Arch Resources (ARCH) 10-Q 22 Oct 19 2019 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 18, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	1-13105
Entity Registrant Name	Arch Coal Inc
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	43-0921172
Entity Address, Address Line One	One CityPlace Drive
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63141
City Area Code	314
Local Phone Number	994-2700
Title of 12(b) Security	Common stock, $.01 par value
Trading Symbol	ARCH
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 Bankruptcy Proceedings, Reporting Current	true
Entity Common Stock, Shares Outstanding		15,041,754
Entity Central Index Key	0001037676
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3

Condensed Consolidated Income S

Condensed Consolidated Income Statements - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenues	$ 619,467	$ 633,180	$ 1,744,872	$ 1,800,824
Costs, expenses and other operating
Cost of sales (exclusive of items shown separately below)	491,004	482,029	1,380,563	1,411,197
Depreciation, depletion and amortization	30,402	31,775	82,199	92,027
Accretion on asset retirement obligations	5,137	6,992	15,411	20,977
Amortization of sales contracts, net	(153)	3,241	(77)	9,540
Change in fair value of coal derivatives and coal trading activities, net	1,530	10,418	(19,851)	22,142
Selling, general and administrative expenses	24,566	22,909	73,864	73,613
Costs related to proposed joint venture with Peabody Energy	3,754	0	6,772	0
Loss on sale of Lone Mountain Processing, LLC	0	0	(4,304)	0
Preference Rights Lease Application settlement income	(39,000)	0	(39,000)	0
Other operating income, net	(4,254)	(7,070)	(9,143)	(21,320)
Costs, expenses and other operating	512,986	550,294	1,495,042	1,608,176
Income from operations	106,481	82,886	249,830	192,648
Interest expense, net
Interest expense	(4,049)	(5,179)	(12,856)	(15,624)
Interest and investment income	3,709	1,801	7,940	4,626
Interest expense, net	(340)	(3,378)	(4,916)	(10,998)
Income before nonoperating expenses	106,141	79,508	244,914	181,650
Nonoperating (expenses) income
Non-service related pension and postretirement benefit (costs) credits	975	(971)	(2,127)	(2,206)
Net loss resulting from early retirement of debt and debt restructuring	0	0	0	(485)
Reorganization items, net	0	(560)	71	(1,601)
Nonoperating expenses	975	(1,531)	(2,056)	(4,292)
Income before income taxes	107,116	77,977	242,858	177,358
Provision for (benefit from) income taxes	347	(45,215)	508	(49,125)
Net income	$ 106,769	$ 123,192	$ 242,350	$ 226,483
Net income per common share
Basic earnings per common share (in dollars per share)	$ 6.79	$ 6.40	$ 14.61	$ 11.27
Diluted earnings per common share (in dollars per share)	$ 6.34	$ 6.10	$ 13.66	$ 10.76
Weighted average shares outstanding
Basic weighted average shares outstanding (in shares)	15,736	19,250	16,591	20,102
Diluted weighted average shares outstanding (in shares)	16,852	20,208	17,744	21,040
Dividends declared per common share (in dollars per share)	$ 0.45	$ 0.40	$ 1.35	$ 1.20

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income	$ 106,769	$ 123,192	$ 242,350	$ 226,483
Derivative instruments
Comprehensive income (loss) before tax	(2,360)	64	(2,421)	(5,672)
Income tax benefit (provision)	0	0	0	0
Other comprehensive income (loss), derivative instruments, net of tax	(2,360)	64	(2,421)	(5,672)
Pension, postretirement and other post-employment benefits
Comprehensive income (loss) before tax	(4,019)	2,736	(1,117)	6,389
Income tax benefit (provision)	0	0	0	0
Other comprehensive income (loss), pension, postretirement and other post-employment benefits, net of tax	(4,019)	2,736	(1,117)	6,389
Available-for-sale securities
Comprehensive income (loss) before tax	(98)	102	553	(379)
Income tax benefit (provision)	0	0	0	0
Other comprehensive income (loss), available-for-sale securities, net of tax	(98)	102	553	(379)
Total other comprehensive income (loss)	(6,477)	2,902	(2,985)	338
Total comprehensive income	$ 100,292	$ 126,094	$ 239,365	$ 226,821

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 175,428	$ 264,937
Short term investments	176,056	162,797
Trade accounts receivable	206,149	200,904
Other receivables	24,291	48,926
Inventories	171,543	125,470
Other current assets	113,502	75,749
Total current assets	866,969	878,783
Property, plant and equipment, net	889,295	834,828
Other assets
Equity investments	107,543	104,676
Other noncurrent assets	70,793	68,773
Total other assets	178,336	173,449
Total assets	1,934,600	1,887,060
Current Liabilities
Accounts payable	166,129	128,024
Accrued expenses and other current liabilities	161,939	183,514
Current maturities of debt	11,925	17,797
Total current liabilities	339,993	329,335
Long-term debt	292,781	300,186
Asset retirement obligations	238,440	230,304
Accrued pension benefits	12,491	16,147
Accrued postretirement benefits other than pension	78,308	83,163
Accrued workers’ compensation	174,118	174,303
Other noncurrent liabilities	93,033	48,801
Total liabilities	1,229,164	1,182,239
Stockholders' equity
Common stock, $0.01 par value, authorized 300,000 shares, issued 25,050 and 25,047 shares at September 30, 2019 and December 31, 2018, respectively	250	250
Paid-in capital	734,829	717,492
Retained earnings	746,928	527,666
Treasury stock, 9,955 shares and 7,216 shares at September 30, 2019 and December 31, 2018, respectively, at cost	(816,882)	(583,883)
Accumulated other comprehensive income	40,311	43,296
Total stockholders’ equity	705,436	704,821
Total liabilities and stockholders’ equity	$ 1,934,600	$ 1,887,060

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	25,050,000	25,047,000
Treasury stock, shares (in shares)	9,955,000	7,216,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net income	$ 242,350	$ 226,483
Adjustments to reconcile to cash provided by operating activities:
Depreciation, depletion and amortization	82,199	92,027
Accretion on asset retirement obligations	15,411	20,977
Amortization of sales contracts, net	(77)	9,540
Deferred income taxes	13,680	(22,999)
Employee stock-based compensation expense	17,305	12,161
Gains on disposals and divestitures, net	(818)	(54)
Net loss resulting from early retirement of debt and debt restructuring	0	485
Amortization relating to financing activities	2,757	3,300
Preference Rights Lease Application settlement income	(39,000)	0
Changes in:
Receivables	(4,622)	(5,983)
Inventories	(46,073)	(34,918)
Accounts payable, accrued expenses and other current liabilities	1,569	(24,762)
Income taxes, net	32,440	(1,942)
Other	16,932	(8,200)
Cash provided by operating activities	334,053	266,115
Investing activities
Capital expenditures	(137,396)	(55,742)
Minimum royalty payments	(1,187)	(522)
Proceeds from disposals and divestitures	1,799	512
Purchases of short term investments	(158,578)	(140,097)
Proceeds from sales of short term investments	146,170	133,400
Investments in and advances to affiliates, net	(4,810)	(1,817)
Cash used in investing activities	(154,002)	(64,266)
Financing activities
Payments on term loan due 2024	(2,250)	(2,250)
Net payments on other debt	(12,077)	(10,286)
Debt financing costs	0	(1,009)
Net loss resulting from early retirement of debt and debt restructuring	0	(50)
Dividends paid	(22,264)	(23,966)
Purchases of treasury stock	(232,999)	(192,221)
Other	30	10
Cash used in financing activities	(269,560)	(229,772)
Decrease in cash and cash equivalents, including restricted cash	(89,509)	(27,923)
Cash and cash equivalents, including restricted cash, beginning of period	264,937	273,602
Cash and cash equivalents, including restricted cash, end of period	175,428	245,679
Cash and cash equivalents, including restricted cash, end of period
Cash and cash equivalents, including restricted cash, end of period	$ 264,937	$ 273,602

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Treasury Stock, at cost	Accumulated Other Comprehensive Income
Beginning Balance at Dec. 31, 2017	$ 665,865	$ 250	$ 700,125	$ 247,232	$ (302,109)	$ 20,367
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares	(8,553)			(8,553)
Total comprehensive income	65,884			59,985		5,899
Employee stock-based compensation	3,845		3,845
Purchase of common stock under share repurchase program	(38,589)				(38,589)
Warrants exercised	10		10
Ending Balance at Mar. 31, 2018	688,462	250	703,980	298,664	(340,698)	26,266
Beginning Balance at Dec. 31, 2017	665,865	250	700,125	247,232	(302,109)	20,367
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income	226,821
Ending Balance at Sep. 30, 2018	687,140	250	712,295	449,122	(495,232)	20,705
Beginning Balance at Mar. 31, 2018	688,462	250	703,980	298,664	(340,698)	26,266
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares	(8,217)			(8,217)
Total comprehensive income	34,843			43,306		(8,463)
Employee stock-based compensation	4,147		4,147
Purchase of common stock under share repurchase program	(78,287)				(78,287)
Warrants exercised	0		0
Ending Balance at Jun. 30, 2018	640,948	250	708,127	333,753	(418,985)	17,803
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares	(7,823)			(7,823)
Total comprehensive income	126,094			123,192		2,902
Employee stock-based compensation	4,168		4,168
Purchase of common stock under share repurchase program	(76,247)				(76,247)
Ending Balance at Sep. 30, 2018	687,140	250	712,295	449,122	(495,232)	20,705
Beginning Balance at Dec. 31, 2018	704,821	250	717,492	527,666	(583,883)	43,296
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares	(8,111)			(8,111)
Total comprehensive income	75,835			72,741		3,094
Employee stock-based compensation	5,651		5,651
Purchase of common stock under share repurchase program	(78,249)				(78,249)
Ending Balance at Mar. 31, 2019	699,947	250	723,143	592,296	(662,132)	46,390
Beginning Balance at Dec. 31, 2018	704,821	250	717,492	527,666	(583,883)	43,296
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income	239,365
Ending Balance at Sep. 30, 2019	705,436	250	734,829	746,928	(816,882)	40,311
Beginning Balance at Mar. 31, 2019	699,947	250	723,143	592,296	(662,132)	46,390
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares	(7,696)			(7,696)
Total comprehensive income	63,238			62,840		398
Employee stock-based compensation	5,822		5,822
Purchase of common stock under share repurchase program	(63,392)				(63,392)
Warrants exercised	31		31
Ending Balance at Jun. 30, 2019	697,950	250	728,996	647,440	(725,524)	46,788
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares	(7,281)			(7,281)
Total comprehensive income	100,292			106,769		(6,477)
Employee stock-based compensation	5,833		5,833
Purchase of common stock under share repurchase program	(91,358)				(91,358)
Ending Balance at Sep. 30, 2019	$ 705,436	$ 250	$ 734,829	$ 746,928	$ (816,882)	$ 40,311

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical) - $ / shares shares in Thousands	3 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in dollars per share)	$ 0.45	$ 0.45	$ 0.45	$ 0.40	$ 0.40	$ 0.40
Purchase of shares of common stock under share repurchase program (in shares)	1,169,597	697,255	872,317	870,358	960,105	407,091

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of Arch Coal, Inc. (“Arch Coal”) and its subsidiaries (“Arch” or the “Company”). Unless the context indicates otherwise, the terms “Arch” and the “Company” are used interchangeably in this Quarterly Report on Form 10-Q. The Company’s primary business is the production of thermal and metallurgical coal from surface and underground mines located throughout the United States, for sale to utility, industrial and steel producers both in the United States and around the world. The Company currently operates mining complexes in West Virginia, Illinois, Wyoming and Colorado. All subsidiaries are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and U.S. Securities and Exchange Commission regulations. In the opinion of management, all adjustments, consisting of normal, recurring accruals considered necessary for a fair presentation, have been included. Results of operations for the three and nine months ended September 30, 2019 are not necessarily indicative of results to be expected for the year ending December 31, 2019 . These financial statements should be read in conjunction with the audited financial statements and related notes as of and for the year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.

Accounting Policies

Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Accounting Policies	Accounting Policies Recently Adopted Accounting Guidance In February 2016, the FASB established Topic 842, Leases, by issuing ASU 2016-02, “Leases” which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. The ASU was subsequently amended by ASU 2018-01, “Land Easements Practical Expedient for Transition to Topic 842;” ASU 2018-10, “Codification Improvements to Topic 842, Leases;” and ASU 2018-11, “Targeted Improvements.” The new standard establishes a right-of-use (“ROU”) model that requires a lessee to recognize an ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. The standard also requires a lessee to recognize a single lease cost, calculated so that the cost of the lease is allocated over the term of the lease, on a generally straight line basis. Leases of mineral reserves and related land leases have been exempted from the standard. The Company adopted ASU 2016-02 effective January 1, 2019 and elected the option to not restate comparative periods in transition and also elected the “package of practical expedients” within the standard which permits the Company not to reassess its prior conclusions about lease identification, lease classification and initial direct costs. Additionally, the Company made an election to not separate lease and non-lease components for all leases, and will not use hindsight. Finally, the Company will continue its current policy for accounting for land easements as executory contracts. The adoption of the standard had no impact on the Company’s consolidated income statement or statement of cash flows. In April 2017, the FASB issued ASU 2017-08, “Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities.” The new guidance shortens the amortization period for the premium on certain purchased callable debt securities to the earliest call date. The new guidance does not change the accounting for purchased callable debt securities held at a discount. The Company adopted ASU 2017-08 effective January 1, 2019 with no impact on the Company’s financial statements. In August 2017, the FASB issued ASU 2017-12, “Targeted Improvements to Accounting for Hedging Activities.” The new guidance provides targeted improvements to the accounting for hedging activities to better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedging results. The Company adopted ASU 2017-12 effective January 1, 2019 with no impact on the Company’s financial statements. In February 2018, the FASB issued ASU 2018-02, “Income Statement-Reporting Comprehensive Income (Topic 220) Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” ASU 2018-02 provides an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings due to the change in the U.S. federal tax rate in the Tax Cuts and Jobs Act of 2017. The Company adopted ASU 2018-02 effective January 1, 2019 with no impact on the Company’s financial statements. In June 2018, the FASB issued ASU 2018-07, “Compensation-Stock Compensation (Topic 718), Improvements to Non-employee Share-Based Payment Accounting.” ASU 2018-07 aligns the measurement and classification guidance for share-based payments to non-employees with the guidance for share-based payments to employees. The Company adopted ASU 2018-07 effective January 1, 2019 with no impact on the Company’s financial statements. In October 2018, the FASB issued ASU 2018-16, “Derivatives and Hedging (Topic 815), Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate of Hedge Accounting Purposes.” The Company adopted ASU 2018-16 effective January 1, 2019 with no impact on the Company’s financial statements.

Joint Venture with Peabody Ener

Joint Venture with Peabody Energy	9 Months Ended
	Sep. 30, 2019
Equity Method Investments and Joint Ventures [Abstract]
Joint Venture with Peabody Energy	Joint Venture with Peabody Energy On June 18, 2019, Arch Coal entered into a definitive implementation agreement (the “Implementation Agreement”) with Peabody Energy Corporation (“Peabody”), to establish a joint venture that will combine the respective Powder River Basin and Colorado mining operations of Arch Coal and Peabody. Pursuant to the terms of the Implementation Agreement, Arch Coal will hold a 33.5% economic interest, and Peabody will hold a 66.5% economic interest in the joint venture. At the closing of the joint venture transaction, certain of the respective subsidiaries of Arch Coal and Peabody will enter into an Amended and Restated Limited Liability Company Agreement (the “LLC Agreement”). Under the terms of the LLC Agreement, the governance of the joint venture will be overseen by the joint venture’s board of managers, which will initially be comprised of three representatives appointed by Peabody and two representatives appointed by Arch. Decisions of the board of managers will be determined by a majority vote subject to certain specified matters set forth in the LLC Agreement that will require a supermajority vote. Peabody, or one of its affiliates, will initially be appointed as the operator of the joint venture and will manage the day-to-day operations of the joint venture, subject to the supervision of the joint venture’s board of managers. Formation of the joint venture is subject to customary closing conditions, including the termination or expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, the receipt of certain other required regulatory approvals and the absence of injunctions or other legal restraints preventing the formation of the joint venture. Formation of the joint venture does not require approval of the respective stockholders of either Arch or Peabody. The Company has incurred expenses of $3.8 million and $6.8 million for the three and nine months ended September 30, 2019 related to the regulatory approval process related to the joint venture.

Loss on Sale of Lone Mountain P

Loss on Sale of Lone Mountain Processing, LLC	9 Months Ended
	Sep. 30, 2019
Discontinued Operations and Disposal Groups [Abstract]
Loss on Sale of Lone Mountain Processing, Inc	Loss on Sale of Lone Mountain Processing, LLC On September 14, 2017, the Company sold Lone Mountain Processing, LLC and two idled mining companies, Cumberland River Coal LLC and Powell Mountain Energy LLC to Revelation Energy LLC, and recorded a gain on the transaction in that year of $21.3 million . Under the terms of the purchase agreement, Revelation assumed certain traumatic workers compensation claims and pneumoconiosis (occupational disease) benefits. On July 1, 2019, Blackjewel LLC and four affiliates, including Revelation Energy LLC, filed for Chapter 11 bankruptcy. As a result of the bankruptcy, the Company has recorded a $4.3 million charge for these claims during the second quarter of 2019.

Preference Rights Lease Applica

Preference Rights Lease Application (PRLA) Settlement Income	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Preference Rights Lease Application (PRLA) Settlement Income	Preference Rights Lease Application Settlement Income The Company recorded a $39.0 million gain during the quarter related to a settlement with the United States Department of Interior over a long-standing dispute, dating back to the 1970’s, on the valuation and disposition of Preference Rights Lease Application that Arch controlled in northwestern New Mexico with a joint venture partner. As part of the settlement, Arch will receive $67.0 million in the form of royalty credits on its federal coal leases which will be used to settle 50% of the Company’s monthly royalty obligations. The Company expects to realize the royalty credits beginning in September 2019 through the next 18- 24 months depending on market conditions. Additionally, as part of the settlement, Arch will make a one-time payment of $27.0 million during October 2019 to its’ partner in the venture for their ownership interest in the underlying mineral reserves, as well as pay $1.0 million

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income	Accumulated Other Comprehensive Income The following items are included in accumulated other comprehensive income (“AOCI”): Pension, Postretirement and Other Accumulated Post- Other Derivative Employment Available-for- Comprehensive Instruments Benefits Sale Securities Income (In thousands) Balance at December 31, 2018 $ 3,328 $ 40,311 $ (343 ) $ 43,296 Unrealized gains 3,836 1,745 603 6,184 Amounts reclassified from AOCI (6,257 ) (2,862 ) (50 ) (9,169 ) Balance at September 30, 2019 $ 907 $ 39,194 $ 210 $ 40,311 The following amounts were reclassified out of AOCI: Three Months Ended September 30, Nine Months Ended September 30, Details About AOCI Components 2019 2018 2019 2018 Line Item in the Condensed Consolidated Statement of Operations (In thousands) Coal hedges $ 2,963 $ (4,824 ) $ 5,067 $ (4,824 ) Revenues Interest rate hedges 161 265 1,190 753 Interest expense — — — — Provision for (benefit from) income taxes $ 3,124 $ (4,559 ) $ 6,257 $ (4,071 ) Net of tax Pension, postretirement and other post-employment benefits Amortization of actuarial gains (losses), net $ 2,236 $ — $ 2,236 $ — Non-service related pension and postretirement benefit (costs) credits Pension settlement 197 613 626 1,984 Non-service related pension and postretirement benefit (costs) credits — — — — Provision for (benefit from) income taxes $ 2,433 $ 613 $ 2,862 $ 1,984 Net of tax Available-for-sale securities $ 35 $ 8 $ 50 $ 24 Interest and investment income — — — — Provision for (benefit from) income taxes $ 35 $ 8 $ 50 $ 24 Net of tax

Inventories

Inventories	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consist of the following: September 30, December 31, 2019 2018 (In thousands) Coal $ 79,746 $ 40,982 Repair parts and supplies 91,797 84,488 $ 171,543 $ 125,470 The repair parts and supplies are stated net of an allowance for slow-moving and obsolete inventories of $1.7 million at September 30, 2019 and $0.6 million at December 31, 2018 .

Investments in Available-for-Sa

Investments in Available-for-Sale Securities	9 Months Ended
	Sep. 30, 2019
Debt Securities, Available-for-sale [Abstract]
Investments in Available-for-Sale Securities	Investments in Available-for-Sale Securities The Company has invested in marketable debt securities, primarily highly liquid U.S. Treasury securities and investment grade corporate bonds. These investments are held in the custody of a major financial institution. These securities are classified as available-for-sale securities and, accordingly, the unrealized gains and losses are recorded through other comprehensive income. The Company’s investments in available-for-sale marketable securities are as follows: September 30, 2019 Balance Sheet Classification Gross Unrealized Fair Short-Term Other Cost Basis Gains Losses Value Investments Assets (In thousands) Available-for-sale: U.S. government and agency securities $ 64,930 $ 52 $ (17 ) $ 64,965 $ 64,965 $ — Corporate notes and bonds 110,917 275 (101 ) 111,091 111,091 — Total Investments $ 175,847 $ 327 $ (118 ) $ 176,056 $ 176,056 $ — December 31, 2018 Balance Sheet Classification Gross Unrealized Fair Short-Term Other Cost Basis Gains Losses Value Investments Assets (In thousands) Available-for-sale: U.S. government and agency securities $ 100,003 $ 11 $ (126 ) $ 99,888 $ 99,888 $ — Corporate notes and bonds 63,137 4 (232 ) 62,909 62,909 — Total Investments $ 163,140 $ 15 $ (358 ) $ 162,797 $ 162,797 $ — The aggregate fair value of investments with unrealized losses that were owned for less than a year was $51.7 million and $115.2 million at September 30, 2019 and December 31, 2018 , respectively. The aggregate fair value of investments with unrealized losses that were owned for over a year was $0.0 million and $32.4 million at September 30, 2019 and December 31, 2018 , respectively. The unrealized losses in the Company’s portfolio at September 30, 2019 are the result of normal market fluctuations. The Company does not currently intend to sell these investments before recovery of their amortized cost base. The debt securities outstanding at September 30, 2019 have maturity dates ranging from the fourth quarter of 2019 through the first quarter of 2021 . The Company classifies its investments as current based on the nature of the investments and their availability to provide cash for use in current operations.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives Interest rate risk management The Company has entered into interest rate swaps to reduce the variability of cash outflows associated with interest payments on its variable rate term loan. These swaps have been designated as cash flow hedges. For additional information on these arrangements, see Note 11 , “ Debt and Financing Arrangements ,” in the Condensed Consolidated Financial Statements. Diesel fuel price risk management The Company is exposed to price risk with respect to diesel fuel purchased for use in its operations. The Company anticipates purchasing approximately 40 to 47 million gallons of diesel fuel for use in its operations annually. To protect the Company’s cash flows from increases in the price of diesel fuel for its operations, the Company uses forward physical diesel purchase contracts, purchased heating oil call options and New York Mercantile Exchange (“NYMEX”) gulf coast diesel swaps and options. At September 30, 2019 , the Company had protected the price on the majority of its expected diesel fuel purchases for the remainder of 2019 with approximately 4 million gallons of heating oil call options with an average strike price of $2.30 per gallon and 6 million gallons of NYMEX gulf coast diesel swaps at an average price of approximately $1.92 per gallon. Additionally, the Company has protected approximately 34% of its expected 2020 purchases using gulf coast diesel call options with an average strike price of $2.24 per gallon. At September 30, 2019 , the Company had outstanding heating oil call options and NYMEX gulf coast swaps and options of approximately 26 million gallons for the purpose of managing the price risk associated with future diesel purchases. These positions are not designated as hedges for accounting purposes, and therefore, changes in the fair value are recorded immediately to earnings. Coal price risk management positions The Company may sell or purchase forward contracts, swaps and options in the over-the-counter coal market in order to manage its exposure to coal prices. The Company has exposure to the risk of fluctuating coal prices related to forecasted, index-priced sales or purchases of coal or to the risk of changes in the fair value of a fixed price physical sales contract. Certain derivative contracts may be designated as hedges of these risks. At September 30, 2019 , the Company held derivatives for risk management purposes that are expected to settle in the following years: (Tons in thousands) 2019 2020 Total Coal sales 607 668 1,275 Coal purchases 385 337 722 The Company has also entered into a minimal quantity of natural gas put options to protect the Company from decreases in natural gas prices, which could impact thermal coal demand. These options are not designated as hedges. Coal trading positions The Company may sell or purchase forward contracts, swaps and options in the over-the-counter coal market for trading purposes. The Company is exposed to the risk of changes in coal prices on the value of its coal trading portfolio. The estimated future realization of the value of the trading portfolio is $0.2 million of losses during the remainder of 2019 and $0.6 million of losses during 2020 . Tabular derivatives disclosures The Company has master netting agreements with all of its counterparties which allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. Such netting arrangements reduce the Company’s credit exposure related to these counterparties. For classification purposes, the Company records the net fair value of all the positions with a given counterparty as a net asset or liability in the Condensed Consolidated Balance Sheets. The amounts shown in the table below represent the fair value position of individual contracts, and not the net position presented in the accompanying Condensed Consolidated Balance Sheets. The fair value and location of derivatives reflected in the accompanying Condensed Consolidated Balance Sheets are as follows: September 30, 2019 December 31, 2018 Fair Value of Derivatives Asset Liability Asset Liability (In thousands) Derivative Derivative Derivative Derivative Derivatives Designated as Hedging Instruments Coal $ 3,842 $ (671 ) $ 2,342 $ (805 ) Derivatives Not Designated as Hedging Instruments Heating oil -- diesel purchases 383 (629 ) 532 — Coal -- held for trading purposes 20,116 (20,925 ) 10,329 (10,701 ) Coal -- risk management 18,305 (11,067 ) 5,672 (19,579 ) Natural gas — — 4 (4 ) Total $ 38,804 $ (32,621 ) $ 16,537 $ (30,284 ) Total derivatives $ 42,646 $ (33,292 ) $ 18,879 $ (31,089 ) Effect of counterparty netting (32,663 ) 32,663 (17,801 ) 17,801 Net derivatives as classified in the balance sheets $ 9,983 $ (629 ) $ 9,354 $ 1,078 $ (13,288 ) $ (12,210 ) September 30, 2019 December 31, 2018 Net derivatives as reflected on the balance sheets (in thousands) Heating oil and coal Other current assets $ 9,983 $ 1,078 Coal Accrued expenses and other current liabilities (629 ) (13,288 ) $ 9,354 $ (12,210 ) The Company had a current asset representing cash collateral posted to a margin account for derivative positions primarily related to coal derivatives of $1.9 million and $24.7 million at September 30, 2019 and December 31, 2018 , respectively. These amounts are not included with the derivatives presented in the table above and are included in “other current assets” in the accompanying Condensed Consolidated Balance Sheets. The effects of derivatives on measures of financial performance are as follows: Derivatives used in Cash Flow Hedging Relationships (in thousands) Three Months Ended September 30, Gain (Loss) Recognized in Other Comprehensive Income Gains (Losses) Reclassified from Other Comprehensive Income into Income 2019 2018 2019 2018 Coal sales (1) $ 225 $ (4,631 ) $ 2,963 $ (6,996 ) Coal purchases (2) (34 ) 424 — 2,171 Totals $ 191 $ (4,207 ) $ 2,963 $ (4,825 ) No ineffectiveness or amounts excluded from effectiveness testing relating to the Company’s cash flow hedging relationships were recognized in the results of operations in the three month periods ended September 30, 2019 and 2018 . Derivatives Not Designated as Hedging Instruments (in thousands) Three Months Ended September 30, Gain (Loss) Recognized 2019 2018 Coal trading — realized and unrealized (3) $ (127 ) $ (928 ) Coal risk management — unrealized (3) (1,417 ) (9,486 ) Natural gas trading— realized and unrealized (3) 14 (4 ) Change in fair value of coal derivatives and coal trading activities, net total $ (1,530 ) $ (10,418 ) Coal risk management— realized (4) $ 3,216 $ (2,537 ) Heating oil — diesel purchases (4) $ (1,670 ) $ 719 ____________________________________________________________ Location in statement of operations: (1) — Revenues (2) — Cost of sales (3) — Change in fair value of coal derivatives and coal trading activities, net (4) — Other operating (income) expense, net Derivatives used in Cash Flow Hedging Relationships (in thousands) Nine Months Ended September 30, Gain (Loss) Recognized in Other Comprehensive Income Gains (Losses) Reclassified from Other Comprehensive Income into Income 2019 2018 2019 2018 Coal sales (1) $ 9,472 $ (14,862 ) $ 5,750 $ (6,996 ) Coal purchases (2) (940 ) 2,587 (686 ) 2,171 Totals $ 8,532 $ (12,275 ) $ 5,064 $ (4,825 ) No ineffectiveness or amounts excluded from effectiveness testing relating to the Company’s cash flow hedging relationships were recognized in the results of operations in the nine month periods ended September 30, 2019 and 2018 . Derivatives Not Designated as Hedging Instruments (in thousands) Nine Months Ended September 30, Gain (Loss) Recognized 2019 2018 Coal trading — realized and unrealized (3) $ (1,228 ) $ 14 Coal risk management — unrealized (3) 21,145 (22,116 ) Natural gas trading— realized and unrealized (3) (66 ) (40 ) Change in fair value of coal derivatives and coal trading activities, net total $ 19,851 $ (22,142 ) Coal risk management— realized (4) $ (2,076 ) $ (5,217 ) Heating oil — diesel purchases (4) $ (2,402 ) $ 4,394 ____________________________________________________________ Location in statement of operations: (1) — Revenues (2) — Cost of sales (3) — Change in fair value of coal derivatives and coal trading activities, net (4) — Other operating (income) expense, net Based on fair values at September 30, 2019 , amounts on derivative contracts designated as hedge instruments in cash flow hedges to be reclassified from other comprehensive income into earnings during the next twelve months are gains of approximately $3.1 million

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following: September 30, December 31, 2019 2018 (In thousands) Payroll and employee benefits $ 49,566 $ 57,166 Taxes other than income taxes 71,738 75,017 Interest 131 156 Acquired sales contracts 203 570 Workers’ compensation 18,053 20,044 Asset retirement obligations 12,297 13,113 Other 9,951 17,448 $ 161,939 $ 183,514

Debt and Financing Arrangements

Debt and Financing Arrangements	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt and Financing Arrangements	Debt and Financing Arrangements September 30, December 31, 2019 2018 (In thousands) Term loan due 2024 ($292.5 million face value) $ 291,524 $ 293,626 Other 18,471 30,449 Debt issuance costs (5,289 ) (6,092 ) 304,706 317,983 Less: current maturities of debt 11,925 17,797 Long-term debt $ 292,781 $ 300,186 Term Loan Facility In 2017, the Company entered into a senior secured term loan credit agreement (the “Credit Agreement”) in an aggregate principal amount of $300 million (the “Term Loan Debt Facility”) with Credit Suisse AG, Cayman Islands Branch, as administrative agent and collateral agent, and the other financial institutions from time to time party thereto (collectively, the “Lenders”). The Term Loan Debt Facility was issued at 99.50% of the face amount and will mature on March 7, 2024. The term loans provided under the Term Loan Debt Facility (the “Term Loans”) are subject to quarterly principal amortization payments in an amount equal to $750,000 . During 2018, the Company entered into the Second Amendment (the “Second Amendment”) to its Credit Agreement. The Second Amendment reduced the interest rate on its Term Loan Debt Facility to, at the option of Arch Coal, either (i) the London interbank offered rate (“LIBOR”) plus an applicable margin of 2.75% , subject to a 1.00% LIBOR floor, or (ii) a base rate plus an applicable margin of 1.75% . The LIBOR floor remains at 1.00% . There is no change to the maturities as a result of the Second Amendment. The Term Loan Debt Facility is guaranteed by all existing and future wholly owned domestic subsidiaries of the Company (collectively, the “Subsidiary Guarantors” and, together with Arch Coal, the “Loan Parties”), subject to customary exceptions, and is secured by first priority security interests on substantially all assets of the Loan Parties, including 100% of the voting equity interests of directly owned domestic subsidiaries and 65% of the voting equity interests of directly owned foreign subsidiaries, subject to customary exceptions. The Company has the right to prepay Term Loans at any time, and from time to time, in whole or in part without premium or penalty, upon written notice, except that any prepayment of Term Loans that bear interest at the LIBOR Rate other than at the end of the applicable interest periods therefor shall be made with reimbursement for any funding losses and redeployment costs of the Lenders resulting therefrom. The Term Loan Debt Facility is subject to certain usual and customary mandatory prepayment events, including 100% of net cash proceeds of (i) debt issuances (other than debt permitted to be incurred under the terms of the Term Loan Debt Facility) and (ii) non-ordinary course asset sales or dispositions, subject to customary thresholds, exceptions and reinvestment rights. The Term Loan Debt Facility contains customary affirmative covenants and representations. The Term Loan Debt Facility also contains customary negative covenants, which, among other things, and subject to certain exceptions, include restrictions on (i) indebtedness, (ii) liens, (iii) liquidations, mergers, consolidations and acquisitions, (iv) disposition of assets or subsidiaries, (v) affiliate transactions, (vi) creation or ownership of certain subsidiaries, partnerships and joint ventures, (vii) continuation of or change in business, (viii) restricted payments, (ix) prepayment of subordinated and junior lien indebtedness, (x) restrictions in agreements on dividends, intercompany loans and granting liens on the collateral, (xi) loans and investments, (xii) sale and leaseback transactions, (xiii) changes in organizational documents and fiscal year and (xiv) transactions with respect to bonding subsidiaries. The Term Loan Debt Facility does not contain any financial maintenance covenants. The Term Loan Debt Facility contains customary events of default, subject to customary thresholds and exceptions, including, among other things, (i) nonpayment of principal and nonpayment of interest and fees, (ii) a material inaccuracy of a representation or warranty at the time made, (iii) a failure to comply with any covenant, subject to customary grace periods in the case of certain affirmative covenants, (iv) cross-events of default to indebtedness of at least $50 million , (v) cross-events of default to surety, reclamation or similar bonds securing obligations with an aggregate face amount of at least $50 million , (vi) uninsured judgments in excess of $50 million , (vii) any loan document shall cease to be a legal, valid and binding agreement, (viii) uninsured losses or proceedings against assets with a value in excess of $50 million , (ix) certain ERISA events, (x) a change of control or (xi) bankruptcy or insolvency proceedings relating to the Company or any material subsidiary of the Company. Accounts Receivable Securitization Facility In 2018, the Company extended and amended its existing trade accounts receivable securitization facility provided to Arch Receivable Company, LLC, a special-purpose entity that is a wholly owned subsidiary of Arch Coal (“Arch Receivable”) (the “Extended Securitization Facility”), which supports the issuance of letters of credit and requests for cash advances. The amendment to the Extended Securitization Facility maintained the $160 million borrowing capacity and extended the maturity date to the date that is three years after the Securitization Facility Closing Date. Additionally, the amendment provided the Company the opportunity to use credit insurance to increase the pool of eligible receivables for borrowing. Pursuant to the Extended Securitization Facility, Arch Receivable also agreed to a revised schedule of fees payable to the administrator and the providers of the Extended Securitization Facility. The Extended Securitization Facility will terminate at the earliest of (i) three years from the Securitization Facility Closing Date, (ii) if the Liquidity (defined in the Extended Securitization Facility and consistent with the definition in the Inventory Facility) is less than $175 million for a period of 60 consecutive days, the date that is the 364 th day after the first day of such 60 consecutive day period, and (iii) the occurrence of certain predefined events substantially consistent with the existing transaction documents. Under the Extended Securitization Facility, Arch Receivable, Arch Coal and certain of Arch Coal’s subsidiaries party to the Extended Securitization Facility have granted to the administrator of the Extended Securitization Facility a first priority security interest in eligible trade accounts receivable generated by such parties from the sale of coal and all proceeds thereof. As of September 30, 2019 , letters of credit totaling $15.5 million were outstanding under the facility with $92.6 million available for borrowings. Inventory-Based Revolving Credit Facility In 2017, the Company and certain subsidiaries of Arch Coal entered into a senior secured inventory-based revolving credit facility in an aggregate principal amount of $40 million (the “Inventory Facility”) with Regions Bank (“Regions”) as administrative agent and collateral agent, as lender and swingline lender (in such capacities, the “Lender”) and as letter of credit issuer. Availability under the Inventory Facility is subject to a borrowing base consisting of (i) 85% of the net orderly liquidation value of eligible coal inventory, (ii) the lesser of (x) 85% of the net orderly liquidation value of eligible parts and supplies inventory and (y) 35% of the amount determined pursuant to clause (i), and (iii) 100% of Arch Coal’s Eligible Cash (defined in the Inventory Facility), subject to reduction for reserves imposed by Regions. In 2018, the Company and certain subsidiaries of Arch Coal amended and extended the Inventory Facility by increasing the facility size by $10 million , bringing the total aggregate amount available to $50 million , subject to borrowing base calculations described above. The commitments under the Inventory Facility will terminate on the date that is the earliest to occur of (i) the date, if any, that is 364 days following the first day that Liquidity (defined in the Inventory Facility and consistent with the definition in the Extended Securitization Facility (as defined below)) is less than $250 million for a period of 60 consecutive days and (ii) the date, if any, that is 60 days following the maturity, termination or repayment in full of the Extended Securitization Facility. Revolving loan borrowings under the Inventory Facility bear interest at a per annum rate equal to, at the option of Arch Coal, either the base rate or the London interbank offered rate plus, in each case, a margin ranging from 2.00% to 2.50% (in the case of LIBOR loans) and 1.00% to 1.50% (in the case of base rate loans) determined using a Liquidity-based grid. Letters of credit under the Inventory Facility are subject to a fee in an amount equal to the applicable margin for LIBOR loans, plus customary fronting and issuance fees. All existing and future direct and indirect domestic subsidiaries of Arch Coal, subject to customary exceptions, will either constitute co-borrowers under or guarantors of the Inventory Facility (collectively with Arch Coal, the “Loan Parties”). The Inventory Facility is secured by first priority security interests in the ABL Priority Collateral (defined in the Inventory Facility) of the Loan Parties and second priority security interests in substantially all other assets of the Loan Parties, subject to customary exceptions (including an exception for the collateral that secures the Extended Securitization Facility). Arch Coal has the right to prepay borrowings under the Inventory Facility at any time and from time to time in whole or in part without premium or penalty, upon written notice, except that any prepayment of such borrowings that bear interest at the LIBOR rate other than at the end of the applicable interest periods therefore shall be made with reimbursement for any funding losses and redeployment costs of the Lender resulting therefrom. The Inventory Facility is subject to certain usual and customary mandatory prepayment events, including non-ordinary course asset sales or dispositions, subject to customary thresholds, exceptions (including exceptions for required prepayments under Arch Coal’s term loan facility) and reinvestment rights. The Inventory Facility contains certain customary affirmative and negative covenants; events of default, subject to customary thresholds and exceptions; and representations, including certain cash management and reporting requirements that are customary for asset-based credit facilities. The Inventory Facility also includes a requirement to maintain Liquidity equal to or exceeding $175 million at all times. As of September 30, 2019 , letters of credit totaling $35.9 million were outstanding under the facility with $14.1 million available for borrowings. Interest Rate Swaps The Company has entered into a series of interest rate swaps to fix a portion of the LIBOR interest rate within the term loan. The interest rate swaps qualify for cash flow hedge accounting treatment and as such, the change in the fair value of the interest rate swaps is recorded on the Company’s Condensed Consolidated Balance Sheet as an asset or liability with the effective portion of the gains or losses reported as a component of accumulated other comprehensive income and the ineffective portion reported in earnings. As interest payments are made on the term loan, amounts in accumulated other comprehensive income will be reclassified into earnings through interest expense to reflect a net interest on the term loan equal to the effective yield of the fixed rate of the swap plus 2.75% which is the spread on the revised LIBOR term loan. In the event that an interest rate swap is terminated prior to maturity, gains or losses in accumulated other comprehensive income will remain deferred and be reclassified into earnings in the periods which the hedged forecasted transaction affects earnings. Below is a summary of the Company’s outstanding interest rate swap agreements designated as hedges as of September 30, 2019 : Notional Amount (in millions) Effective Date Fixed Rate Receive Rate Expiration Date $250.0 June 28, 2019 2.025% 1-month LIBOR June 30, 2020 $200.0 June 30, 2020 2.249% 1-month LIBOR June 30, 2021 $100.0 June 30, 2021 2.315% 1-month LIBOR June 30, 2023 The fair value of the interest rate swaps at September 30, 2019 is a liability of $3.4 million , which is recorded within Other noncurrent liabilities, with the offset to accumulated other comprehensive income on the Company’s Condensed Consolidated Balance Sheet. The Company realized $0.2 million and $1.2 million of gains during the three and nine months ended September 30, 2019 , respectively, related to settlements of the interest rate swaps which was recorded to interest expense on the Company’s Condensed Consolidated Income Statements. The interest rate swaps are classified as level 2 within the fair value hierarchy.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes A reconciliation of the statutory federal income tax provision at the statutory rate to the actual provision for (benefit from) income taxes follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Income tax provision at statutory rate $ 22,494 $ 16,375 $ 51,000 $ 37,245 Percentage depletion allowance (6,347 ) (5,964 ) (14,111 ) (13,059 ) State taxes, net of effect of federal taxes 1,825 4,528 3,668 5,865 Change in valuation allowance (19,120 ) (44,278 ) (42,925 ) (62,234 ) Current expense associated with uncertain tax positions 1,495 511 2,932 (599 ) Impact of Tax Cuts and Jobs Act of 2017 — (19,780 ) — (19,780 ) Other, net — 3,393 (56 ) 3,437 Provision for (benefit from) income taxes $ 347 $ (45,215 ) $ 508 $ (49,125 ) During the prior year quarter, the IRS completed an audit of alternative minimum tax (“AMT”) net operating loss carryback claims the Company filed in prior periods. In addition, the Company filed an amended 2016 return which changed the amount of available tax attributes and the mix used to offset its bankruptcy cancellation of indebtedness income as of January 1, 2017. As a result, the Company increased AMT credits and reduced other tax attributes as of that date that were available for attribute reduction. The AMT credits did not require a valuation allowance to be recorded against them due to the law changes enacted as part of the Tax Cut and Jobs Act of 2017 (the “Act”), while the Company’s other tax attributes are fully offset by a valuation allowance. The associated valuation allowance released related to the shift in attributes reflects what the Company believes will be realized. The Company anticipates all AMT credits will be converted to cash in the next five years as provided by the Act. In total, these changes resulted in a recorded benefit from income taxes of $45.2 million , which was net of a $24.9 million uncertain tax position charge.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The hierarchy of fair value measurements assigns a level to fair value measurements based on the inputs used in the respective valuation techniques. The levels of the hierarchy, as defined below, give the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. · Level 1 is defined as observable inputs such as quoted prices in active markets for identical assets. Level 1 assets include U.S. Treasury securities, and coal swaps and futures that are submitted for clearing on the New York Mercantile Exchange. · Level 2 is defined as observable inputs other than Level 1 prices. These include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s level 2 assets and liabilities include U.S. government agency securities, coal commodity contracts and interest rate swaps with fair values derived from quoted prices in over-the-counter markets or from prices received from direct broker quotes. · Level 3 is defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. These include the Company’s commodity option contracts (coal, natural gas and heating oil) valued using modeling techniques, such as Black-Scholes, that require the use of inputs, particularly volatility, that are rarely observable. Changes in the unobservable inputs would not have a significant impact on the reported Level 3 fair values at September 30, 2019 . The table below sets forth, by level, the Company’s financial assets and liabilities that are recorded at fair value in the accompanying Condensed Consolidated Balance Sheet: September 30, 2019 Total Level 1 Level 2 Level 3 (In thousands) Assets: Investments in marketable securities $ 176,056 $ 64,965 $ 111,091 $ — Derivatives 9,983 8,366 1,234 383 Total assets $ 186,039 $ 73,331 $ 112,325 $ 383 Liabilities: Derivatives $ 4,071 $ — $ 4,130 $ (59 ) The Company’s contracts with its counterparties allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. For classification purposes, the Company records the net fair value of all the positions with these counterparties as a net asset or liability. Each level in the table above displays the underlying contracts according to their classification in the accompanying Condensed Consolidated Balance Sheet, based on this counterparty netting. The following table summarizes the change in the fair values of financial instruments categorized as Level 3. Three Months Ended September 30, 2019 Nine Months Ende d September 30, 2019 (In thousands) Balance, beginning of period $ 755 $ 532 Realized and unrealized gains recognized in earnings, net (1,252 ) (1,794 ) Purchases 562 1,562 Issuances (45 ) (45 ) Settlements 422 187 Ending balance $ 442 $ 442 Net unrealized losses of $1.0 million and $1.9 million were recognized in the Condensed Consolidated Income Statements within Other operating income, net during the three and nine months ended September 30, 2019 , respectively, related to Level 3 financial instruments held on September 30, 2019 . Fair Value of Long-Term Debt At September 30, 2019 and December 31, 2018 , the fair value of the Company’s debt, including amounts classified as current, was $306.9 million and $318.6 million , respectively. Fair values are based upon observed prices in an active market, when available, or from valuation models using market information, which fall into Level 2 in the fair value hierarchy.

Earnings per Common Share

Earnings per Common Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings per Common Share	Earnings per Common Share The Company computes basic net income per share using the weighted average number of common shares outstanding during the period. Diluted net income per share is computed using the weighted average number of common shares and the effect of potentially dilutive securities outstanding during the period. Potentially dilutive securities may consist of warrants, restricted stock units or other contingently issuable shares. The dilutive effect of outstanding warrants, restricted stock units and other contingently issuable shares is reflected in diluted earnings per share by application of the treasury stock method. The following table provides the basis for basic and diluted earnings per share by reconciling the denominators of the computations: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Weighted average shares outstanding: Basic weighted average shares outstanding 15,736 19,250 16,591 20,102 Effect of dilutive securities 1,116 958 1,153 938 Diluted weighted average shares outstanding 16,852 20,208 17,744 21,040

Workers Compensation Expense

Workers Compensation Expense	9 Months Ended
	Sep. 30, 2019
Compensation Related Costs [Abstract]
Workers Compensation Expense	Workers Compensation Expense The Company is liable under the Federal Mine Safety and Health Act of 1969, as subsequently amended, to provide for pneumoconiosis (occupational disease) benefits to eligible employees, former employees and dependents. The Company currently provides for federal claims principally through a self-insurance program. The Company is also liable under various state workers’ compensation statutes for occupational disease benefits. The occupational disease benefit obligation represents the present value of the actuarially computed present and future liabilities for such benefits over the employees’ applicable years of service. In addition, the Company is liable for workers’ compensation benefits for traumatic injuries which are calculated using actuarially-based loss rates, loss development factors and discounted based on a risk free rate. Traumatic workers’ compensation claims are insured with varying retentions/deductibles, or through state-sponsored workers’ compensation programs. Workers’ compensation expense consists of the following components: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Self-insured occupational disease benefits: Service cost $ 1,670 $ 1,860 $ 5,008 $ 5,580 Interest cost (1) 1,354 1,196 4,062 3,585 Total occupational disease $ 3,024 $ 3,056 $ 9,070 $ 9,165 Traumatic injury claims and assessments 2,088 (2,069 ) 6,642 3,130 Total workers’ compensation expense $ 5,112 $ 987 $ 15,712 $ 12,295

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2019
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Employee Benefit Plans	Employee Benefit Plans The following table details the components of pension benefit costs (credits): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Interest cost (1) $ 1,922 $ 2,376 $ 6,439 $ 6,917 Expected return on plan assets (1) (2,699 ) (2,906 ) (8,146 ) (9,067 ) Pension settlement (1) (197 ) (613 ) (626 ) (1,984 ) Amortization of prior service costs (credits) 4 — 4 — Net benefit credit $ (970 ) $ (1,143 ) $ (2,329 ) $ (4,134 ) The following table details the components of other postretirement benefit costs: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Service cost $ 120 $ 140 $ 360 $ 419 Interest cost (1) 876 918 2,629 2,755 Amortization of other actuarial losses (gains) (2,236 ) — (2,236 ) — Net benefit cost (credit) $ (1,240 ) $ 1,058 $ 753 $ 3,174

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company accrues for costs related to contingencies when a loss is probable and the amount is reasonably determinable. Disclosure of contingencies is included in the financial statements when it is at least reasonably possible that a material loss or an additional material loss in excess of amounts already accrued may be incurred. In addition, the Company is a party to numerous other claims and lawsuits with respect to various matters. The ultimate resolution of any such legal matter could result in outcomes that may be materially different from amounts the Company has accrued for such matters. The Company believes it has recorded adequate reserves for these matters.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information The Company’s reportable business segments are based on two distinct lines of business, metallurgical and thermal, and may include a number of mine complexes. The Company manages its coal sales by market, not by individual mining complex. Geology, coal transportation routes to customers, and regulatory environments also have a significant impact on the Company’s marketing and operations management. Mining operations are evaluated based on Adjusted EBITDA, per-ton cash operating costs (defined as including all mining costs except depreciation, depletion, amortization, accretion on asset retirement obligations, and pass-through transportation expenses), and on other non-financial measures, such as safety and environmental performance. Adjusted EBITDA is not a measure of financial performance in accordance with generally accepted accounting principles, and items excluded from Adjusted EBITDA are significant in understanding and assessing the Company’s financial condition. Therefore, Adjusted EBITDA should not be considered in isolation, nor as an alternative to net income, income from operations, cash flows from operations or as a measure of our profitability, liquidity or performance under generally accepted accounting principles. The Company uses Adjusted EBITDA to measure the operating performance of its segments and allocate resources to the segments. Furthermore, analogous measures are used by industry analysts and investors to evaluate the Company’s operating performance. Investors should be aware that the Company’s presentation of Adjusted EBITDA may not be comparable to similarly titled measures used by other companies. The Company reports its results of operations primarily through the following reportable segments: Powder River Basin (PRB) segment containing the Company’s primary thermal operations in Wyoming; the Metallurgical (MET) segment, containing the Company’s metallurgical operations in West Virginia, and the Other Thermal segment containing the Company’s supplementary thermal operations in Colorado, Illinois, and West Virginia. Operating segment results for the three and nine months ended September 30, 2019 and 2018 , are presented below. The Company measures its segments based on “adjusted earnings before interest, taxes, depreciation, depletion, amortization, accretion on asset retirements obligations, and nonoperating expenses (Adjusted EBITDA).” Adjusted EBITDA does not reflect mine closure or impairment costs, since those are not reflected in the operating income reviewed by management. The Corporate, Other and Eliminations grouping includes these charges, as well as the change in fair value of coal derivatives and coal trading activities, net; corporate overhead; land management activities; other support functions; and the elimination of intercompany transactions. PRB MET Other Thermal Corporate, Other and Eliminations Consolidated (in thousands) Three Months Ended September 30, 2019 Revenues $ 269,967 $ 254,493 $ 94,052 $ 955 $ 619,467 Adjusted EBITDA 50,153 70,814 16,659 (31,005 ) 106,621 Depreciation, depletion and amortization 5,956 19,962 3,852 632 30,402 Accretion on asset retirement obligation 3,135 531 603 868 5,137 Total assets 236,656 609,378 148,994 939,572 1,934,600 Capital expenditures 5,402 36,475 6,837 738 49,452 Three Months Ended September 30, 2018 Revenues $ 261,927 $ 236,328 $ 130,663 $ 4,262 $ 633,180 Adjusted EBITDA 48,646 81,250 25,200 (30,202 ) 124,894 Depreciation, depletion and amortization 9,114 18,106 3,924 631 31,775 Accretion on asset retirement obligation 4,885 469 565 1,073 6,992 Total assets 374,092 561,989 127,904 933,637 1,997,622 Capital expenditures 3,458 17,827 3,332 1,076 25,693 Nine Months Ende d September 30, 2019 Revenues $ 692,845 $ 769,000 $ 278,235 $ 4,792 $ 1,744,872 Adjusted EBITDA 85,433 264,284 33,699 (63,977 ) 319,439 Depreciation, depletion and amortization 15,702 53,687 10,976 1,834 82,199 Accretion on asset retirement obligation 9,406 1,592 1,810 2,603 15,411 Total assets 236,656 609,378 148,994 939,572 1,934,600 Capital expenditures 19,026 98,849 16,299 3,222 137,396 Nine Months Ended September 30, 2018 Revenues $ 737,233 $ 733,707 $ 321,997 $ 7,887 $ 1,800,824 Adjusted EBITDA 102,639 251,649 52,710 (91,806 ) 315,192 Depreciation, depletion and amortization 25,841 53,109 11,459 1,618 92,027 Accretion on asset retirement obligation 14,656 1,406 1,696 3,219 20,977 Total assets 374,092 561,989 127,904 933,637 1,997,622 Capital expenditures 7,221 35,555 7,097 5,869 55,742 A reconciliation of net income to adjusted EBITDA follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Net income $ 106,769 $ 123,192 $ 242,350 $ 226,483 Provision for (benefit from) income taxes 347 (45,215 ) 508 (49,125 ) Interest expense, net 340 3,378 4,916 10,998 Depreciation, depletion and amortization 30,402 31,775 82,199 92,027 Accretion on asset retirement obligations 5,137 6,992 15,411 20,977 Amortization of sales contracts, net (153 ) 3,241 (77 ) 9,540 Loss on sale of Lone Mountain Processing, LLC — — 4,304 — Preference Rights Lease Application (PRLA) settlement income (39,000 ) — (39,000 ) — Net loss resulting from early retirement of debt and debt restructuring — — — 485 Non-service related pension and postretirement benefit costs (975 ) 971 2,127 2,206 Reorganization items, net — 560 (71 ) 1,601 Costs associated with proposed joint venture with Peabody Energy 3,754 — 6,772 — Adjusted EBITDA $ 106,621 $ 124,894 $ 319,439 $ 315,192

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition ASC 606-10-50-5 requires that entities disclose disaggregated revenue information in categories (such as type of good or service, geography, market, type of contract, etc.) that depict how the nature, amount, timing, and uncertainty of revenue and cash flow are affected by economic factors. ASC 606-10-55-89 explains that the extent to which an entity’s revenue is disaggregated depends on the facts and circumstances that pertain to the entity’s contracts with customers and that some entities may need to use more than one type of category to meet the objective for disaggregating revenue. In general, the Company’s business segmentation is aligned according to the nature and economic characteristics of its coal and customer relationships and provides meaningful disaggregation of each segment’s results. The Company has further disaggregated revenue between North America and Seaborne revenues which depicts the pricing and contract differences between the two. North America revenue is characterized by contracts with a term of one year or longer and typically the pricing is fixed; whereas Seaborne revenue generally is derived by spot or short term contracts with an indexed based pricing mechanism. PRB MET Other Thermal Corporate, Other and Eliminations Consolidated (in thousands) Three Months Ended September 30, 2019 North America revenues $ 269,967 $ 63,755 $ 47,571 $ 955 $ 382,248 Seaborne revenues — 190,738 46,481 — 237,219 Total revenues $ 269,967 $ 254,493 $ 94,052 $ 955 $ 619,467 Three Months Ended September 30, 2018 North America revenues $ 261,927 $ 49,698 $ 56,051 $ 4,262 $ 371,938 Seaborne revenues — 186,630 74,612 — 261,242 Total revenues $ 261,927 $ 236,328 $ 130,663 $ 4,262 $ 633,180 Nine Months Ende d September 30, 2019 North America revenues $ 692,845 $ 163,317 $ 141,985 $ 4,792 $ 1,002,939 Seaborne revenues — 605,683 136,250 — 741,933 Total revenues $ 692,845 $ 769,000 $ 278,235 $ 4,792 $ 1,744,872 Nine Months Ended September 30, 2018 North America revenues $ 735,322 $ 117,699 $ 140,265 $ 7,887 $ 1,001,173 Seaborne revenues 1,911 616,008 181,732 — 799,651 Total revenues $ 737,233 $ 733,707 $ 321,997 $ 7,887 $ 1,800,824 As of September 30, 2019 , the Company has outstanding performance obligations for the remainder of 2019 of 17.3 million tons of fixed price contracts and 1.8 million tons of variable price contracts. Additionally, the Company has outstanding performance obligations beyond 2019 of approximately 96.8 million tons of fixed price contracts and 6.0 million tons of variable price contracts.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases The Company has operating leases for mining equipment, office equipment and office space with remaining lease terms ranging from less than 1 year to approximately 8 years . Some of these leases include both lease and non-lease components which are accounted for as a single lease component as the Company has elected the practical expedient to combine these components for all leases. As most of the leases do not provide an implicit rate, the Company calculated the ROU assets and lease liabilities using its’ secured incremental borrowing rate at the lease commencement date. The Company currently does not have any finance leases outstanding. Information related to leases was as follows: Three Months Ended September 30, 2019 (In thousands) Operating lease information: Operating lease cost $ 1,071 Operating cash flows from operating leases 1,078 Weighted average remaining lease term in years 6.19 Weighted average discount rate 5.5 % Future minimum lease payments under non-cancellable leases as of September 30, 2019 were as follows: Year Amount (In thousands) 2019 $ 1,024 2020 3,616 2021 3,367 2022 3,292 2023 3,261 Thereafter 11,153 Total minimum lease payments $ 25,713 Less imputed interest (4,725 ) Total operating lease liability $ 20,988 As reflected on balance sheet: Accrued expenses and other current liabilities $ 2,713 Other noncurrent liabilities 18,275 Total operating lease liability $ 20,988 At September 30, 2019 , the Company had a $20.3 million ROU operating lease asset recorded within “Other noncurrent assets” on the Condensed Consolidated Balance Sheet.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events During September 2019, the Company entered into a definitive agreement to acquire 20 million tons of low-cost, high quality, High-Vol A coking coal reserves directly adjacent to its Leer mine for $52.5 million . The reserves are contiguous to the existing Leer mine reserves and accessible underground by the longwall operation without meaningful incremental capital. The reserve addition is expected to extend the life of the Leer mine approximately six years . Closing of the transaction is subject to title work and satisfaction of closing conditions and is anticipated to close during the fourth quarter of 2019.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and U.S. Securities and Exchange Commission regulations. In the opinion of management, all adjustments, consisting of normal, recurring accruals considered necessary for a fair presentation, have been included. Results of operations for the three and nine months ended September 30, 2019 are not necessarily indicative of results to be expected for the year ending December 31, 2019 . These financial statements should be read in conjunction with the audited financial statements and related notes as of and for the year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.
Recently Adopted Accounting Guidance	Recently Adopted Accounting Guidance In February 2016, the FASB established Topic 842, Leases, by issuing ASU 2016-02, “Leases” which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. The ASU was subsequently amended by ASU 2018-01, “Land Easements Practical Expedient for Transition to Topic 842;” ASU 2018-10, “Codification Improvements to Topic 842, Leases;” and ASU 2018-11, “Targeted Improvements.” The new standard establishes a right-of-use (“ROU”) model that requires a lessee to recognize an ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. The standard also requires a lessee to recognize a single lease cost, calculated so that the cost of the lease is allocated over the term of the lease, on a generally straight line basis. Leases of mineral reserves and related land leases have been exempted from the standard. The Company adopted ASU 2016-02 effective January 1, 2019 and elected the option to not restate comparative periods in transition and also elected the “package of practical expedients” within the standard which permits the Company not to reassess its prior conclusions about lease identification, lease classification and initial direct costs. Additionally, the Company made an election to not separate lease and non-lease components for all leases, and will not use hindsight. Finally, the Company will continue its current policy for accounting for land easements as executory contracts. The adoption of the standard had no impact on the Company’s consolidated income statement or statement of cash flows. In April 2017, the FASB issued ASU 2017-08, “Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities.” The new guidance shortens the amortization period for the premium on certain purchased callable debt securities to the earliest call date. The new guidance does not change the accounting for purchased callable debt securities held at a discount. The Company adopted ASU 2017-08 effective January 1, 2019 with no impact on the Company’s financial statements. In August 2017, the FASB issued ASU 2017-12, “Targeted Improvements to Accounting for Hedging Activities.” The new guidance provides targeted improvements to the accounting for hedging activities to better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedging results. The Company adopted ASU 2017-12 effective January 1, 2019 with no impact on the Company’s financial statements. In February 2018, the FASB issued ASU 2018-02, “Income Statement-Reporting Comprehensive Income (Topic 220) Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” ASU 2018-02 provides an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings due to the change in the U.S. federal tax rate in the Tax Cuts and Jobs Act of 2017. The Company adopted ASU 2018-02 effective January 1, 2019 with no impact on the Company’s financial statements. In June 2018, the FASB issued ASU 2018-07, “Compensation-Stock Compensation (Topic 718), Improvements to Non-employee Share-Based Payment Accounting.” ASU 2018-07 aligns the measurement and classification guidance for share-based payments to non-employees with the guidance for share-based payments to employees. The Company adopted ASU 2018-07 effective January 1, 2019 with no impact on the Company’s financial statements. In October 2018, the FASB issued ASU 2018-16, “Derivatives and Hedging (Topic 815), Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate of Hedge Accounting Purposes.” The Company adopted ASU 2018-16 effective January 1, 2019 with no impact on the Company’s financial statements.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following items are included in accumulated other comprehensive income (“AOCI”): Pension, Postretirement and Other Accumulated Post- Other Derivative Employment Available-for- Comprehensive Instruments Benefits Sale Securities Income (In thousands) Balance at December 31, 2018 $ 3,328 $ 40,311 $ (343 ) $ 43,296 Unrealized gains 3,836 1,745 603 6,184 Amounts reclassified from AOCI (6,257 ) (2,862 ) (50 ) (9,169 ) Balance at September 30, 2019 $ 907 $ 39,194 $ 210 $ 40,311
Schedule of Comprehensive Income Reclassifications	The following amounts were reclassified out of AOCI: Three Months Ended September 30, Nine Months Ended September 30, Details About AOCI Components 2019 2018 2019 2018 Line Item in the Condensed Consolidated Statement of Operations (In thousands) Coal hedges $ 2,963 $ (4,824 ) $ 5,067 $ (4,824 ) Revenues Interest rate hedges 161 265 1,190 753 Interest expense — — — — Provision for (benefit from) income taxes $ 3,124 $ (4,559 ) $ 6,257 $ (4,071 ) Net of tax Pension, postretirement and other post-employment benefits Amortization of actuarial gains (losses), net $ 2,236 $ — $ 2,236 $ — Non-service related pension and postretirement benefit (costs) credits Pension settlement 197 613 626 1,984 Non-service related pension and postretirement benefit (costs) credits — — — — Provision for (benefit from) income taxes $ 2,433 $ 613 $ 2,862 $ 1,984 Net of tax Available-for-sale securities $ 35 $ 8 $ 50 $ 24 Interest and investment income — — — — Provision for (benefit from) income taxes $ 35 $ 8 $ 50 $ 24 Net of tax

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Inventories	Inventories consist of the following: September 30, December 31, 2019 2018 (In thousands) Coal $ 79,746 $ 40,982 Repair parts and supplies 91,797 84,488 $ 171,543 $ 125,470

Investments in Available-for-_2

Investments in Available-for-Sale Securities (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Securities, Available-for-sale [Abstract]
Available-for-sale Securities	The Company’s investments in available-for-sale marketable securities are as follows: September 30, 2019 Balance Sheet Classification Gross Unrealized Fair Short-Term Other Cost Basis Gains Losses Value Investments Assets (In thousands) Available-for-sale: U.S. government and agency securities $ 64,930 $ 52 $ (17 ) $ 64,965 $ 64,965 $ — Corporate notes and bonds 110,917 275 (101 ) 111,091 111,091 — Total Investments $ 175,847 $ 327 $ (118 ) $ 176,056 $ 176,056 $ — December 31, 2018 Balance Sheet Classification Gross Unrealized Fair Short-Term Other Cost Basis Gains Losses Value Investments Assets (In thousands) Available-for-sale: U.S. government and agency securities $ 100,003 $ 11 $ (126 ) $ 99,888 $ 99,888 $ — Corporate notes and bonds 63,137 4 (232 ) 62,909 62,909 — Total Investments $ 163,140 $ 15 $ (358 ) $ 162,797 $ 162,797 $ —

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Price Risk Derivatives	At September 30, 2019 , the Company held derivatives for risk management purposes that are expected to settle in the following years: (Tons in thousands) 2019 2020 Total Coal sales 607 668 1,275 Coal purchases 385 337 722
Disclosure of Fair Value of Derivatives	The fair value and location of derivatives reflected in the accompanying Condensed Consolidated Balance Sheets are as follows: September 30, 2019 December 31, 2018 Fair Value of Derivatives Asset Liability Asset Liability (In thousands) Derivative Derivative Derivative Derivative Derivatives Designated as Hedging Instruments Coal $ 3,842 $ (671 ) $ 2,342 $ (805 ) Derivatives Not Designated as Hedging Instruments Heating oil -- diesel purchases 383 (629 ) 532 — Coal -- held for trading purposes 20,116 (20,925 ) 10,329 (10,701 ) Coal -- risk management 18,305 (11,067 ) 5,672 (19,579 ) Natural gas — — 4 (4 ) Total $ 38,804 $ (32,621 ) $ 16,537 $ (30,284 ) Total derivatives $ 42,646 $ (33,292 ) $ 18,879 $ (31,089 ) Effect of counterparty netting (32,663 ) 32,663 (17,801 ) 17,801 Net derivatives as classified in the balance sheets $ 9,983 $ (629 ) $ 9,354 $ 1,078 $ (13,288 ) $ (12,210 ) September 30, 2019 December 31, 2018 Net derivatives as reflected on the balance sheets (in thousands) Heating oil and coal Other current assets $ 9,983 $ 1,078 Coal Accrued expenses and other current liabilities (629 ) (13,288 ) $ 9,354 $ (12,210 )
Effects of Derivatives on Measures of Financial Performance	The effects of derivatives on measures of financial performance are as follows: Derivatives used in Cash Flow Hedging Relationships (in thousands) Three Months Ended September 30, Gain (Loss) Recognized in Other Comprehensive Income Gains (Losses) Reclassified from Other Comprehensive Income into Income 2019 2018 2019 2018 Coal sales (1) $ 225 $ (4,631 ) $ 2,963 $ (6,996 ) Coal purchases (2) (34 ) 424 — 2,171 Totals $ 191 $ (4,207 ) $ 2,963 $ (4,825 ) Derivatives Not Designated as Hedging Instruments (in thousands) Three Months Ended September 30, Gain (Loss) Recognized 2019 2018 Coal trading — realized and unrealized (3) $ (127 ) $ (928 ) Coal risk management — unrealized (3) (1,417 ) (9,486 ) Natural gas trading— realized and unrealized (3) 14 (4 ) Change in fair value of coal derivatives and coal trading activities, net total $ (1,530 ) $ (10,418 ) Coal risk management— realized (4) $ 3,216 $ (2,537 ) Heating oil — diesel purchases (4) $ (1,670 ) $ 719 ____________________________________________________________ Location in statement of operations: (1) — Revenues (2) — Cost of sales (3) — Change in fair value of coal derivatives and coal trading activities, net (4) — Other operating (income) expense, net Derivatives used in Cash Flow Hedging Relationships (in thousands) Nine Months Ended September 30, Gain (Loss) Recognized in Other Comprehensive Income Gains (Losses) Reclassified from Other Comprehensive Income into Income 2019 2018 2019 2018 Coal sales (1) $ 9,472 $ (14,862 ) $ 5,750 $ (6,996 ) Coal purchases (2) (940 ) 2,587 (686 ) 2,171 Totals $ 8,532 $ (12,275 ) $ 5,064 $ (4,825 ) Derivatives Not Designated as Hedging Instruments (in thousands) Nine Months Ended September 30, Gain (Loss) Recognized 2019 2018 Coal trading — realized and unrealized (3) $ (1,228 ) $ 14 Coal risk management — unrealized (3) 21,145 (22,116 ) Natural gas trading— realized and unrealized (3) (66 ) (40 ) Change in fair value of coal derivatives and coal trading activities, net total $ 19,851 $ (22,142 ) Coal risk management— realized (4) $ (2,076 ) $ (5,217 ) Heating oil — diesel purchases (4) $ (2,402 ) $ 4,394 ____________________________________________________________ Location in statement of operations: (1) — Revenues (2) — Cost of sales (3) — Change in fair value of coal derivatives and coal trading activities, net (4) — Other operating (income) expense, net

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following: September 30, December 31, 2019 2018 (In thousands) Payroll and employee benefits $ 49,566 $ 57,166 Taxes other than income taxes 71,738 75,017 Interest 131 156 Acquired sales contracts 203 570 Workers’ compensation 18,053 20,044 Asset retirement obligations 12,297 13,113 Other 9,951 17,448 $ 161,939 $ 183,514

Debt and Financing Arrangemen_2

Debt and Financing Arrangements (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	September 30, December 31, 2019 2018 (In thousands) Term loan due 2024 ($292.5 million face value) $ 291,524 $ 293,626 Other 18,471 30,449 Debt issuance costs (5,289 ) (6,092 ) 304,706 317,983 Less: current maturities of debt 11,925 17,797 Long-term debt $ 292,781 $ 300,186
Schedule of Interest Rate Derivatives	Below is a summary of the Company’s outstanding interest rate swap agreements designated as hedges as of September 30, 2019 : Notional Amount (in millions) Effective Date Fixed Rate Receive Rate Expiration Date $250.0 June 28, 2019 2.025% 1-month LIBOR June 30, 2020 $200.0 June 30, 2020 2.249% 1-month LIBOR June 30, 2021 $100.0 June 30, 2021 2.315% 1-month LIBOR June 30, 2023

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	A reconciliation of the statutory federal income tax provision at the statutory rate to the actual provision for (benefit from) income taxes follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Income tax provision at statutory rate $ 22,494 $ 16,375 $ 51,000 $ 37,245 Percentage depletion allowance (6,347 ) (5,964 ) (14,111 ) (13,059 ) State taxes, net of effect of federal taxes 1,825 4,528 3,668 5,865 Change in valuation allowance (19,120 ) (44,278 ) (42,925 ) (62,234 ) Current expense associated with uncertain tax positions 1,495 511 2,932 (599 ) Impact of Tax Cuts and Jobs Act of 2017 — (19,780 ) — (19,780 ) Other, net — 3,393 (56 ) 3,437 Provision for (benefit from) income taxes $ 347 $ (45,215 ) $ 508 $ (49,125 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities Accounted for at Fair Value	The table below sets forth, by level, the Company’s financial assets and liabilities that are recorded at fair value in the accompanying Condensed Consolidated Balance Sheet: September 30, 2019 Total Level 1 Level 2 Level 3 (In thousands) Assets: Investments in marketable securities $ 176,056 $ 64,965 $ 111,091 $ — Derivatives 9,983 8,366 1,234 383 Total assets $ 186,039 $ 73,331 $ 112,325 $ 383 Liabilities: Derivatives $ 4,071 $ — $ 4,130 $ (59 )
Summary of Change in the Fair Values of Financial Instruments Categorized as Level 3	The following table summarizes the change in the fair values of financial instruments categorized as Level 3. Three Months Ended September 30, 2019 Nine Months Ende d September 30, 2019 (In thousands) Balance, beginning of period $ 755 $ 532 Realized and unrealized gains recognized in earnings, net (1,252 ) (1,794 ) Purchases 562 1,562 Issuances (45 ) (45 ) Settlements 422 187 Ending balance $ 442 $ 442

Earnings per Common Share (Tabl

Earnings per Common Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Schedule of Weighted Average Number of Shares	The following table provides the basis for basic and diluted earnings per share by reconciling the denominators of the computations: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Weighted average shares outstanding: Basic weighted average shares outstanding 15,736 19,250 16,591 20,102 Effect of dilutive securities 1,116 958 1,153 938 Diluted weighted average shares outstanding 16,852 20,208 17,744 21,040

Workers Compensation Expense (T

Workers Compensation Expense (Tables)	9 Months Ended
	Sep. 30, 2019
Compensation Related Costs [Abstract]
Workers' compensation expense	Workers’ compensation expense consists of the following components: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Self-insured occupational disease benefits: Service cost $ 1,670 $ 1,860 $ 5,008 $ 5,580 Interest cost (1) 1,354 1,196 4,062 3,585 Total occupational disease $ 3,024 $ 3,056 $ 9,070 $ 9,165 Traumatic injury claims and assessments 2,088 (2,069 ) 6,642 3,130 Total workers’ compensation expense $ 5,112 $ 987 $ 15,712 $ 12,295

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2019
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension Benefit Costs	The following table details the components of pension benefit costs (credits): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Interest cost (1) $ 1,922 $ 2,376 $ 6,439 $ 6,917 Expected return on plan assets (1) (2,699 ) (2,906 ) (8,146 ) (9,067 ) Pension settlement (1) (197 ) (613 ) (626 ) (1,984 ) Amortization of prior service costs (credits) 4 — 4 — Net benefit credit $ (970 ) $ (1,143 ) $ (2,329 ) $ (4,134 ) The following table details the components of other postretirement benefit costs: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Service cost $ 120 $ 140 $ 360 $ 419 Interest cost (1) 876 918 2,629 2,755 Amortization of other actuarial losses (gains) (2,236 ) — (2,236 ) — Net benefit cost (credit) $ (1,240 ) $ 1,058 $ 753 $ 3,174

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Schedule of Operating Segment Results	PRB MET Other Thermal Corporate, Other and Eliminations Consolidated (in thousands) Three Months Ended September 30, 2019 Revenues $ 269,967 $ 254,493 $ 94,052 $ 955 $ 619,467 Adjusted EBITDA 50,153 70,814 16,659 (31,005 ) 106,621 Depreciation, depletion and amortization 5,956 19,962 3,852 632 30,402 Accretion on asset retirement obligation 3,135 531 603 868 5,137 Total assets 236,656 609,378 148,994 939,572 1,934,600 Capital expenditures 5,402 36,475 6,837 738 49,452 Three Months Ended September 30, 2018 Revenues $ 261,927 $ 236,328 $ 130,663 $ 4,262 $ 633,180 Adjusted EBITDA 48,646 81,250 25,200 (30,202 ) 124,894 Depreciation, depletion and amortization 9,114 18,106 3,924 631 31,775 Accretion on asset retirement obligation 4,885 469 565 1,073 6,992 Total assets 374,092 561,989 127,904 933,637 1,997,622 Capital expenditures 3,458 17,827 3,332 1,076 25,693 Nine Months Ende d September 30, 2019 Revenues $ 692,845 $ 769,000 $ 278,235 $ 4,792 $ 1,744,872 Adjusted EBITDA 85,433 264,284 33,699 (63,977 ) 319,439 Depreciation, depletion and amortization 15,702 53,687 10,976 1,834 82,199 Accretion on asset retirement obligation 9,406 1,592 1,810 2,603 15,411 Total assets 236,656 609,378 148,994 939,572 1,934,600 Capital expenditures 19,026 98,849 16,299 3,222 137,396 Nine Months Ended September 30, 2018 Revenues $ 737,233 $ 733,707 $ 321,997 $ 7,887 $ 1,800,824 Adjusted EBITDA 102,639 251,649 52,710 (91,806 ) 315,192 Depreciation, depletion and amortization 25,841 53,109 11,459 1,618 92,027 Accretion on asset retirement obligation 14,656 1,406 1,696 3,219 20,977 Total assets 374,092 561,989 127,904 933,637 1,997,622 Capital expenditures 7,221 35,555 7,097 5,869 55,742
Reconciliation Statement of Segment Income from Operations to Consolidated Income Before Income Taxes	A reconciliation of net income to adjusted EBITDA follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Net income $ 106,769 $ 123,192 $ 242,350 $ 226,483 Provision for (benefit from) income taxes 347 (45,215 ) 508 (49,125 ) Interest expense, net 340 3,378 4,916 10,998 Depreciation, depletion and amortization 30,402 31,775 82,199 92,027 Accretion on asset retirement obligations 5,137 6,992 15,411 20,977 Amortization of sales contracts, net (153 ) 3,241 (77 ) 9,540 Loss on sale of Lone Mountain Processing, LLC — — 4,304 — Preference Rights Lease Application (PRLA) settlement income (39,000 ) — (39,000 ) — Net loss resulting from early retirement of debt and debt restructuring — — — 485 Non-service related pension and postretirement benefit costs (975 ) 971 2,127 2,206 Reorganization items, net — 560 (71 ) 1,601 Costs associated with proposed joint venture with Peabody Energy 3,754 — 6,772 — Adjusted EBITDA $ 106,621 $ 124,894 $ 319,439 $ 315,192

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Schedule of effects of revenue recognition	PRB MET Other Thermal Corporate, Other and Eliminations Consolidated (in thousands) Three Months Ended September 30, 2019 North America revenues $ 269,967 $ 63,755 $ 47,571 $ 955 $ 382,248 Seaborne revenues — 190,738 46,481 — 237,219 Total revenues $ 269,967 $ 254,493 $ 94,052 $ 955 $ 619,467 Three Months Ended September 30, 2018 North America revenues $ 261,927 $ 49,698 $ 56,051 $ 4,262 $ 371,938 Seaborne revenues — 186,630 74,612 — 261,242 Total revenues $ 261,927 $ 236,328 $ 130,663 $ 4,262 $ 633,180 Nine Months Ende d September 30, 2019 North America revenues $ 692,845 $ 163,317 $ 141,985 $ 4,792 $ 1,002,939 Seaborne revenues — 605,683 136,250 — 741,933 Total revenues $ 692,845 $ 769,000 $ 278,235 $ 4,792 $ 1,744,872 Nine Months Ended September 30, 2018 North America revenues $ 735,322 $ 117,699 $ 140,265 $ 7,887 $ 1,001,173 Seaborne revenues 1,911 616,008 181,732 — 799,651 Total revenues $ 737,233 $ 733,707 $ 321,997 $ 7,887 $ 1,800,824

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Information related to leases	Information related to leases was as follows: Three Months Ended September 30, 2019 (In thousands) Operating lease information: Operating lease cost $ 1,071 Operating cash flows from operating leases 1,078 Weighted average remaining lease term in years 6.19 Weighted average discount rate 5.5 %
Schedule of future minimum lease payments	Future minimum lease payments under non-cancellable leases as of September 30, 2019 were as follows: Year Amount (In thousands) 2019 $ 1,024 2020 3,616 2021 3,367 2022 3,292 2023 3,261 Thereafter 11,153 Total minimum lease payments $ 25,713 Less imputed interest (4,725 ) Total operating lease liability $ 20,988 As reflected on balance sheet: Accrued expenses and other current liabilities $ 2,713 Other noncurrent liabilities 18,275 Total operating lease liability $ 20,988

Joint Venture with Peabody En_2

Joint Venture with Peabody Energy (Details) - Implementation Agreement - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Jun. 18, 2019
Schedule of Equity Method Investments [Line Items]
Economic interest held			33.50%
Incurred expenses related to regulatory approval process	$ 3.8	$ 6.8
Peabody Energy Corporation
Schedule of Equity Method Investments [Line Items]
Economic interest held			66.50%

Loss on Sale of Lone Mountain_2

Loss on Sale of Lone Mountain Processing, LLC (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale of Lone Mountain Processing, LLC	$ 0	$ 0	$ (4,304)	$ 0
Lone Mountain Processing Inc and 2 idled mining companies | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale of Lone Mountain Processing, LLC			$ (4,300)		$ 21,300

Preference Rights Lease Appli_2

Preference Rights Lease Application (PRLA) Settlement Income (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Gain Contingencies [Line Items]
Gain related to settlement		$ 39,000	$ 0	$ 39,000	$ 0
Preference Rights Lease Application (PRLA)
Gain Contingencies [Line Items]
Gain related to settlement		39,000
Royalty credits to be received due to settlement		$ 67,000
Royalty credits to be received due to settlement, percentage of royalty obligations		50.00%
Minimum | Preference Rights Lease Application (PRLA)
Gain Contingencies [Line Items]
Royalty credits to be received due to settlement, period of recognition				18 months
Maximum | Preference Rights Lease Application (PRLA)
Gain Contingencies [Line Items]
Royalty credits to be received due to settlement, period of recognition				24 months
Forecast | Preference Rights Lease Application (PRLA)
Gain Contingencies [Line Items]
One-time payment for ownership interest	$ 27,000
Payment to acquire investment, closing fees	$ 1,000

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning Balance	$ 704,821
Unrealized gains	6,184
Amounts reclassified from AOCI	(9,169)
Ending Balance	705,436
Accumulated Other Comprehensive Income
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning Balance	43,296
Ending Balance	40,311
Derivative instruments
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning Balance	3,328
Unrealized gains	3,836
Amounts reclassified from AOCI	(6,257)
Ending Balance	907
Pension, postretirement and other post-employment benefits
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning Balance	40,311
Unrealized gains	1,745
Amounts reclassified from AOCI	(2,862)
Ending Balance	39,194
Available-for-sale securities
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning Balance	(343)
Unrealized gains	603
Amounts reclassified from AOCI	(50)
Ending Balance	$ 210

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Schedule of Reclassifications) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues	$ 619,467	$ 633,180	$ 1,744,872	$ 1,800,824
Interest expense	(4,049)	(5,179)	(12,856)	(15,624)
Provision for (benefit from) income taxes	(347)	45,215	(508)	49,125
Interest and investment income	3,709	1,801	7,940	4,626
Net income	106,769	123,192	242,350	226,483
Reclassification out of Accumulated Other Comprehensive Income | Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues	2,963	(4,824)	5,067	(4,824)
Interest expense	161	265	1,190	753
Provision for (benefit from) income taxes	0	0	0	0
Net income	3,124	(4,559)	6,257	(4,071)
Reclassification out of Accumulated Other Comprehensive Income | Pension, postretirement and other post-employment benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Provision for (benefit from) income taxes	0	0	0	0
Amortization of actuarial gains (losses), net	2,236	0	2,236	0
Pension settlement	197	613	626	1,984
Net income	2,433	613	2,862	1,984
Reclassification out of Accumulated Other Comprehensive Income | Available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Provision for (benefit from) income taxes	0	0	0	0
Interest and investment income	35	8	50	24
Net income	$ 35	$ 8	$ 50	$ 24

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Coal	$ 79,746	$ 40,982
Repair parts and supplies	91,797	84,488
Inventories	171,543	125,470
Allowance for slow-moving and obsolete inventories	$ 1,700	$ 600

Investments in Available-for-_3

Investments in Available-for-Sale Securities (Schedule of Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Cost Basis	$ 175,847	$ 163,140
Available-for-sale, Gains	327	15
Available-for-sale, Losses	(118)	(358)
Available-for-sale, Fair Value	176,056	162,797
Available-for-sale, Short-Term Investments	176,056	162,797
Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Short-Term Investments	176,056	162,797
Other Assets
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Other Assets	0	0
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Cost Basis	64,930	100,003
Available-for-sale, Gains	52	11
Available-for-sale, Losses	(17)	(126)
Available-for-sale, Fair Value	64,965	99,888
U.S. government and agency securities | Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Short-Term Investments	64,965	99,888
U.S. government and agency securities | Other Assets
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Other Assets	0	0
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Cost Basis	110,917	63,137
Available-for-sale, Gains	275	4
Available-for-sale, Losses	(101)	(232)
Available-for-sale, Fair Value	111,091	62,909
Corporate notes and bonds | Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Short-Term Investments	111,091	62,909
Corporate notes and bonds | Other Assets
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Other Assets	$ 0	$ 0

Investments in Available-for-_4

Investments in Available-for-Sale Securities (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Abstract]
Unrealized losses owned for less than 12 months	$ 51.7	$ 115.2
Unrealized losses owed for over a year	$ 0	$ 32.4

Derivatives (Narrative) (Detail

Derivatives (Narrative) (Details) gal in Millions, $ in Millions	6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)$ / optiongal	Dec. 31, 2020USD ($)	Jun. 30, 2020$ / option	Dec. 31, 2018USD ($)
Derivative [Line Items]
Current asset representing cash collateral posted | $		$ 1.9			$ 24.7
Derivative contracts expected to be reclassified from OCI into earnings | $		$ 3.1
Not Designated as Hedging Instrument | Heating Oil
Derivative [Line Items]
Quantities under derivative contracts (in gallons)		4
Derivative, average price risk option strike price (in usd per gallon) | $ / option		2.30
Percent of expected requirements covered		34.00%
Not Designated as Hedging Instrument | Diesel Purchases | Minimum
Derivative [Line Items]
Diesel fuel purchased annually (in gallons)		40
Not Designated as Hedging Instrument | Diesel Purchases | Maximum
Derivative [Line Items]
Diesel fuel purchased annually (in gallons)		47
Forecast
Derivative [Line Items]
Value of trading portfolio realized - gains (losses) | $	$ (0.2)		$ (0.6)
Forecast | Not Designated as Hedging Instrument | Heating Oil
Derivative [Line Items]
Derivative, average price risk option strike price (in usd per gallon) | $ / option				2.24
NYMEX | Not Designated as Hedging Instrument | Diesel Purchases
Derivative [Line Items]
Quantities under derivative contracts (in gallons)		6
Derivative, average price risk option strike price (in usd per gallon) | $ / option		1.92
NYMEX | Not Designated as Hedging Instrument | Diesel Purchases | Heating Oil
Derivative [Line Items]
Quantities under derivative contracts (in gallons)		26

Derivatives (Schedule of Price

Derivatives (Schedule of Price Risk Derivatives) (Details) T in Thousands	9 Months Ended
	Sep. 30, 2019T
Coal sales
Derivative [Line Items]
Derivatives held (in tons)	1,275
Coal purchases
Derivative [Line Items]
Derivatives held (in tons)	722
2019 | Coal sales
Derivative [Line Items]
Derivatives held (in tons)	607
2019 | Coal purchases
Derivative [Line Items]
Derivatives held (in tons)	385
2020 | Coal sales
Derivative [Line Items]
Derivatives held (in tons)	668
2020 | Coal purchases
Derivative [Line Items]
Derivatives held (in tons)	337

Derivatives (Disclosure Of Fair

Derivatives (Disclosure Of Fair Value Of Derivatives) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Assets	$ 42,646	$ 18,879
Derivative Liabilities	(33,292)	(31,089)
Effect of counterparty netting in derivative assets	(32,663)	(17,801)
Effect of counterparty netting in derivative liabilities	32,663	17,801
Derivative Asset	9,983	1,078
Derivative Liability	(629)	(13,288)
Net derivatives as classified in the balance sheets	9,354	(12,210)
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	38,804	16,537
Derivative Liabilities	(32,621)	(30,284)
Not Designated as Hedging Instrument | Coal Contract
Derivative [Line Items]
Derivative Assets	20,116	10,329
Derivative Liabilities	(20,925)	(10,701)
Coal Contract | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	3,842	2,342
Derivative Liabilities	(671)	(805)
Coal Contract | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	18,305	5,672
Derivative Liabilities	(11,067)	(19,579)
Heating oil — diesel purchases | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	383	532
Derivative Liabilities	(629)	0
Natural gas | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	0	4
Derivative Liabilities	$ 0	$ (4)

Derivatives (Net Derivatives As

Derivatives (Net Derivatives As Reflected On The Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 9,354	$ (12,210)
Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	(629)	(13,288)
Heating oil and coal | Other current assets
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 9,983	$ 1,078

Derivatives (Effects Of Derivat

Derivatives (Effects Of Derivatives On Measures Of Financial Performance) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of coal derivatives and coal trading activities, net	$ (1,530)	$ (10,418)	$ 19,851	$ (22,142)
Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Other Comprehensive Income	191	(4,207)	8,532	(12,275)
Gains (Losses) Reclassified from Other Comprehensive Income into Income	2,963	(4,825)	5,064	(4,825)
Designated as Hedging Instrument | Coal sales | Coal Contract | Coal sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Other Comprehensive Income	225	(4,631)	9,472	(14,862)
Gains (Losses) Reclassified from Other Comprehensive Income into Income	2,963	(6,996)	5,750	(6,996)
Designated as Hedging Instrument | Coal purchases | Coal Contract | Coal purchases
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Other Comprehensive Income	(34)	424	(940)	2,587
Gains (Losses) Reclassified from Other Comprehensive Income into Income	0	2,171	(686)	2,171
Not Designated as Hedging Instrument | Coal Contract | Coal and natural gas realized and unrealized
Derivative Instruments, Gain (Loss) [Line Items]
Realized and Unrealized Gain (Loss) on Derivatives	(127)	(928)	(1,228)	14
Unrealized Gain (Loss) on Derivatives	(1,417)	(9,486)	21,145	(22,116)
Not Designated as Hedging Instrument | Coal Contract | Other operating (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives	3,216	(2,537)	(2,076)	(5,217)
Not Designated as Hedging Instrument | Natural gas | Coal and natural gas realized and unrealized
Derivative Instruments, Gain (Loss) [Line Items]
Realized and Unrealized Gain (Loss) on Derivatives	14	(4)	(66)	(40)
Not Designated as Hedging Instrument | Heating oil — diesel purchases | Other operating (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Heating oil realized and unrealized gains and losses	$ (1,670)	$ 719	$ (2,402)	$ 4,394

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Payroll and employee benefits	$ 49,566	$ 57,166
Taxes other than income taxes	71,738	75,017
Interest	131	156
Acquired sales contracts	203	570
Workers’ compensation	18,053	20,044
Asset retirement obligations	12,297	13,113
Other	9,951	17,448
Accrued expenses and other current liabilities	$ 161,939	$ 183,514

Debt and Financing Arrangemen_3

Debt and Financing Arrangements (Long term Debt) (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018	Mar. 07, 2017
Debt Instrument [Line Items]
Term loan	$ 291,524,000	$ 293,626,000
Other	18,471,000	30,449,000
Debt issuance costs	(5,289,000)	(6,092,000)
Total	304,706,000	317,983,000
Less: current maturities of debt	11,925,000	17,797,000
Long-term debt	292,781,000	$ 300,186,000
Senior Notes | New Term Loan Debt Facility
Debt Instrument [Line Items]
Debt instrument, face amount	$ 292,500,000		$ 300,000,000

Debt and Financing Arrangemen_4

Debt and Financing Arrangements (Narrative) (Details) - USD ($)	Aug. 27, 2018	Apr. 27, 2018	Apr. 03, 2018	Apr. 27, 2017	Mar. 07, 2017	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Fair value of derivative assets						$ 42,646,000	$ 42,646,000	$ 18,879,000
Interest Rate Swap
Line of Credit Facility [Line Items]
Interest rate swaps settlements gains						200,000	1,200,000
Other Noncurrent Assets | Interest Rate Swap
Line of Credit Facility [Line Items]
Fair value of derivative assets						(3,400,000)	(3,400,000)
Senior Notes | New Term Loan Debt Facility
Line of Credit Facility [Line Items]
Net cash proceeds of from debt issuances and other non-ordinary sales or dispositions (percent)					100.00%
Default to indebtedness					$ 50,000,000
Default to surety, reclamation or similar bond					50,000,000
Default to uninsured judgment					50,000,000
Uninsured losses or proceedings against					50,000,000
Senior Notes | New Term Loan Debt Facility | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate			2.75%
Basis spread on variable rate, floor			1.00%
Senior Notes | New Term Loan Debt Facility | Base Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.75%
New Term Loan Debt Facility | Senior Notes
Line of Credit Facility [Line Items]
Debt instrument, face amount					$ 300,000,000	$ 292,500,000	292,500,000
Percentage of face amount					99.50%
Quarterly amortization payments					$ 750,000
Amount of voting equity interests of domestic subsidiaries guaranteed (percent)					100.00%
Amount of voting equity interests of foreign owned subsidiaries guaranteed (percent)					65.00%
New Term Loan Debt Facility | Senior Notes | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate						2.75%
Line of Credit | Secured Debt | Regions Bank
Line of Credit Facility [Line Items]
Maximum borrowing capacity								50,000,000
Facility size, increase								$ 10,000,000
Line of Credit | Secured Debt | Accounts Receivable Securitization Facility | Arch Receivable Company, LLC
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 160,000,000
Maturity date	3 years	3 years
Covenant minimum amount				$ 175,000,000
Liquidity threshold, consecutive days		60 days
Liquidity threshold		364 days
Liquidity threshold, expiration period		60 days
Letters of credit outstanding						$ 15,500,000	15,500,000
Current borrowing capacity						92,600,000	92,600,000
Line of Credit | Secured Debt | Inventory-Based Revolving Credit Facility | Regions Bank
Line of Credit Facility [Line Items]
Debt instrument, face amount				40,000,000
Covenant minimum amount				$ 175,000,000
Liquidity threshold, consecutive days		60 days
Liquidity threshold		364 days
Liquidity threshold, expiration period		60 days
Letters of credit outstanding						35,900,000	35,900,000
Percentage of coal inventory borrowing base				85.00%
Percentage of parts and supplies inventory borrowing base				85.00%
Percentage of clause borrowing base				35.00%
Percent of eligible cash				100.00%
Covenant amount (less than)				$ 250,000,000
Additional availability for borrowings						$ 14,100,000	$ 14,100,000
Line of Credit | Secured Debt | Inventory-Based Revolving Credit Facility | LIBOR | Regions Bank | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate				2.00%
Line of Credit | Secured Debt | Inventory-Based Revolving Credit Facility | LIBOR | Regions Bank | Maximum
Line of Credit Facility [Line Items]
Percentage of clause borrowing base				2.50%
Line of Credit | Secured Debt | Inventory-Based Revolving Credit Facility | Base Rate | Regions Bank | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate				1.00%
Line of Credit | Secured Debt | Inventory-Based Revolving Credit Facility | Base Rate | Regions Bank | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate				1.50%

Debt and Financing Arrangemen_5

Debt and Financing Arrangements (Interest rate derivatives) (Details) $ in Millions	Sep. 30, 2019USD ($)
Interest rate swap, effective 2019
Debt Instrument [Line Items]
Notional Amount	$ 250
Fixed Rate	2.025%
Interest rate swap, effective 2020
Debt Instrument [Line Items]
Notional Amount	$ 200
Fixed Rate	2.249%
Interest rate swap, effective 2021
Debt Instrument [Line Items]
Notional Amount	$ 100
Fixed Rate	2.315%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income tax provision at statutory rate	$ 22,494	$ 16,375	$ 51,000	$ 37,245
Percentage depletion allowance	(6,347)	(5,964)	(14,111)	(13,059)
State taxes, net of effect of federal taxes	1,825	4,528	3,668	5,865
Change in valuation allowance	(19,120)	(44,278)	(42,925)	(62,234)
Current expense associated with uncertain tax positions	1,495	511	2,932	(599)
Impact of Tax Cuts and Jobs Act of 2017	0	(19,780)	0	(19,780)
Other, net	0	3,393	(56)	3,437
Provision for (benefit from) income taxes	$ 347	(45,215)	$ 508	$ (49,125)
Unrecognized tax benefit, change during period		$ 24,900

Fair Value Measurements (Summar

Fair Value Measurements (Summary Of Financial Assets And Liabilities Accounted For At Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets:
Investments in marketable securities	$ 176,056	$ 162,797
Liabilities:
Derivatives	629	$ 13,288
Interest Rate Swap
Assets:
Investments in marketable securities	176,056
Derivatives	9,983
Total assets	186,039
Liabilities:
Derivatives	4,071
Interest Rate Swap | Level 1
Assets:
Investments in marketable securities	64,965
Derivatives	8,366
Total assets	73,331
Liabilities:
Derivatives	0
Interest Rate Swap | Level 2
Assets:
Investments in marketable securities	111,091
Derivatives	1,234
Total assets	112,325
Liabilities:
Derivatives	4,130
Interest Rate Swap | Level 3
Assets:
Investments in marketable securities	0
Derivatives	383
Total assets	383
Liabilities:
Derivatives	$ (59)

Fair Value Measurements (Summ_2

Fair Value Measurements (Summary Of Change In The Fair Values Of Financial Instruments Categorized As Level 3) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 755	$ 532
Realized and unrealized gains recognized in earnings, net	(1,252)	(1,794)
Purchases	562	1,562
Issuances	(45)	(45)
Settlements	422	187
Ending balance	$ 442	$ 442

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of senior notes and other long-term debt, including amounts classified as current	$ 306.9	$ 306.9	$ 318.6
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net unrealized gains (losses) related to level 3 financial instruments	$ (1)	$ (1.9)

Earnings per Common Share (Deta

Earnings per Common Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Weighted average shares outstanding:
Basic weighted average shares outstanding (in shares)	15,736	19,250	16,591	20,102
Effect of dilutive securities (in shares)	1,116	958	1,153	938
Diluted weighted average shares outstanding (in shares)	16,852	20,208	17,744	21,040

Workers Compensation Expense (D

Workers Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Occupational disease
Accrued Workers Compensation [Line Items]
Service cost	$ 1,670	$ 1,860	$ 5,008	$ 5,580
Interest cost	1,354	1,196	4,062	3,585
Net benefit credit	3,024	3,056	9,070	9,165
Traumatic injury claims and assessments
Accrued Workers Compensation [Line Items]
Traumatic injury claims and assessments	2,088	(2,069)	6,642	3,130
Total workers’ compensation expense
Accrued Workers Compensation [Line Items]
Total workers’ compensation expense	$ 5,112	$ 987	$ 15,712	$ 12,295

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2015
Defined benefit pension plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,922	$ 2,376	$ 6,439	$ 6,917
Expected return on plan assets	(2,699)	(2,906)	(8,146)	(9,067)
Pension settlement	(197)	(613)	(626)	(1,984)
Amortization of prior service costs (credits)	4	0	4		$ 0
Net benefit credit	(970)	(1,143)	(2,329)	(4,134)
Other postretirement benefits plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	120	140	360	419
Interest cost	876	918	2,629	2,755
Amortization of other actuarial losses (gains)	(2,236)	0	(2,236)	0
Net benefit credit	$ (1,240)	$ 1,058	$ 753	$ 3,174

Segment Information (Schedule O

Segment Information (Schedule Of Operating Segment Results) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)Segment	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Segment Reporting [Abstract]
Number of reportable segments | Segment			2
Segment Reporting Information [Line Items]
Revenues	$ 619,467	$ 633,180	$ 1,744,872	$ 1,800,824
Adjusted EBITDA	106,621	124,894	319,439	315,192
Depreciation, depletion and amortization	30,402	31,775	82,199	92,027
Accretion on asset retirement obligations	5,137	6,992	15,411	20,977
Total assets	1,934,600	1,997,622	1,934,600	1,997,622	$ 1,887,060
Capital expenditures	49,452	25,693	137,396	55,742
Operating Segments | PRB
Segment Reporting Information [Line Items]
Revenues	269,967	261,927	692,845	737,233
Adjusted EBITDA	50,153	48,646	85,433	102,639
Depreciation, depletion and amortization	5,956	9,114	15,702	25,841
Accretion on asset retirement obligations	3,135	4,885	9,406	14,656
Total assets	236,656	374,092	236,656	374,092
Capital expenditures	5,402	3,458	19,026	7,221
Operating Segments | MET
Segment Reporting Information [Line Items]
Revenues	254,493	236,328	769,000	733,707
Adjusted EBITDA	70,814	81,250	264,284	251,649
Depreciation, depletion and amortization	19,962	18,106	53,687	53,109
Accretion on asset retirement obligations	531	469	1,592	1,406
Total assets	609,378	561,989	609,378	561,989
Capital expenditures	36,475	17,827	98,849	35,555
Operating Segments | Other Thermal
Segment Reporting Information [Line Items]
Revenues	94,052	130,663	278,235	321,997
Adjusted EBITDA	16,659	25,200	33,699	52,710
Depreciation, depletion and amortization	3,852	3,924	10,976	11,459
Accretion on asset retirement obligations	603	565	1,810	1,696
Total assets	148,994	127,904	148,994	127,904
Capital expenditures	6,837	3,332	16,299	7,097
Corporate, Other and Eliminations
Segment Reporting Information [Line Items]
Revenues	955	4,262	4,792	7,887
Adjusted EBITDA	(31,005)	(30,202)	(63,977)	(91,806)
Depreciation, depletion and amortization	632	631	1,834	1,618
Accretion on asset retirement obligations	868	1,073	2,603	3,219
Total assets	939,572	933,637	939,572	933,637
Capital expenditures	$ 738	$ 1,076	$ 3,222	$ 5,869

Segment Information (Reconcilia

Segment Information (Reconciliation Segment Income To Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting [Abstract]
Net income	$ 106,769	$ 123,192	$ 242,350	$ 226,483
Provision for (benefit from) income taxes	347	(45,215)	508	(49,125)
Interest expense, net	340	3,378	4,916	10,998
Depreciation, depletion and amortization	30,402	31,775	82,199	92,027
Accretion on asset retirement obligations	5,137	6,992	15,411	20,977
Amortization of sales contracts, net	(153)	3,241	(77)	9,540
Loss on sale of Lone Mountain Processing, Inc.	0	0	4,304	0
Preference Rights Lease Application settlement income	(39,000)	0	(39,000)	0
Net loss resulting from early retirement of debt and debt restructuring	0	0	0	485
Non-service related pension and postretirement benefit costs	(975)	971	2,127	2,206
Reorganization items, net	0	560	(71)	1,601
Costs associated with proposed joint venture with Peabody Energy, Inc.	3,754	0	6,772	0
Adjusted EBITDA	$ 106,621	$ 124,894	$ 319,439	$ 315,192

Revenue Recognition (Disaggrega

Revenue Recognition (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 619,467	$ 633,180	$ 1,744,872	$ 1,800,824
Corporate, Other and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	955	4,262	4,792	7,887
North America revenues
Disaggregation of Revenue [Line Items]
Revenues	382,248	371,938	1,002,939	1,001,173
North America revenues | Corporate, Other and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	955	4,262	4,792	7,887
Seaborne revenues
Disaggregation of Revenue [Line Items]
Revenues	237,219	261,242	741,933	799,651
Seaborne revenues | Corporate, Other and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
PRB | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	269,967	261,927	692,845	737,233
PRB | North America revenues | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	269,967	261,927	692,845	735,322
PRB | Seaborne revenues | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	1,911
MET | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	254,493	236,328	769,000	733,707
MET | North America revenues | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	63,755	49,698	163,317	117,699
MET | Seaborne revenues | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	190,738	186,630	605,683	616,008
Other Thermal | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	94,052	130,663	278,235	321,997
Other Thermal | North America revenues | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	47,571	56,051	141,985	140,265
Other Thermal | Seaborne revenues | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	$ 46,481	$ 74,612	$ 136,250	$ 181,732

Revenue Recognition (Narrative)

Revenue Recognition (Narrative) (Details) T in Millions	Sep. 30, 2019T
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, fixed price contracts (in tons)	17.3
Remaining performance obligations, variable price contracts (in tons)	1.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, fixed price contracts (in tons)	96.8
Remaining performance obligations, variable price contracts (in tons)	6

Leases (Narrative) (Details)

Leases (Narrative) (Details) $ in Millions	Sep. 30, 2019USD ($)
Lessee, Lease, Description [Line Items]
Right-of-use operating lease asset	$ 20.3
Minimum
Lessee, Lease, Description [Line Items]
Operating lease, remaining lease terms	1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating lease, remaining lease terms	8 years

Leases (Information Related to

Leases (Information Related to Leases) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Operating lease information:
Operating lease cost	$ 1,071
Operating cash flows from operating leases	$ 1,078
Weighted average remaining lease term in years	6 years 2 months 9 days
Weighted average discount rate	5.50%

Leases (Future Minimum Lease Pa

Leases (Future Minimum Lease Payments) (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
2019	$ 1,024
2020	3,616
2021	3,367
2022	3,292
2023	3,261
Thereafter	11,153
Total minimum lease payments	25,713
Less imputed interest	(4,725)
Total operating lease liability	20,988
As reflected on balance sheet:
Accrued expenses and other current liabilities	2,713
Other noncurrent liabilities	18,275
Total operating lease liability	$ 20,988

Subsequent Events (Details)

Subsequent Events (Details) - High-Vol A cooking coal reserve, adjacent to Leer Mine T in Millions, $ in Millions	1 Months Ended
	Sep. 30, 2019USD ($)T
Subsequent Event [Line Items]
Reserve, mass (in tons) | T	20
Payments to acquire productive assets | $	$ 52.5
Productive asset, increase to useful life	6 years

Uncategorized Items - aci-20190

Label	Element	Value
Restricted Cash and Cash Equivalents, Current	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue	$ 0
Restricted Cash and Cash Equivalents, Current	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue	$ 0