	201
Cash and cash equivalents at end of period	$ 95	$ 29	$ 95	$ 29

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Common Stock in Treasury
Balance (in shares) at Dec. 31, 2018		585,407,107				39,092,537
Balance beginning at Dec. 31, 2018	$ 2,362	$ 6	$ 4,715	$ (2,142)	$ (36)	$ (181)
Comprehensive (loss) income:
Net (loss) income	594			594
Comprehensive income (loss)	594
Stock-based compensation	$ 3		3
Issuance of restricted stock (in shares)		8,798
Cancellation of restricted stock (in shares)		(128,324)
Treasury stock (in shares)	5,260,687					5,260,687
Treasury stock	$ (21)					$ (21)
Performance units vested (in shares)		535,802
Tax withholding - stock compensation (in shares)		(274,657)
Tax withholding – stock compensation	(1)		(1)
Balance (in shares) at Mar. 31, 2019		585,548,726				44,353,224
Balance ending at Mar. 31, 2019	2,937	$ 6	4,717	(1,548)	(36)	$ (202)
Balance (in shares) at Dec. 31, 2018		585,407,107				39,092,537
Balance beginning at Dec. 31, 2018	2,362	$ 6	4,715	(2,142)	(36)	$ (181)
Comprehensive (loss) income:
Net (loss) income	781
Comprehensive income (loss)	786
Balance (in shares) at Sep. 30, 2019		585,637,420				44,353,224
Balance ending at Sep. 30, 2019	3,135	$ 6	4,723	(1,361)	(31)	$ (202)
Balance (in shares) at Dec. 31, 2018		585,407,107				39,092,537
Balance beginning at Dec. 31, 2018	2,362	$ 6	4,715	(2,142)	(36)	$ (181)
Balance (in shares) at Dec. 31, 2019		585,555,923				44,353,224
Balance ending at Dec. 31, 2019	3,246	$ 6	4,726	(1,251)	(33)	$ (202)
Balance (in shares) at Mar. 31, 2019		585,548,726				44,353,224
Balance beginning at Mar. 31, 2019	2,937	$ 6	4,717	(1,548)	(36)	$ (202)
Comprehensive (loss) income:
Net (loss) income	138			138
Other comprehensive income	4				4
Comprehensive income (loss)	142
Stock-based compensation	3		3
Issuance of restricted stock (in shares)		6,424
Cancellation of restricted stock (in shares)		(72,555)
Tax withholding - stock compensation (in shares)		(4,250)
Balance (in shares) at Jun. 30, 2019		585,478,345				44,353,224
Balance ending at Jun. 30, 2019	3,082	$ 6	4,720	(1,410)	(32)	$ (202)
Comprehensive (loss) income:
Net (loss) income	49			49
Other comprehensive income	1				1
Comprehensive income (loss)	50
Stock-based compensation	3		3
Issuance of restricted stock (in shares)		205,883
Cancellation of restricted stock (in shares)		(33,851)
Tax withholding - stock compensation (in shares)		(12,957)
Balance (in shares) at Sep. 30, 2019		585,637,420				44,353,224
Balance ending at Sep. 30, 2019	3,135	$ 6	4,723	(1,361)	(31)	$ (202)
Balance (in shares) at Dec. 31, 2019		585,555,923				44,353,224
Balance beginning at Dec. 31, 2019	3,246	$ 6	4,726	(1,251)	(33)	$ (202)
Comprehensive (loss) income:
Net (loss) income	(1,547)			(1,547)
Comprehensive income (loss)	(1,547)
Stock-based compensation	1		1
Issuance of restricted stock (in shares)		12,397
Cancellation of restricted stock (in shares)		(167,130)
Restricted units granted (in shares)		1,005,976
Restricted units granted	1		1
Tax withholding - stock compensation (in shares)		(383,731)
Balance (in shares) at Mar. 31, 2020		586,023,435				44,353,224
Balance ending at Mar. 31, 2020	1,701	$ 6	4,728	(2,798)	(33)	$ (202)
Balance (in shares) at Dec. 31, 2019		585,555,923				44,353,224
Balance beginning at Dec. 31, 2019	3,246	$ 6	4,726	(1,251)	(33)	$ (202)
Comprehensive (loss) income:
Net (loss) income	(3,020)
Other comprehensive income					1
Comprehensive income (loss)	(3,019)
Balance (in shares) at Sep. 30, 2020		649,899,653				44,353,224
Balance ending at Sep. 30, 2020	384	$ 7	4,882	(4,271)	(32)	$ (202)
Balance (in shares) at Mar. 31, 2020		586,023,435				44,353,224
Balance beginning at Mar. 31, 2020	1,701	$ 6	4,728	(2,798)	(33)	$ (202)
Comprehensive (loss) income:
Net (loss) income	(880)			(880)
Comprehensive income (loss)	(880)
Stock-based compensation	1		1
Issuance of restricted stock (in shares)		222,489
Cancellation of restricted stock (in shares)		(1,079,515)
Restricted units granted (in shares)		1,649,294
Restricted units granted	2		2
Tax withholding - stock compensation (in shares)		(222,163)
Tax withholding – stock compensation	(1)		(1)
Balance (in shares) at Jun. 30, 2020		586,593,540				44,353,224
Balance ending at Jun. 30, 2020	823	$ 6	4,730	(3,678)	(33)	$ (202)
Comprehensive (loss) income:
Net (loss) income	(593)			(593)
Other comprehensive income	1				1
Comprehensive income (loss)	(592)
Stock-based compensation	1		1
Issuance of common stock (in shares)		63,250,000
Issuance of common stock	152	$ 1	151
Issuance of restricted stock (in shares)		63,344
Cancellation of restricted stock (in shares)		(5,196)
Tax withholding - stock compensation (in shares)		(2,035)
Balance (in shares) at Sep. 30, 2020		649,899,653				44,353,224
Balance ending at Sep. 30, 2020	$ 384	$ 7	$ 4,882	$ (4,271)	$ (32)	$ (202)

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION Southwestern Energy Company (including its subsidiaries, collectively “Southwestern” or the “Company”) is an independent energy company engaged in natural gas, oil and NGL exploration, development and production (“E&P”). The Company is also focused on creating and capturing additional value through its marketing business (“Marketing”), which was previously referred to as “Midstream” when it included the operation of gathering systems. Southwestern conducts most of its business through subsidiaries and operates principally in two segments: E&P and Marketing. E&P. Southwestern’s primary business is the exploration for and production of natural gas, oil and NGLs, with ongoing operations focused on the development of unconventional natural gas and oil reservoirs located in Pennsylvania and West Virginia. The Company’s operations in northeast Pennsylvania, herein referred to as “Northeast Appalachia,” are primarily focused on the unconventional natural gas reservoir known as the Marcellus Shale. Operations in West Virginia and southwest Pennsylvania, herein referred to as “Southwest Appalachia,” are focused on the Marcellus Shale, the Utica and the Upper Devonian unconventional natural gas and oil reservoirs. Collectively, Southwestern refers to its properties located in Pennsylvania and West Virginia as “Appalachia.” The Company also operates drilling rigs located in Pennsylvania and West Virginia, and provides certain oilfield products and services, principally serving the Company’s E&P activities through vertical integration. Marketing. Southwestern’s marketing activities capture opportunities that arise through the marketing and transportation of natural gas, oil and NGLs primarily produced in its E&P operations. The accompanying consolidated financial statements were prepared using accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and in accordance with the rules and regulations of the Securities and Exchange Commission. Certain information relating to the Company’s organization and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been appropriately condensed or omitted in this Quarterly Report. The Company believes the disclosures made are adequate to make the information presented not misleading. The consolidated financial statements contained in this report include all normal and recurring material adjustments that, in the opinion of management, are necessary for a fair statement of the financial position, results of operations and cash flows for the interim periods presented herein. It is recommended that these consolidated financial statements be read in conjunction with the consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (“2019 Annual Report”). The Company’s significant accounting policies, which have been reviewed and approved by the Audit Committee of the Company’s Board of Directors, are summarized in Note 1 in the Notes to the Consolidated Financial Statements included in the Company’s 2019 Annual Report.

ACQUISITION

ACQUISITION	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
ACQUISITION	ACQUISITION On August 12, 2020, Southwestern and Montage Resources Corporation (“Montage”) entered into an Agreement and Plan of Merger (the “Merger Agreement”) pursuant to which Montage will merge with and into Southwestern, with Southwestern continuing as the surviving company (the “Merger”). The Company will acquire at the effective time of the Merger (the “Effective Time”) all of the outstanding shares of common stock of Montage in exchange for 1.8656 shares of common stock of the Company per share of Montage common stock. No fractional Southwestern common shares will be issued in the Merger, and holders of Montage common shares will, instead, receive cash in lieu of fractional Southwestern common shares, if any. This exchange ratio is fixed and will not be adjusted for changes in the Company’s stock price. Following the closing of the Merger, Southwestern’s existing shareholders and Montage’s existing shareholders will own approximately 90% and 10%, respectively, of the outstanding shares of the combined company. The transaction is expected to close in the fourth quarter of 2020, subject to customary closing conditions, including the approval of the Montage shareholders. The Merger Agreement provides that, upon consummation of the Merger, the directors and officers of Southwestern immediately prior to the Effective Time shall, from and after the Effective Time, be the directors and officers of the combined company. Southwestern will continue to be headquartered in Spring, Texas. In August 2020, the Company completed an underwritten public offering of 63,250,000 shares of common stock with an offering price to the public of $2.50 per share, with net proceeds from the offering totaling $152 million after deducting underwriting discounts and offering expenses. Also in August 2020, the Company completed an underwritten public offering of $350 million aggregate principal amount of 8.375% senior notes due 2028 (the “2028 Notes”). The net proceeds from the offering, after deducting the underwriting discount and estimated offering expenses, were approximately $345 million. The Company intends to use the net proceeds from the debt offering, together with the net proceeds received from the common stock offering and borrowings under its revolving credit facility, to fund a redemption of $510 million aggregate principal amount of Montage’s outstanding 8.875% Senior Notes due 2023 (the “Montage Notes”) and related accrued interest in connection with the closing of the Merger. Pending the consummation of the Merger, a portion of these net proceeds has temporarily been used to repay revolving credit facility borrowings until the anticipated redemption of the Montage Notes. The 2028 Notes are subject to special mandatory redemption at par plus accrued and unpaid interest if the Merger does not close on or prior to February 12, 2021 or the Company determines in its sole discretion that the consummation of the Merger cannot or is not reasonably likely to be satisfied by February 12, 2021. The Company has recorded approximately $3 million in transaction related expenses for the three and nine months ended September 30, 2020.

RESTRUCTURING CHARGES

RESTRUCTURING CHARGES	9 Months Ended
	Sep. 30, 2020
Restructuring and Related Activities [Abstract]
RESTRUCTURING CHARGES	RESTRUCTURING CHARGES On February 4, 2020, the Company notified employees of a workforce reduction plan as a result of a strategic realignment of the Company’s organizational structure. This reduction was substantially complete by the end of the first quarter of 2020. Affected employees were offered a severance package, which included a one-time payment depending on length of service and, if applicable, the current value of unvested long-term incentive awards that were forfeited. These costs were recognized as restructuring charges for the nine months ended September 30, 2020, and were substantially complete by the end of the first quarter of 2020. In December 2018, the Company closed on the sale of the equity in certain of its subsidiaries that owned and operated its Fayetteville Shale E&P and related midstream gathering assets in Arkansas. As part of this transaction, most employees associated with those assets became employees of the buyer although the employment of some was terminated. All affected employees were offered a severance package, which included a one-time cash payment depending on length of service and, if applicable, the current value of a portion of equity awards that were forfeited. As of September 30, 2019, the Company had substantially completed the Fayetteville Shale sale-related employment terminations. As a result of the Fayetteville Shale sale, the Company relocated certain employees and infrastructure to other locations and began the process of consolidating and reorganizing its office space. These charges related to office consolidation and reorganization have been recognized as restructuring charges. In July 2019, the Company terminated its existing lease agreement in its headquarters office building and entered into a new 10-year lease agreement for a smaller portion of the building. Approximately $3 million and $5 million of the fees associated with the Company’s headquarters office consolidation and other office consolidation are reflected as restructuring charges for the three and nine months ended September 30, 2019, respectively. The Company also recognized additional severance costs in the third quarter of 2019 related to continued organizational restructuring. The following table presents a summary of the restructuring charges included in Operating Income (Loss) for the three and nine months ended September 30, 2020 and 2019: For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Severance (including payroll taxes) $ — $ 1 $ 12 $ 4 Office consolidation — 3 — 5 Total restructuring charges (1) $ — $ 4 $ 12 $ 9 (1) Total restructuring charges were $12 million for the Company’s E&P segment for the nine months ended September 30, 2020, and $4 million and $9 million for the three and nine months ended September 30, 2019, respectively. The following table presents a reconciliation of the liability associated with the Company’s restructuring activities at September 30, 2020, which is reflected in accounts payable on the consolidated balance sheet: (in millions) Liability at December 31, 2019 $ 2 Additions 12 Distributions (14) Liability at September 30, 2020 $ —

REVENUE RECOGNITION

REVENUE RECOGNITION	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION Revenues from Contracts with Customers Natural gas and liquids. Natural gas, oil and NGL sales are recognized when control of the product is transferred to the customer at a designated delivery point. The pricing provisions of the Company’s contracts are primarily tied to a market index with certain adjustments based on factors such as delivery, quality of the product and prevailing supply and demand conditions in the geographic areas in which the Company operates. Under the Company’s sales contracts, the delivery of each unit of natural gas, oil and NGLs represents a separate performance obligation, and revenue is recognized at the point in time when the performance obligations are fulfilled. There is no significant financing component to the Company’s revenues as payment terms are typically within 30 to 60 days of control transfer. Furthermore, consideration from a customer corresponds directly with the value to the customer of the Company’s performance completed to date. As a result, the Company recognizes revenue in the amount for which the Company has a right to invoice and has not disclosed information regarding its remaining performance obligations. The Company records revenue from its natural gas and liquids production in the amount of its net revenue interest in sales from its properties. Accordingly, natural gas and liquid sales are not recognized for deliveries in excess of the Company’s net revenue interest, while natural gas and liquid sales are recognized for any under-delivered volumes. Production imbalances are generally recorded as receivables and payables and not contract assets or contract liabilities as the imbalances are between the Company and other working interest owners, not the end customer. Marketing. The Company, through its marketing affiliate, markets natural gas, oil and NGLs for its affiliated E&P company as well as other joint interest owners that choose to market with the Company. In addition, the Company markets some products purchased from third parties. Marketing revenues for natural gas, oil and NGL sales are recognized when control of the product is transferred to the customer at a designated delivery point. The pricing provisions of the Company’s contracts are primarily tied to market indices with certain adjustments based on factors such as delivery, quality of the product and prevailing supply and demand conditions. Under the Company’s marketing contracts, the delivery of each unit of natural gas, oil and NGLs represents a separate performance obligation, and revenue is recognized at the point in time when the performance obligations are fulfilled. Customers are invoiced and revenues are recorded each month as natural gas, oil and NGLs are delivered, and payment terms are typically within 30 to 60 days of control transfer. Furthermore, consideration from a customer corresponds directly with the value to the customer of the Company’s performance completed to date. As a result, the Company recognizes revenue in the amount for which the Company has a right to invoice and has not disclosed information regarding its remaining performance obligations. Disaggregation of Revenues The Company presents a disaggregation of E&P revenues by product on the consolidated statements of operations net of intersegment revenues. The following table reconciles operating revenues as presented on the consolidated statements of operations to the operating revenues by segment: (in millions) E&P Marketing Intersegment Total Three months ended September 30, 2020 Gas sales $ 190 $ — $ 9 $ 199 Oil sales 39 — 1 40 NGL sales 68 — — 68 Marketing — 495 (276) 219 Other 1 — — 1 Total $ 298 $ 495 $ (266) $ 527 Three months ended September 30, 2019 Gas sales $ 230 $ — $ 8 $ 238 Oil sales 66 — 1 67 NGL sales 52 — — 52 Marketing — 592 (313) 279 Total $ 348 $ 592 $ (304) $ 636 (in millions) E&P Marketing Intersegment Total Nine months ended September 30, 2020 Gas sales $ 584 $ — $ 27 $ 611 Oil sales 107 — 4 111 NGL sales 158 — — 158 Marketing — 1,432 (787) 645 Other (1) 4 — — 4 Total $ 853 $ 1,432 $ (756) $ 1,529 Nine months ended September 30, 2019 Gas sales $ 918 $ — $ 25 $ 943 Oil sales 151 — 2 153 NGL sales 191 — — 191 Marketing — 2,158 (1,154) 1,004 Other (2) 1 1 — 2 Total $ 1,261 $ 2,159 $ (1,127) $ 2,293 (1) For the nine months ended September 30, 2020, other E&P revenues consists primarily of gains on purchaser imbalances associated with certain NGLs. (2) For the nine months ended September 30, 2019, other E&P revenues consists primarily of water sales to third-party operators, and other Marketing revenues consists primarily of sales of gas from storage. Associated E&P revenues are also disaggregated for analysis on a geographic basis by the core areas in which the Company operates, which are in Pennsylvania and West Virginia. For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Northeast Appalachia $ 131 $ 175 $ 443 $ 740 Southwest Appalachia 166 173 409 519 Other 1 — 1 2 Total $ 298 $ 348 $ 853 $ 1,261 Receivables from Contracts with Customers The following table reconciles the Company’s receivables from contracts with customers to consolidated accounts receivable as presented on the consolidated balance sheet: (in millions) September 30, 2020 December 31, 2019 Receivables from contracts with customers $ 218 $ 284 Other accounts receivable 21 61 Total accounts receivable $ 239 $ 345 Amounts recognized against the Company’s allowance for doubtful accounts related to receivables arising from contracts with customers were immaterial for the three and nine months ended September 30, 2020 and 2019. The Company has no contract assets or contract liabilities associated with its revenues from contracts with customers.

CASH AND CASH EQUIVALENTS

CASH AND CASH EQUIVALENTS	9 Months Ended
	Sep. 30, 2020
Cash and Cash Equivalents [Abstract]
CASH AND CASH EQUIVALENTS	CASH AND CASH EQUIVALENTS The following table presents a summary of cash and cash equivalents as of September 30, 2020 and December 31, 2019: (in millions) September 30, 2020 December 31, 2019 Cash $ 93 $ 5 Marketable securities (1) 2 — Total $ 95 $ 5 (1) Consists of government stable value money market funds.

NATURAL GAS AND OIL PROPERTIES

NATURAL GAS AND OIL PROPERTIES	9 Months Ended
	Sep. 30, 2020
Oil and Gas Exploration and Production Industries Disclosures [Abstract]
NATURAL GAS AND OIL PROPERTIES	NATURAL GAS AND OIL PROPERTIES The Company utilizes the full cost method of accounting for costs related to the exploration, development and acquisition of natural gas and oil properties. Under this method, all such costs (productive and nonproductive), including salaries, benefits and other internal costs directly attributable to these activities, are capitalized on a country-by-country basis and amortized over the estimated lives of the properties using the units-of-production method. These capitalized costs are subject to a ceiling test that limits such pooled costs, net of applicable deferred taxes, to the aggregate of the present value of future net revenues attributable to proved natural gas, oil and NGL reserves discounted at 10% (standardized measure). Any costs in excess of the ceiling are written off as a non-cash expense. The expense may not be reversed in future periods, even though higher natural gas, oil and NGL prices may subsequently increase the ceiling. Companies using the full cost method are required to use the average quoted price from the first day of each month from the previous 12 months, including the impact of derivatives designated for hedge accounting, to calculate the ceiling value of their reserves. The Company had no hedge positions that were designated for hedge accounting as of September 30, 2020. Prices used to calculate the ceiling value of reserves were as follows: September 30, 2020 September 30, 2019 Natural gas (per MMBtu) $ 1.97 $ 2.87 Oil (per Bbl) $ 43.40 $ 57.77 NGLs (per Bbl) $ 9.26 $ 12.59 Using the average quoted prices above, adjusted for market differentials, the Company’s net book value of its United States natural gas and oil properties exceeded the ceiling by $361 million at September 30, 2020, resulting in a non-cash ceiling test impairment. In the first and second quarters of 2020, the Company’s net book value of its United States natural gas and oil properties exceeded the ceiling by approximately $1.48 billion and $650 million, respectively, and resulted in a non-cash ceiling test impairments. Decreases in market prices as well as changes in production rates, levels of reserves, evaluation of costs excluded from amortization, future development costs and production costs could result in future ceiling test impairments. Given the decline in commodity prices in late 2019 and the first three quarters of 2020, an additional non-cash impairment of the Company’s assets may occur in the fourth quarter of 2020. For the nine months ended September 30, 2020, the Company recognized a $5 million impairment related to other non-core assets not included in natural gas and oil properties. The Company’s net book value of its United States natural gas and oil properties did not exceed the ceiling amount at September 30, 2019, and the Company had no derivative positions that were designated for hedge accounting as of September 30, 2019. In June 2019, the Company sold non-core acreage for $25 million. There was no production or proved reserves associated with this acreage.

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Basic earnings per common share is computed by dividing net income by the weighted average number of common shares outstanding during the reportable period. The diluted earnings per share calculation adds to the weighted average number of common shares outstanding: the incremental shares that would have been outstanding assuming the exercise of dilutive stock options, the vesting of unvested restricted shares of common stock, restricted stock units and performance units. An antidilutive impact is an increase in earnings per share or a reduction in net loss per share resulting from the conversion, exercise or contingent issuance of certain securities. In August 2020, the Company completed an underwritten public offering of 63,250,000 shares of its common stock with an offering price to the public of $2.50 per share. Net proceeds after deducting underwriting discounts and offering expenses were approximately $152 million. See Note 2 for additional details regarding the Company’s use of proceeds from the equity offering. In the first quarter of 2019, the Company repurchased 5,260,687 shares of its outstanding common stock as part of a share repurchase program for approximately $21 million at an average price of $3.84 per share. The following table presents the computation of earnings per share for the three and nine months ended September 30, 2020 and 2019:  For the three months ended September 30, For the nine months ended September 30, (in millions, except share/per share amounts) 2020 2019 2020 2019 Net income (loss) $ (593) $ 49 $ (3,020) $ 781  Number of common shares: Weighted average outstanding 571,872,413 539,221,101 551,162,559 539,315,170 Issued upon assumed exercise of outstanding stock options — — — — Effect of issuance of non-vested restricted common stock — 187,706 — 400,120 Effect of issuance of non-vested restricted units — — — — Effect of issuance of non-vested performance units — 629,380 — 727,359 Weighted average and potential dilutive outstanding 571,872,413 540,038,187 551,162,559 540,442,649  Earnings per common share Basic $ (1.04) $ 0.09 $ (5.48) $ 1.45 Diluted $ (1.04) $ 0.09 $ (5.48) $ 1.44 The following table presents the common stock shares equivalent excluded from the calculation of diluted earnings per share for the three and nine months ended September 30, 2020 and 2019, as they would have had an antidilutive effect:  For the three months ended September 30, For the nine months ended September 30,  2020 2019 2020 2019 Unexercised stock options 4,425,886 5,102,882 4,519,385 5,115,334 Unvested share-based payment 939,941 2,136,453 946,547 1,797,963 Restricted stock units 1,935,781 — 2,001,621 — Performance units 2,282,211 240,450 2,027,985 247,443 Total 9,583,819 7,479,785 9,495,538 7,160,740

DERIVATIVES AND RISK MANAGEMENT

DERIVATIVES AND RISK MANAGEMENT	9 Months Ended
	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES AND RISK MANAGEMENT	DERIVATIVES AND RISK MANAGEMENT The Company is exposed to volatility in market prices and basis differentials for natural gas, oil and NGLs which impacts the predictability of its cash flows related to the sale of those commodities. These risks are managed by the Company’s use of certain derivative financial instruments. As of September 30, 2020, the Company’s derivative financial instruments consisted of fixed price swaps, two-way costless collars, three-way costless collars, basis swaps and call options. The Company’s interest rate swaps expired in June 2020. A description of the Company’s derivative financial instruments is provided below: Fixed price swaps If the Company sells a fixed price swap, the Company receives a fixed price for the contract and pays a floating market price to the counterparty. If the Company purchases a fixed price swap, the Company receives a floating market price for the contract and pays a fixed price to the counterparty.  Two-way costless collars Arrangements that contain a fixed floor price (purchased put option) and a fixed ceiling price (sold call option) based on an index price which, in aggregate, have no net cost. At the contract settlement date, (1) if the index price is higher than the ceiling price, the Company pays the counterparty the difference between the index price and ceiling price, (2) if the index price is between the floor and ceiling prices, no payments are due from either party, and (3) if the index price is below the floor price, the Company will receive the difference between the floor price and the index price.  Three-way costless collars Arrangements that contain a purchased put option, a sold call option and a sold put option based on an index price that, in aggregate, have no net cost. At the contract settlement date, (1) if the index price is higher than the sold call strike price, the Company pays the counterparty the difference between the index price and sold call strike price, (2) if the index price is between the purchased put strike price and the sold call strike price, no payments are due from either party, (3) if the index price is between the sold put strike price and the purchased put strike price, the Company will receive the difference between the purchased put strike price and the index price, and (4) if the index price is below the sold put strike price, the Company will receive the difference between the purchased put strike price and the sold put strike price.  Basis swaps Arrangements that guarantee a price differential for natural gas from a specified delivery point. If the Company sells a basis swap, the Company receives a payment from the counterparty if the price differential is greater than the stated terms of the contract and pays the counterparty if the price differential is less than the stated terms of the contract. If the Company purchases a basis swap, the Company pays the counterparty if the price differential is greater than the stated terms of the contract and receives a payment from the counterparty if the price differential is less than the stated terms of the contract.  Call options The Company purchases and sells call options in exchange for a premium. If the Company purchases a call option, the Company receives from the counterparty the excess (if any) of the market price over the strike price of the call option at the time of settlement, but if the market price is below the call’s strike price, no payment is due from either party. If the Company sells a call option, the Company pays the counterparty the excess (if any) of the market price over the strike price of the call option at the time of settlement, but if the market price is below the call’s strike price, no payment is due from either party.  Interest rate swaps Interest rate swaps were used to fix or float interest rates on existing or anticipated indebtedness. The purpose of these instruments was to manage the Company’s existing or anticipated exposure to unfavorable interest rate changes. The Company’s interest rate swaps expired in June 2020. The Company contracts with counterparties for its derivative instruments that it believes are creditworthy at the time the transactions are entered into, and the Company actively monitors the credit ratings and credit default swap rates of these counterparties where applicable. However, there can be no assurance that a counterparty will be able to meet its obligations to the Company. The fair value of the Company’s derivative assets and liabilities includes a non-performance risk factor. See Note 1 0 for additional details regarding the Company’s fair value measurements of its derivative positions. The Company presents its derivative positions on a gross basis and does not net the asset and liability positions. The following tables provide information about the Company’s financial instruments that are sensitive to changes in commodity prices and that are used to protect the Company’s exposure. None of the financial instruments below are designated for hedge accounting treatment. The tables present the notional amount, the weighted average contract prices and the fair value by expected maturity dates as of September 30, 2020: Financial Protection on Production  Weighted Average Price per MMBtu  Volume (Bcf) Swaps Sold Puts Purchased Puts Sold Calls Basis Differential Fair Value at September 30, 2020 (in millions) Natural Gas 2020 Fixed price swaps 91 $ 2.46 $ — $ — $ — $ — $ 16 (1) Two-way costless collars 57 — — 2.45 2.75 — (7) Three-way costless collars 25 — 2.19 2.58 2.96 — (11) (2) Total 173 $ (2) 2021 Fixed price swaps 93 $ 2.67 $ — $ — $ — $ — $ (13) Two-way costless collars 166 — — 2.51 2.89 — (27) Three-way costless collars 291 — 2.16 2.49 2.84 — (113) (3) Total 550 $ (153) 2022 Fixed price swaps 37 $ 2.75 $ — $ — $ — $ — $ (2) Two-way costless collars 32 — — 2.17 2.88 — (5) Three-way costless collars 116 — 2.07 2.44 2.87 — (24) Total 185 $ (31) 2023 Three-way costless collars 25 $ — $ 2.07 $ 2.48 $ 3.18 $ — $ (2) Basis Swaps 2020 66 $ — $ — $ — $ — $ (0.37) $ 21 2021 155 — — — — (0.12) 21 2022 127 — — — — (0.38) 4 Total 348 $ 46 (1) Includes $1 million in premiums paid related to certain natural gas fixed price swaps recognized as a component of derivative assets within current assets on the consolidated balance sheet at September 30, 2020. As certain natural gas fixed price swaps settle, the premium will be amortized and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. (2) Includes $2 million in deferred premiums related to certain natural gas three-way costless collars recognized as a component of derivative liabilities within current liabilities on the consolidated balance sheet at September 30, 2020. As certain three-way costless collars settle, the premium will be paid and recognized as a component of gain (loss) on derivatives on the consolidated statement of operations. (3) Includes $1 million in deferred premiums related to certain natural gas three-way costless collars recognized as a component of derivative liabilities within current liabilities on the consolidated balance sheet at September 30, 2020. As certain three-way costless collars settle, the premium will be paid and recognized as a component of gain (loss) on derivatives on the consolidated statement of operations.  Volume (MBbls) Weighted Average Strike Price per Bbl Fair Value at September 30, 2020 (in millions) Swaps Sold Puts Purchased Puts Sold Calls Oil 2020 Fixed price swaps (1) 584 $ 75.44 $ — $ — $ — $ 20 Two-way costless collars 261 — — 56.76 59.75 4 Three-way costless collars 404 — 43.71 52.85 57.78 3 Total 1,249 $ 27 2021 Fixed price swaps 2,574 $ 52.84 $ — $ — $ — $ 27 Three-way costless collars 1,445 — 43.52 53.25 58.14 8 Total 4,019 $ 35 2022 Fixed price swaps 762 $ 48.85 $ — $ — $ — $ 4 Three-way costless collars 666 — 42.50 53.20 58.00 2 Total 1,428 $ 6 2023 Three-way costless collars 111 $ — $ 30.00 $ 40.00 $ 57.85 $ — Ethane 2020 Fixed price swaps 2,629 $ 8.62 $ — $ — $ — $ — 2021 Fixed price swaps 5,889 $ 7.12 $ — $ — $ — $ (12) Two-way costless collar 584 — — 7.14 10.40 — Total 6,473 $ (12) 2022 Fixed price swaps 190 $ 7.41 $ — $ — $ — $ — Two-way costless collar 135 — — 7.56 9.66 — Total 325 $ — Propane 2020 Fixed price swaps 1,435 $ 23.11 $ — $ — $ — $ 2 Two-way costless collars 92 — — 25.20 29.40 — Total 1,527 $ 2 2021 Fixed price swaps 4,298 $ 19.99 $ — $ — $ — $ (3) 2022 Fixed price swaps 156 $ 19.25 $ — $ — $ — $ — Normal Butane 2020 Fixed price swaps 195 $ 22.44 $ — $ — $ — $ — Natural Gasoline 2020 Fixed price swaps 184 $ 34.59 $ — $ — $ — $ — (1) Includes 448 MBbls of purchased fixed price oil swaps at $33.94 per barrel with a fair value of $3 million and 1,032 MBbls of sold fixed price oil swaps at $57.44 per barrel with a fair value of $17 million. Other Derivative Contracts  Volume (Bcf) Weighted Average Strike Price per MMBtu Fair Value at September 30, 2020 (in millions) Call Options – Natural Gas (Net) 2020 6 $ 3.15 $ (2) 2021 57 3.15 (17) 2022 58 3.00 (15) 2023 17 2.84 (4) 2024 9 3.00 (2) Total 147 $ (40) ໿ Volume (MBbls) Weighted Average Strike Price per Bbl Fair Value at September 30, 2020 (in millions) Call Options – Oil 2021 226 $ 60.00 $ — Volume (Bcf) Weighted Average Strike Price per MMBtu Fair Value at September 30, 2020 (in millions)  Swaps Basis Differential Storage (1) 2020 Purchased fixed price swaps 1 $ 1.94 $ — $ — Purchased basis swaps — — (0.63) — Fixed price swaps — 2.09 — — Basis swaps — — (0.70) — Total 1 $ — 2021 Purchased fixed price swaps 1 $ 2.04 $ — $ — Fixed price swaps 2 2.49 — (1) Basis swaps 1 — (0.38) — Total 4 $ (1) (1) The Company has entered into certain derivatives to protect the value of volumes of natural gas injected into a storage facility that will be withdrawn and sold at a later date. Purchased Fixed Price Swaps – Marketing (Natural Gas) (1) Volume (Bcf) Weighted Average Strike Price per MMBtu Fair Value at September 30, 2020 (in millions) 2020 2 $ 2.44 $ — 2021 6 2.44 3 Total 8 $ 3 (1) The Company has entered into a limited number of derivatives to protect the value of certain long-term sales contracts. At September 30, 2020, the net fair value of the Company’s financial instruments related to commodities was a $125 million liability and included a net reduction of the liability of $1 million related to non-performance risk. See Note 10 for additional details regarding the Company’s fair value measurements of its derivative positions. As of September 30, 2020, the Company had no positions designated for hedge accounting treatment. Gains and losses on derivatives that are not designated for hedge accounting treatment, or do not meet hedge accounting requirements, are recorded as a component of gain (loss) on derivatives on the consolidated statements of operations. Accordingly, the gain (loss) on derivatives component of the statement of operations reflects the gain and losses on both settled and unsettled derivatives. Only the settled gains and losses are included in the Company’s realized commodity price calculations. The Company was a party to interest rate swaps that were entered into to mitigate the Company’s exposure to volatility in interest rates. The interest rate swaps had a notional amount of $170 million and expired in June 2020. Changes in the fair value of the interest rate swaps were included in gain (loss) on derivatives on the consolidated statements of operations. The balance sheet classification of the assets and liabilities related to derivative financial instruments (none of which are designated for hedge accounting treatment) is summarized below as of September 30, 2020 and December 31, 2019: Derivative Assets  Fair Value (in millions) Balance Sheet Classification September 30, 2020 December 31, 2019 Derivatives not designated as hedging instruments: Purchased fixed price swaps – natural gas Derivative assets $ 3 $ — Fixed price swaps – natural gas Derivative assets 21 (1) 77 (1) Fixed price swaps – oil Derivative assets 42 4 Fixed price swaps – ethane Derivative assets 2 11 Fixed price swaps – propane Derivative assets 5 21 Two-way costless collars – natural gas Derivative assets 27 10 Two-way costless collars – oil Derivative assets 6 5 Two-way costless collars – propane Derivative assets — 2 Three-way costless collars – natural gas Derivative assets 64 (2) 126 Three-way costless collars – oil Derivative assets 19 3 Basis swaps – natural gas Derivative assets 40 17 Call options – natural gas Derivative assets 9 1 Fixed price swaps – natural gas storage Derivative assets — 1 Fixed price swaps – natural gas Other long-term assets 1 7 Fixed price swaps – oil Other long-term assets 10 1 Fixed price swaps – propane Other long-term assets 1 3 Two-way costless collars – natural gas Other long-term assets 13 4 Three-way costless collars – natural gas Other long-term assets 56 74 Three-way costless collars – oil Other long-term assets 14 7 Basis swaps – natural gas Other long-term assets 13 15 Call options – natural gas Other long-term assets 4 2 Total derivative assets $ 350 $ 391 (1) Includes $1 million and $9 million at September 30, 2020 and December 31, 2019, respectively, in premiums paid related to certain natural gas fixed price swaps recognized as a component of derivative assets within current assets on the consolidated balance sheet. As certain natural gas fixed price swaps settle, the premium will be amortized and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. (2) Includes $3 million as of September 30, 2020 in deferred premiums related to certain natural gas three-way costless collars recognized as a component of derivative liabilities within current liabilities on the consolidated balance sheet. As certain natural gas three-way costless collars settle, the premium will be paid and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. Derivative Liabilities  Fair Value (in millions) Balance Sheet Classification September 30, 2020 December 31, 2019 Derivatives not designated as hedging instruments: Purchased fixed price swaps – natural gas Derivative liabilities $ — $ 1 Fixed price swaps – natural gas Derivative liabilities 15 1 Fixed price swaps – oil Derivative liabilities 1 6 Fixed price swaps – ethane Derivative liabilities 10 — Fixed price swaps – propane Derivative liabilities 5 — Two-way costless collars – natural gas Derivative liabilities 52 4 Two-way costless collars – oil Derivative liabilities 2 5 Three-way costless collars – natural gas Derivative liabilities 164 84 Three-way costless collars – oil Derivative liabilities 10 4 Basis swaps – natural gas Derivative liabilities 3 17 Call options – natural gas Derivative liabilities 24 3 Fixed price swaps – natural gas storage Derivative liabilities 1 — Fixed price swaps – natural gas Long-term derivative liabilities 6 — Fixed price swaps – oil Long-term derivative liabilities — 2 Fixed price swaps – ethane Long-term derivative liabilities 4 — Fixed price swaps – propane Long-term derivative liabilities 2 — Two-way costless collars – natural gas Long-term derivative liabilities 27 4 Three-way costless collars – natural gas Long-term derivative liabilities 106 72 Three-way costless collars – oil Long-term derivative liabilities 10 8 Basis swap – natural gas Long-term derivative liabilities 4 9 Call options – natural gas Long-term derivative liabilities 29 15 Call options – oil Long-term derivative liabilities — 1 Total derivative liabilities $ 475 $ 236 The following tables summarize the before-tax effect of the Company’s derivative instruments on the consolidated statements of operations for the three and nine months ended September 30, 2020 and 2019: Unsettled Gain (Loss) on Derivatives Recognized in Earnings Consolidated statement of Operations Classification of Gain (Loss) on Derivatives, Unsettled For the three months ended September 30, For the nine months ended September 30, Derivative Instrument 2020 2019 2020 2019 (in millions) Purchased fixed price swaps – natural gas Gain (Loss) on Derivatives $ 4 $ — $ 4 $ — Fixed price swaps – natural gas Gain (Loss) on Derivatives (138) (19) (74) 36 Fixed price swaps – oil Gain (Loss) on Derivatives (20) 8 54 5 Fixed price swaps – ethane Gain (Loss) on Derivatives (13) 1 (23) 8 Fixed price swaps – propane Gain (Loss) on Derivatives (17) 10 (25) 19 Two-way costless collars – natural gas Gain (Loss) on Derivatives (34) (11) (45) (2) Two-way costless collars – oil Gain (Loss) on Derivatives (5) — 4 (3) Two-way costless collars – propane Gain (Loss) on Derivatives (1) 1 (2) 3 Three-way costless collars – natural gas Gain (Loss) on Derivatives (98) (1) 3 (194) (1) 27 Three-way costless collars – oil Gain (Loss) on Derivatives (4) 3 15 4 Basis swaps – natural gas Gain (Loss) on Derivatives 54 12 40 6 Call options – natural gas Gain (Loss) on Derivatives (16) 1 (25) 5 Call options – oil Gain (Loss) on Derivatives — — 1 — Purchased fixed price swap – natural gas storage Gain (Loss) on Derivatives 1 — — — Fixed price swap – natural gas storage Gain (Loss) on Derivatives (2) 2 (2) 1 Interest rate swaps Gain (Loss) on Derivatives — 1 — (1) Total gain (loss) on unsettled derivatives $ (289) $ 12 $ (272) $ 108 Settled Gain (Loss) on Derivatives Recognized in Earnings (2) Consolidated statement of Operations Classification of Gain (Loss) on Derivatives, Settled For the three months ended September 30, For the nine months ended September 30, Derivative Instrument 2020 2019 2020 2019 (in millions) Purchased fixed price swaps – natural gas Gain (Loss) on Derivatives $ (2) $ — $ (4) $ — Fixed price swaps – natural gas Gain (Loss) on Derivatives 61 (3) 45 150 (3) 53 Fixed price swaps – oil Gain (Loss) on Derivatives 17 3 44 5 Fixed price swaps – ethane Gain (Loss) on Derivatives (2) 6 6 12 Fixed price swaps – propane Gain (Loss) on Derivatives 2 11 19 20 Two-way costless collars – natural gas Gain (Loss) on Derivatives (5) 10 1 12 Two-way costless collars – oil Gain (Loss) on Derivatives 4 2 13 4 Two-way costless collars – propane Gain (Loss) on Derivatives — 1 2 1 Three-way costless collars – natural gas Gain (Loss) on Derivatives — 15 43 19 Three-way costless collars – oil Gain (Loss) on Derivatives 1 — 5 — Basis swaps – natural gas Gain (Loss) on Derivatives 20 (3) 29 (11) Call options – natural gas Gain (Loss) on Derivatives — (1) (4) — (2) (4) Fixed price swaps – natural gas storage Gain (Loss) on Derivatives 1 (1) 2 (1) Total gain on settled derivatives $ 97 $ 88 $ 310 $ 112 Total gain (loss) on derivatives $ (192) $ 100 $ 38 $ 220 (1) Includes $3 million in delayed premiums related to certain natural gas three-way costless collars for the three and nine months ended September 30, 2020, respectively, which is included in gain (loss) on derivatives on the consolidated statements of operations. (2) The Company calculates gain (loss) on derivatives, settled, as the summation of gains and losses on positions that settled within the period. (3) Includes $4 million and $8 million amortization of premiums paid related to certain natural gas fixed price options for the three and nine months ended September 30, 2020, respectively, which is included in gain (loss) on derivatives on the consolidated statements of operations. (4) Includes $1 million amortization of premiums paid related to certain natural gas purchased call options for the three and nine months ended September 30, 2019, which is included in gain (loss) on derivatives on the consolidated statements of operations.

RECLASSIFICATIONS FROM ACCUMULA

RECLASSIFICATIONS FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	9 Months Ended
	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
RECLASSIFICATIONS FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	RECLASSIFICATIONS FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Changes in accumulated other comprehensive income for the first nine months of 2020 were related to the Company’s pension and other postretirement benefits. The following tables detail the components of accumulated other comprehensive income and the related tax effects for the nine months ended September 30, 2020: (in millions) Pension and Other Postretirement Foreign Currency Total Beginning balance December 31, 2019 $ (19) $ (14) $ (33) Other comprehensive income before reclassifications — — — Amounts reclassified from other comprehensive income (1) 1 — 1 Net current-period other comprehensive income 1 — 1 Ending balance September 30, 2020 $ (18) $ (14) $ (32) Details about Accumulated Other Comprehensive Income Affected Line Item in the Consolidated Statement of Operations Amount Reclassified from Accumulated Other Comprehensive Income For the nine months ended (in millions) Pension and other postretirement: Amortization of prior service cost and net gain (1) Other Income (Loss), Net $ 1 Provision (Benefit) for Income Taxes — Net Income (Loss) $ 1 Total reclassifications for the period Net Income (Loss) $ 1 (1) See Note 1 4 for additional details regarding the Company’s pension and other postretirement benefit plans.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Assets and liabilities measured at fair value on a recurring basis The carrying amounts and estimated fair values of the Company’s financial instruments as of September 30, 2020 and December 31, 2019 were as follows:  September 30, 2020 December 31, 2019 (in millions) Carrying Fair Carrying Fair Cash and cash equivalents $ 95 $ 95 $ 5 $ 5 2018 revolving credit facility due April 2024 — — 34 34 Senior notes (1) 2,471 2,429 2,228 2,085 Derivative instruments, net (125) (2) (125) (2) 155 (2) 155 (2) (1) Excludes unamortized debt issuance costs and debt discounts. (2) Includes $1 million and $9 million in premiums paid as of September 30, 2020 and December 31, 2019, respectively, related to certain natural gas fixed price swaps recognized as a component of derivative assets within current assets on the consolidated balance sheet. Includes $3 million in deferred premiums as of September 30, 2020 related to certain natural gas three-way costless collars recognized as a component of derivative liabilities on the consolidated balance sheet. The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value. As presented in the tables below, this hierarchy consists of three broad levels: Level 1 valuations - Consist of unadjusted quoted prices in active markets for identical assets and liabilities and have the highest priority. Level 2 valuations - Consist of quoted market information for the calculation of fair market value. Level 3 valuations - Consist of internal estimates and have the lowest priority. The carrying values of cash and cash equivalents, including marketable securities, accounts receivable, other current assets, accounts payable and other current liabilities on the consolidated balance sheets approximate fair value because of their short-term nature. For debt and derivative instruments, the following methods and assumptions were used to estimate fair value: Debt: The fair values of the Company’s senior notes are based on the market value of the Company’s publicly traded debt as determined based on the market prices of the Company’s senior notes. The fair value of the Company’s 4.10% Senior Notes due March 2022 is considered to be a Level 2 measurement on the fair value hierarchy. The fair values of the Company’s remaining senior notes are considered the be a Level 1 measurement. The carrying values of the borrowings under the Company’s revolving credit facility (to the extent utilized) approximates fair value because the interest rate is variable and reflective of market rates. The Company considers the fair value of its revolving credit facility to be a Level 1 measurement on the fair value hierarchy. Derivative Instruments: The Company measures the fair value of its derivative instruments based upon a pricing model that utilizes market-based inputs, including, but not limited to, the contractual price of the underlying position, current market prices, natural gas and liquids forward curves, discount rates such as the LIBOR curve for a similar duration of each outstanding position, volatility factors and non-performance risk. Non-performance risk considers the effect of the Company’s credit standing on the fair value of derivative liabilities and the effect of counterparty credit standing on the fair value of derivative assets. Both inputs to the model are based on published credit default swap rates and the duration of each outstanding derivative position. As of September 30, 2020, the impact of non-performance risk on the fair value of the Company’s net derivative liability position was a reduction of the liability of $1 million. The Company has classified its derivative instruments into levels depending upon the data utilized to determine their fair values. The Company’s fixed price swaps (Level 2) are estimated using third-party discounted cash flow calculations using the New York Mercantile Exchange (“NYMEX”) futures index for natural gas and oil derivatives and Oil Price Information Service (“OPIS”) for ethane and propane derivatives. The Company’s call options, two-way costless collars and three-way costless collars (Level 2) are valued using the Black-Scholes model, an industry standard option valuation model that takes into account inputs such as contract terms, including maturity, and market parameters, including assumptions of the NYMEX and OPIS futures index, interest rates, volatility and credit worthiness. Inputs to the Black-Scholes model, including the volatility input, are obtained from a third-party pricing source, with independent verification of the most significant inputs on a monthly basis. An increase (decrease) in volatility would result in an increase (decrease) in fair value measurement, respectively. The Company’s basis swaps (Level 2) are estimated using third-party calculations based upon forward commodity price curves. Assets and liabilities measured at fair value on a recurring basis are summarized below:  September 30, 2020  Fair Value Measurements Using: (in millions) Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets (Liabilities) at Fair Value Assets Purchased fixed price swaps $ — $ 3 $ — $ 3 Fixed price swaps (1) — 82 — 82 Two-way costless collars — 46 — 46 Three-way costless collars (2) — 153 — 153 Basis swaps — 53 — 53 Call options — 13 — 13 Liabilities Fixed price swaps — (43) — (43) Two-way costless collars — (81) — (81) Three-way costless collars — (290) — (290) Basis swaps — (7) — (7) Call options — (53) — (53) Fixed price swaps – storage — (1) — (1) Total (3) $ — $ (125) $ — $ (125) (1) Includes $1 million in premiums paid related to certain natural gas fixed price swaps recognized as a component of derivative assets within current assets on the consolidated balance sheet at September 30, 2020. As certain natural gas fixed price swaps settle, the premium will be amortized and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. (2) Includes $3 million in deferred premiums related to certain natural gas three-way costless collars recognized as a component of derivative liabilities within current liabilities on the consolidated balance sheet as of September 30, 2020. As certain natural gas three-way costless collars settle, the premium will be paid and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. (3) Includes a net reduction to the liability fair value of $1 million related to estimated nonperformance risk.  December 31, 2019  Fair Value Measurements Using: (in millions) Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets (Liabilities) at Fair Value Assets Fixed price swaps (1) $ — $ 124 $ — $ 124 Two-way costless collars — 21 — 21 Three-way costless collars — 210 — 210 Basis swaps — 32 — 32 Call options — 3 — 3 Fixed price swaps - storage — 1 — 1 Liabilities Purchased fixed price swaps — (1) — (1) Fixed price swaps — (9) — (9) Two-way costless collars — (13) — (13) Three-way costless collars — (168) — (168) Basis swaps — (26) — (26) Call options — (19) — (19) Total $ — $ 155 $ — $ 155 (1) Includes $9 million in premiums paid related to certain natural gas fixed price swaps recognized as a component of derivative assets within current assets on the consolidated balance sheet at December 31, 2019. As certain natural gas fixed price swaps settle, the premium will be amortized and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. The fair values of Level 3 derivative instruments are estimated using proprietary valuation models that utilize both market observable and unobservable parameters. Level 3 instruments consist of net derivatives valued using pricing models incorporating assumptions that, in the Company’s judgment, reflect reasonable assumptions a marketplace participant would use. There were no Level 3 derivatives in the third quarters of 2020 and 2019.

DEBT

DEBT	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
DEBT	DEBT The components of debt as of September 30, 2020 and December 31, 2019 consisted of the following: September 30, 2020 (in millions) Debt Instrument Unamortized Issuance Expense Unamortized Debt Discount Total Long-term debt: Variable rate (1.60% at September 30, 2020) 2018 revolving credit facility due April 2024 $ — $ — (1) $ — $ — 4.10% Senior Notes due March 2022 207 — — 207 4.95% Senior Notes due January 2025 (2) 856 (4) (1) 851 7.50% Senior Notes due April 2026 618 (6) — 612 7.75% Senior Notes due October 2027 440 (5) — 435 8.375% Senior Notes due September 2028 (3) 350 (5) — 345 Total long-term debt $ 2,471 $ (20) $ (1) $ 2,450 December 31, 2019 (in millions) Debt Instrument Unamortized Issuance Expense Unamortized Debt Discount Total Long-term debt: Variable rate (4.310% at December 31, 2019) 2018 term loan facility due April 2024 $ 34 $ — (1) $ — $ 34 4.10% Senior Notes due March 2022 213 (1) — 212 4.95% Senior Notes due January 2025 (2) 892 (5) (1) 886 7.50% Senior Notes due April 2026 639 (7) — 632 7.75% Senior Notes due October 2027 484 (6) — 478 Total long-term debt $ 2,262 $ (19) $ (1) $ 2,242 (1) At September 30, 2020 and December 31, 2019, unamortized issuance expense of $10 million and $11 million, respectively, associated with the 2018 credit facility (as defined below) was classified as other long-term assets on the consolidated balance sheets. (2) Effective in July 2018, the interest rate was 6.20% for the 2025 Notes, reflecting a net downgrade in the Company’s bond ratings since the initial offering. On April 7, 2020, S&P downgraded the Company’s bond rating to BB-, which had the effect of increasing the interest rate on the 2025 Notes to 6.45% following the July 23, 2020 interest payment date. The first coupon payment to the bondholders at the higher interest rate will be paid in January 2021. (3) The $350 million of Senior Notes due 2028 are subject to special mandatory redemption if the Montage Merger does not close on or prior to February 12, 2021. Credit Facilities 2018 Revolving Credit Facility In April 2018, the Company replaced its credit facility that was entered into in 2016 with a new revolving credit facility (the “2018 credit facility”) with a group of banks that, as amended, has a maturity date of April 2024. The 2018 credit facility has an aggregate maximum revolving credit amount of $3.5 billion and, in October 2020, the banks participating in the 2018 credit facility reaffirmed the elected borrowing base and aggregate commitments to be $1.8 billion. The borrowing base is subject to redetermination at least twice a year, in April and October, and is secured by substantially all of the assets owned by the Company and its subsidiaries. The permitted lien provisions in certain senior note indentures currently limit liens securing indebtedness to the greater of $2.0 billion or 25% of adjusted consolidated net tangible assets. The Company may utilize the 2018 credit facility in the form of loans and letters of credit. Loans under the 2018 credit facility are subject to varying rates of interest based on whether the loan is a Eurodollar loan or an alternate base rate loan. Eurodollar loans bear interest at the Eurodollar rate, which is adjusted LIBOR for such interest period plus the applicable margin (as those terms are defined in the 2018 credit facility documentation). The applicable margin for Eurodollar loans under the 2018 credit facility, as amended, ranges from 1.75% to 2.75% based on the Company’s utilization of the 2018 credit facility. Alternate base rate loans bear interest at the alternate base rate plus the applicable margin. The applicable margin for alternate base rate loans under the 2018 credit facility, as amended, ranges from 0.75% to 1.75% based on the Company’s utilization of the 2018 credit facility. In conjunction with the October 2020 redetermination process, the Company entered into an amendment to the credit agreement governing the 2018 credit facility to, among other matters: • limit the Company’s unrestricted cash and cash equivalents to $200 million when loans under the 2018 credit facility are outstanding, subject to certain exceptions; and • increase the applicable rate by 25 basis points on loans outstanding under the 2018 credit facility. In addition, certain amendments and redeterminations were made conditioned upon the closing of the Merger. Upon the closing of the Merger and satisfaction of related conditions and pursuant to the amendment and the semi-annual borrowing base redetermination, the elected borrowing base and total aggregate commitments will be increased to $2.0 billion, the maximum permitted lien amount based on provisions in certain of the Company’s senior note indentures, and the credit agreement will be further amended to, among other matters: • include certain Montage entities owning gas and oil properties as guarantors to the 2018 credit facility; and • deem any Montage letters of credit issued prior to the merger close to have been issued under the 2018 credit facility. The 2018 credit facility contains customary representations and warranties and contains covenants including, among others, the following: • a prohibition against incurring debt, subject to permitted exceptions; • a restriction on creating liens on assets, subject to permitted exceptions; • restrictions on mergers and asset dispositions; • restrictions on use of proceeds, investments, transactions with affiliates, or change of principal business; and • maintenance of the following financial covenants, commencing with the fiscal quarter ending June 30, 2018: 1. Minimum current ratio of no less than 1.00 to 1.00, whereby current ratio is defined as the Company’s consolidated current assets (including unused commitments under the credit agreement, but excluding non-cash derivative assets) to consolidated current liabilities (excluding non-cash derivative obligations and current maturities of long-term debt). 2. Maximum total net leverage ratio of no greater than, with respect to each fiscal quarter ending on or after June 30, 2020, 4.00 to 1.00. Total net leverage ratio is defined as total debt less cash on hand (up to the lesser of 10% of credit limit or $150 million) divided by consolidated EBITDAX for the last four consecutive quarters. EBITDAX, as defined in the credit agreement governing the Company’s 2018 credit facility, excludes the effects of interest expense, depreciation, depletion and amortization, income tax, any non-cash impacts from impairments, certain non-cash hedging activities, stock-based compensation expense, non-cash gains or losses on asset sales, unamortized issuance cost, unamortized debt discount and certain restructuring costs. The 2018 credit facility contains customary events of default that include, among other things, the failure to comply with the financial covenants described above, non-payment of principal, interest or fees, violation of covenants, inaccuracy of representations and warranties, bankruptcy and insolvency events, material judgments and cross-defaults to material indebtedness. If an event of default occurs and is continuing, all amounts outstanding under the 2018 credit facility may become immediately due and payable. As of September 30, 2020, the Company was in compliance with all of the covenants contained in the credit agreement governing the 2018 credit facility. Each United States domestic subsidiary of the Company for which the Company owns 100% guarantees the 2018 credit facility. Pursuant to requirements under the indentures governing its senior notes, each subsidiary that became a guarantor of the 2018 credit facility also became a guarantor of each of the Company’s senior notes. As of September 30, 2020, the Company had $203 million in letters of credit and no borrowings outstanding under the 2018 credit facility. The Company currently does not anticipate being required to supply a materially greater amount of letters of credit under its existing contracts. The Company’s exposure to the anticipated transition from LIBOR in late 2021 is limited to the 2018 credit facility. Upon announcement by the administrator of LIBOR identifying a specific date for LIBOR cessation, the credit agreement governing the 2018 credit facility will be amended to reference an alternative rate as established by JP Morgan, as Administrative Agent, and the Company. The alternative rate will be based on the prevailing market convention and is expected to be the Secured Overnight Financing Rate (“SOFR”). Senior Notes In January 2015, the Company completed a public offering of $1.0 billion aggregate principal amount of its 4.95% senior notes due 2025 (the “2025 Notes”). The interest rate on the 2025 Notes is determined based upon the public bond ratings from Moody’s and S&P. Downgrades on the 2025 Notes from either rating agency increase interest costs by 25 basis points per downgrade level and upgrades decrease interest costs by 25 basis points per upgrade level, up to the stated coupon rate, on the following semi-annual bond interest payment. Effective in July 2018, the interest rate for the 2025 Notes was 6.20%, reflecting a net downgrade in the Company’s bond ratings since the initial offering. On April 7, 2020, S&P downgraded the Company’s bond rating to BB-, which had the effect of increasing the interest rate on the 2025 Notes to 6.45% following the July 23, 2020 interest payment date. The first coupon payment to the bondholders at the higher interest rate will be paid in January 2021. In the event of future downgrades, the coupons for this series of notes have been capped at 6.95%. In the first half of 2020, the Company repurchased $6 million of its 4.10% Senior Notes due 2022, $36 million of its 4.95% Senior Notes due 2025, $21 million of its 7.50% Senior Notes due 2026 and $44 million of its 7.75% Senior Notes due 2027 for $72 million, and recognized a $35 million gain on the extinguishment of debt. In August 2020, the Company completed a public offering of $350 million aggregate principal amount of its 2028 Notes, with net proceeds from the offering totaling approximately $345 million after underwriting discounts and offering expenses. The 2028 Notes were sold to the public at 100% of their face value. The net proceeds from the notes are intended to be used, in conjunction with the net proceeds from the recent common stock offering and borrowings under the revolving credit facility, to fund a redemption of $510 million of Montage’s Notes in connection with the closing of the Merger. Pending the consummation of the Merger, a portion of these net proceeds has temporarily been used to repay revolving credit facility borrowings until the anticipated redemption of the Montage Notes. The 2028 Notes are subject to special mandatory redemption at par plus accrued and unpaid interest if the Merger does not close on or prior to February 12, 2021 or the Company determines in its sole discretion that the consummation of the Merger cannot or is not reasonably likely to be satisfied by February 12, 2021.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Operating Commitments and Contingencies As of September 30, 2020, the Company’s contractual obligations for demand and similar charges under firm transportation and gathering agreements to guarantee access capacity on natural gas and liquids pipelines and gathering systems totaled approximately $7.1 billion, $405 million of which related to access capacity on future pipeline and gathering infrastructure projects that still require the granting of regulatory approvals and additional construction efforts. The Company also had guarantee obligations of up to $1.0 billion of that amount. As of September 30, 2020, future payments under non-cancelable firm transportation and gathering agreements were as follows:  Payments Due by Period (in millions) Total Less than 1 1 to 3 Years 3 to 5 Years 5 to 8 Years More than 8 Infrastructure currently in service $ 6,704 $ 582 $ 1,308 $ 1,078 $ 1,411 $ 2,325 Pending regulatory approval and/or construction (1) 405 3 9 23 52 318 Total transportation charges $ 7,109 $ 585 $ 1,317 $ 1,101 $ 1,463 $ 2,643 (1) Based on estimated in-service dates as of September 30, 2020. In December 2018, the Company closed the Fayetteville Shale sale and retained certain contractual commitments related to firm transportation, with the buyer obligated to pay the transportation provider directly for these charges. As of September 30, 2020, approximately $27 million of these contractual commitments remain of which the Company will reimburse the buyer for certain of these potential obligations up to approximately $13 million through December 2020 depending on the buyer’s actual use, and has recorded a $10 million liability for the estimated future payments, down from $46 million recorded at December 31, 2019. In the first quarter of 2019, the Company agreed to acquire firm transportation contracts with pipelines in the Appalachian Basin starting in 2021 and running through 2032 totaling $357 million in total contractual commitments, which is presented in the table above; the releasing shipper has agreed to reimburse $133 million of these commitments. In February 2020, the Company was notified that the proposed Constitution pipeline project was cancelled and that the Company was released from a firm transportation agreement with its sponsor. Prior to its cancellation, the Company had contractual commitments totaling $512 million over the next 17 years related to the Constitution pipeline project. Environmental Risk The Company is subject to laws and regulations relating to the protection of the environment. Environmental and cleanup related costs of a non-capital nature are accrued when it is both probable that a liability has been incurred and when the amount can be reasonably estimated. Management believes any future remediation or other compliance related costs will not have a material effect on the financial position, results of operations or cash flows of the Company. Litigation The Company is subject to various litigation, claims and proceedings, most of which have arisen in the ordinary course of business, such as for alleged breaches of contract, miscalculation of royalties, employment matters, traffic accidents, pollution, contamination, encroachment on others’ property or nuisance. The Company accrues for litigation, claims and proceedings when a liability is both probable and the amount can be reasonably estimated. As of September 30, 2020, the Company does not currently have any material amounts accrued related to litigation matters. For any matters not accrued for, it is not possible at this time to estimate the amount of any additional loss, or range of loss, that is reasonably possible, but, based on the nature of the claims, management believes that current litigation, claims and proceedings, individually or in aggregate and after taking into account insurance, are not likely to have a material adverse impact on the Company’s financial position, results of operations or cash flows, for the period in which the effect of that outcome becomes reasonably estimable. Many of these matters are in early stages, so the allegations and the damage theories have not been fully developed, and are all subject to inherent uncertainties; therefore, management’s view may change in the future. St. Lucie County Fire District Firefighters’ Pension Trust On October 17, 2016, the St. Lucie County Fire District Firefighters’ Pension Trust filed a putative class action in the 61st District Court in Harris County, Texas, against the Company, certain of its former officers and current and former directors and the underwriters on behalf of itself and others that purchased certain depositary shares from the Company’s January 2015 equity offering, alleging material misstatements and omissions in the registration statement for that offering. The Company removed the case to federal court, but after a decision by the United States Supreme Court in an unrelated case that these types of cases are not subject to removal, the federal court remanded the case to the Texas state court. The Texas trial court denied the Company’s motion to dismiss, and in February 2020, the court of appeals declined to exercise discretion to reverse the trial court’s decision. The Company filed a petition to review the trial court’s decision with the Texas Supreme Court, and the Court requested a response from the plaintiff. The Court subsequently requested full briefing on the merits of the case. The Company carries insurance for the claims asserted against it and the officer and director defendants, and the carrier has accepted coverage. The Company denies all allegations and intends to continue to defend this case vigorously. The Company does not expect this case to have a material adverse effect on the results of operations, financial position or cash flows of the Company after taking insurance into account. Additionally, it is not possible at this time to estimate the amount of any additional loss, or range of loss, that is reasonably possible. Indemnifications The Company has provided certain indemnifications to various third parties, including in relation to asset and entity dispositions, securities offerings and other financings, and litigation, such as the St. Lucie County Fire District Firefighters’ Pension Trust case described above. In the case of asset dispositions, these indemnifications typically relate to disputes, litigation or tax matters existing at the date of disposition. The Company likewise obtains indemnification for future matters when it sells assets, although there is no assurance the buyer will be capable of performing those obligations. In the case of equity offerings, these indemnifications typically relate to claims asserted against underwriters in connection with an offering. No material liabilities have been recognized in connection with these indemnifications.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2020
Income Tax Expense (Benefit), Continuing Operations [Abstract]
INCOME TAXES	INCOME TAXESThe Company’s effective tax rate was approximately 0% and (16)% for the three and nine months ended September 30, 2020, respectively. The change in the effective tax rate for the nine months ended September 30, 2020 related to the effects of recording a valuation allowance against the Company’s U.S. deferred tax assets. A valuation allowance for deferred tax assets, including net operating losses, is recognized when it is more likely than not that some or all of the benefit from the deferred tax assets will not be realized. To assess that likelihood, the Company uses estimates and judgment regarding future taxable income, and considers the tax consequences in the jurisdiction where such taxable income is generated, to determine whether a valuation allowance is required. Such evidence can include current financial position, results of operations, both actual and forecasted, the reversal of deferred tax liabilities and tax planning strategies as well as current and forecasted business economics of the oil and gas industry. Due to significant pricing declines and the material write-down of the carrying value of the Company’s natural gas and oil properties in addition to other negative evidence, the Company concluded that it was more likely than not that these deferred tax assets will not be realized and recorded a discrete tax expense of $408 million for the increase in its valuation allowance in the first quarter of 2020. The net change in valuation allowance is reflected as a component of income tax expense. The Company also has retained a valuation allowance of $87 million related to net operating losses in jurisdictions in which it no longer operates. Management will continue to assess available positive and negative evidence to estimate whether sufficient future taxable income will be generated to permit the use of deferred tax assets. The amount of the deferred tax asset considered realizable, however, could be adjusted based on changes in subjective estimates of future taxable income or if objective negative evidence is no longer present. The Company’s effective tax rate was approximately 18% and (105)% for the three and nine months ended September 30, 2019, respectively. The effective tax rate for the nine months ended September 30, 2019 was primarily the effect of releasing the valuation allowances previously recorded against the Company’s deferred tax assets. As of the first quarter of 2019, the Company had sustained and projected to sustain a three-year cumulative level of profitability. Based on this factor and other positive evidence available at the time, the Company concluded that it was more likely than not that the deferred tax assets would be realized and determined $522 million of the valuation allowance would be released during 2019, of which $400 million was released on a discrete basis in the first nine months of 2019.

PENSION PLAN AND OTHER POSTRETI

PENSION PLAN AND OTHER POSTRETIREMENT BENEFITS	9 Months Ended
	Sep. 30, 2020
Retirement Benefits [Abstract]
PENSION PLAN AND OTHER POSTRETIREMENT BENEFITS	PENSION PLAN AND OTHER POSTRETIREMENT BENEFITS The Company maintains defined pension and other postretirement benefit plans, which cover substantially all of the Company’s employees. Net periodic pension costs include the following components for the three and nine months ended September 30, 2020 and 2019:  Consolidated Statements of For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Service cost General and administrative expenses $ 2 $ 1 $ 6 $ 5 Interest cost Other Income (Loss), Net 1 2 3 4 Expected return on plan assets Other Income (Loss), Net (2) (1) (5) (4) Amortization of prior service cost Other Income (Loss), Net — — — — Amortization of net loss Other Income (Loss), Net 1 — 1 1 Settlement loss Other Income (Loss), Net — 1 — 5 Net periodic benefit cost $ 2 $ 3 $ 5 $ 11 The Company’s other postretirement benefit plan had a net periodic benefit cost of less than $1 million for the three months ended September 30, 2020 and 2019, respectively, and $2 million and $1 million for the nine months ended September 30, 2020 and 2019, respectively. As of September 30, 2020, the Company has contributed $12 million to the pension and other postretirement benefit plans and does not expect to contribute to its pension plan during the remainder of 2020. The Company recognized liabilities of $22 million and $14 million related to its pension and other postretirement benefits, respectively, as of September 30, 2020, compared to liabilities of $30 million and $13 million as of December 31, 2019, respectively. In the first nine months of 2019, the Company recognized a $5 million non-cash settlement loss related to $19 million of lump-sum payments from the pension plan for employees who were terminated as a result of the Fayetteville Shale sale. The Company maintains a non-qualified deferred compensation supplemental retirement savings plan (“Non-Qualified Plan”) for certain key employees who may elect to defer and contribute a portion of their compensation, as permitted by the Non-Qualified Plan. Shares of the Company’s common stock purchased under the terms of the Non-Qualified Plan are included in treasury stock and totaled 3,632 shares and 5,115 shares at September 30, 2020 and December 31, 2019, respectively.

LONG-TERM INCENTIVE COMPENSATIO

LONG-TERM INCENTIVE COMPENSATION	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement, Noncash Expense [Abstract]
LONG-TERM INCENTIVE COMPENSATION	LONG-TERM INCENTIVE COMPENSATIONThe Company’s long-term incentive compensation plans consist of a combination of stock-based awards that derive their value directly or indirectly from the Company’s common stock price, and cash-based awards that are fixed in amount but subject to meeting annual performance thresholds. In March 2020, the Company issued its first long-term fixed cash-based awards. Stock-Based Compensation The Company’s stock-based compensation is classified as either equity awards or liability awards in accordance with GAAP. The fair value of an equity-classified award is determined at the grant date and is amortized to general and administrative expense on a straight-line basis over the vesting period of the award. A portion of this general and administrative expense is capitalized into natural gas and oil properties, included in property and equipment. The fair value of a liability-classified award is determined on a quarterly basis beginning at the grant date until final vesting. Changes in the fair value of liability-classified awards are recorded to general and administrative expense and capitalized expense over the vesting period of the award. Generally, stock options granted to employees and directors vest ratably over three years from the grant date and expire seven years from the date of grant. The Company issues shares of restricted stock, restricted stock units or performance cash awards to employees and directors which generally vest over four years. Restricted stock, restricted stock units, performance cash awards and stock options granted to participants under the 2013 Incentive Plan, as amended and restated, immediately vest upon death, disability or retirement (subject to a minimum of three years of service). The Company issues performance unit awards to employees which historically have vested at or over three years. In February 2020, the Company notified employees of a workforce reduction plan as a result of a strategic realignment of the Company’s organizational structure. This reduction was substantially complete by the end of the first quarter of 2020. Affected employees were offered a severance package which, if applicable, included the current value of unvested long-term incentive awards that were forfeited. The Company recognized the following amounts in total employee stock-based compensation costs for the three and nine months ended September 30, 2020 and 2019:  For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Stock-based compensation cost – expensed $ 2 $ 1 $ 8 $ 12 Stock-based compensation cost – capitalized 2 1 3 7 Equity-Classified Awards The Company recognized the following amounts in employee equity-classified stock-based compensation costs for the three and nine months ended September 30, 2020 and 2019:  For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Equity-classified awards – expensed $ — $ 2 $ 2 $ 6 Equity-classified awards – capitalized 1 1 1 3 As of September 30, 2020, there was $2 million of total unrecognized compensation cost related to the Company’s unvested equity-classified stock option grants, equity-classified restricted stock grants and equity-classified performance units. This cost is expected to be recognized over a weighted-average period of 0.5 years. Equity-Classified Stock Options The following table summarizes equity-classified stock option activity for the nine months ended September 30, 2020 and provides information for options outstanding and options exercisable as of September 30, 2020:  Number Weighted Average  (in thousands) Outstanding at December 31, 2019 4,635 $ 15.26 Granted — $ — Exercised — $ — Forfeited or expired (357) $ 7.06 Outstanding at September 30, 2020 4,278 $ 15.95 Exercisable at September 30, 2020 4,278 $ 15.95 Equity-Classified Restricted Stock The following table summarizes equity-classified restricted stock activity for the nine months ended September 30, 2020 and provides information for unvested shares as of September 30, 2020:  Number Weighted Average  (in thousands) Unvested shares at December 31, 2019 1,480 $ 7.00 Granted 570 $ 2.88 Vested (1,083) $ 5.30 Forfeited (246) $ 7.71 Unvested shares at September 30, 2020 721 $ 6.05 Equity-Classified Performance Units The following table summarizes equity-classified performance unit activity for the nine months ended September 30, 2020 and provides information for unvested units as of September 30, 2020. The performance unit awards granted in 2018 include a market condition based exclusively on the Total Shareholder Return (“TSR”), with their fair value calculated by a Monte Carlo model. The total fair value of the performance units is amortized to compensation expense on a straight line basis over the vesting period of the award. The grant date fair value is calculated using the closing price of the Company’s common stock at the grant date.  Number of Units (1) Weighted Average  (in thousands) Unvested units at December 31, 2019 178 $ 10.47 Granted — $ — Vested (178) $ 10.47 Forfeited — $ — Unvested units at September 30, 2020 — $ — (1) The actual payout of shares may range from a minimum of zero shares to a maximum of two shares per unit contingent upon TSR. The performance units have a three-year vesting term and the actual disbursement of shares, if any, is determined during the first quarter following the end of the three-year vesting period. Liability-Classified Awards The Company recognized the following amounts in employee liability-classified stock-based compensation costs for the three and nine months ended September 30, 2020:  For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Liability-classified stock-based compensation cost – expensed $ 2 $ (1) $ 6 $ 6 Liability-classified stock-based compensation cost – capitalized 1 — 2 4 Liability-Classified Restricted Stock Units In the first quarter of each year beginning with 2018, the Company granted restricted stock units that vest over a period of four years and are payable in either cash or shares at the option of the Compensation Committee of the Company’s Board of Directors. The Company has accounted for these as liability-classified awards, and accordingly changes in the market value of the instruments will be recorded to general and administrative expense and capitalized expense over the vesting period of the award. As of September 30, 2020, there was $21 million of total unrecognized compensation cost related to liability-classified restricted stock units that is expected to be recognized over a weighted-average period of 2.5 years. The amount of unrecognized compensation cost for liability-classified awards will fluctuate over time as they are marked to market.  Number Weighted Average  (in thousands) Unvested units at December 31, 2019 12,992 $ 2.42 Granted 6,172 $ 1.41 Vested (3,946) $ 1.42 Forfeited (3,060) $ 1.53 Unvested units at September 30, 2020 12,158 $ 2.17 Liability-Classified Performance Units In each year beginning with 2018, the Company granted performance units that vest at the end of, or over, a three-year period and are payable in either cash or shares at the option of the Compensation Committee of the Company’s Board of Directors. The Company has accounted for these as liability-classified awards, and accordingly changes in the fair market value of the instruments will be recorded to general and administrative expense and capitalized expense over the vesting period of the awards. The performance unit awards granted in 2018 include a performance condition based on cash flow per debt-adjusted share and two market conditions, one based on absolute TSR and the other on relative TSR as compared to a group of the Company’s peers. The performance unit awards granted in 2019 include performance conditions based on return on average capital employed and two market conditions, one based on absolute TSR and the other on relative TSR. The performance units granted in 2020 include a performance condition based on return on average capital employed and a market condition based on relative TSR. The fair values of the market conditions are calculated by Monte Carlo models on a quarterly basis. As of September 30, 2020, there was $14 million of total unrecognized compensation cost related to liability-classified performance units. This cost is expected to be recognized over a weighted-average period of 2.2 years. The amount of unrecognized compensation cost for liability-classified awards will fluctuate over time as they are marked to market. The final value of the performance unit awards is contingent upon the Company’s actual performance against these performance measures.  Number Weighted Average  (in thousands) Unvested units at December 31, 2019 5,142 $ 2.42 Granted 6,172 $ 1.41 Vested — $ — Forfeited (2,300) $ 3.06 Unvested units at September 30, 2020 9,014 $ 2.10 Cash-Based Compensation Performance Cash Awards In 2020, the Company granted performance cash awards that vest over a four-year period and are payable in cash on an annual basis. The value of each unit of the award equals one dollar. The Company recognizes the cost of these awards as general and administrative expense and capitalized expense over the vesting period of the awards. The performance cash awards granted in 2020 include a performance condition determined annually by the Company. In 2020, the performance measure is a targeted discretionary cash flow amount. If the Company, in its sole discretion, determines that the threshold was not met, the amount for that vesting period will not vest and will be cancelled. As of September 30, 2020, there was $16 million of total unrecognized compensation cost related to performance cash awards. This cost is expected to be recognized over a weighted average 3.4 years. The final value of the performance cash awards is contingent upon the Company’s actual performance against these performance measures. Number Weighted Average Fair Value (in thousands) Unvested units at December 31, 2019 — $ — Granted 20,044 $ 1.00 Vested (100) $ 1.00 Forfeited (729) $ 1.00 Unvested units at September 30, 2020 19,215 $ 1.00

SEGMENT INFORMATION

SEGMENT INFORMATION	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION The Company’s reportable business segments have been identified based on the differences in products or services provided. Revenues for the E&P segment are derived from the production and sale of natural gas and liquids. The Marketing segment generates revenue through the marketing of both Company and third-party produced natural gas and liquids volumes. Summarized financial information for the Company’s reportable segments is shown in the following table. The accounting policies of the segments are the same as those described in Note 1 of the Notes to Consolidated Financial Statements included in Item 8 of the 2019 Annual Report. Management evaluates the performance of its segments based on operating income, defined as operating revenues less operating costs. Income before income taxes, for the purpose of reconciling the operating income amount shown below to consolidated income before income taxes, is the sum of operating income, interest expense, gain (loss) on derivatives, gain on early extinguishment of debt and other income (loss). The “Other” column includes items not related to the Company’s reportable segments, including real estate and corporate items. Corporate general and administrative costs, depreciation expense and taxes, other than income taxes, are allocated to the segments. E&P Marketing Other Total (in millions) Three months ended September 30, 2020 Revenues from external customers $ 308 $ 219 $ — $ 527 Intersegment revenues (10) 276 — 266 Depreciation, depletion and amortization expense 68 2 — 70 Impairments 361 — — 361 Operating loss (379) (1) (2) — (381) Interest expense (2) 22 — — 22 Loss on derivatives (192) — — (192) Other income, net 2 — — 2 Assets 3,705 (3) 240 212 (4) 4,157 Capital investments (5) 223 — — 223 Three months ended September 30, 2019 Revenues from external customers $ 357 $ 279 $ — $ 636 Intersegment revenues (9) 313 — 304 Depreciation, depletion and amortization expense 123 2 — 125 Impairments — 2 — 2 Operating loss (21) (1) (8) — (29) Interest expense (2) 17 — — 17 Gain on derivatives 100 — — 100 Gain on early extinguishment of debt — — 7 7 Other income (loss), net (4) — 2 (2) Provision for income taxes (2) 10 — — 10 Assets 6,099 (3) 272 227 (4) 6,598 Capital investments (5) 239 — 1 240 E&P Marketing Other Total Nine months ended September 30, 2020 (in millions) Revenues from external customers $ 884 $ 645 $ — $ 1,529 Intersegment revenues (31) 787 — 756 Depreciation, depletion and amortization expense 260 7 — 267 Impairments 2,495 — — 2,495 Operating loss (2,613) (1) (14) — (2,627) Interest expense (2) 63 — — 63 Gain on derivatives 38 — — 38 Gain on early extinguishment of debt — — 35 35 Other income, net 2 — 1 3 Provision for income taxes (2) 406 — — 406 Assets 3,705 (3) 240 212 (4) 4,157 Capital investments (5) 705 — — 705 Nine months ended September 30, 2019 Revenues from external customers $ 1,288 $ 1,005 $ — $ 2,293 Intersegment revenues (27) 1,154 — 1,127 Depreciation, depletion and amortization expense 345 7 — 352 Impairments 6 2 — 8 Operating income (loss) 219 (1) (13) — 206 Interest expense (2) 46 — — 46 Gain on derivatives 220 — — 220 Gain on early extinguishment of debt — — 7 7 Other income (loss), net (8) — 1 (7) Benefit from income taxes (2) (401) — — (401) Assets 6,099 (3) 272 227 (4) 6,598 Capital investments (5) 931 — 2 933 (1) Operating income (loss) for the E&P segment includes $4 million of restructuring charges for the three months ended September 30, 2019 and $12 million and $9 million of restructuring charges for the nine months ended September 30, 2020 and 2019, respectively. The E&P segment operating income (loss) also includes $3 million for the three and nine months ended September 30, 2020 related to acquisition-related charges. (2) Interest expense and provision (benefit) for income taxes by segment is an allocation of corporate amounts as they are incurred at the corporate level. (3) E&P assets includes office, technology, water infrastructure, drilling rigs and other ancillary equipment not directly related to natural gas and oil properties. E&P assets also includes deferred tax assets which are an allocation of corporate amounts as they are incurred at the corporate level. (4) Other assets represent corporate assets not allocated to segments and assets for non-reportable segments. At September 30, 2020 and 2019, other assets included approximately $95 million and $29 million, respectively, in cash and cash equivalents, $74 million and $84 million in right-of-use lease assets, respectively, $18 million and $31 million, respectively, in property, plant and equipment, $10 million and $9 million, respectively, in unamortized debt expense, $5 million and $7 million, respectively, in a non-qualified retirement plan and $3 million and $7 million in prepayments, respectively. Additionally, the September 30, 2019 other asset balance includes $61 million in income taxes receivable and the September 30, 2020 other asset balance includes $7 million in account receivable assets.

NEW ACCOUNTING PRONOUNCEMENTS

NEW ACCOUNTING PRONOUNCEMENTS	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
NEW ACCOUNTING PRONOUNCEMENTS	NEW ACCOUNTING PRONOUNCEMENTS Recently Adopted In August 2018, the FASB issued Accounting Standards Update No. 2018-13, Fair Value Measurement (ASC 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurements (“ASU 2018-13”), which modifies the disclosure requirements on fair value measurements. ASU 2018-13 became effective for public business entities for annual and interim periods in fiscal years beginning after December 15, 2019. As a result of adoption, this standard did not have a material impact on the Company’s consolidated financial statements. In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“Update 2016-13”). Update 2016-13 replaced the incurred loss model with an expected loss model, which is referred to as the current expected credit loss (“CECL”) model. The CECL model is applicable to the measurement of credit losses on financial assets measured at amortized cost, including but not limited to trade receivables. For public business entities, the new standard became effective for annual reporting periods beginning after December 15, 2019, including interim periods within that reporting period. From an evaluation of the Company’s existing credit portfolio, which includes trade receivables from commodity sales, joint interest billings due from partners and other receivables and cash equivalents, historical credit losses have been de minimis and are expected to remain so in the future assuming no substantial changes to the business or creditworthiness of our business counterparties. Update 2016-13 did not have a significant impact on the Company’s consolidated financial statements or related control environment upon adoption on January 1, 2020. Issued but Not Yet Adopted In August 2018, the FASB issued ASU 2018-14, Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans (“ASU 2018-14”). This ASU amends, adds and removes certain disclosure requirements under FASB ASC Topic 715 – Compensation-Retirement Benefits. The guidance in ASU 2018-14 is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. This ASU will result in expanded disclosures within the Company’s interim and annual footnote disclosures, however, the adoption of ASU 2018-14 is not expected to have a material impact on the Company’s consolidated financial statements.

New Accounting Pronouncements (

New Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
New Accounting Standards Implemented/New Accounting Standards Not Yet Implemented	In August 2018, the FASB issued Accounting Standards Update No. 2018-13, Fair Value Measurement (ASC 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurements (“ASU 2018-13”), which modifies the disclosure requirements on fair value measurements. ASU 2018-13 became effective for public business entities for annual and interim periods in fiscal years beginning after December 15, 2019. As a result of adoption, this standard did not have a material impact on the Company’s consolidated financial statements. In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“Update 2016-13”). Update 2016-13 replaced the incurred loss model with an expected loss model, which is referred to as the current expected credit loss (“CECL”) model. The CECL model is applicable to the measurement of credit losses on financial assets measured at amortized cost, including but not limited to trade receivables. For public business entities, the new standard became effective for annual reporting periods beginning after December 15, 2019, including interim periods within that reporting period. From an evaluation of the Company’s existing credit portfolio, which includes trade receivables from commodity sales, joint interest billings due from partners and other receivables and cash equivalents, historical credit losses have been de minimis and are expected to remain so in the future assuming no substantial changes to the business or creditworthiness of our business counterparties. Update 2016-13 did not have a significant impact on the Company’s consolidated financial statements or related control environment upon adoption on January 1, 2020. Issued but Not Yet Adopted In August 2018, the FASB issued ASU 2018-14, Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans (“ASU 2018-14”). This ASU amends, adds and removes certain disclosure requirements under FASB ASC Topic 715 – Compensation-Retirement Benefits. The guidance in ASU 2018-14 is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. This ASU will result in expanded disclosures within the Company’s interim and annual footnote disclosures, however, the adoption of ASU 2018-14 is not expected to have a material impact on the Company’s consolidated financial statements.

Restructuring Charges (Tables)

Restructuring Charges (Tables)	9 Months Ended
	Sep. 30, 2020
Restructuring and Related Activities [Abstract]
Summary of Restructuring Charges	The following table presents a summary of the restructuring charges included in Operating Income (Loss) for the three and nine months ended September 30, 2020 and 2019: For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Severance (including payroll taxes) $ — $ 1 $ 12 $ 4 Office consolidation — 3 — 5 Total restructuring charges (1) $ — $ 4 $ 12 $ 9 (1) Total restructuring charges were $12 million for the Company’s E&P segment for the nine months ended September 30, 2020, and $4 million and $9 million for the three and nine months ended September 30, 2019, respectively. The following table presents a reconciliation of the liability associated with the Company’s restructuring activities at September 30, 2020, which is reflected in accounts payable on the consolidated balance sheet: (in millions) Liability at December 31, 2019 $ 2 Additions 12 Distributions (14) Liability at September 30, 2020 $ —

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue by Segment	The following table reconciles operating revenues as presented on the consolidated statements of operations to the operating revenues by segment: (in millions) E&P Marketing Intersegment Total Three months ended September 30, 2020 Gas sales $ 190 $ — $ 9 $ 199 Oil sales 39 — 1 40 NGL sales 68 — — 68 Marketing — 495 (276) 219 Other 1 — — 1 Total $ 298 $ 495 $ (266) $ 527 Three months ended September 30, 2019 Gas sales $ 230 $ — $ 8 $ 238 Oil sales 66 — 1 67 NGL sales 52 — — 52 Marketing — 592 (313) 279 Total $ 348 $ 592 $ (304) $ 636 (in millions) E&P Marketing Intersegment Total Nine months ended September 30, 2020 Gas sales $ 584 $ — $ 27 $ 611 Oil sales 107 — 4 111 NGL sales 158 — — 158 Marketing — 1,432 (787) 645 Other (1) 4 — — 4 Total $ 853 $ 1,432 $ (756) $ 1,529 Nine months ended September 30, 2019 Gas sales $ 918 $ — $ 25 $ 943 Oil sales 151 — 2 153 NGL sales 191 — — 191 Marketing — 2,158 (1,154) 1,004 Other (2) 1 1 — 2 Total $ 1,261 $ 2,159 $ (1,127) $ 2,293 (1) For the nine months ended September 30, 2020, other E&P revenues consists primarily of gains on purchaser imbalances associated with certain NGLs. (2) For the nine months ended September 30, 2019, other E&P revenues consists primarily of water sales to third-party operators, and other Marketing revenues consists primarily of sales of gas from storage.
Disaggregation of Revenue on Geographic Basis	Associated E&P revenues are also disaggregated for analysis on a geographic basis by the core areas in which the Company operates, which are in Pennsylvania and West Virginia. For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Northeast Appalachia $ 131 $ 175 $ 443 $ 740 Southwest Appalachia 166 173 409 519 Other 1 — 1 2 Total $ 298 $ 348 $ 853 $ 1,261
Reconciliation of Accounts Receivable	The following table reconciles the Company’s receivables from contracts with customers to consolidated accounts receivable as presented on the consolidated balance sheet: (in millions) September 30, 2020 December 31, 2019 Receivables from contracts with customers $ 218 $ 284 Other accounts receivable 21 61 Total accounts receivable $ 239 $ 345

Cash and Cash Equivalents (Tabl

Cash and Cash Equivalents (Tables)	9 Months Ended
	Sep. 30, 2020
Cash and Cash Equivalents [Abstract]
Summary of Cash and Cash Equivalents	The following table presents a summary of cash and cash equivalents as of September 30, 2020 and December 31, 2019: (in millions) September 30, 2020 December 31, 2019 Cash $ 93 $ 5 Marketable securities (1) 2 — Total $ 95 $ 5 (1) Consists of government stable value money market funds.

Natural Gas and Oil Properties

Natural Gas and Oil Properties (Tables)	9 Months Ended
	Sep. 30, 2020
Oil and Gas Exploration and Production Industries Disclosures [Abstract]
Oil and Gas Exploration and Production Industries Disclosures	Prices used to calculate the ceiling value of reserves were as follows: September 30, 2020 September 30, 2019 Natural gas (per MMBtu) $ 1.97 $ 2.87 Oil (per Bbl) $ 43.40 $ 57.77 NGLs (per Bbl) $ 9.26 $ 12.59

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share	The following table presents the computation of earnings per share for the three and nine months ended September 30, 2020 and 2019:  For the three months ended September 30, For the nine months ended September 30, (in millions, except share/per share amounts) 2020 2019 2020 2019 Net income (loss) $ (593) $ 49 $ (3,020) $ 781  Number of common shares: Weighted average outstanding 571,872,413 539,221,101 551,162,559 539,315,170 Issued upon assumed exercise of outstanding stock options — — — — Effect of issuance of non-vested restricted common stock — 187,706 — 400,120 Effect of issuance of non-vested restricted units — — — — Effect of issuance of non-vested performance units — 629,380 — 727,359 Weighted average and potential dilutive outstanding 571,872,413 540,038,187 551,162,559 540,442,649  Earnings per common share Basic $ (1.04) $ 0.09 $ (5.48) $ 1.45 Diluted $ (1.04) $ 0.09 $ (5.48) $ 1.44
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table presents the common stock shares equivalent excluded from the calculation of diluted earnings per share for the three and nine months ended September 30, 2020 and 2019, as they would have had an antidilutive effect:  For the three months ended September 30, For the nine months ended September 30,  2020 2019 2020 2019 Unexercised stock options 4,425,886 5,102,882 4,519,385 5,115,334 Unvested share-based payment 939,941 2,136,453 946,547 1,797,963 Restricted stock units 1,935,781 — 2,001,621 — Performance units 2,282,211 240,450 2,027,985 247,443 Total 9,583,819 7,479,785 9,495,538 7,160,740

Derivatives and Risk Manageme_2

Derivatives and Risk Management (Tables)	9 Months Ended
	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments Notional Amount, Weighted Average Contract Prices and Fair Value	The following tables provide information about the Company’s financial instruments that are sensitive to changes in commodity prices and that are used to protect the Company’s exposure. None of the financial instruments below are designated for hedge accounting treatment. The tables present the notional amount, the weighted average contract prices and the fair value by expected maturity dates as of September 30, 2020: Financial Protection on Production  Weighted Average Price per MMBtu  Volume (Bcf) Swaps Sold Puts Purchased Puts Sold Calls Basis Differential Fair Value at September 30, 2020 (in millions) Natural Gas 2020 Fixed price swaps 91 $ 2.46 $ — $ — $ — $ — $ 16 (1) Two-way costless collars 57 — — 2.45 2.75 — (7) Three-way costless collars 25 — 2.19 2.58 2.96 — (11) (2) Total 173 $ (2) 2021 Fixed price swaps 93 $ 2.67 $ — $ — $ — $ — $ (13) Two-way costless collars 166 — — 2.51 2.89 — (27) Three-way costless collars 291 — 2.16 2.49 2.84 — (113) (3) Total 550 $ (153) 2022 Fixed price swaps 37 $ 2.75 $ — $ — $ — $ — $ (2) Two-way costless collars 32 — — 2.17 2.88 — (5) Three-way costless collars 116 — 2.07 2.44 2.87 — (24) Total 185 $ (31) 2023 Three-way costless collars 25 $ — $ 2.07 $ 2.48 $ 3.18 $ — $ (2) Basis Swaps 2020 66 $ — $ — $ — $ — $ (0.37) $ 21 2021 155 — — — — (0.12) 21 2022 127 — — — — (0.38) 4 Total 348 $ 46 (1) Includes $1 million in premiums paid related to certain natural gas fixed price swaps recognized as a component of derivative assets within current assets on the consolidated balance sheet at September 30, 2020. As certain natural gas fixed price swaps settle, the premium will be amortized and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. (2) Includes $2 million in deferred premiums related to certain natural gas three-way costless collars recognized as a component of derivative liabilities within current liabilities on the consolidated balance sheet at September 30, 2020. As certain three-way costless collars settle, the premium will be paid and recognized as a component of gain (loss) on derivatives on the consolidated statement of operations. (3) Includes $1 million in deferred premiums related to certain natural gas three-way costless collars recognized as a component of derivative liabilities within current liabilities on the consolidated balance sheet at September 30, 2020. As certain three-way costless collars settle, the premium will be paid and recognized as a component of gain (loss) on derivatives on the consolidated statement of operations.  Volume (MBbls) Weighted Average Strike Price per Bbl Fair Value at September 30, 2020 (in millions) Swaps Sold Puts Purchased Puts Sold Calls Oil 2020 Fixed price swaps (1) 584 $ 75.44 $ — $ — $ — $ 20 Two-way costless collars 261 — — 56.76 59.75 4 Three-way costless collars 404 — 43.71 52.85 57.78 3 Total 1,249 $ 27 2021 Fixed price swaps 2,574 $ 52.84 $ — $ — $ — $ 27 Three-way costless collars 1,445 — 43.52 53.25 58.14 8 Total 4,019 $ 35 2022 Fixed price swaps 762 $ 48.85 $ — $ — $ — $ 4 Three-way costless collars 666 — 42.50 53.20 58.00 2 Total 1,428 $ 6 2023 Three-way costless collars 111 $ — $ 30.00 $ 40.00 $ 57.85 $ — Ethane 2020 Fixed price swaps 2,629 $ 8.62 $ — $ — $ — $ — 2021 Fixed price swaps 5,889 $ 7.12 $ — $ — $ — $ (12) Two-way costless collar 584 — — 7.14 10.40 — Total 6,473 $ (12) 2022 Fixed price swaps 190 $ 7.41 $ — $ — $ — $ — Two-way costless collar 135 — — 7.56 9.66 — Total 325 $ — Propane 2020 Fixed price swaps 1,435 $ 23.11 $ — $ — $ — $ 2 Two-way costless collars 92 — — 25.20 29.40 — Total 1,527 $ 2 2021 Fixed price swaps 4,298 $ 19.99 $ — $ — $ — $ (3) 2022 Fixed price swaps 156 $ 19.25 $ — $ — $ — $ — Normal Butane 2020 Fixed price swaps 195 $ 22.44 $ — $ — $ — $ — Natural Gasoline 2020 Fixed price swaps 184 $ 34.59 $ — $ — $ — $ — (1) Includes 448 MBbls of purchased fixed price oil swaps at $33.94 per barrel with a fair value of $3 million and 1,032 MBbls of sold fixed price oil swaps at $57.44 per barrel with a fair value of $17 million. Other Derivative Contracts  Volume (Bcf) Weighted Average Strike Price per MMBtu Fair Value at September 30, 2020 (in millions) Call Options – Natural Gas (Net) 2020 6 $ 3.15 $ (2) 2021 57 3.15 (17) 2022 58 3.00 (15) 2023 17 2.84 (4) 2024 9 3.00 (2) Total 147 $ (40) ໿ Volume (MBbls) Weighted Average Strike Price per Bbl Fair Value at September 30, 2020 (in millions) Call Options – Oil 2021 226 $ 60.00 $ — Volume (Bcf) Weighted Average Strike Price per MMBtu Fair Value at September 30, 2020 (in millions)  Swaps Basis Differential Storage (1) 2020 Purchased fixed price swaps 1 $ 1.94 $ — $ — Purchased basis swaps — — (0.63) — Fixed price swaps — 2.09 — — Basis swaps — — (0.70) — Total 1 $ — 2021 Purchased fixed price swaps 1 $ 2.04 $ — $ — Fixed price swaps 2 2.49 — (1) Basis swaps 1 — (0.38) — Total 4 $ (1) (1) The Company has entered into certain derivatives to protect the value of volumes of natural gas injected into a storage facility that will be withdrawn and sold at a later date. Purchased Fixed Price Swaps – Marketing (Natural Gas) (1) Volume (Bcf) Weighted Average Strike Price per MMBtu Fair Value at September 30, 2020 (in millions) 2020 2 $ 2.44 $ — 2021 6 2.44 3 Total 8 $ 3 (1) The Company has entered into a limited number of derivatives to protect the value of certain long-term sales contracts.
Balance Sheet Classification of Derivative Financial Instruments	The balance sheet classification of the assets and liabilities related to derivative financial instruments (none of which are designated for hedge accounting treatment) is summarized below as of September 30, 2020 and December 31, 2019: Derivative Assets  Fair Value (in millions) Balance Sheet Classification September 30, 2020 December 31, 2019 Derivatives not designated as hedging instruments: Purchased fixed price swaps – natural gas Derivative assets $ 3 $ — Fixed price swaps – natural gas Derivative assets 21 (1) 77 (1) Fixed price swaps – oil Derivative assets 42 4 Fixed price swaps – ethane Derivative assets 2 11 Fixed price swaps – propane Derivative assets 5 21 Two-way costless collars – natural gas Derivative assets 27 10 Two-way costless collars – oil Derivative assets 6 5 Two-way costless collars – propane Derivative assets — 2 Three-way costless collars – natural gas Derivative assets 64 (2) 126 Three-way costless collars – oil Derivative assets 19 3 Basis swaps – natural gas Derivative assets 40 17 Call options – natural gas Derivative assets 9 1 Fixed price swaps – natural gas storage Derivative assets — 1 Fixed price swaps – natural gas Other long-term assets 1 7 Fixed price swaps – oil Other long-term assets 10 1 Fixed price swaps – propane Other long-term assets 1 3 Two-way costless collars – natural gas Other long-term assets 13 4 Three-way costless collars – natural gas Other long-term assets 56 74 Three-way costless collars – oil Other long-term assets 14 7 Basis swaps – natural gas Other long-term assets 13 15 Call options – natural gas Other long-term assets 4 2 Total derivative assets $ 350 $ 391 (1) Includes $1 million and $9 million at September 30, 2020 and December 31, 2019, respectively, in premiums paid related to certain natural gas fixed price swaps recognized as a component of derivative assets within current assets on the consolidated balance sheet. As certain natural gas fixed price swaps settle, the premium will be amortized and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. (2) Includes $3 million as of September 30, 2020 in deferred premiums related to certain natural gas three-way costless collars recognized as a component of derivative liabilities within current liabilities on the consolidated balance sheet. As certain natural gas three-way costless collars settle, the premium will be paid and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. Derivative Liabilities  Fair Value (in millions) Balance Sheet Classification September 30, 2020 December 31, 2019 Derivatives not designated as hedging instruments: Purchased fixed price swaps – natural gas Derivative liabilities $ — $ 1 Fixed price swaps – natural gas Derivative liabilities 15 1 Fixed price swaps – oil Derivative liabilities 1 6 Fixed price swaps – ethane Derivative liabilities 10 — Fixed price swaps – propane Derivative liabilities 5 — Two-way costless collars – natural gas Derivative liabilities 52 4 Two-way costless collars – oil Derivative liabilities 2 5 Three-way costless collars – natural gas Derivative liabilities 164 84 Three-way costless collars – oil Derivative liabilities 10 4 Basis swaps – natural gas Derivative liabilities 3 17 Call options – natural gas Derivative liabilities 24 3 Fixed price swaps – natural gas storage Derivative liabilities 1 — Fixed price swaps – natural gas Long-term derivative liabilities 6 — Fixed price swaps – oil Long-term derivative liabilities — 2 Fixed price swaps – ethane Long-term derivative liabilities 4 — Fixed price swaps – propane Long-term derivative liabilities 2 — Two-way costless collars – natural gas Long-term derivative liabilities 27 4 Three-way costless collars – natural gas Long-term derivative liabilities 106 72 Three-way costless collars – oil Long-term derivative liabilities 10 8 Basis swap – natural gas Long-term derivative liabilities 4 9 Call options – natural gas Long-term derivative liabilities 29 15 Call options – oil Long-term derivative liabilities — 1 Total derivative liabilities $ 475 $ 236
Summary of Before Tax Effect of Fair Value Hedges not Designated for Hedge Accounting	The following tables summarize the before-tax effect of the Company’s derivative instruments on the consolidated statements of operations for the three and nine months ended September 30, 2020 and 2019: Unsettled Gain (Loss) on Derivatives Recognized in Earnings Consolidated statement of Operations Classification of Gain (Loss) on Derivatives, Unsettled For the three months ended September 30, For the nine months ended September 30, Derivative Instrument 2020 2019 2020 2019 (in millions) Purchased fixed price swaps – natural gas Gain (Loss) on Derivatives $ 4 $ — $ 4 $ — Fixed price swaps – natural gas Gain (Loss) on Derivatives (138) (19) (74) 36 Fixed price swaps – oil Gain (Loss) on Derivatives (20) 8 54 5 Fixed price swaps – ethane Gain (Loss) on Derivatives (13) 1 (23) 8 Fixed price swaps – propane Gain (Loss) on Derivatives (17) 10 (25) 19 Two-way costless collars – natural gas Gain (Loss) on Derivatives (34) (11) (45) (2) Two-way costless collars – oil Gain (Loss) on Derivatives (5) — 4 (3) Two-way costless collars – propane Gain (Loss) on Derivatives (1) 1 (2) 3 Three-way costless collars – natural gas Gain (Loss) on Derivatives (98) (1) 3 (194) (1) 27 Three-way costless collars – oil Gain (Loss) on Derivatives (4) 3 15 4 Basis swaps – natural gas Gain (Loss) on Derivatives 54 12 40 6 Call options – natural gas Gain (Loss) on Derivatives (16) 1 (25) 5 Call options – oil Gain (Loss) on Derivatives — — 1 — Purchased fixed price swap – natural gas storage Gain (Loss) on Derivatives 1 — — — Fixed price swap – natural gas storage Gain (Loss) on Derivatives (2) 2 (2) 1 Interest rate swaps Gain (Loss) on Derivatives — 1 — (1) Total gain (loss) on unsettled derivatives $ (289) $ 12 $ (272) $ 108 Settled Gain (Loss) on Derivatives Recognized in Earnings (2) Consolidated statement of Operations Classification of Gain (Loss) on Derivatives, Settled For the three months ended September 30, For the nine months ended September 30, Derivative Instrument 2020 2019 2020 2019 (in millions) Purchased fixed price swaps – natural gas Gain (Loss) on Derivatives $ (2) $ — $ (4) $ — Fixed price swaps – natural gas Gain (Loss) on Derivatives 61 (3) 45 150 (3) 53 Fixed price swaps – oil Gain (Loss) on Derivatives 17 3 44 5 Fixed price swaps – ethane Gain (Loss) on Derivatives (2) 6 6 12 Fixed price swaps – propane Gain (Loss) on Derivatives 2 11 19 20 Two-way costless collars – natural gas Gain (Loss) on Derivatives (5) 10 1 12 Two-way costless collars – oil Gain (Loss) on Derivatives 4 2 13 4 Two-way costless collars – propane Gain (Loss) on Derivatives — 1 2 1 Three-way costless collars – natural gas Gain (Loss) on Derivatives — 15 43 19 Three-way costless collars – oil Gain (Loss) on Derivatives 1 — 5 — Basis swaps – natural gas Gain (Loss) on Derivatives 20 (3) 29 (11) Call options – natural gas Gain (Loss) on Derivatives — (1) (4) — (2) (4) Fixed price swaps – natural gas storage Gain (Loss) on Derivatives 1 (1) 2 (1) Total gain on settled derivatives $ 97 $ 88 $ 310 $ 112 Total gain (loss) on derivatives $ (192) $ 100 $ 38 $ 220 (1) Includes $3 million in delayed premiums related to certain natural gas three-way costless collars for the three and nine months ended September 30, 2020, respectively, which is included in gain (loss) on derivatives on the consolidated statements of operations. (2) The Company calculates gain (loss) on derivatives, settled, as the summation of gains and losses on positions that settled within the period. (3) Includes $4 million and $8 million amortization of premiums paid related to certain natural gas fixed price options for the three and nine months ended September 30, 2020, respectively, which is included in gain (loss) on derivatives on the consolidated statements of operations. (4) Includes $1 million amortization of premiums paid related to certain natural gas purchased call options for the three and nine months ended September 30, 2019, which is included in gain (loss) on derivatives on the consolidated statements of operations.

Reclassifications from Accumu_2

Reclassifications from Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Components of Accumulated Other Comprehensive Income (Loss)	The following tables detail the components of accumulated other comprehensive income and the related tax effects for the nine months ended September 30, 2020: (in millions) Pension and Other Postretirement Foreign Currency Total Beginning balance December 31, 2019 $ (19) $ (14) $ (33) Other comprehensive income before reclassifications — — — Amounts reclassified from other comprehensive income (1) 1 — 1 Net current-period other comprehensive income 1 — 1 Ending balance September 30, 2020 $ (18) $ (14) $ (32)
Reclassification out of Accumulated Other Comprehensive Income	Details about Accumulated Other Comprehensive Income Affected Line Item in the Consolidated Statement of Operations Amount Reclassified from Accumulated Other Comprehensive Income For the nine months ended (in millions) Pension and other postretirement: Amortization of prior service cost and net gain (1) Other Income (Loss), Net $ 1 Provision (Benefit) for Income Taxes — Net Income (Loss) $ 1 Total reclassifications for the period Net Income (Loss) $ 1 (1) See Note 1 4 for additional details regarding the Company’s pension and other postretirement benefit plans.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Carrying Amount and Estimated Fair Values of Financial Instruments	The carrying amounts and estimated fair values of the Company’s financial instruments as of September 30, 2020 and December 31, 2019 were as follows:  September 30, 2020 December 31, 2019 (in millions) Carrying Fair Carrying Fair Cash and cash equivalents $ 95 $ 95 $ 5 $ 5 2018 revolving credit facility due April 2024 — — 34 34 Senior notes (1) 2,471 2,429 2,228 2,085 Derivative instruments, net (125) (2) (125) (2) 155 (2) 155 (2) (1) Excludes unamortized debt issuance costs and debt discounts.
Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are summarized below:  September 30, 2020  Fair Value Measurements Using: (in millions) Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets (Liabilities) at Fair Value Assets Purchased fixed price swaps $ — $ 3 $ — $ 3 Fixed price swaps (1) — 82 — 82 Two-way costless collars — 46 — 46 Three-way costless collars (2) — 153 — 153 Basis swaps — 53 — 53 Call options — 13 — 13 Liabilities Fixed price swaps — (43) — (43) Two-way costless collars — (81) — (81) Three-way costless collars — (290) — (290) Basis swaps — (7) — (7) Call options — (53) — (53) Fixed price swaps – storage — (1) — (1) Total (3) $ — $ (125) $ — $ (125) (1) Includes $1 million in premiums paid related to certain natural gas fixed price swaps recognized as a component of derivative assets within current assets on the consolidated balance sheet at September 30, 2020. As certain natural gas fixed price swaps settle, the premium will be amortized and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. (2) Includes $3 million in deferred premiums related to certain natural gas three-way costless collars recognized as a component of derivative liabilities within current liabilities on the consolidated balance sheet as of September 30, 2020. As certain natural gas three-way costless collars settle, the premium will be paid and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations. (3) Includes a net reduction to the liability fair value of $1 million related to estimated nonperformance risk.  December 31, 2019  Fair Value Measurements Using: (in millions) Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets (Liabilities) at Fair Value Assets Fixed price swaps (1) $ — $ 124 $ — $ 124 Two-way costless collars — 21 — 21 Three-way costless collars — 210 — 210 Basis swaps — 32 — 32 Call options — 3 — 3 Fixed price swaps - storage — 1 — 1 Liabilities Purchased fixed price swaps — (1) — (1) Fixed price swaps — (9) — (9) Two-way costless collars — (13) — (13) Three-way costless collars — (168) — (168) Basis swaps — (26) — (26) Call options — (19) — (19) Total $ — $ 155 $ — $ 155 (1) Includes $9 million in premiums paid related to certain natural gas fixed price swaps recognized as a component of derivative assets within current assets on the consolidated balance sheet at December 31, 2019. As certain natural gas fixed price swaps settle, the premium will be amortized and recognized as a component of gain (loss) on derivatives on the consolidated statements of operations.

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Components of Debt	The components of debt as of September 30, 2020 and December 31, 2019 consisted of the following: September 30, 2020 (in millions) Debt Instrument Unamortized Issuance Expense Unamortized Debt Discount Total Long-term debt: Variable rate (1.60% at September 30, 2020) 2018 revolving credit facility due April 2024 $ — $ — (1) $ — $ — 4.10% Senior Notes due March 2022 207 — — 207 4.95% Senior Notes due January 2025 (2) 856 (4) (1) 851 7.50% Senior Notes due April 2026 618 (6) — 612 7.75% Senior Notes due October 2027 440 (5) — 435 8.375% Senior Notes due September 2028 (3) 350 (5) — 345 Total long-term debt $ 2,471 $ (20) $ (1) $ 2,450 December 31, 2019 (in millions) Debt Instrument Unamortized Issuance Expense Unamortized Debt Discount Total Long-term debt: Variable rate (4.310% at December 31, 2019) 2018 term loan facility due April 2024 $ 34 $ — (1) $ — $ 34 4.10% Senior Notes due March 2022 213 (1) — 212 4.95% Senior Notes due January 2025 (2) 892 (5) (1) 886 7.50% Senior Notes due April 2026 639 (7) — 632 7.75% Senior Notes due October 2027 484 (6) — 478 Total long-term debt $ 2,262 $ (19) $ (1) $ 2,242 (1) At September 30, 2020 and December 31, 2019, unamortized issuance expense of $10 million and $11 million, respectively, associated with the 2018 credit facility (as defined below) was classified as other long-term assets on the consolidated balance sheets. (2) Effective in July 2018, the interest rate was 6.20% for the 2025 Notes, reflecting a net downgrade in the Company’s bond ratings since the initial offering. On April 7, 2020, S&P downgraded the Company’s bond rating to BB-, which had the effect of increasing the interest rate on the 2025 Notes to 6.45% following the July 23, 2020 interest payment date. The first coupon payment to the bondholders at the higher interest rate will be paid in January 2021. (3) The $350 million of Senior Notes due 2028 are subject to special mandatory redemption if the Montage Merger does not close on or prior to February 12, 2021.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Obligation under Transportation Agreements	As of September 30, 2020, future payments under non-cancelable firm transportation and gathering agreements were as follows:  Payments Due by Period (in millions) Total Less than 1 1 to 3 Years 3 to 5 Years 5 to 8 Years More than 8 Infrastructure currently in service $ 6,704 $ 582 $ 1,308 $ 1,078 $ 1,411 $ 2,325 Pending regulatory approval and/or construction (1) 405 3 9 23 52 318 Total transportation charges $ 7,109 $ 585 $ 1,317 $ 1,101 $ 1,463 $ 2,643 (1) Based on estimated in-service dates as of September 30, 2020.

Pension Plan and Other Postre_2

Pension Plan and Other Postretirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2020
Retirement Benefits [Abstract]
Pension and Other Postretirement Benefit Costs	The Company maintains defined pension and other postretirement benefit plans, which cover substantially all of the Company’s employees. Net periodic pension costs include the following components for the three and nine months ended September 30, 2020 and 2019:  Consolidated Statements of For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Service cost General and administrative expenses $ 2 $ 1 $ 6 $ 5 Interest cost Other Income (Loss), Net 1 2 3 4 Expected return on plan assets Other Income (Loss), Net (2) (1) (5) (4) Amortization of prior service cost Other Income (Loss), Net — — — — Amortization of net loss Other Income (Loss), Net 1 — 1 1 Settlement loss Other Income (Loss), Net — 1 — 5 Net periodic benefit cost $ 2 $ 3 $ 5 $ 11

Long-term Incentive Compensat_2

Long-term Incentive Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement, Noncash Expense [Abstract]
Schedule of Stock-Based Compensation Costs	The Company recognized the following amounts in total employee stock-based compensation costs for the three and nine months ended September 30, 2020 and 2019:  For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Stock-based compensation cost – expensed $ 2 $ 1 $ 8 $ 12 Stock-based compensation cost – capitalized 2 1 3 7
Schedule of Equity-Classified Stock-Based Compensation Costs	The Company recognized the following amounts in employee equity-classified stock-based compensation costs for the three and nine months ended September 30, 2020 and 2019:  For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Equity-classified awards – expensed $ — $ 2 $ 2 $ 6 Equity-classified awards – capitalized 1 1 1 3
Summary of Equity-Classified Stock Option Activity	The following table summarizes equity-classified stock option activity for the nine months ended September 30, 2020 and provides information for options outstanding and options exercisable as of September 30, 2020:  Number Weighted Average  (in thousands) Outstanding at December 31, 2019 4,635 $ 15.26 Granted — $ — Exercised — $ — Forfeited or expired (357) $ 7.06 Outstanding at September 30, 2020 4,278 $ 15.95 Exercisable at September 30, 2020 4,278 $ 15.95
Summary of Equity-Classified Restricted Stock Activity	The following table summarizes equity-classified restricted stock activity for the nine months ended September 30, 2020 and provides information for unvested shares as of September 30, 2020:  Number Weighted Average  (in thousands) Unvested shares at December 31, 2019 1,480 $ 7.00 Granted 570 $ 2.88 Vested (1,083) $ 5.30 Forfeited (246) $ 7.71 Unvested shares at September 30, 2020 721 $ 6.05
Summary of Equity-Classified Performance Units Activity	The following table summarizes equity-classified performance unit activity for the nine months ended September 30, 2020 and provides information for unvested units as of September 30, 2020. The performance unit awards granted in 2018 include a market condition based exclusively on the Total Shareholder Return (“TSR”), with their fair value calculated by a Monte Carlo model. The total fair value of the performance units is amortized to compensation expense on a straight line basis over the vesting period of the award. The grant date fair value is calculated using the closing price of the Company’s common stock at the grant date.  Number of Units (1) Weighted Average  (in thousands) Unvested units at December 31, 2019 178 $ 10.47 Granted — $ — Vested (178) $ 10.47 Forfeited — $ — Unvested units at September 30, 2020 — $ — (1) The actual payout of shares may range from a minimum of zero shares to a maximum of two shares per unit contingent upon TSR. The performance units have a three-year vesting term and the actual disbursement of shares, if any, is determined during the first quarter following the end of the three-year vesting period.
Schedule of Liability-Classified Stock-Based Compensation Costs	The Company recognized the following amounts in employee liability-classified stock-based compensation costs for the three and nine months ended September 30, 2020:  For the three months ended September 30, For the nine months ended September 30, (in millions) 2020 2019 2020 2019 Liability-classified stock-based compensation cost – expensed $ 2 $ (1) $ 6 $ 6 Liability-classified stock-based compensation cost – capitalized 1 — 2 4
Summary of Liability-Classified Restricted Stock Unit Activity	As of September 30, 2020, there was $21 million of total unrecognized compensation cost related to liability-classified restricted stock units that is expected to be recognized over a weighted-average period of 2.5 years. The amount of unrecognized compensation cost for liability-classified awards will fluctuate over time as they are marked to market.  Number Weighted Average  (in thousands) Unvested units at December 31, 2019 12,992 $ 2.42 Granted 6,172 $ 1.41 Vested (3,946) $ 1.42 Forfeited (3,060) $ 1.53 Unvested units at September 30, 2020 12,158 $ 2.17
Summary of Liability-Classified Performance Unit Activity	 Number Weighted Average  (in thousands) Unvested units at December 31, 2019 5,142 $ 2.42 Granted 6,172 $ 1.41 Vested — $ — Forfeited (2,300) $ 3.06 Unvested units at September 30, 2020 9,014 $ 2.10
Summary of Liability-Classified Performance Unit Activity	Number Weighted Average Fair Value (in thousands) Unvested units at December 31, 2019 — $ — Granted 20,044 $ 1.00 Vested (100) $ 1.00 Forfeited (729) $ 1.00 Unvested units at September 30, 2020 19,215 $ 1.00

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Summary of Financial Information for Company's Reportable Segments	Summarized financial information for the Company’s reportable segments is shown in the following table. The accounting policies of the segments are the same as those described in Note 1 of the Notes to Consolidated Financial Statements included in Item 8 of the 2019 Annual Report. Management evaluates the performance of its segments based on operating income, defined as operating revenues less operating costs. Income before income taxes, for the purpose of reconciling the operating income amount shown below to consolidated income before income taxes, is the sum of operating income, interest expense, gain (loss) on derivatives, gain on early extinguishment of debt and other income (loss). The “Other” column includes items not related to the Company’s reportable segments, including real estate and corporate items. Corporate general and administrative costs, depreciation expense and taxes, other than income taxes, are allocated to the segments. E&P Marketing Other Total (in millions) Three months ended September 30, 2020 Revenues from external customers $ 308 $ 219 $ — $ 527 Intersegment revenues (10) 276 — 266 Depreciation, depletion and amortization expense 68 2 — 70 Impairments 361 — — 361 Operating loss (379) (1) (2) — (381) Interest expense (2) 22 — — 22 Loss on derivatives (192) — — (192) Other income, net 2 — — 2 Assets 3,705 (3) 240 212 (4) 4,157 Capital investments (5) 223 — — 223 Three months ended September 30, 2019 Revenues from external customers $ 357 $ 279 $ — $ 636 Intersegment revenues (9) 313 — 304 Depreciation, depletion and amortization expense 123 2 — 125 Impairments — 2 — 2 Operating loss (21) (1) (8) — (29) Interest expense (2) 17 — — 17 Gain on derivatives 100 — — 100 Gain on early extinguishment of debt — — 7 7 Other income (loss), net (4) — 2 (2) Provision for income taxes (2) 10 — — 10 Assets 6,099 (3) 272 227 (4) 6,598 Capital investments (5) 239 — 1 240 E&P Marketing Other Total Nine months ended September 30, 2020 (in millions) Revenues from external customers $ 884 $ 645 $ — $ 1,529 Intersegment revenues (31) 787 — 756 Depreciation, depletion and amortization expense 260 7 — 267 Impairments 2,495 — — 2,495 Operating loss (2,613) (1) (14) — (2,627) Interest expense (2) 63 — — 63 Gain on derivatives 38 — — 38 Gain on early extinguishment of debt — — 35 35 Other income, net 2 — 1 3 Provision for income taxes (2) 406 — — 406 Assets 3,705 (3) 240 212 (4) 4,157 Capital investments (5) 705 — — 705 Nine months ended September 30, 2019 Revenues from external customers $ 1,288 $ 1,005 $ — $ 2,293 Intersegment revenues (27) 1,154 — 1,127 Depreciation, depletion and amortization expense 345 7 — 352 Impairments 6 2 — 8 Operating income (loss) 219 (1) (13) — 206 Interest expense (2) 46 — — 46 Gain on derivatives 220 — — 220 Gain on early extinguishment of debt — — 7 7 Other income (loss), net (8) — 1 (7) Benefit from income taxes (2) (401) — — (401) Assets 6,099 (3) 272 227 (4) 6,598 Capital investments (5) 931 — 2 933 (1) Operating income (loss) for the E&P segment includes $4 million of restructuring charges for the three months ended September 30, 2019 and $12 million and $9 million of restructuring charges for the nine months ended September 30, 2020 and 2019, respectively. The E&P segment operating income (loss) also includes $3 million for the three and nine months ended September 30, 2020 related to acquisition-related charges. (2) Interest expense and provision (benefit) for income taxes by segment is an allocation of corporate amounts as they are incurred at the corporate level. (3) E&P assets includes office, technology, water infrastructure, drilling rigs and other ancillary equipment not directly related to natural gas and oil properties. E&P assets also includes deferred tax assets which are an allocation of corporate amounts as they are incurred at the corporate level. (4) Other assets represent corporate assets not allocated to segments and assets for non-reportable segments. At September 30, 2020 and 2019, other assets included approximately $95 million and $29 million, respectively, in cash and cash equivalents, $74 million and $84 million in right-of-use lease assets, respectively, $18 million and $31 million, respectively, in property, plant and equipment, $10 million and $9 million, respectively, in unamortized debt expense, $5 million and $7 million, respectively, in a non-qualified retirement plan and $3 million and $7 million in prepayments, respectively. Additionally, the September 30, 2019 other asset balance includes $61 million in income taxes receivable and the September 30, 2020 other asset balance includes $7 million in account receivable assets.

Basis of Presentation (Narrativ

Basis of Presentation (Narrative) (Details)	9 Months Ended
	Sep. 30, 2020segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of segments	2

Acquisition (Details)

Acquisition (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 12, 2020	Aug. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Transaction related expneses			$ 3	$ 0	$ 3	$ 0
8.375% Senior Notes due September 2028 (3) | Senior Notes
Business Acquisition [Line Items]
Senior notes		$ 350
Stated interest rate			8.375%		8.375%
Proceeds from issuance of long-term debt		$ 345
Montage Resources Corporation | Eight Point Eight Seven Five Percent Senior Notes Due 2023 | Senior Notes
Business Acquisition [Line Items]
Senior notes			$ 510		$ 510
Stated interest rate			8.875%		8.875%
Montage Resources Corporation
Business Acquisition [Line Items]
Number of Southwestern Energy common stock for each share of Montage Resources Corporation common stock converted (in shares)	1.8656
Percentage of voting interest			90.00%		90.00%
Offering price (in dollars per share)		$ 2.50
Transaction related expneses			$ 3		$ 3
Montage Resources Corporation | Public Stock Offering
Business Acquisition [Line Items]
Underwritten public offering of common stock (in shares)		63,250,000
Net proceeds from public offering		$ 152
Montage Resources Corporation | 8.375% Senior Notes due September 2028 (3) | Senior Notes
Business Acquisition [Line Items]
Senior notes		$ 350
Stated interest rate		8.375%
Proceeds from issuance of long-term debt		$ 345
Montage Resources Corporation | Montage Resources Corporation
Business Acquisition [Line Items]
Percentage of voting interest			10.00%		10.00%

Restructuring Charges (Addition

Restructuring Charges (Additional Information) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Term of contract	10 years
Workforce Reduction
Restructuring Cost and Reserve [Line Items]
Office consolidation	$ 3	$ 0	$ 3	$ 0	$ 5

Restructuring Charges (Summary

Restructuring Charges (Summary of Restructuring Charges) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		$ 0	$ 4	$ 12	$ 9
E&P
Restructuring Cost and Reserve [Line Items]
Total restructuring charges			4	12	9
Workforce Reduction
Restructuring Cost and Reserve [Line Items]
Severance (including payroll taxes)		0	1	12	4
Office consolidation	$ 3	0	3	0	5
Total restructuring charges		$ 0	4	12	9
Workforce Reduction | E&P
Restructuring Cost and Reserve [Line Items]
Total restructuring charges			$ 4	$ 12	$ 9

Restructuring Charges (Restruct

Restructuring Charges (Restructuring Rollforward) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Reserve [Roll Forward]
Additions	$ 0	$ 4	$ 12	$ 9
Workforce Reduction
Restructuring Reserve [Roll Forward]
Liability at December 31, 2019			2
Additions	0	$ 4	12	$ 9
Distributions			(14)
Liability at September 30, 2020	$ 0		$ 0

Revenue Recognition (Narrative)

Revenue Recognition (Narrative) (Details)	9 Months Ended
	Sep. 30, 2020USD ($)
Disaggregation of Revenue [Line Items]
Contract asset associated with revenues from contracts with customers	$ 0
Contract liability associated with revenues from contracts with customers	$ 0
Minimum | NGL sales
Disaggregation of Revenue [Line Items]
Payment terms	30 days
Minimum | Marketing
Disaggregation of Revenue [Line Items]
Payment terms	30 days
Maximum | NGL sales
Disaggregation of Revenue [Line Items]
Payment terms	60 days
Maximum | Marketing
Disaggregation of Revenue [Line Items]
Payment terms	60 days

Revenue Recognition (Disaggrega

Revenue Recognition (Disaggregation of Revenue by Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 527	$ 636	$ 1,529	$ 2,293
E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	308	357	884	1,288
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	219	279	645	1,005
Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	298	348	853	1,261
Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	495	592	1,432	2,159
Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	266	304	756	1,127
Intersegment Revenues | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	(10)	(9)	(31)	(27)
Intersegment Revenues | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	276	313	787	1,154
Gas sales
Disaggregation of Revenue [Line Items]
Total operating revenues	199	238	611	943
Gas sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	190	230	584	918
Gas sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
Gas sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	(9)	(8)	(27)	(25)
Oil sales
Disaggregation of Revenue [Line Items]
Total operating revenues	40	67	111	153
Oil sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	39	66	107	151
Oil sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
Oil sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	(1)	(1)	(4)	(2)
NGL sales
Disaggregation of Revenue [Line Items]
Total operating revenues	68	52	158	191
NGL sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	68	52	158	191
NGL sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
NGL sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	219	279	645	1,004
Marketing | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
Marketing | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	495	592	1,432	2,158
Marketing | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	276	313	787	1,154
Other
Disaggregation of Revenue [Line Items]
Total operating revenues	1	$ 0	4	2
Other | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	1		4	1
Other | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0		0	1
Other | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 0		$ 0	$ 0

Revenue Recognition (Disaggre_2

Revenue Recognition (Disaggregation of Revenue on Geographic Basis) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 527	$ 636	$ 1,529	$ 2,293
E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	308	357	884	1,288
Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	298	348	853	1,261
Operating Segments | E&P | Northeast Appalachia
Disaggregation of Revenue [Line Items]
Total operating revenues	131	175	443	740
Operating Segments | E&P | Southwest Appalachia
Disaggregation of Revenue [Line Items]
Total operating revenues	166	173	409	519
Operating Segments | E&P | Other
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 1	$ 0	$ 1	$ 2

Revenue Recognition (Reconcilia

Revenue Recognition (Reconciliation of Accounts Receivable) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Receivables from contracts with customers	$ 218	$ 284
Other accounts receivable	21	61
Total accounts receivable	$ 239	$ 345

Cash and Cash Equivalents (Summ

Cash and Cash Equivalents (Summary of Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Cash	$ 93	$ 5
Marketable securities	2	0
Total	$ 95	$ 5

Natural Gas and Oil Propertie_2

Natural Gas and Oil Properties (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)derivative_position$ / bbl$ / MMBTU	Sep. 30, 2019USD ($)derivative_position$ / bbl$ / MMBTU	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Jun. 30, 2019USD ($)
Natural Gas and Oil Properties [Line Items]
Natural gas, oil and NGL reserves discount			10.00%
Period of time needed to calculate ceiling value of reserves			12 months
Net book value adjusted for market differentials	$ 361		$ 361		$ 650	$ 1,480
Impairments	$ 361	$ 2	$ 2,495	$ 8
Number of hedge positions designated for hedge accounting | derivative_position			0	0
Other Non-Core Assets
Natural Gas and Oil Properties [Line Items]
Impairments			$ 5
Non-Core Leasehold
Natural Gas and Oil Properties [Line Items]
Consideration amount							$ 25
Natural Gas
Natural Gas and Oil Properties [Line Items]
Full cost ceiling test, price per MMBtu (in dollars per MMBtu) | $ / MMBTU			1.97	2.87
Oil
Natural Gas and Oil Properties [Line Items]
Full cost ceiling test, price per barrel (in dollars per bbl) | $ / bbl			43.40	57.77
NGL
Natural Gas and Oil Properties [Line Items]
Full cost ceiling test, price per barrel (in dollars per bbl) | $ / bbl			9.26	12.59

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	Aug. 31, 2020	Mar. 31, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Treasury stock acquired (in shares)		5,260,687
Treasury stock acquired		$ 21
Treasury stock acquired, average cost per share (in dollars per share)		$ 3.84
Montage Resources Corporation
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Offering price (in dollars per share)	$ 2.50
Montage Resources Corporation | Public Stock Offering
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Underwritten public offering of common stock (in shares)	63,250,000
Net proceeds from public offering	$ 152

Earnings Per Share (Schedule of

Earnings Per Share (Schedule of Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income (loss)	$ (593)	$ (880)	$ (1,547)	$ 49	$ 138	$ 594	$ (3,020)	$ 781
Number of common shares:
Weighted average outstanding (in shares)	571,872,413			539,221,101			551,162,559	539,315,170
Issued upon assumed exercise of outstanding stock options (in shares)	0			0			0	0
Effect of issuance of non-vested restricted common stock (in shares)	0			187,706			0	400,120
Effect of issuance of non-vested performance units (in shares)	0			629,380			0	727,359
Weighted average and potential dilutive outstanding (in shares)	571,872,413			540,038,187			551,162,559	540,442,649
Earnings per common share
Basic (in dollars per share)	$ (1.04)			$ 0.09			$ (5.48)	$ 1.45
Diluted (in dollars per share)	$ (1.04)			$ 0.09			$ (5.48)	$ 1.44

Earnings Per Share (Schedule _2

Earnings Per Share (Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share) (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	9,583,819	7,479,785	9,495,538	7,160,740
Unexercised stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	4,425,886	5,102,882	4,519,385	5,115,334
Unvested share-based payment
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	939,941	2,136,453	946,547	1,797,963
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)	1,935,781	0	2,001,621	0
Performance units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	2,282,211	240,450	2,027,985	247,443

Derivatives and Risk Manageme_3

Derivatives and Risk Management (Schedule of Derivative Instruments Notional Amount, Weighted Average Contract Prices and Fair Value) (Details) bbl in Thousands, Mcf in Millions, $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)$ / MMBTU$ / bblbbl	Sep. 30, 2020USD ($)$ / bbl$ / MMBTUMcfbbl	Dec. 31, 2019USD ($)
Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		91
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.46	2.46
Fair value	$ 16	$ 16
Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		584
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	75.44	75.44
Fair value	$ 20	$ 20
Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		2,629
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	8.62	8.62
Fair value	$ 0	$ 0
Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		1,435
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	23.11	23.11
Fair value	$ 2	$ 2
Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Normal Butane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		195
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	22.44	22.44
Fair value	$ 0	$ 0
Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Natural Gasoline
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		184
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	34.59	34.59
Fair value	$ 0	$ 0
Two-way Costless-collars - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		57
Fair value	(7)	$ (7)
Two-way Costless-collars - 2020 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		261
Fair value	4	$ 4
Two-way Costless-collars - 2020 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		92
Fair value	$ 0	$ 0
Two-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.75	2.75
Two-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	59.75	59.75
Two-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	29.40	29.40
Three-Way Costless Collars - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		25
Fair value	$ (11)	$ (11)
Three-Way Costless Collars - 2020 | Not Designated as Hedging Instrument | Natural Gas | Derivative liabilities
Derivative [Line Items]
Deferred premiums		$ 2
Three-Way Costless Collars - 2020 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		404
Fair value	$ 3	$ 3
Three-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.96	2.96
Three-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	57.78	57.78
Financial protection on production - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		173
Fair value	$ (2)	$ (2)
Financial protection on production - 2020 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		1,249
Fair value	27	$ 27
Financial protection on production - 2020 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		1,527
Fair value	$ 2	$ 2
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		93
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.67	2.67
Fair value	$ (13)	$ (13)
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		2,574
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	52.84	52.84
Fair value	$ 27	$ 27
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		5,889
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	7.12	7.12
Fair value	$ (12)	$ (12)
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		4,298
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	19.99	19.99
Fair value	$ (3)	$ (3)
Two-way Costless Collars-2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		166
Fair value	(27)	$ (27)
Two-way Costless Collars-2021 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		584
Fair value	$ 0	$ 0
Two-way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.89	2.89
Two-way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	10.40	10.40
Three-way Costless-collars - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		291
Fair value	$ (113)	$ (113)
Three-way Costless-collars - 2021 | Not Designated as Hedging Instrument | Natural Gas | Derivative liabilities
Derivative [Line Items]
Deferred premiums		$ 1
Three-way Costless-collars - 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		1,445
Fair value	$ 8	$ 8
Three-Way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.84	2.84
Three-Way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	58.14	58.14
Financial protection on production - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		550
Fair value	$ (153)	$ (153)
Financial protection on production - 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		4,019
Fair value	35	$ 35
Financial protection on production - 2021 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		6,473
Fair value	$ (12)	$ (12)
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		37
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.75	2.75
Fair value	$ (2)	$ (2)
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		762
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	48.85	48.85
Fair value	$ 4	$ 4
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		190
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	7.41	7.41
Fair value	$ 0	$ 0
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		156
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	19.25	19.25
Fair value	$ 0	$ 0
Two Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		32
Fair value	(5)	$ (5)
Two Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		135
Fair value	$ 0	$ 0
Two Way Costless Collars - 2022 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.88	2.88
Two Way Costless Collars - 2022 Sold Calls | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	9.66	9.66
Three-Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		116
Fair value	$ (24)	$ (24)
Three-Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		666
Fair value	$ 2	$ 2
Three-way Costless Collars 2022 - Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.87	2.87
Three-way Costless Collars 2022 - Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	58	58
Financial protection on production - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		185
Fair value	$ (31)	$ (31)
Financial protection on production - 2022 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		1,428
Fair value	6	$ 6
Financial protection on production - 2022 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		325
Fair value	0	$ 0
Three Way Costless Collars - 2023 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		25
Fair value	(2)	$ (2)
Three Way Costless Collars - 2023 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		111
Fair value	$ 0	$ 0
Three Way Costless Collars - 2023 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.18	3.18
Three Way Costless Collars - 2023 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	57.85	57.85
Basis Swaps - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		66
Basis differential per MMBtu | $ / MMBTU		(0.37)
Fair value	$ 21	$ 21
Basis Swaps - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		155
Basis differential per MMBtu | $ / MMBTU		(0.12)
Fair value	21	$ 21
Basis Swaps - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		127
Basis differential per MMBtu | $ / MMBTU		(0.38)
Fair value	4	$ 4
Basis Swaps | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		348
Fair value	$ 46	$ 46
Fixed price swaps | Natural Gas
Derivative [Line Items]
Premium paid		1	$ 9
Fixed price swaps | Not Designated as Hedging Instrument | Natural Gas | Derivative assets
Derivative [Line Items]
Premium paid		$ 1	$ 9
Call Options 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		6
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.15	3.15
Fair value	$ (2)	$ (2)
Call Options 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		57
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.15	3.15
Fair value	$ (17)	$ (17)
Call Options 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		226
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	60	60
Fair value	$ 0	$ 0
Call Options 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		58
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3	3
Fair value	$ (15)	$ (15)
Call Options 2023 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		17
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.84	2.84
Fair value	$ (4)	$ (4)
Call Options 2024 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		9
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3	3
Fair value	$ (2)	$ (2)
Call options | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		147
Fair value	$ (40)	$ (40)
Purchased Fixed Price Swaps, Storage, 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		1
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	1.94	1.94
Basis differential per MMBtu | $ / MMBTU		0
Fair value	$ 0	$ 0
Purchased Basis Swaps, Storage, 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	0	0
Basis differential per MMBtu | $ / MMBTU		(0.63)
Fair value	$ 0	$ 0
Fixed Price Swaps, Storage, 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.09	2.09
Basis differential per MMBtu | $ / MMBTU		0
Fair value	$ 0	$ 0
Basis Swaps, Storage, 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	0	0
Basis differential per MMBtu | $ / MMBTU		(0.70)
Fair value	$ 0	$ 0
Storage 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		1
Fair value	$ 0	$ 0
Purchased Fixed Price Swaps, Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		1
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.04	2.04
Basis differential per MMBtu | $ / MMBTU		0
Fair value	$ 0	$ 0
Fixed Price Swap, Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		2
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.49	2.49
Basis differential per MMBtu | $ / MMBTU		0
Fair value	$ (1)	$ (1)
Basis Swaps Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		1
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	0	0
Basis differential per MMBtu | $ / MMBTU		(0.38)
Fair value	$ 0	$ 0
Storage 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		4
Fair value	$ (1)	$ (1)
Purchased Fixed Price Swaps, Marketing, 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		2
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.44	2.44
Fair value	$ 0	$ 0
Purchased Fixed Price Swaps, Marketing, 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		6
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.44	2.44
Fair value	$ 3	$ 3
Marketing 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		8
Fair value	$ 3	$ 3
Purchased fixed price swaps | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		448
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	33.94	33.94
Fair value	$ 3	$ 3
Three-way costless collars | Natural Gas
Derivative [Line Items]
Deferred premiums		3
Three-way costless collars | Not Designated as Hedging Instrument | Natural Gas | Derivative liabilities
Derivative [Line Items]
Deferred premiums		$ 3
Sold fixed price swaps | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,032
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	57.44	57.44
Fair value	$ 17	$ 17
Short Puts | Three-way Costless-collars - 2020 Sold Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.19	2.19
Short Puts | Three-way Costless-collars - 2020 Sold Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	43.71	43.71
Short Puts | Three-Way Costless Collars - 2021 Sold Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.16	2.16
Short Puts | Three-Way Costless Collars - 2021 Sold Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	43.52	43.52
Short Puts | Three-Way Costless Collars - 2022 Sold Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.07	2.07
Short Puts | Three-Way Costless Collars - 2022 Sold Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	42.50	42.50
Short Puts | Three Way Costless Collars - 2023 Sold Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.07	2.07
Short Puts | Three Way Costless Collars - 2023 Sold Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	30	30
Purchased Puts | Two-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.45	2.45
Purchased Puts | Two-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	56.76	56.76
Purchased Puts | Two-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	25.20	25.20
Purchased Puts | Three-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.58	2.58
Purchased Puts | Three-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	52.85	52.85
Purchased Puts | Two-way Costless Collars - 2021 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.51	2.51
Purchased Puts | Two-way Costless Collars - 2021 Purchased Puts | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	7.14	7.14
Purchased Puts | Three-Way Costless Collars - 2021 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.49	2.49
Purchased Puts | Three-Way Costless Collars - 2021 Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	53.25	53.25
Purchased Puts | Two Way Costless Collars - 2022 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.17	2.17
Purchased Puts | Two Way Costless Collars - 2022 Purchased Puts | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	7.56	7.56
Purchased Puts | Three Way Costless Collars 2022 - Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.44	2.44
Purchased Puts | Three Way Costless Collars 2022 - Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	53.20	53.20
Purchased Puts | Three Way Costless Collars - 2023 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.48	2.48
Purchased Puts | Three Way Costless Collars - 2023 Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	40	40

Derivatives and Risk Manageme_4

Derivatives and Risk Management (Narrative) (Details) - Not Designated as Hedging Instrument $ in Millions	Sep. 30, 2020USD ($)
Derivative [Line Items]
Fair value of net derivative liability position	$ 1
Commodities
Derivative [Line Items]
Derivative liability	(125)
Interest rate swaps
Derivative [Line Items]
Derivative notional amount	$ 170

Derivatives and Risk Manageme_5

Derivatives and Risk Management (Balance Sheet Classification of Derivative Financial Instruments) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative assets	$ 350	$ 391
Derivative liabilities	475	236
Natural Gas | Fixed price swaps
Derivatives, Fair Value [Line Items]
Premium paid	1	9
Natural Gas | Three-way costless collars
Derivatives, Fair Value [Line Items]
Deferred premiums	3
Natural Gas | Not Designated as Hedging Instrument | Purchased fixed price swaps | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	3	0
Natural Gas | Not Designated as Hedging Instrument | Purchased fixed price swaps | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	0	1
Natural Gas | Not Designated as Hedging Instrument | Fixed price swaps | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	21	77
Premium paid	1	9
Natural Gas | Not Designated as Hedging Instrument | Fixed price swaps | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	1	7
Natural Gas | Not Designated as Hedging Instrument | Fixed price swaps | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	15	1
Natural Gas | Not Designated as Hedging Instrument | Fixed price swaps | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	6	0
Natural Gas | Not Designated as Hedging Instrument | Two-way costless collars | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	27	10
Natural Gas | Not Designated as Hedging Instrument | Two-way costless collars | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	13	4
Natural Gas | Not Designated as Hedging Instrument | Two-way costless collars | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	52	4
Natural Gas | Not Designated as Hedging Instrument | Two-way costless collars | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	27	4
Natural Gas | Not Designated as Hedging Instrument | Three-way costless collars | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	64	126
Natural Gas | Not Designated as Hedging Instrument | Three-way costless collars | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	56	74
Natural Gas | Not Designated as Hedging Instrument | Three-way costless collars | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	164	84
Deferred premiums	3
Natural Gas | Not Designated as Hedging Instrument | Three-way costless collars | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	106	72
Natural Gas | Not Designated as Hedging Instrument | Basis swaps | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	40	17
Natural Gas | Not Designated as Hedging Instrument | Basis swaps | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	13	15
Natural Gas | Not Designated as Hedging Instrument | Basis swaps | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	3	17
Natural Gas | Not Designated as Hedging Instrument | Basis swaps | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	4	9
Natural Gas | Not Designated as Hedging Instrument | Call options | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	9	1
Natural Gas | Not Designated as Hedging Instrument | Call options | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	4	2
Natural Gas | Not Designated as Hedging Instrument | Call options | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	24	3
Natural Gas | Not Designated as Hedging Instrument | Call options | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	29	15
Oil | Not Designated as Hedging Instrument | Fixed price swaps | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	42	4
Oil | Not Designated as Hedging Instrument | Fixed price swaps | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	10	1
Oil | Not Designated as Hedging Instrument | Fixed price swaps | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	1	6
Oil | Not Designated as Hedging Instrument | Fixed price swaps | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	0	2
Oil | Not Designated as Hedging Instrument | Two-way costless collars | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	6	5
Oil | Not Designated as Hedging Instrument | Two-way costless collars | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	2	5
Oil | Not Designated as Hedging Instrument | Three-way costless collars | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	19	3
Oil | Not Designated as Hedging Instrument | Three-way costless collars | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	14	7
Oil | Not Designated as Hedging Instrument | Three-way costless collars | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	10	4
Oil | Not Designated as Hedging Instrument | Three-way costless collars | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	10	8
Oil | Not Designated as Hedging Instrument | Call options | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	0	1
Ethane | Not Designated as Hedging Instrument | Fixed price swaps | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	2	11
Ethane | Not Designated as Hedging Instrument | Fixed price swaps | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	10	0
Ethane | Not Designated as Hedging Instrument | Fixed price swaps | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	4	0
Propane | Not Designated as Hedging Instrument | Fixed price swaps | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	5	21
Propane | Not Designated as Hedging Instrument | Fixed price swaps | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	1	3
Propane | Not Designated as Hedging Instrument | Fixed price swaps | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	5	0
Propane | Not Designated as Hedging Instrument | Fixed price swaps | Long-term derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	2	0
Propane | Not Designated as Hedging Instrument | Two-way costless collars | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	0	2
Natural Gas Storage | Not Designated as Hedging Instrument | Fixed price swaps | Derivative assets
Derivatives, Fair Value [Line Items]
Derivative assets	0	1
Natural Gas Storage | Not Designated as Hedging Instrument | Fixed price swaps | Derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ 1	$ 0

Derivatives and Risk Manageme_6

Derivatives and Risk Management (Summary of Before Tax Effect of Fair Value Hedges not Designated for Hedge Accounting) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	$ (289)	$ 12	$ (272)	$ 108
Settled Gain (Loss) on Derivatives Recognized in Earnings	97	88	310	112
Total gain (loss) on derivatives	(192)	100	38	220
Purchased fixed price swaps | Natural Gas
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	4	0	4	0
Settled Gain (Loss) on Derivatives Recognized in Earnings	(2)	0	(4)	0
Purchased fixed price swaps | Natural Gas Storage
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	1	0	0	0
Fixed price swaps | Natural Gas
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(138)	(19)	(74)	36
Settled Gain (Loss) on Derivatives Recognized in Earnings	61	45	150	53
Amortization of premium paid	4		8
Fixed price swaps | Oil
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(20)	8	54	5
Settled Gain (Loss) on Derivatives Recognized in Earnings	17	3	44	5
Fixed price swaps | Ethane
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(13)	1	(23)	8
Settled Gain (Loss) on Derivatives Recognized in Earnings	(2)	6	6	12
Fixed price swaps | Propane
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(17)	10	(25)	19
Settled Gain (Loss) on Derivatives Recognized in Earnings	2	11	19	20
Two-way costless collars | Natural Gas
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(34)	(11)	(45)	(2)
Settled Gain (Loss) on Derivatives Recognized in Earnings	(5)	10	1	12
Two-way costless collars | Oil
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(5)	0	4	(3)
Settled Gain (Loss) on Derivatives Recognized in Earnings	4	2	13	4
Two-way costless collars | Propane
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(1)	1	(2)	3
Settled Gain (Loss) on Derivatives Recognized in Earnings	0	1	2	1
Three-way costless collars | Natural Gas
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(98)	3	(194)	27
Settled Gain (Loss) on Derivatives Recognized in Earnings	0	15	43	19
Three-way costless collars | Oil
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(4)	3	15	4
Settled Gain (Loss) on Derivatives Recognized in Earnings	1	0	5	0
Basis swaps | Natural Gas
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	54	12	40	6
Settled Gain (Loss) on Derivatives Recognized in Earnings	20	(3)	29	(11)
Call options | Natural Gas
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(16)	1	(25)	5
Settled Gain (Loss) on Derivatives Recognized in Earnings	0	(1)	0	(2)
Amortization of premium paid				1
Call options | Oil
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	0	0	1	0
Fixed price swaps – storage | Natural Gas Storage
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	(2)	2	(2)	1
Settled Gain (Loss) on Derivatives Recognized in Earnings	1	(1)	2	(1)
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Unsettled Gain (Loss) on Derivatives Recognized in Earnings	$ 0	$ 1	$ 0	$ (1)

Reclassifications from Accumu_3

Reclassifications from Accumulated Other Comprehensive Income (Loss) (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	$ 823	$ 3,082	$ 2,937	$ 3,246
Net current-period other comprehensive income	1	1	4
Balance ending	384	3,135	3,082	384
Pension and Other Postretirement
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning				(19)
Other comprehensive income before reclassifications				0
Amounts reclassified from other comprehensive income				1
Net current-period other comprehensive income				1
Balance ending	(18)			(18)
Foreign Currency
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning				(14)
Other comprehensive income before reclassifications				0
Amounts reclassified from other comprehensive income				0
Net current-period other comprehensive income				0
Balance ending	(14)			(14)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	(33)	(32)	(36)	(33)
Other comprehensive income before reclassifications				0
Amounts reclassified from other comprehensive income				1
Net current-period other comprehensive income	1	1	4	1
Balance ending	$ (32)	$ (31)	$ (32)	$ (32)

Reclassifications from Accumu_4

Reclassifications from Accumulated Other Comprehensive Income (Loss) (Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Income (Loss), Net	$ 2			$ (2)			$ 3	$ (7)
Provision (Benefit) for Income Taxes	0			10			406	(401)
Net income (loss)	$ (593)	$ (880)	$ (1,547)	$ 49	$ 138	$ 594	(3,020)	$ 781
Amount Reclassified from Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)							1
Amortization of prior service cost and net loss | Amount Reclassified from Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Income (Loss), Net							1
Provision (Benefit) for Income Taxes							0
Net income (loss)							$ 1

Fair Value Measurements (Carryi

Fair Value Measurements (Carrying Amount and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, net	$ (125)	$ 155
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	95	5
Derivative instruments, net	(125)	155
Carrying Amount | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior notes	2,471	2,228
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	95	5
Derivative instruments, net	(125)	155
Fair Value | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior notes	2,429	2,085
2018 revolving credit facility due April 2024 | Carrying Amount | Long-term debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
2018 revolving credit facility due April 2024	0	34
2018 revolving credit facility due April 2024 | Fair Value | Long-term debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
2018 revolving credit facility due April 2024	0	34
Fixed price swaps | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Premium paid	1	$ 9
Three-way costless collars | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred premiums	$ 3

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) $ in Millions	Sep. 30, 2020USD ($)
Not Designated as Hedging Instrument
Debt Instrument [Line Items]
Fair value of net derivative liability position	$ 1
Senior Notes | 4.20% Senior Notes Due March 2022
Debt Instrument [Line Items]
Stated interest rate	4.10%

Fair Value Measurements (Summar

Fair Value Measurements (Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, net	$ (125)	$ 155
Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, net	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, net	(125)	155
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, net	0	0
Purchased fixed price swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	3
Derivative liabilities		(1)
Purchased fixed price swaps | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0
Derivative liabilities		0
Purchased fixed price swaps | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	3
Derivative liabilities		(1)
Purchased fixed price swaps | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0
Derivative liabilities		0
Fixed price swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	82	124
Derivative liabilities	(43)	(9)
Fixed price swaps | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Premium paid	1	9
Fixed price swaps | Nonperforming Financial Instruments | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of net derivative liability position	1
Fixed price swaps | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Fixed price swaps | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	82	124
Derivative liabilities	(43)	(9)
Fixed price swaps | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Two-way costless collars
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	46	21
Derivative liabilities	(81)	(13)
Two-way costless collars | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Two-way costless collars | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	46	21
Derivative liabilities	(81)	(13)
Two-way costless collars | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Three-way costless collars
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	153	210
Derivative liabilities	(290)	(168)
Three-way costless collars | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred premiums	3
Three-way costless collars | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Three-way costless collars | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	153	210
Derivative liabilities	(290)	(168)
Three-way costless collars | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Basis swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	53	32
Derivative liabilities	(7)	(26)
Basis swaps | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Basis swaps | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	53	32
Derivative liabilities	(7)	(26)
Basis swaps | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Call options
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	13	3
Derivative liabilities	(53)	(19)
Call options | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Call options | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	13	3
Derivative liabilities	(53)	(19)
Call options | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liabilities	0	0
Fixed price swaps – storage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		1
Derivative liabilities	(1)
Fixed price swaps – storage | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		0
Derivative liabilities	0
Fixed price swaps – storage | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		1
Derivative liabilities	(1)
Fixed price swaps – storage | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		$ 0
Derivative liabilities	$ 0

Debt (Components of Debt) (Deta

Debt (Components of Debt) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Apr. 07, 2020	Jul. 31, 2018	Jan. 31, 2015
Debt Instrument [Line Items]
Debt Instrument	$ 2,471	$ 2,262
Unamortized Issuance Expense	20	19
Unamortized Debt Discount	(1)	(1)
Total debt	2,450	2,242
Line of Credit | Variable rate (2.120% at March 31, 2020) 2018 revolving credit facility, due April 2024
Debt Instrument [Line Items]
Debt Instrument	0
Unamortized Issuance Expense	0
Unamortized Debt Discount	0
Total debt	$ 0
Variable interest rate	1.60%
Line of Credit | Variable rate (2.120% at March 31, 2020) 2018 revolving credit facility, due April 2024 | Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument		34
Unamortized Issuance Expense		0
Unamortized Debt Discount		0
Total debt		$ 34
Line of Credit | Variable rate (4.310% at December 31, 2019) 2018 term loan facility, due April 2024
Debt Instrument [Line Items]
Variable interest rate		4.31%
Senior Notes | 4.10% Senior Notes due March 2022
Debt Instrument [Line Items]
Debt Instrument	$ 207	$ 213
Unamortized Issuance Expense	0	1
Unamortized Debt Discount	0	0
Total debt	$ 207	$ 212
Stated interest rate	4.10%	4.10%
Senior Notes | 4.95% Senior Notes due January 2025
Debt Instrument [Line Items]
Debt Instrument	$ 856	$ 892
Unamortized Issuance Expense	4	5
Unamortized Debt Discount	(1)	(1)
Total debt	851	$ 886
Stated interest rate		4.95%	6.45%	6.20%	4.95%
Senior Notes | 7.50% Senior Notes due April 2026
Debt Instrument [Line Items]
Debt Instrument	618	$ 639
Unamortized Issuance Expense	6	7
Unamortized Debt Discount	0	0
Total debt	$ 612	632
Stated interest rate	7.50%
Senior Notes | 7.75% Senior Notes due October 2027
Debt Instrument [Line Items]
Debt Instrument	$ 440	484
Unamortized Issuance Expense	5	6
Unamortized Debt Discount	0	0
Total debt	$ 435	478
Stated interest rate	7.75%
Senior Notes | 8.375% Senior Notes due September 2028 (3)
Debt Instrument [Line Items]
Debt Instrument	$ 350
Unamortized Issuance Expense	5
Unamortized Debt Discount	0
Total debt	$ 345
Stated interest rate	8.375%
Other long-term assets | Line of Credit | Variable rate (2.120% at March 31, 2020) 2018 revolving credit facility, due April 2024
Debt Instrument [Line Items]
Unamortized Issuance Expense	$ 10	$ 11

Debt (2018 Revolving Credit Fac

Debt (2018 Revolving Credit Facility - Narrative) (Details) - USD ($)	1 Months Ended		9 Months Ended
	Oct. 31, 2020	Apr. 30, 2018	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Subsidiary ownership			100.00%
Letters of credit			$ 203,000,000
Debt instrument			2,471,000,000	$ 2,262,000,000
October 2020 Amendment [Member] | Subsequent Event
Debt Instrument [Line Items]
Basis points	0.25%
Limit of unrestricted cash and cash equivalents	$ 200,000,000
Long-term debt | 2018 revolving credit facility due April 2024
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 3,500,000,000
Current borrowing base			1,800,000,000
Aggregate commitment			1,800,000,000
Limit on securing indebtedness		$ 2,000,000,000
Percentage of consolidated net tangible assets		25.00%
Minimum interest coverage ratio		1
Long-term debt | 2018 revolving credit facility due April 2024 | Subsequent Event
Debt Instrument [Line Items]
Current borrowing base	2,000,000,000
Aggregate commitment	$ 2,000,000,000
Long-term debt | 2018 revolving credit facility due April 2024 | Maximum
Debt Instrument [Line Items]
Leverage ratio, percentage of credit limit		10.00%
Leverage ratio, amount of credit limit		$ 150,000,000
Long-term debt | 2018 revolving credit facility due April 2024 | Eurodollar | Minimum
Debt Instrument [Line Items]
Basis points		1.75%
Long-term debt | 2018 revolving credit facility due April 2024 | Eurodollar | Maximum
Debt Instrument [Line Items]
Basis points		2.75%
Long-term debt | 2018 revolving credit facility due April 2024 | Base Rate | Minimum
Debt Instrument [Line Items]
Basis points		0.75%
Long-term debt | 2018 revolving credit facility due April 2024 | Base Rate | Maximum
Debt Instrument [Line Items]
Basis points		1.75%
Line of Credit | 2018 Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument			$ 0
After June 30, 2020 | Long-term debt | 2018 revolving credit facility due April 2024 | Maximum
Debt Instrument [Line Items]
Leverage ratio		4

Debt (Senior Notes - Narrative)

Debt (Senior Notes - Narrative) (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended		9 Months Ended
	Aug. 31, 2020	Jan. 31, 2015	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Apr. 07, 2020	Dec. 31, 2019	Jul. 31, 2018	Jul. 31, 2016
Debt Instrument [Line Items]
Gain on extinguishment of debt			$ 0	$ 7	$ 35	$ 7
Senior Notes
Debt Instrument [Line Items]
Gain on extinguishment of debt					35
Senior Notes | LIBOR
Debt Instrument [Line Items]
Incremental increase in basis points resulting from downgrades		0.25%
Incremental decrease in basis points resulting from upgrades		0.25%
4.95% Senior Notes due January 2025 | Senior Notes
Debt Instrument [Line Items]
Senior notes		$ 1,000
Stated interest rate		4.95%					6.45%	4.95%	6.20%
Stated interest rate cap										6.95%
Repurchased amount			$ 36		$ 36
4.10% Senior Notes due March 2022 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate			4.10%		4.10%			4.10%
Repurchased amount			$ 6		$ 6
7.50% Senior Notes Due April 2026 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate			7.50%		7.50%
Repurchased amount			$ 21		$ 21
7.75% Senior Notes due October 2027 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate			7.75%		7.75%
Repurchased amount			$ 44		$ 44
4.50% Senior Notes due January 2020 | Senior Notes
Debt Instrument [Line Items]
Repurchased amount			$ 72		$ 72
8.375% Senior Notes due September 2028 (3) | Senior Notes
Debt Instrument [Line Items]
Senior notes	$ 350
Stated interest rate			8.375%		8.375%
Proceeds from issuance of long-term debt	$ 345
Percentage price of face value of the notes sold to the public	100.00%
Eight Point Eight Seven Five Percent Senior Notes Due 2023 | Senior Notes | Montage Resources Corporation
Debt Instrument [Line Items]
Senior notes			$ 510		$ 510
Stated interest rate			8.875%		8.875%

Commitments and Contingencies_2

Commitments and Contingencies (Narrative) (Details) - USD ($)	1 Months Ended
	Feb. 29, 2020	Sep. 30, 2020	Dec. 31, 2019	Mar. 31, 2019
Commitments And Contingencies [Line Items]
Obligation under transportation agreements		$ 7,109,000,000
Guarantee obligations relative to the firms transportation agreements and gathering project and services		1,000,000,000
Contractual commitments assumed by buyer		27,000,000
Potential amount to be reimbursed to buyer		13,000,000
Liability for estimated future payments		10,000,000	$ 46,000,000
Contractual commitments	$ 512,000,000
Commitment period	17 years
Material liabilities recognized		0
Pending regulatory approval and/or construction
Commitments And Contingencies [Line Items]
Obligation under transportation agreements		$ 405,000,000
Appalachian Basin
Commitments And Contingencies [Line Items]
Obligation under transportation agreements				$ 357,000,000
Reimbursed by seller				$ 133,000,000

Commitments and Contingencies_3

Commitments and Contingencies (Schedule of Future Obligation under Transportation Agreements) (Details) $ in Millions	Sep. 30, 2020USD ($)
Other Commitments [Line Items]
Total	$ 7,109
Less than 1 Year	585
1 to 3 Years	1,317
3 to 5 Years	1,101
5 to 8 Years	1,463
More than 8 Years	2,643
Infrastructure currently in service
Other Commitments [Line Items]
Total	6,704
Less than 1 Year	582
1 to 3 Years	1,308
3 to 5 Years	1,078
5 to 8 Years	1,411
More than 8 Years	2,325
Pending regulatory approval and/or construction
Other Commitments [Line Items]
Total	405
Less than 1 Year	3
1 to 3 Years	9
3 to 5 Years	23
5 to 8 Years	52
More than 8 Years	$ 318

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Effective tax rate	0.00%		18.00%	(16.00%)	(105.00%)
Discrete tax benefit		$ 408			$ 400
Valuation allowance related to operating loss		$ 87
Valuation allowance decreased during the period					$ 522

Pension Plan and Other Postre_3

Pension Plan and Other Postretirement Benefits (Pension and Other Postretirement Benefit Costs) (Details) - Pension - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 1	$ 6	$ 5
Interest cost	1	2	3	4
Expected return on plan assets	(2)	(1)	(5)	(4)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	1	0	1	1
Settlement loss	0	1	0	5
Net periodic benefit cost	$ 2	$ 3	$ 5	$ 11

Pension Plan and Other Postre_4

Pension Plan and Other Postretirement Benefits (Narrative) (Details) - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Employer contributions				$ 12,000,000
Treasury stock acquired (in shares)			5,260,687
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost (gain)	$ 1,000,000	$ 1,000,000		2,000,000	$ 1,000,000
Benefit obligation	14,000,000			14,000,000		$ 13,000,000
Pension
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost (gain)	2,000,000	3,000,000		5,000,000	11,000,000
Expected future employer contributions, remainder of fiscal year	0			0
Benefit obligation	22,000,000			22,000,000		$ 30,000,000
Settlement loss	$ 0	$ 1,000,000		$ 0	5,000,000
Payments for pension plan					$ 19,000,000
Non-Qualified Supplemental Employee Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Treasury stock acquired (in shares)				3,632		5,115

Long-term Incentive Compensat_3

Long-term Incentive Compensation (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Stock Based Compensation 2013 Plan
Long-term Incentive Compensation [Line Items]
Service period				3 years
Stock options
Long-term Incentive Compensation [Line Items]
Vesting period				3 years
Expiration period				7 years
Restricted stock
Long-term Incentive Compensation [Line Items]
Vesting period				4 years
Performance units
Long-term Incentive Compensation [Line Items]
Vesting period				3 years	3 years	3 years
Weighted average period over which unrecognized cost is recognized, years				2 years 2 months 12 days
Liability classified awards, unrecognized compensation costs				$ 14
Restricted stock units
Long-term Incentive Compensation [Line Items]
Vesting period	4 years	4 years	4 years
Weighted average period over which unrecognized cost is recognized, years				2 years 6 months
Liability classified awards, unrecognized compensation costs				$ 21
Performance cash awards
Long-term Incentive Compensation [Line Items]
Vesting period				4 years
Weighted average period over which unrecognized cost is recognized, years				3 years 4 months 24 days
Liability classified awards, unrecognized compensation costs				$ 16
Share-based payment arrangement
Long-term Incentive Compensation [Line Items]
Equity-classified awards, unrecognized compensation cost				$ 2
Weighted average period over which unrecognized cost is recognized, years				6 months

Long-term Incentive Compensat_4

Long-term Incentive Compensation (Schedule of Stock-Based Compensation Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Noncash Expense [Abstract]
Stock-based compensation cost – expensed	$ 2	$ 1	$ 8	$ 12
Stock-based compensation cost – capitalized	$ 2	$ 1	$ 3	$ 7

Long-term Incentive Compensat_5

Long-term Incentive Compensation (Schedule of Equity-Classified Stock-Based Compensation Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Noncash Expense [Abstract]
Equity-classified awards – expensed	$ 0	$ 2	$ 2	$ 6
Equity-classified awards – capitalized	$ 1	$ 1	$ 1	$ 3

Long-term Incentive Compensat_6

Long-term Incentive Compensation (Summary of Equity-Classified Stock Option Activity) (Details) - Stock options shares in Thousands	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Number of Options
Beginning balance (in shares) | shares	4,635
Granted (in shares) | shares	0
Exercised (in shares) | shares	0
Forfeited or expired (in shares) | shares	(357)
Ending balance (in shares) | shares	4,278
Exercisable (in shares) | shares	4,278
Weighted Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 15.26
Granted (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	0
Forfeited or expired (in dollars per share) | $ / shares	7.06
Ending balance (in dollars per share) | $ / shares	15.95
Exercisable (in dollars per share) | $ / shares	$ 15.95

Long-term Incentive Compensat_7

Long-term Incentive Compensation (Summary of Equity-Classified Restricted Stock Activity) (Details) - Restricted stock shares in Thousands	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Number of Units
Beginning balance (in shares) | shares	1,480
Granted (in shares) | shares	570
Vested (in shares) | shares	(1,083)
Forfeited (in shares) | shares	(246)
Ending balance (in shares) | shares	721
Weighted Average Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 7
Granted (in dollars per share) | $ / shares	2.88
Vested (in dollars per share) | $ / shares	5.30
Forfeited (in dollars per share) | $ / shares	7.71
Ending balance (in dollars per share) | $ / shares	$ 6.05

Long-term Incentive Compensat_8

Long-term Incentive Compensation (Summary of Equity-Classified Performance Units Activity) (Details) - Performance units - $ / shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Number of Units
Beginning balance (in shares)	178,000
Granted (in shares)	0
Vested (in shares)	(178,000)
Forfeited (in shares)	0
Ending balance (in shares)	0
Weighted Average Fair Value
Beginning balance (in dollars per share)	$ 10.47
Granted (in dollars per share)	0
Vested (in dollars per share)	10.47
Forfeited (in dollars per share)	0
Ending balance (in dollars per share)	$ 0
Vesting period	3 years	3 years	3 years
Minimum
Number of Units
Granted (in shares)	0
Maximum
Number of Units
Granted (in shares)	2

Long-term Incentive Compensat_9

Long-term Incentive Compensation (Schedule of Liability-Classified Stock-Based Compensation Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Noncash Expense [Abstract]
Liability-classified stock-based compensation cost – expensed	$ 2	$ (1)	$ 6	$ 6
Liability-classified stock-based compensation cost – capitalized	$ 1	$ 0	$ 2	$ 4

Long-term Incentive Compensa_10

Long-term Incentive Compensation (Summary of Liability-Classified Restricted Stock Unit Activity) (Details) - Restricted stock units shares in Thousands	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Number of Units
Beginning balance (in shares) | shares	12,992
Granted (in shares) | shares	6,172
Vested (in shares) | shares	(3,946)
Forfeited (in shares) | shares	(3,060)
Ending balance (in shares) | shares	12,158
Weighted Average Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 2.42
Granted (in dollars per share) | $ / shares	1.41
Vested (in dollars per share) | $ / shares	1.42
Forfeited (in dollars per share) | $ / shares	1.53
Ending balance (in dollars per share) | $ / shares	$ 2.17

Long-term Incentive Compensa_11

Long-term Incentive Compensation (Summary of Liability-Classified Performance Cash Awards ) (Details) - Performance units - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Number of Units
Beginning balance (in shares)	5,142
Granted (in shares)	6,172
Vested (in shares)	0
Forfeited (in shares)	(2,300)
Ending balance (in shares)	9,014
Weighted Average Fair Value
Beginning balance (in dollars per share)	$ 2.42
Granted (in dollars per share)	1.41
Vested (in dollars per share)	0
Forfeited (in dollars per share)	3.06
Ending balance (in dollars per share)	$ 2.10
Vesting period	3 years	3 years	3 years

Long-term Incentive Compensa_12

Long-term Incentive Compensation (Summary of Liability-Classified Restricted Cash Unit Activity) (Details) - Performance cash awards shares in Thousands	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Number of Units
Beginning balance (in shares) | shares	0
Granted (in shares) | shares	20,044
Vested (in shares) | shares	(100)
Forfeited (in shares) | shares	(729)
Ending balance (in shares) | shares	19,215
Weighted Average Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 0
Granted (in dollars per share) | $ / shares	1
Vested (in dollars per share) | $ / shares	1
Forfeited (in dollars per share) | $ / shares	1
Ending balance (in dollars per share) | $ / shares	$ 1

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total operating revenues	$ 527	$ 636	$ 1,529	$ 2,293
Depreciation, depletion and amortization expense	70	125	267	352
Impairments	361	2	2,495	8
Operating (loss) income	(381)	(29)	(2,627)	206
Interest expense	22	17	63	46
(Loss) gain on derivatives	(192)	100	38	220
Gain on early extinguishment of debt	0	7	35	7
Other income, net	2	(2)	3	(7)
Provision (benefit) from income taxes	0	10	406	(401)
Assets	4,157	6,598	4,157	6,598	$ 6,717
Capital investments	223	240	705	933
Restructuring charges	0	4	12	9
Montage acquisition-related expenses	3	0	3	0
Cash and cash equivalents	95		95		5
Right-of-use asset	145		145		159
Property, plant and equipment	3,222		3,222		5,267
Unamortized debt expense	20		20		19
Accounts receivable	239		239		$ 345
Change in accrued expenditures	(7)	(53)	1	52
Intersegment Revenues
Segment Reporting Information [Line Items]
Total operating revenues	266	304	756	1,127
E&P
Segment Reporting Information [Line Items]
Total operating revenues	308	357	884	1,288
Depreciation, depletion and amortization expense	68	123	260	345
Impairments	361	0	2,495	6
Operating (loss) income	(379)	(21)	(2,613)	219
Interest expense	22	17	63	46
(Loss) gain on derivatives	(192)	100	38	220
Gain on early extinguishment of debt		0	0	0
Other income, net	2	(4)	2	(8)
Provision (benefit) from income taxes		10	406	(401)
Assets	3,705	6,099	3,705	6,099
Capital investments	223	239	705	931
Restructuring charges		4	12	9
Montage acquisition-related expenses	3		3
E&P | Intersegment Revenues
Segment Reporting Information [Line Items]
Total operating revenues	(10)	(9)	(31)	(27)
Marketing
Segment Reporting Information [Line Items]
Total operating revenues	219	279	645	1,005
Depreciation, depletion and amortization expense	2	2	7	7
Impairments	0	2	0	2
Operating (loss) income	(2)	(8)	(14)	(13)
Interest expense	0	0	0	0
(Loss) gain on derivatives	0	0	0	0
Gain on early extinguishment of debt		0	0	0
Other income, net	0	0	0	0
Provision (benefit) from income taxes		0	0	0
Assets	240	272	240	272
Capital investments	0	0	0	0
Marketing | Intersegment Revenues
Segment Reporting Information [Line Items]
Total operating revenues	276	313	787	1,154
Other
Segment Reporting Information [Line Items]
Total operating revenues	0	0	0	0
Depreciation, depletion and amortization expense	0	0	0	0
Impairments	0	0	0	0
Operating (loss) income	0	0	0	0
Interest expense	0	0	0	0
(Loss) gain on derivatives	0	0	0	0
Gain on early extinguishment of debt		7	35	7
Other income, net	0	2	1	1
Provision (benefit) from income taxes		0	0	0
Assets	212	227	212	227
Capital investments	0	1	0	2
Cash and cash equivalents	95	29	95	29
Right-of-use asset	74	84	74	84
Property, plant and equipment	18	31	18	31
Unamortized debt expense	10	9	10	9
Prepayments	3	7	3	7
Income tax receivable		61		61
Accounts receivable	7		7
Other | Non-Qualified Supplemental Employee Retirement Plan
Segment Reporting Information [Line Items]
Non-qualified retirement plan	5	7	5	7
Other | Intersegment Revenues
Segment Reporting Information [Line Items]
Total operating revenues	$ 0	$ 0	$ 0	$ 0