Warrior Met Coal (HCC) 10-Q 1 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	3 Months Ended
	Mar. 31, 2019	Apr. 26, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	WARRIOR MET COAL, INC.
Entity Central Index key	0001691303
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Amendment Flag	false
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding (in shares)		51,554,805

CONDENSED STATEMENTS OF OPERATI

CONDENSED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues:
Total revenues	$ 378,290,000	$ 421,788,000
Costs and expenses:
Cost of sales (exclusive of items shown separately below)	182,628,000	190,676,000
Cost of other revenues (exclusive of items shown separately below)	7,745,000	7,784,000
Depreciation and depletion	22,233,000	24,552,000
Selling, general and administrative	8,905,000	8,234,000
Transaction and other expenses	0	3,288,000
Total costs and expenses	221,511,000	234,534,000
Operating income	156,779,000	187,254,000
Interest expense, net	(8,592,000)	(8,560,000)
Loss on early extinguishment of debt	(9,756,000)	0
Income before income tax expense	138,431,000	178,694,000
Income tax expense	27,984,000	0
Net income	$ 110,447,000	$ 178,694,000
Basic and diluted net income per share:
Net income per share—basic and diluted (in dollars per share)	$ 2.14	$ 3.36
Weighted average number of shares outstanding—basic (in shares)	51,511	53,149
Weighted average number of shares outstanding—diluted (in shares)	51,630	53,152
Dividends per share (in dollars per share)	$ 0.05	$ 0.05
Sales
Revenues:
Total revenues	$ 369,681,000	$ 412,879,000
Other revenues
Revenues:
Total revenues	$ 8,609,000	$ 8,909,000

CONDENSED BALANCE SHEETS

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 154,912	$ 205,577
Short-term investments	17,501	17,501
Trade accounts receivable	182,728	138,399
Income tax receivable	21,310	21,607
Inventories, net	70,356	56,719
Prepaid expenses and other receivables	19,199	29,366
Total current assets	466,006	469,169
Mineral interests, net	117,552	120,427
Property, plant and equipment, net	578,662	540,315
Non-current income tax receivable	21,310	21,310
Deferred income taxes	194,796	222,780
Other long-term assets	21,675	21,039
Total assets	1,400,001	1,395,040
Current liabilities:
Accounts payable	42,222	33,588
Accrued expenses	69,456	82,342
Other current liabilities	9,822	7,742
Current portion of long-term debt	0	760
Total current liabilities	121,500	124,432
Long-term debt	338,699	468,231
Asset retirement obligations	59,644	59,049
Other long-term liabilities	61,094	30,716
Total liabilities	580,937	682,428
Commitments and contingencies
Stockholders’ Equity:
Common stock, $0.01 par value per share (Authorized -140,000,000 shares, 53,282,529 issued and 51,560,688 outstanding as of March 31, 2019 and 53,256,098 issued and 51,622,898 outstanding as of December 31, 2018)	533	533
Preferred stock, $0.01 par value per share (10,000,000 shares authorized, no shares issued and outstanding)	0	0
Treasury stock, at cost (1,721,841 shares)	(40,000)	(38,030)
Additional paid in capital	240,408	239,827
Retained earnings	618,123	510,282
Total stockholders’ equity	819,064	712,612
Total liabilities and stockholders’ equity	$ 1,400,001	$ 1,395,040

CONDENSED BALANCE SHEETS CONDEN

CONDENSED BALANCE SHEETS CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 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)	140,000,000	140,000,000
Common stock shares issued (in shares)	53,282,529	53,256,098
Common stock shares outstanding (in shares)	51,560,688	51,622,898
Preferred stock par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock shares authorized (in shares)	10,000,000	10,000,000
Preferred stock shares issued (in shares)	0	0
Preferred stock shares outstanding (in shares)	0	0
Treasury stock (in shares)	1,721,841,000	1,721,841,000

CONDENSED STATEMENT OF CHANGES

CONDENSED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Preferred Stock	Treasury Stock	Additional Paid in Capital	Retained Earnings
Balance at beginning of period at Dec. 31, 2017	$ 413,023	$ 534	$ 0	$ 0	$ 329,993	$ 82,496
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	178,694
Dividends paid ($0.05 per share)	(2,685)					(2,685)
Stock compensation	198				198
Common Shares issued	0
Other	(4,320)				(4,320)
Balance at end of period at Mar. 31, 2018	584,910	534	0	0	325,871	258,505
Balance at beginning of period at Dec. 31, 2018	712,612	533	0	(38,030)	239,827	510,282
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	110,447
Dividends paid ($0.05 per share)	(2,606)					(2,606)
Stock compensation	1,108				1,108
Treasury stock purchase	(1,970)			(1,970)
Other	(527)				(527)
Balance at end of period at Mar. 31, 2019	$ 819,064	$ 533	$ 0	$ (40,000)	$ 240,408	$ 618,123

CONDENSED STATEMENT OF CHANGE_2

CONDENSED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends per share (in dollars per share)	$ 0.05	$ 0.05

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
OPERATING ACTIVITIES
Net income	$ 110,447	$ 178,694
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and depletion	22,233	24,552
Deferred income tax expense	27,984	0
Stock based compensation expense	1,194	198
Amortization of debt issuance costs and debt discount/premium, net	381	638
Accretion of asset retirement obligations	812	1,155
Loss on early extinguishment of debt	9,756	0
Changes in operating assets and liabilities:
Trade accounts receivable	(44,329)	(34,579)
Income tax receivable	297	0
Inventories	(10,823)	1,784
Prepaid expenses and other receivables	10,167	11,893
Accounts payable	10,640	2,931
Accrued expenses and other current liabilities	(15,133)	8,948
Other	2,782	(2,476)
Net cash provided by operating activities	126,408	193,738
INVESTING ACTIVITIES
Purchase of property, plant and equipment	(24,395)	(22,542)
Deferred mine development costs	(5,578)	0
Proceeds from sale of property, plant and equipment	234	0
Net cash used in investing activities	(29,739)	(22,542)
FINANCING ACTIVITIES
Dividends paid	(2,606)	(2,685)
Proceeds from issuance of debt	0	126,875
Retirements of debt	(140,272)	(765)
Principal repayments of capital lease obligations	(1,957)	0
Debt issuance costs paid	0	(3,713)
Common shares repurchased	(1,970)	0
Other	(527)	(4,320)
Net cash (used in) provided by financing activities	(147,332)	115,392
Net increase (decrease) in cash and cash equivalents and restricted cash	(50,663)	286,588
Cash and cash equivalents and restricted cash at beginning of period	206,405	36,264
Cash and cash equivalents and restricted cash at end of period	$ 155,742	$ 322,852

Business and Basis of Presentat

Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Basis of Presentation	Business and Basis of Presentation Description of the Business Warrior Met Coal, Inc. (the "Company") is a U.S. based producer and exporter of met coal for a diversified customer base of blast furnace steel producers located primarily in Europe, South America and Asia. The Company also generates ancillary revenues from the sale of natural gas extracted as a byproduct from the underground coal mines and royalty revenues from leased properties. Basis of Presentation The accompanying financial statements are presented in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In our opinion, the financial statements include all adjustments (consisting of normal recurring accruals) necessary in order to make the financial statements not misleading. For further information, refer to the consolidated financial statements and related notes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2018. Operating results for the three months ended March 31, 2019 and March 31, 2018 are not necessarily indicative of the final results that may be expected for the year ended December 31, 2019 . The balance sheet at December 31, 2018 has been derived from the audited financial statements for the year ended December 31, 2018 included in the Company's Annual Report on Form 10-K for the year ended December 31, 2018 (the "2018 Annual Report").

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Our significant accounting policies are consistent with those disclosed in Note 2 to our audited financial statements included in the 2018 Annual Report, except for changes related to new accounting pronouncements described in "New Accounting Pronouncements". Cash and Cash Equivalents and Restricted Cash The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the Condensed Balance Sheets that sum to the total of the same such amounts shown in the Condensed Statements of Cash Flows (in thousands): March 31, 2019 December 31, 2018 Cash and cash equivalents $ 154,912 $ 205,577 Restricted cash included in other long-term assets 830 828 Total cash and cash equivalents and restricted cash included in the Condensed Statements of Cash Flows $ 155,742 $ 206,405 Cash and cash equivalents include short-term deposits and highly liquid investments that have original maturities of three months or less when purchased and are stated at cost, which approximates fair value. As of March 31, 2019 and December 31, 2018 , restricted cash included in other long-term assets in the Condensed Balance Sheets represents amounts invested in certificates of deposits as financial assurance for post mining reclamation obligations. Short-Term Investments Instruments with maturities greater than three months, but less than twelve months, are included in short-term investments. The Company purchases United States Treasury ("Treasury") bills with maturities ranging from six to twelve months which are classified as held to maturity and are carried at amortized cost, which approximates fair value. Securities classified as held to maturity are those securities that management has the intent and ability to hold to maturity. As of March 31, 2019 and December 31, 2018 , the Company’s short-term investments consisted of $17.5 million in Treasury bills with a maturity of six months . These Treasury bills were posted as collateral for the self-insured black lung related claims asserted by or on behalf of former employees of Walter Energy, Inc. and its subsidiaries, which were assumed by the Company and relate to periods prior to March 31, 2016. Revenue Recognition Revenue is recognized when performance obligations under the terms of a contract with our customers are satisfied; for all contracts this occurs when control of the promised goods have been transferred to our customers. For coal shipments to domestic customers via rail, control is transferred when the railcar is loaded. For coal shipments to international customers via ocean vessel, control is transferred when the vessel is loaded at the Port of Mobile, Alabama. For natural gas sales, control is transferred when the gas has been transferred to the pipeline. Revenue is disaggregated between coal sales within the Company's mining segment and natural gas sales included in all other revenues, as disclosed in Note 14. Since February 2017, we have had an arrangement with XCoal Energy & Resource ("XCoal") to serve as XCoal's strategic partner for exports of low-volatility HCC. Under this arrangement, XCoal takes title to and markets coal that we would historically have sold on the spot market, in an amount of the greater of (i) 10% of our total production during the applicable term of the arrangement or (ii) 250,000 metric tons. During the three months ended March 31, 2019 and 2018 , XCoal accounted for approximately $94.9 million , or 25.8% of total revenues, and $86.2 million , or 20.8% of total revenues, respectively. New Accounting Pronouncements The Company adopted Accounting Standards Update (“ASU”) No. 2016-02, "Leases (Topic 842)" as of January 1, 2019 using the modified retrospective approach (the "New Leases Standard"). The New Leases Standard requires a lessee to recognize a right-of-use asset and lease liability on its balance sheet for all leases. The Company has chosen to use its adoption date as its date of initial application. As a result, financial information will not be updated and the disclosures required under the new standard will not be provided for dates and periods before January 1, 2019. The Company made an accounting policy election that leases with an initial term of 12 months or less will remain off of its balance sheet and lease payments will instead be recognized in the Condensed Statements of Operations on a straight-line basis over the lease term. Additionally, the Company elected the package of practical expedients for all leases, which permits the Company to forego reassessing expired or existing contracts to determine: whether they are or contain leases, lease classification, and initial direct costs. Management elected the optional transition expedient which allows the Company to continue applying the current policy for accounting for expired or existing land easement contracts that were not previously accounted for under GAAP. New or modified land easements executed after adoption will be considered under the New Lease Standard. The Company elected the practical expedient as an accounting policy election for all asset classifications, which allows it to account for them as a single lease component, rather than as separate lease and non-lease components. As the Company’s historical operating leases are primarily short term rental agreements of less than one year, the Company did not record any additional lease assets or lease liabilities upon adoption of the New Leases Standard. The New Leases Standard did not impact the Company's balance sheet or consolidated net income and had no impact on cash flows. As of March 31, 2019, the Company has a right-of-use asset of $5.8 million , net of accumulated amortization, and a liability of $6.9 million . On August 17, 2018, the SEC adopted a final rule that eliminates or amends certain disclosure requirements that were deemed redundant and outdated in light of changes in SEC requirements, U.S. GAAP or changes in technology or the business environment. The rule also requires registrants to include in their interim financial statements a reconciliation of changes in stockholders’ equity in the notes or as a separate statement. The analysis should reconcile the beginning balance to the ending balance of each caption in shareholders’ equity for each period for which an income statement is required to be filed. The final rule became effective November 5, 2018. Beginning in the first quarter of fiscal 2019, we have provided a reconciliation for the quarterly period as well as the comparable prior period in this Form 10-Q. The eliminated or amended disclosures did not have a material impact on the Company’s unaudited condensed financial statements.

Inventories, net

Inventories, net	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Inventories, net	Inventories, net Inventories, net are summarized as follows (in thousands): March 31, 2019 December 31, 2018 Coal $ 43,444 $ 32,854 Raw materials, parts, supplies and other, net 26,912 23,865 Total inventories, net $ 70,356 $ 56,719

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three months ended March 31, 2019 , the Company estimated its annual effective tax rate and applied this effective tax rate to its year-to-date pretax income at the end of the interim reporting period. The tax effect of unusual or infrequently occurring items, including effects of changes in tax laws or rates and changes in judgment about the realizability of deferred tax assets, are reported in the interim period in which they occur. The Company had income tax expense of $28.0 million for the three months ended March 31, 2019 . The Company had no income tax expense for the three months ended March 31, 2018 due to the utilization of NOLs to offset taxable income for which a full valuation allowance was recorded. As a result of various favorable factors further discussed in the 2018 Annual Report, the Company released its valuation allowance against its net deferred income tax assets in the fourth quarter of 2018.

Debt

Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt	Debt Debt consisted of the following (in thousands): March 31, 2019 December 31, 2018 Weighted Average Interest Rate at March 31, 2019 Final Maturity Senior Secured Notes $ 343,435 $ 475,000 8% 2024 Promissory note — 760 Debt discount/premium, net (4,736 ) (6,769 ) Total debt 338,699 468,991 Less: current debt — (760 ) Total long-term debt $ 338,699 $ 468,231 The Company's minimum debt repayment schedule, excluding interest, as of March 31, 2019 is as follows (in thousands): Payments Due 2019 2020 2021 2022 2023 Thereafter Senior Secured Notes $ — $ — $ — $ — $ — $343,435 Total $ — $ — $ — $ — $ — $ 343,435 Senior Secured Notes On November 2, 2017, the Company issued $350.0 million aggregate principal amount of its 8.00% Senior Secured Notes due 2024 (the "Original Notes"). It then issued an additional $125.0 million in aggregate principal amount of its 8.00% Senior Secured Notes due 2024 (the “New Notes” and, together with the Original Notes, the "Notes") on March 1, 2018. The New Notes were issued as "Additional Notes" under the indenture dated as of November 2, 2017 (the "Original Indenture"), among the Company, the subsidiary guarantors party thereto and Wilmington Trust, National Association, as trustee and priority lien collateral trustee, as supplemented by the First Supplemental Indenture, dated as of March 1, 2018 (the "First Supplemental Indenture" and, the Original Indenture as supplemented thereby and by the Second Supplemental Indenture, dated as of March 2, 2018, the "Indenture"). The Notes mature on November 1, 2024 and interest is payable on May 1 and November 1 of each year. Offers to Purchase the Notes On February 21, 2019, the Company commenced an offer to purchase (the “Restricted Payment Offer”), in cash, up to $150,000,000 principal amount of its outstanding Notes, at a repurchase price of 103% of the aggregate principal amount of such Notes, plus accrued and unpaid interest with respect to such Notes to, but not including, the date of repurchase (the “Restricted Payment Repurchase Price”). Concurrently with, but separate from, the Restricted Payment Offer, the Company commenced a cash tender offer (the “Tender Offer” and, together with the Restricted Payment Offer, the “Offers”) to purchase up to $150,000,000 principal amount of the Notes at a repurchase price of 104.25% of the aggregate principal amount of such Notes, plus accrued and unpaid interest to, but not including, the date of repurchase (the “TO Repurchase Price”). The Offers expired on March 22, 2019 (the “Expiration Date”). Restricted Payment Offer As of the Expiration Date, $1,900,000 aggregate principal amount of the Notes were validly tendered and not validly withdrawn pursuant to the Restricted Payment Offer. Pursuant to the terms of the Restricted Payment Offer: (1) an automatic pro ration factor of 31.5789% was applied to the $1,900,000 aggregate principal amount of the Notes that were validly tendered and not validly withdrawn in the Restricted Payment Offer (rounded down to avoid the purchase of Notes in a principal amount other than in integrals of $1,000 ), which resulted in $599,000 aggregate principal amount of the Notes (the “RP Pro-Rated Tendered Notes”); (2) the Company accepted all $599,000 aggregate principal amount of the RP Pro-Rated Tendered Notes for payment of the Restricted Payment Repurchase Price in cash; and (3) the remaining balance of $1,301,000 aggregate principal amount of the Notes tendered that were not RP Pro-Rated Tendered Notes were not accepted for payment and were returned to the tendering holder of the Notes. The Company consummated the Restricted Payment Offer on March 25, 2019. Accordingly, pursuant to the terms of the Indenture, the Company was permitted to make one or more restricted payments in the form of special dividends to holders of the Company’s common stock and/or repurchases of the Company’s common stock in the aggregate amount of up to $299,401,000 (the "RP Basket") without having to make another offer to repurchase Notes. The Company intends to use the RP Basket to pay the April 2019 Special Dividend (as defined below) and make repurchases under the New Stock Repurchase Program (as defined below). Tender Offer As of the Expiration Date, $415,099,000 aggregate principal amount of the Notes were validly tendered and not validly withdrawn pursuant to the Tender Offer. Pursuant to the terms of the Tender Offer: (1) an automatic pro ration factor of 31.5789% was applied to the $415,099,000 aggregate principal amount of the Notes that were validly tendered and not validly withdrawn in the Tender Offer (rounded down to avoid the purchase of Notes in a principal amount other than in integrals of $1,000 ), which resulted in $130,966,000 aggregate principal amount of the Notes (the “TO Pro-Rated Tendered Notes”); (2) the Company accepted all $130,966,000 aggregate principal amount of the TO Pro-Rated Tendered Notes for payment of the TO Repurchase Price in cash; and (3) the remaining balance of $284,133,000 aggregate principal amount of the Notes tendered that were not TO Pro-Rated Tendered Notes were not accepted for payment and were returned to the tendering holder of the Notes. The Company consummated the Tender Offer on March 26, 2019. In connection with the payments for the RP Pro-Rated Tendered Notes and the TO Pro-Rated Tendered Notes, the Company recognized a loss on early extinguishment of debt of $9.8 million during the three months ended March 31, 2019 .

Other Long-Term Liabilities

Other Long-Term Liabilities	3 Months Ended
	Mar. 31, 2019
Other Liabilities Disclosure [Abstract]
Other Long-Term Liabilities	Other Long-Term Liabilities Other long-term liabilities are summarized as follows (in thousands): March 31, 2019 December 31, 2018 Black lung obligations $ 25,297 $ 25,206 Property, plant, and equipment obligation (1) 32,727 — Other (2) 3,070 5,510 Total other long-term liabilities $ 61,094 $ 30,716 (1) Represents a noncash investing activity that is not included in our Condensed Statements of Cash Flows. (2) Approximately $2.1 million as of March 31, 2019 represents a capital lease that is a noncash investing activity that is not included in our Condensed Statements of Cash Flows.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases The Company primarily enters into rental agreements for certain mining equipment that are for periods of 12 months or less, some of which include options to extend the leases. Leases that are for periods of 12 months or less are not recorded on the balance sheet in accordance with the Company's accounting policy election described in Note 2. The Company recognizes lease expense on these agreements on a straight-line basis over the lease term. Additionally, the Company has finance leases for certain mining equipment that expires over various contractual periods. The leases have remaining lease terms of one to two years. These leases do not include an option to renew. Amortization expense for finance leases is included in depreciation and depletion expense. Supplemental balance sheet information related to leases was as follows (in thousands): March 31, 2019 Finance lease right-of-use assets, net (1) $ 5,771 Finance lease liabilities Current 4,559 Noncurrent 2,350 Total finance lease liabilities $ 6,909 Weighted average remaining lease term - finance leases (in months) 10.2 Weighted average discount rate - finance leases (2) 1.25 % (1) Finance lease right-of-use assets are recorded net of accumulated amortization of $2.8 million as of March 31, 2019 . (2) As most of the Company's leases do not provide an implicit discount rate, the Company uses its incremental borrowing rate based on information available at the commencement date when determining the present value of lease payments. The components of lease expense were as follows (in thousands): For the three months ended March 31, 2019 Operating lease cost (1): $ 144 Finance lease cost: Amortization of leased assets 1,957 Interest on lease liabilities 13 Net lease cost $ 2,114 (1) Includes leases that are for periods of 12 months or less. Maturities of lease liabilities were as follows (in thousands): Finance Leases (1) 2019 $ 4,582 2020 2,368 2021 — 2022 — 2023 — Total 6,950 Less: amount representing interest (41 ) Present value of lease liabilities $ 6,909 (1) Finance lease payments exclude $3.2 M of future payments required under signed lease agreements that have not yet commenced. Supplemental cash flow information related to leases was as follows (in thousands): For the three months ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from finance leases $ 13 Financing cash flows from finance leases $ 1,957 Right-of-use assets obtained in exchange for lease obligations: Finance leases $ 2,086 As of March 31, 2019 , the Company had additional finance leases, primarily for mining equipment, that have not yet commenced of $3.2 million . These finance leases will commence between fiscal year 2019 and 2021 with lease terms of one to two years.
Leases	Leases The Company primarily enters into rental agreements for certain mining equipment that are for periods of 12 months or less, some of which include options to extend the leases. Leases that are for periods of 12 months or less are not recorded on the balance sheet in accordance with the Company's accounting policy election described in Note 2. The Company recognizes lease expense on these agreements on a straight-line basis over the lease term. Additionally, the Company has finance leases for certain mining equipment that expires over various contractual periods. The leases have remaining lease terms of one to two years. These leases do not include an option to renew. Amortization expense for finance leases is included in depreciation and depletion expense. Supplemental balance sheet information related to leases was as follows (in thousands): March 31, 2019 Finance lease right-of-use assets, net (1) $ 5,771 Finance lease liabilities Current 4,559 Noncurrent 2,350 Total finance lease liabilities $ 6,909 Weighted average remaining lease term - finance leases (in months) 10.2 Weighted average discount rate - finance leases (2) 1.25 % (1) Finance lease right-of-use assets are recorded net of accumulated amortization of $2.8 million as of March 31, 2019 . (2) As most of the Company's leases do not provide an implicit discount rate, the Company uses its incremental borrowing rate based on information available at the commencement date when determining the present value of lease payments. The components of lease expense were as follows (in thousands): For the three months ended March 31, 2019 Operating lease cost (1): $ 144 Finance lease cost: Amortization of leased assets 1,957 Interest on lease liabilities 13 Net lease cost $ 2,114 (1) Includes leases that are for periods of 12 months or less. Maturities of lease liabilities were as follows (in thousands): Finance Leases (1) 2019 $ 4,582 2020 2,368 2021 — 2022 — 2023 — Total 6,950 Less: amount representing interest (41 ) Present value of lease liabilities $ 6,909 (1) Finance lease payments exclude $3.2 M of future payments required under signed lease agreements that have not yet commenced. Supplemental cash flow information related to leases was as follows (in thousands): For the three months ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from finance leases $ 13 Financing cash flows from finance leases $ 1,957 Right-of-use assets obtained in exchange for lease obligations: Finance leases $ 2,086 As of March 31, 2019 , the Company had additional finance leases, primarily for mining equipment, that have not yet commenced of $3.2 million . These finance leases will commence between fiscal year 2019 and 2021 with lease terms of one to two years.

Net Income per Share

Net Income per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Income per Share	Net Income per Share Basic and diluted net income per share was calculated as follows (in thousands, except per share data): For the three months ended 2019 2018 Numerator: Net income $ 110,447 $ 178,694 Denominator: Weighted-average shares used to compute net income per share—basic 51,511 53,149 Dilutive restrictive stock awards 119 3 Weighted-average shares used to compute net income per share—diluted 51,630 53,152 Net income per share—basic and diluted $ 2.14 $ 3.36 2017 Equity Plan On February 8, 2019, the Company awarded 306,314 restricted stock unit awards under the Company's 2017 Equity Incentive Plan (the "2017 Equity Plan"). These awards have certain service-based, performance-based and market-based vesting conditions, as applicable. The service-based awards vest over a period of three years and the performance-based and market-based awards are based on the Company's performance in each of the three years. The Company recognized approximately $0.5 million in stock compensation expense associated with these awards for the three months ended March 31, 2019 . Additionally, the Company awarded $1.5 million of restricted stock unit awards under the 2017 Equity Plan that can be settled in shares or in cash at the election of employees. These awards have certain service-based and performance-based vesting conditions and can be earned no later than December 31, 2021. If the Company were to settle these awards in shares these awards would represent 49,342 shares based on the Company's closing share price on March 31, 2019 . The Company recognized approximately $86 thousand in stock compensation expense associated with these awards for the three months ended March 31, 2019 . As of March 31, 2019 , there were 157,124 restricted stock unit awards for which the service-based vesting conditions for these awards were not met as of the measurement date. As such, these awards were excluded from basic earnings per share. These awards had a 28,302 share impact on dilutive weighted average shares. As of March 31, 2019 , there were 280,492 restricted stock unit awards for which the performance-based and market-based vesting conditions were not met as of the measurement date and, as such, these awards were excluded from basic and diluted earnings per share. For the 49,342 restricted stock unit awards classified as a liability, the Company considered the impact on diluted earnings as if the award was settled in cash or in shares. As the impact of these shares is anti-dilutive, they have been excluded from both basic and diluted earnings per share. As of March 31, 2019 , there were 43,580 shares of our common stock contingently issuable upon the settlement of a vested phantom unit award granted under our 2016 Equity Plan (as defined below) and 13,157 shares of our common stock contingently issuable upon the settlement of a vested restricted stock unit award under our 2017 Equity Plan, as applicable. The settlement date for these awards is the earlier of a change in control as described in our 2016 Equity Plan or 2017 Equity Plan, as applicable, or five years from the grant date. These awards are vested and, as such, have been included in the weighted average shares used to compute basic and diluted net income per share. 2016 Equity Plan As of March 31, 2019 , there were 124,307 restricted stock unit awards granted under the Company's 2016 Equity Incentive Plan (the "2016 Equity Plan") to certain directors and employees, for which the service-based vesting conditions for these awards were not met as of the measurement date. As such, these awards were excluded from basic earnings per share. These awards had an 90,419 share impact on dilutive weighted average shares.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company owns a 50% interest in Black Warrior Methane (“BWM”) and Black Warrior Transmission (“BWT”), which are accounted for under the proportionate consolidation method and equity method, respectively. The Company has granted the rights to produce and sell methane gas from its coal mines to BWM and BWT. The Company’s net investments in, advances to/from BWT and equity in earnings or loss of BWT are not material to the Company. The Company supplied labor to BWM and incurred costs, including property and liability insurance, to support the joint venture. The Company charged the joint venture for such costs on a monthly basis, which were $0.1 million for the three months ended March 31, 2019 and $0.8 million for the three months ended March 31, 2018 .

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Environmental Matters The Company is subject to a wide variety of laws and regulations concerning the protection of the environment, both with respect to the construction and operation of its plants, mines and other facilities and with respect to remediating environmental conditions that may exist at its own and other properties. The Company believes that it is in substantial compliance with federal, state and local environmental laws and regulations. The Company accrues for environmental expenses resulting from existing conditions that relate to past operations when the costs are probable and can be reasonably estimated. As of March 31, 2019 and December 31, 2018 , there were no accruals for environmental matters other than asset retirement obligations for mine reclamation. Miscellaneous Litigation From time to time, the Company is party to a number of lawsuits arising in the ordinary course of their businesses. The Company records costs relating to these matters when a loss is probable and the amount can be reasonably estimated. The effect of the outcome of these matters on the Company’s future results of operations cannot be predicted with certainty as any such effect depends on future results of operations and the amount and timing of the resolution of such matters. As of March 31, 2019 and December 31, 2018 , there were no items accrued for miscellaneous litigation. Commitments and Contingencies—Other The Company is party to various transportation and throughput agreements with rail and barge transportation providers and the Alabama State Port Authority. These agreements contain annual minimum tonnage guarantees with respect to coal transported from the mine sites to the Port of Mobile, Alabama, the unloading of rail cars or barges, and the loading of vessels. If the Company does not meet its minimum throughput obligations, which are based on annual minimum amounts, it is required to pay the transportation providers or the Alabama State Port Authority a contractually specified amount per metric ton for the difference between the actual throughput and the minimum throughput requirement. At March 31, 2019 and December 31, 2018 , the Company had no liability recorded for minimum throughput requirements. Royalty Obligations A substantial amount of the coal that the Company mines is produced from mineral reserves leased from third-party land owners. These leases convey mining rights to the Company in exchange for royalties to be paid to the land owner as either a fixed amount per ton or as a percentage of the sales price. Although coal leases have varying renewal terms and conditions, they generally last for the economic life of the reserves. Coal royalty expense was $26.7 million for the three months ended March 31, 2019 and $22.3 million for the three months ended March 31, 2018 .

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Pursuant to the Company's certificate of incorporation, the Company is authorized to issue up to 140,000,000 shares of common stock $0.01 , par value per share and 10,000,000 shares of preferred stock $0.01 par value per share. New Stock Repurchase Program On March 26, 2019, the Company's board of directors (the "Board") approved the Company's second stock repurchase program (the “New Stock Repurchase Program”) that authorizes repurchases of up to an aggregate of $70.0 million of the Company's outstanding common stock. The Company fully exhausted its previous stock repurchase program (the "First Stock Repurchase Program") of $40.0 million of its outstanding common stock. The New Stock Repurchase Program does not require the Company to repurchase a specific number of shares or have an expiration date. The New Stock Repurchase Program may be suspended or discontinued by the Board at any time without prior notice. Under the New Stock Repurchase Program, the Company may repurchase shares of its common stock from time to time, in amounts, at prices and at such times as the Company deems appropriate, subject to market and industry conditions, share price, regulatory requirements as determined from time to time by the Company and other considerations. The Company’s repurchases may be executed using open market purchases or privately negotiated transactions in accordance with applicable securities laws and regulations, including Rule 10b-18 of the Exchange Act and repurchases may be executed pursuant to Rule 10b5-1 under the Exchange Act. Repurchases will be subject to limitations in the ABL Facility and the Indenture. The Company intends to fund repurchases under the New Stock Repurchase Program from cash on hand and/or other sources of liquidity.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments The Company enters into natural gas swap contracts from time to time to hedge the exposure to variability in expected future cash flows associated with the fluctuations in the price of natural gas related to the Company’s forecasted sales. As of March 31, 2019 , the Company had no natural gas swap contracts outstanding. As of December 31, 2018 , the Company had natural gas swap contracts outstanding with notional amounts totaling 2,100 million British thermal units maturing in the first quarter of 2019. The Company’s natural gas swap contracts economically hedge certain risk but are not designated as hedges for financial reporting purposes. All changes in the fair value of these derivative instruments are recorded as other revenues in the Condensed Statements of Operations. The Company records all derivative instruments at fair value and had no liability as of March 31, 2019 and a liability of $0.2 million as of December 31, 2018 included in other current liabilities in the accompanying Condensed Balance Sheets.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company had no assets or any other liabilities measured at fair value on a recurring basis as of March 31, 2019 . The following table presents information about the Company’s financial liabilities measured at fair value on a recurring basis as of December 31, 2018 and indicates the level of the fair value hierarchy utilized to determine such fair value (in thousands): Fair Value Measurements as of December 31, 2018 Using: Level 1 Level 2 Level 3 Total Liabilities: Natural gas swap contracts $ — $ 178 $ — $ 178 The following methods and assumptions were used to estimate the fair value for which the fair value option was not elected: Cash and cash equivalents, short-term investments, restricted cash, receivables and accounts payable— The carrying amounts reported in the Condensed Balance Sheets approximate fair value due to the short-term nature of these assets and liabilities. Debt— The Company's outstanding debt is carried at cost. As of March 31, 2019 , there were no borrowings outstanding under the ABL Facility, with $120.4 million available, net of outstanding letters of credit of $4.6 million . There were no borrowings outstanding under the ABL Facility and there were $4.6 million of letters of credit issued and outstanding under the ABL Facility as of December 31, 2018 . The estimated fair value of the Notes is approximately $358.9 million based upon observable market data (Level 2).

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information The Company identifies a business as an operating segment if: (i) it engages in business activities from which it may earn revenues and incur expenses; (ii) its operating results are regularly reviewed by the Chief Operating Decision Maker (“CODM”), who is the Company’s Chief Executive Officer, to make decisions about resources to be allocated to the segment and assess its performance; and (iii) it has available discrete financial information. The Company has determined that its two underground mining operations are its operating segments. The CODM reviews financial information at the operating segment level to allocate resources and to assess the operating results and financial performance for each operating segment. Operating segments are aggregated into a reportable segment if the operating segments have similar quantitative economic characteristics and if the operating segments are similar in the following qualitative characteristics: (i) nature of products and services; (ii) nature of production processes; (iii) type or class of customer for their products and services; (iv) methods used to distribute the products or provide services; and (v) if applicable, the nature of the regulatory environment. The Company has determined that the two operating segments are similar in both quantitative and qualitative characteristics and thus the two operating segments have been aggregated into one reportable segment. The Company has determined that its natural gas and royalty businesses did not meet the criteria in ASC 280 to be considered as operating or reportable segments. Therefore, the Company has included their results in an “all other” category as a reconciling item to consolidated amounts. The Company does not allocate all of its assets, or its depreciation and depletion expense, selling, general and administrative expenses, transactions costs, interest expense, and income tax expense by segment. The following tables include reconciliations of segment information to consolidated amounts (in thousands): For the three months ended 2019 2018 Revenues Mining $ 369,681 $ 412,879 All other 8,609 8,909 Total revenues $ 378,290 $ 421,788 For the three months ended 2019 2018 Capital Expenditures Mining 23,210 $ 21,096 All other 1,185 1,446 Total capital expenditures 24,395 $ 22,542 The Company evaluates the performance of its segment based on Segment Adjusted EBITDA, which is defined as net income adjusted for other revenues, cost of other revenues, depreciation and depletion, selling, general and administrative, net interest expense, income tax expense, loss on early extinguishment of debt and certain transactions or adjustments that the CODM does not consider for the purposes of making decisions to allocate resources among segments or assessing segment performance. Segment Adjusted EBITDA does not represent and should not be considered as an alternative to cost of sales under GAAP and may not be comparable to other similarly titled measures used by other companies. Below is a reconciliation of Segment Adjusted EBITDA to net income, which is its most directly comparable financial measure calculated and presented in accordance with GAAP (in thousands): For the three months ended 2019 2018 Segment Adjusted EBITDA $ 187,053 $ 222,203 Other revenues 8,609 8,909 Cost of other revenues (7,745 ) (7,784 ) Depreciation and depletion (22,233 ) (24,552 ) Selling, general and administrative (8,905 ) (8,234 ) Transaction and other expenses — (3,288 ) Loss on early extinguishment of debt (9,756 ) — Interest expense, net (8,592 ) (8,560 ) Income tax expense (27,984 ) — Net income $ 110,447 $ 178,694

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Regular Quarterly Dividend On April 23, 2019, the Board declared a regular quarterly cash dividend of $0.05 per share, totaling approximately $2.6 million , which will be paid on May 10, 2019 to stockholders of record as of the close of business on May 3, 2019. April 2019 Special Dividend On April 23, 2019, the Board declared a special cash dividend of approximately $230.0 million (the "April 2019 Special Dividend"), which will be paid on May 14, 2019 to stockholders of record as of the close of business on May 6, 2019. The Company intends to fund the April 2019 Special Dividend with cash on hand.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	The accompanying financial statements are presented in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In our opinion, the financial statements include all adjustments (consisting of normal recurring accruals) necessary in order to make the financial statements not misleading.
Cash and Cash Equivalents and Restricted Cash	Cash and cash equivalents include short-term deposits and highly liquid investments that have original maturities of three months or less when purchased and are stated at cost, which approximates fair value. As of March 31, 2019 and December 31, 2018 , restricted cash included in other long-term assets in the Condensed Balance Sheets represents amounts invested in certificates of deposits as financial assurance for post mining reclamation obligations.
Short-Term Investments	Short-Term Investments Instruments with maturities greater than three months, but less than twelve months, are included in short-term investments. The Company purchases United States Treasury ("Treasury") bills with maturities ranging from six to twelve months which are classified as held to maturity and are carried at amortized cost, which approximates fair value. Securities classified as held to maturity are those securities that management has the intent and ability to hold to maturity.
Revenue Recognition	Revenue Recognition Revenue is recognized when performance obligations under the terms of a contract with our customers are satisfied; for all contracts this occurs when control of the promised goods have been transferred to our customers. For coal shipments to domestic customers via rail, control is transferred when the railcar is loaded. For coal shipments to international customers via ocean vessel, control is transferred when the vessel is loaded at the Port of Mobile, Alabama. For natural gas sales, control is transferred when the gas has been transferred to the pipeline. Revenue is disaggregated between coal sales within the Company's mining segment and natural gas sales included in all other revenues, as disclosed in Note 14.
New Accounting Pronouncements	New Accounting Pronouncements The Company adopted Accounting Standards Update (“ASU”) No. 2016-02, "Leases (Topic 842)" as of January 1, 2019 using the modified retrospective approach (the "New Leases Standard"). The New Leases Standard requires a lessee to recognize a right-of-use asset and lease liability on its balance sheet for all leases. The Company has chosen to use its adoption date as its date of initial application. As a result, financial information will not be updated and the disclosures required under the new standard will not be provided for dates and periods before January 1, 2019. The Company made an accounting policy election that leases with an initial term of 12 months or less will remain off of its balance sheet and lease payments will instead be recognized in the Condensed Statements of Operations on a straight-line basis over the lease term. Additionally, the Company elected the package of practical expedients for all leases, which permits the Company to forego reassessing expired or existing contracts to determine: whether they are or contain leases, lease classification, and initial direct costs. Management elected the optional transition expedient which allows the Company to continue applying the current policy for accounting for expired or existing land easement contracts that were not previously accounted for under GAAP. New or modified land easements executed after adoption will be considered under the New Lease Standard. The Company elected the practical expedient as an accounting policy election for all asset classifications, which allows it to account for them as a single lease component, rather than as separate lease and non-lease components. As the Company’s historical operating leases are primarily short term rental agreements of less than one year, the Company did not record any additional lease assets or lease liabilities upon adoption of the New Leases Standard. The New Leases Standard did not impact the Company's balance sheet or consolidated net income and had no impact on cash flows. As of March 31, 2019, the Company has a right-of-use asset of $5.8 million , net of accumulated amortization, and a liability of $6.9 million . On August 17, 2018, the SEC adopted a final rule that eliminates or amends certain disclosure requirements that were deemed redundant and outdated in light of changes in SEC requirements, U.S. GAAP or changes in technology or the business environment. The rule also requires registrants to include in their interim financial statements a reconciliation of changes in stockholders’ equity in the notes or as a separate statement. The analysis should reconcile the beginning balance to the ending balance of each caption in shareholders’ equity for each period for which an income statement is required to be filed. The final rule became effective November 5, 2018. Beginning in the first quarter of fiscal 2019, we have provided a reconciliation for the quarterly period as well as the comparable prior period in this Form 10-Q. The eliminated or amended disclosures did not have a material impact on the Company’s unaudited condensed financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the Condensed Balance Sheets that sum to the total of the same such amounts shown in the Condensed Statements of Cash Flows (in thousands): March 31, 2019 December 31, 2018 Cash and cash equivalents $ 154,912 $ 205,577 Restricted cash included in other long-term assets 830 828 Total cash and cash equivalents and restricted cash included in the Condensed Statements of Cash Flows $ 155,742 $ 206,405
Schedule of Restricted Cash and Cash Equivalents	The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the Condensed Balance Sheets that sum to the total of the same such amounts shown in the Condensed Statements of Cash Flows (in thousands): March 31, 2019 December 31, 2018 Cash and cash equivalents $ 154,912 $ 205,577 Restricted cash included in other long-term assets 830 828 Total cash and cash equivalents and restricted cash included in the Condensed Statements of Cash Flows $ 155,742 $ 206,405

Inventories, net (Tables)

Inventories, net (Tables)	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Schedule of Inventories, Net	Inventories, net are summarized as follows (in thousands): March 31, 2019 December 31, 2018 Coal $ 43,444 $ 32,854 Raw materials, parts, supplies and other, net 26,912 23,865 Total inventories, net $ 70,356 $ 56,719

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Debt consisted of the following (in thousands): March 31, 2019 December 31, 2018 Weighted Average Interest Rate at March 31, 2019 Final Maturity Senior Secured Notes $ 343,435 $ 475,000 8% 2024 Promissory note — 760 Debt discount/premium, net (4,736 ) (6,769 ) Total debt 338,699 468,991 Less: current debt — (760 ) Total long-term debt $ 338,699 $ 468,231
Schedule of Maturities of Long-term Debt	The Company's minimum debt repayment schedule, excluding interest, as of March 31, 2019 is as follows (in thousands): Payments Due 2019 2020 2021 2022 2023 Thereafter Senior Secured Notes $ — $ — $ — $ — $ — $343,435 Total $ — $ — $ — $ — $ — $ 343,435

Other Long-Term Liabilities (Ta

Other Long-Term Liabilities (Tables)	3 Months Ended
	Mar. 31, 2019
Other Liabilities Disclosure [Abstract]
Other Long-Term Liabilities	Other long-term liabilities are summarized as follows (in thousands): March 31, 2019 December 31, 2018 Black lung obligations $ 25,297 $ 25,206 Property, plant, and equipment obligation (1) 32,727 — Other (2) 3,070 5,510 Total other long-term liabilities $ 61,094 $ 30,716 (1) Represents a noncash investing activity that is not included in our Condensed Statements of Cash Flows. (2) Approximately $2.1 million as of March 31, 2019 represents a capital lease that is a noncash investing activity that is not included in our Condensed Statements of Cash Flows.

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Supplemental Balance Sheet Information	Supplemental balance sheet information related to leases was as follows (in thousands): March 31, 2019 Finance lease right-of-use assets, net (1) $ 5,771 Finance lease liabilities Current 4,559 Noncurrent 2,350 Total finance lease liabilities $ 6,909 Weighted average remaining lease term - finance leases (in months) 10.2 Weighted average discount rate - finance leases (2) 1.25 % (1) Finance lease right-of-use assets are recorded net of accumulated amortization of $2.8 million as of March 31, 2019 . (2) As most of the Company's leases do not provide an implicit discount rate, the Company uses its incremental borrowing rate based on information available at the commencement date when determining the present value of lease payments.
Direct Financing Lease, Lease Expense	The components of lease expense were as follows (in thousands): For the three months ended March 31, 2019 Operating lease cost (1): $ 144 Finance lease cost: Amortization of leased assets 1,957 Interest on lease liabilities 13 Net lease cost $ 2,114 (1) Includes leases that are for periods of 12 months or less.
Operating Lease, Lease Expense	The components of lease expense were as follows (in thousands): For the three months ended March 31, 2019 Operating lease cost (1): $ 144 Finance lease cost: Amortization of leased assets 1,957 Interest on lease liabilities 13 Net lease cost $ 2,114
Finance Lease, Liability, Maturity	Maturities of lease liabilities were as follows (in thousands): Finance Leases (1) 2019 $ 4,582 2020 2,368 2021 — 2022 — 2023 — Total 6,950 Less: amount representing interest (41 ) Present value of lease liabilities $ 6,909
Supplemental Cash Flow Information	Supplemental cash flow information related to leases was as follows (in thousands): For the three months ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from finance leases $ 13 Financing cash flows from finance leases $ 1,957 Right-of-use assets obtained in exchange for lease obligations: Finance leases $ 2,086

Net Income per Share (Tables)

Net Income per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Basic and diluted net income per share was calculated as follows (in thousands, except per share data): For the three months ended 2019 2018 Numerator: Net income $ 110,447 $ 178,694 Denominator: Weighted-average shares used to compute net income per share—basic 51,511 53,149 Dilutive restrictive stock awards 119 3 Weighted-average shares used to compute net income per share—diluted 51,630 53,152 Net income per share—basic and diluted $ 2.14 $ 3.36

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities Measured on Recurring Basis	The following table presents information about the Company’s financial liabilities measured at fair value on a recurring basis as of December 31, 2018 and indicates the level of the fair value hierarchy utilized to determine such fair value (in thousands): Fair Value Measurements as of December 31, 2018 Using: Level 1 Level 2 Level 3 Total Liabilities: Natural gas swap contracts $ — $ 178 $ — $ 178

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Reconciliation of Revenue from Segments to Consolidated	The following tables include reconciliations of segment information to consolidated amounts (in thousands): For the three months ended 2019 2018 Revenues Mining $ 369,681 $ 412,879 All other 8,609 8,909 Total revenues $ 378,290 $ 421,788
Reconciliation of Capital Expenditures from Segments to Consolidated	For the three months ended 2019 2018 Capital Expenditures Mining 23,210 $ 21,096 All other 1,185 1,446 Total capital expenditures 24,395 $ 22,542
Reconciliation of Net Income (Loss) from Segments to Consolidated	Below is a reconciliation of Segment Adjusted EBITDA to net income, which is its most directly comparable financial measure calculated and presented in accordance with GAAP (in thousands): For the three months ended 2019 2018 Segment Adjusted EBITDA $ 187,053 $ 222,203 Other revenues 8,609 8,909 Cost of other revenues (7,745 ) (7,784 ) Depreciation and depletion (22,233 ) (24,552 ) Selling, general and administrative (8,905 ) (8,234 ) Transaction and other expenses — (3,288 ) Loss on early extinguishment of debt (9,756 ) — Interest expense, net (8,592 ) (8,560 ) Income tax expense (27,984 ) — Net income $ 110,447 $ 178,694

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 154,912	$ 205,577
Restricted cash included in other long-term assets	830	828
Total cash and cash equivalents and restricted cash included in the Condensed Statements of Cash Flows	$ 155,742	$ 206,405	$ 322,852	$ 36,264

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Short-Term Investments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Short-term investments	$ 17,501	$ 17,501
Treasury bills
Schedule of Held-to-maturity Securities [Line Items]
Short-term investments	$ 17,500	$ 17,500
Maturity term for short-term investments	6 months	6 months

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Revenue Recognition (Details) $ in Thousands	3 Months Ended		14 Months Ended
	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Mar. 31, 2018t
Concentration Risk [Line Items]
Percent of total production transferred for title and marketing			10.00%
Maximum total production transferred for title and marketing | t			250,000
Other revenues	$ 378,290	$ 421,788
XCoal | Customer Concentration Risk | Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	26.00%	21.00%
Other revenues	$ 94,900	$ 86,200

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Leases (Details) $ in Thousands	Mar. 31, 2019USD ($)
Accounting Policies [Abstract]
Right-of-use asset	$ 5,771
Finance lease liability	$ 6,909

Inventories, net (Details)

Inventories, net (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Coal	$ 43,444	$ 32,854
Raw materials, parts, supplies and other, net	26,912	23,865
Total inventories, net	$ 70,356	$ 56,719

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income tax expense	$ 27,984,000	$ 0

Debt - Schedule of Long-Term De

Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt discount/premium, net	$ (4,736)	$ (6,769)
Total debt	338,699	468,991
Less: current debt	0	(760)
Total long-term debt	338,699	468,231
Senior secured notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 343,435	475,000
Weighted average interest rate	8.00%
Promissory note
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	$ 760

Debt - Debt Repayment Schedule

Debt - Debt Repayment Schedule (Details) $ in Thousands	Mar. 31, 2019USD ($)
Debt Instrument [Line Items]
2019	$ 0
2020	0
2021	0
2022	0
2023	0
Thereafter	343,435
Senior secured notes
Debt Instrument [Line Items]
2019	0
2020	0
2021	0
2022	0
2023	0
Thereafter	$ 343,435

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($)	Feb. 21, 2019	Mar. 31, 2019	Mar. 31, 2018	Mar. 25, 2019	Mar. 22, 2019	Mar. 01, 2018	Nov. 02, 2017
Debt Instrument [Line Items]
Amount that can be authorized without making an offer to buy back debt				$ 299,401,000
Loss on early extinguishment of debt		$ 9,756,000	$ 0
Senior secured notes | Senior Secured Notes Due 2024, New Notes
Debt Instrument [Line Items]
Face amount of debt						$ 125,000,000
Senior secured notes | Senior Secured Notes Due 2024, Existing Notes, Restricted Payment Offer
Debt Instrument [Line Items]
Maximum amount available for repurchase	$ 150,000,000
Stated interest rate						8.00%
Redemption price, percentage	103.00%
Debt instrument, amount validly tendered and not withdrawn					$ 1,900,000
Pro-ration factor					31.5789%
Purchase integrals					$ 1,000
Senior secured notes | Senior Secured Notes Due 2024, Tendered Notes, Restricted Payment Pro-Rated Offer
Debt Instrument [Line Items]
Debt instrument, amount validly tendered and not withdrawn					599,000
Debt instrument, amount accepted					599,000
Debt instrument, not accepted					1,301,000
Senior secured notes | Senior Secured Notes Due 2024, Existing Notes
Debt Instrument [Line Items]
Face amount of debt							$ 350,000,000
Stated interest rate							8.00%
Senior secured notes | Senior Secured Notes Due 2024, Existing Notes, Tender Offer
Debt Instrument [Line Items]
Maximum amount available for repurchase	$ 150,000,000
Redemption price, percentage	104.25%
Debt instrument, amount validly tendered and not withdrawn					$ 415,099,000
Pro-ration factor					31.5789%
Purchase integrals					$ 1,000
Senior secured notes | Senior Secured Notes Due 2024, Tendered Notes, Tender Offer Pro-Rated Offer
Debt Instrument [Line Items]
Debt instrument, amount validly tendered and not withdrawn					130,966,000
Debt instrument, amount accepted					130,966,000
Debt instrument, not accepted					$ 284,133,000

Other Long-Term Liabilities (De

Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Black lung obligations	$ 25,297	$ 25,206
Property, plant, and equipment obligation	32,727	0
Other	3,070	5,510
Total other long-term liabilities	61,094	30,716
Capital lease, noncash and not included in the Condensed Statements of Cash Flows	$ 2,100	$ 2,100

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Lessor, Lease, Description [Line Items]
Finance leases that have not yet commenced	$ 3.2
Minimum
Lessor, Lease, Description [Line Items]
Remaining lease terms	1 year
Maximum
Lessor, Lease, Description [Line Items]
Remaining lease terms	2 years

Leases - Supplemental Balance S

Leases - Supplemental Balance Sheet Information (Details) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
Finance lease right-of-use assets, net(1)	$ 5,771
Finance lease liabilities
Current	4,559
Noncurrent	2,350
Total finance lease liabilities	$ 6,909
Weighted average remaining lease term - finance leases (in months)	10 months 5 days
Weighted average discount rate - finance leases(2)	1.25%
Accumulated amortization	$ 2,800

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Operating lease cost	$ 144
Finance lease cost:
Amortization of leased assets	1,957
Interest on lease liabilities	13
Net lease cost	$ 2,114

Leases - Maturities of Lease Li

Leases - Maturities of Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
2019	$ 4,582
2020	2,368
2021	0
2022	0
2023	0
Total	6,950
Less: amount representing interest	(41)
Present value of lease liabilities	6,909
Future payments required under signed lease agreements that have not yet commenced	$ 3,200

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Operating cash flows from finance leases	$ 13
Financing cash flows from finance leases	1,957
Right-of-use assets obtained in exchange for finance lease obligations	$ 2,086

Net Income per Share - Schedule

Net Income per Share - Schedule of Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net income	$ 110,447	$ 178,694
Denominator:
Weighted average number of shares outstanding—basic (in shares)	51,511	53,149
Dilutive restrictive stock awards	119	3
Weighted average number of shares outstanding—diluted (in shares)	51,630	53,152
Net income per share—basic and diluted (in dollars per share)	$ 2.14	$ 3.36

Net Income per Share - Narrativ

Net Income per Share - Narrative (Details) - USD ($) $ in Thousands	Feb. 08, 2019	Mar. 31, 2019	Mar. 31, 2018
Class of Stock [Line Items]
Stock compensation expense		$ 500
Dilutive awards (in shares)		119,000	3,000
2016 Equity Plan
Class of Stock [Line Items]
Dilutive awards (in shares)		90,419
Phantom Share Units (PSUs) | 2016 and 2017 Equity Plans
Class of Stock [Line Items]
Settlement period		5 years
Phantom Share Units (PSUs) | 2016 Equity Plan
Class of Stock [Line Items]
Common stock shares contingently issuable (in shares)		43,580
Restricted Stock Units (RSUs) | 2017 Equity Plan
Class of Stock [Line Items]
Restricted stock unit awards awarded (in shares)	306,314
Stock compensation expense		$ 86
Restricted stock unit awards awarded, value		$ 1,500
Shares to be issued upon settlement of awards (in shares)		49,342
Common stock shares contingently issuable (in shares)		13,157
Service-based RSUs | 2016 Equity Plan
Class of Stock [Line Items]
RSUs excluded from computation of earnings per share (in shares)		124,307
Service-based RSUs | 2017 Equity Plan
Class of Stock [Line Items]
RSUs excluded from computation of earnings per share (in shares)		157,124
Dilutive awards (in shares)		28,302
Performance and market-based RSUs | 2017 Equity Plan
Class of Stock [Line Items]
RSUs excluded from computation of earnings per share (in shares)		280,492

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Nov. 05, 2015
Black Warrior Methane (BWM)
Related Party Transaction [Line Items]
Proportionate consolidation method, ownership percentage			50.00%
Black Warrior Transmission (BWT)
Related Party Transaction [Line Items]
Equity method investment, ownership percentage			50.00%
Allocated Expenses to Joint Venture | Corporate Joint Venture
Related Party Transaction [Line Items]
Expenses from transactions with related party	$ 0.1	$ 0.8

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Throughput obligation	$ 0		$ 0
Coal royalty expense	$ 26,700,000	$ 22,300,000

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 31, 2019	Mar. 26, 2019	Dec. 31, 2018	May 02, 2018	Apr. 12, 2017
Class of Stock [Line Items]
Common stock shares authorized (in shares)	140,000,000		140,000,000		140,000,000
Common stock par value (in dollars per share)	$ 0.01		$ 0.01		$ 0.01
Preferred stock shares authorized (in shares)	10,000,000		10,000,000		10,000,000
Preferred stock par value (in dollars per share)	$ 0.01		$ 0.01		$ 0.01
New Stock Repurchase Program
Class of Stock [Line Items]
Authorized amount of stock to be repurchased, value		$ 70
First Stock Repurchase Program
Class of Stock [Line Items]
Authorized amount of stock to be repurchased, value				$ 40

Derivative Instruments (Details

Derivative Instruments (Details) - Not Designated as Hedging Instrument - Natural gas swap contracts	3 Months Ended	12 Months Ended
	Mar. 31, 2019USD ($)BTU	Dec. 31, 2018USD ($)BTU
Commodity Contract, Maturity Q4 2018
Derivative [Line Items]
Derivative energy measure (in BTUs) | BTU	0	2,100,000,000
Commodity Contract
Derivative [Line Items]
Natural gas swap contracts, current liability | $	$ 0	$ 200,000

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 338,699,000	$ 468,231,000
Letters of credit outstanding	4,600,000	0
Fair Value, Measurements, Recurring | Commodity Contract | Natural gas swap contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Natural gas swap contracts, asset		178,000
Fair Value, Measurements, Recurring | Commodity Contract | Natural gas swap contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Natural gas swap contracts, asset		0
Fair Value, Measurements, Recurring | Commodity Contract | Natural gas swap contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Natural gas swap contracts, asset		178,000
Fair Value, Measurements, Recurring | Commodity Contract | Natural gas swap contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Natural gas swap contracts, asset		0
ABL Facility | Revolving credit facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of borrowings available	120,400,000
Senior Secured Notes Due 2024, Existing Notes | Senior secured notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	0
Senior Secured Notes Due 2024, Existing Notes | Senior secured notes | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt instrument	$ 358,900,000
Revolving credit facility | Citibank | Letter of Credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Letters of credit issued and outstanding		$ 4,600,000

Segment Information - Narrative

Segment Information - Narrative (Details)	3 Months Ended
	Mar. 31, 2019segment
Segment Reporting [Abstract]
Number of operating segments	2
Number of reportable segments	1

Segment Information - Reconcili

Segment Information - Reconciliation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 378,290	$ 421,788
Mining | Mining | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	369,681	412,879
All other
Segment Reporting Information [Line Items]
Total revenues	8,609	8,909
All other | Segment Reconciling Items
Segment Reporting Information [Line Items]
Total revenues	$ 8,609	$ 8,909

Segment Information - Reconci_2

Segment Information - Reconciliation of Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Capital Expenditures	$ 24,395	$ 22,542
Segment Reconciling Items
Segment Reporting Information [Line Items]
Capital Expenditures	1,185	1,446
Mining | Operating Segments
Segment Reporting Information [Line Items]
Capital Expenditures	$ 23,210	$ 21,096

Segment Information - Reconci_3

Segment Information - Reconciliation of Net Income (Loss) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue from External Customer [Line Items]
Segment Adjusted EBITDA	$ 187,053,000	$ 222,203,000
Other revenues	378,290,000	421,788,000
Cost of other revenues	(7,745,000)	(7,784,000)
Depreciation and depletion	(22,233,000)	(24,552,000)
Selling, general and administrative	(8,905,000)	(8,234,000)
Transaction and other expenses	0	(3,288,000)
Loss on early extinguishment of debt	(9,756,000)	0
Interest expense, net	(8,592,000)	(8,560,000)
Income tax expense	(27,984,000)	0
Net income	110,447,000	178,694,000
Other revenues
Revenue from External Customer [Line Items]
Other revenues	$ 8,609,000	$ 8,909,000

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event $ / shares in Units, $ in Millions	Apr. 23, 2019USD ($)$ / shares
Subsequent Event [Line Items]
Dividends declared (in dollars per share) | $ / shares	$ 0.05
Regular quarterly cash dividend	$ 2.6
Special dividends	$ 230