Westmoreland Resource Partners (WMLPQ) 10-Q 6 Aug 18 2018 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	Westmoreland Resource Partners, LP
Entity Central Index Key	1,412,347
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,284,840

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 28,233	$ 36,739
Receivables	21,020	27,409
Inventories	13,676	14,927
Other current assets	7,099	1,891
Total current assets	70,028	80,966
Property, plant and equipment:
Land, mineral rights, property, plant and equipment	208,385	358,375
Less accumulated depreciation, depletion and amortization	(82,348)	(164,711)
Net property, plant and equipment	126,037	193,664
Advanced coal royalties	3,990	10,143
Restricted investments	35,811	37,239
Intangible assets, net of accumulated amortization of $6.2 million at December 31, 2017	0	24,800
Deposits and other assets	904	592
Total Assets	236,770	347,404
Current liabilities:
Current installments of long-term debt	318,950	314,228
Accounts payable and accrued expenses:
Trade	15,326	15,565
Deferred revenue	2,037	3,141
Production taxes	15,535	16,670
Asset retirement obligations	11,124	15,187
Other current liabilities	2,317	2,091
Total current liabilities	365,289	366,882
Long-term debt, less current installments	7,345	9,605
Asset retirement obligations, less current portion	30,808	30,609
Other liabilities	1,711	1,942
Total liabilities	405,153	409,038
Partners' capital (deficit):
Limited partners	20,024	25,959
General partner units (35,291 units outstanding as of June 30, 2018 and December 31, 2017)	31,529	31,687
Accumulated other comprehensive loss	(84)	80
Total Westmoreland Resource Partners, LP capital	(168,383)	(61,634)
Total Liabilities and Partners’ Deficit	236,770	347,404
Series A Convertible Units [Member]
Partners' capital (deficit):
Limited partners	(149,068)	(69,605)
Series B Convertible Units [Member]
Partners' capital (deficit):
Limited partners	(70,784)	(49,755)
Liquidation Units [Member]
Partners' capital (deficit):
General partner units (35,291 units outstanding as of June 30, 2018 and December 31, 2017)	$ 0	$ 0

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parentheticals) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Accumulated amortization		$ 6,200,000
Limited partner capital account, units outstanding	1,284,840	1,284,840
General partner capital account, units outstanding	35,291	35,291
Series A Convertible Units [Member]
Limited partner capital account, units outstanding	17,050,680	17,050,680
Series B Convertible Units [Member]
Limited partner capital account, units outstanding	4,512,500	4,512,500
Liquidation Units [Member]
General partner capital account, units outstanding	856,698	856,698

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues	$ 64,295	$ 81,051	$ 132,102	$ 155,856
Costs and expenses:
Cost of sales (exclusive of depreciation, depletion and amortization, shown separately)	54,065	59,812	109,691	119,228
Depreciation, depletion and amortization	9,189	10,110	17,354	20,461
Selling and administrative	7,008	3,714	12,919	7,611
Loss (gain) on sales of assets	(1,169)	(220)	(1,068)	(362)
Loss on impairment	77,675	0	77,675	0
Total cost and expenses	146,768	73,416	216,571	146,938
Operating (loss) income	(82,473)	7,635	(84,469)	8,918
Other (expense) income:
Interest expense	(11,609)	(10,653)	(22,959)	(21,132)
Interest income	239	233	498	439
Other income	84	433	293	608
Total other expenses	(11,286)	(9,987)	(22,168)	(20,085)
Net loss	(93,759)	(2,352)	(106,637)	(11,167)
Less net loss allocated to general partner	(140)	(4)	(158)	(17)
Net loss allocated to limited partners	(93,619)	(2,348)	(106,479)	(11,150)
Unrealized and realized (loss) gain on available-for-sale debt securities	(97)	105	(164)	251
Comprehensive loss attributable to the Partnership	$ (93,856)	$ (2,247)	$ (106,801)	$ (10,916)
Weighted average number of limited partner common units outstanding, basic and diluted:
Distribution per general partner unit (dollars per unit)	$ 0	$ 0.1333	$ 0	$ 0.2666
Common units [Member]
Net loss per limited partner common unit, basic and diluted:
Basic and diluted (in dollars per share)	$ (4.10)	$ (0.08)	$ (4.66)	$ (0.45)
Weighted average number of limited partner common units outstanding, basic and diluted:
Basic and diluted (in units)	1,285	1,285	1,285	1,264
Distribution per limited partner unit (dollars per unit)	$ 0	$ 0.1333	$ 0	$ 0.2666

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Partners' Capital - 6 months ended Jun. 30, 2018 - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income (Loss) [Member]	Limited Partner [Member]	Limited Partner [Member]Common Units [Member]	Limited Partner [Member]Liquidation [Member]	General Partner [Member]	Series A Convertible Units [Member]Limited Partner [Member]	Series B Convertible Units [Member]Limited Partner [Member]
Beginning balance at Dec. 31, 2017	$ (61,634)	$ 80	$ (93,401)	$ 25,959	$ 0	$ 31,687	$ (69,605)	$ (49,755)
Beginning balance (in units) at Dec. 31, 2017			23,704,718	1,284,840	856,698	35,291	17,050,680	4,512,500
Increase (Decrease) in Partners' Capital [Roll Forward]
Net loss	(106,637)		$ (106,479)	$ (5,987)		$ (158)	$ (79,463)	$ (21,029)
Equity-based compensation	52		52	52
Other comprehensive income	(164)	(164)
Ending balance at Jun. 30, 2018	$ (168,383)	$ (84)	$ (199,828)	$ 20,024	$ 0	$ 31,529	$ (149,068)	$ (70,784)
Ending balance (in units) at Jun. 30, 2018			23,704,718	1,284,840	856,698	35,291	17,050,680	4,512,500

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (106,637)	$ (11,167)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion and amortization	17,354	20,461
Accretion of asset retirement obligations	3,551	2,672
Equity-based compensation	52	81
Loss on impairment	77,675	0
Non-cash interest expense	4,782	4,639
Amortization of deferred financing costs	1,362	1,421
Other	(1,068)	(1,263)
Changes in operating assets and liabilities:
Receivables, net	6,389	3,202
Inventories	1,251	867
Accounts payable and accrued expenses	1,374	2,679
Interest payable	226	21
Deferred revenue	(1,104)	(1,375)
Other assets and liabilities	(3,221)	2,721
Asset retirement obligations	(5,260)	(5,219)
Net cash provided by operating activities	(3,274)	19,740
Net cash provided by (used in) investing activities
Additions to property, plant, equipment and other	(3,151)	(7,054)
Advance royalties payments	(98)	(318)
Proceeds from sales of restricted investments	5,939	6,981
Purchases of restricted investments	(4,395)	(8,854)
Net proceeds from sales of assets	600	608
Net cash provided by (used in) investing activities	(1,105)	(8,637)
Cash flows from financing activities:
Repayments of long-term debt	(3,845)	(2,620)
Cash distributions to unitholders	0	(388)
Acquisition under common control of Johnson Run	0	(1,526)
Net cash used in financing activities	(3,845)	(4,534)
Net (decrease) increase in cash and cash equivalents, including restricted cash	(8,224)	6,569
Cash and cash equivalents, including restricted cash, beginning of period	44,493	23,675
Cash and cash equivalents, including restricted cash, end of period	36,269	30,244
Supplemental disclosures of cash flow information:
Cash paid for interest	16,495	15,174
Non-cash transactions:
Accrued purchases of property and equipment	738	332
Economic value of Series A convertible unit distributions	0	2,124
Cash and cash equivalents, including restricted cash, end of period
Cash and cash equivalents, including restricted cash, end of period	$ 44,493	$ 23,675

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	1. BASIS OF PRESENTATION The accompanying consolidated financial statements (unaudited) include the accounts and operations of Westmoreland Resource Partners, LP (the “Partnership”) and its consolidated subsidiaries and have been prepared in accordance with United States Generally Accepted Accounting Principles (“GAAP”) and require the use of management’s estimates. All intercompany transactions and accounts have been eliminated in consolidation. The financial information contained in this Quarterly Report on Form 10-Q (“Quarterly Report”) is unaudited, but reflects all adjustments which, in the opinion of management, are necessary for a fair presentation of the financial information for the periods shown. Such adjustments are of a normal recurring nature. Certain prior-period amounts have been reclassified to conform with the financial statement line items used by Westmoreland Coal Company (“WCC”), the parent of our general partner Westmoreland Resources GP, LLC (the “GP”). The results of operations for the six months ended June 30, 2018 are not necessarily indicative of results to be expected for the year ending December 31, 2018 . These unaudited quarterly consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes to the consolidated financial statements included in the Partnership’s Annual Report on Form 10-K for the year ended December 31, 2017 (“ 2017 Form 10-K”). There were no changes to our significant accounting policies from those disclosed in the audited consolidated financial statements and notes to the consolidated financial statements thereto contained in our 2017 Form 10-K, except as described below in the section titled "Recently Issued Accounting Pronouncements." Going Concern, Liquidity and Management’s Plan Our Term Loan (as defined in Note 6. Debt And Lines Of Credit ) matures on December 31, 2018, and accordingly the principal balance of $315.9 million is classified as a current liability on our Consolidated Balance Sheet as of June 30, 2018 . The Partnership does not currently have liquidity or access to additional capital sufficient to pay off this debt by its maturity date. This condition gives rise to substantial doubt as to the Partnership’s ability to continue as a going concern within one year after the date that these financial statements were issued. Certain affirmative covenants in our 2014 Financing Agreement (as defined in Note 6. Debt And Lines Of Credit ) provide that an audit opinion on our consolidated financial statements that includes an explanatory paragraph referencing our conclusion that substantial doubt exists as to the Partnership's ability to continue as a going concern constitutes an event of default. The audit report included in our 2017 Form 10-K contained such an explanatory paragraph. On March 1, 2018, we entered into a waiver and amendment number three to the 2014 Financing Agreement that waived any such event of default arising from the inclusion of a going concern explanatory paragraph in the audit report included in our 2017 Form 10-K. Prior to the expiration of the aforementioned waiver on May 15, 2018, we entered into a series of amendments that ultimately continued to waive any such event of default through September 8, 2018 (“Waiver”) or the occurrence of any other event of default that has not been waived as part of the Waiver. Accordingly, on expiration of the Waiver, the lenders could accelerate the maturity date of the Term Loan, making it immediately due and payable. If our lenders accelerate the maturity date of the Term Loan, we do not currently have sufficient liquidity to repay such indebtedness and would need additional sources of capital to do so. We have engaged financial advisors to assess our capital structure. Management and our Board, with the assistance of our advisors, are evaluating options to address the Term Loan maturity date, which may include seeking an amendment, restructuring of our existing debt or sales of underlying assets. We cannot provide any assurances that we will be successful addressing the maturity date, and if we fail to do so, it may be necessary for us to seek a private restructuring or protection from creditors under Chapter 11 of the United States Bankruptcy Code. The accompanying consolidated financial statements (unaudited) are prepared on a going concern basis and do not include any adjustments that might result from uncertainty about our ability to continue as a going concern. Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers (Topic 606) (“new revenue standard”), which supersedes all previously existing revenue recognition guidance. Under this guidance, an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard allows for initial application to be performed retrospectively to each period presented or as a cumulative effect adjustment as of the date of adoption. During 2016, the FASB clarified the implementation guidance on principal versus agent, identifying performance obligations and licensing, practical expedients, and made technical corrections on various topics. The Partnership adopted the new revenue standard effective January 1, 2018 using the full retrospective method. The adoption of this standard did not have a material impact to the Partnership's consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“new cash flows standard”), which requires all entities that have restricted cash or restricted cash equivalents to explain the changes during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents in the Consolidated Statements of Cash Flows. As a result, amounts generally described as restricted cash and restricted cash equivalents that are included in other financial statement captions of the Consolidated Balance Sheets should be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts shown on the Consolidated Statements of Cash Flows. The ASU should be adopted using a retrospective transition method to each period presented. The Partnership adopted the new cash flows standard effective January 1, 2018 and applied the ASU retrospectively to the periods presented in the Partnership’s Consolidated Statements of Cash Flows (unaudited). As a result, net cash used in investing activities for the six months ended June 30, 2017 was adjusted to exclude the change in restricted cash as follows: Six Months Ended June 30, 2017 (In thousands) Cash used in investing activities, as previously reported $ (7,204 ) Less: Purchases of restricted investments (1,433 ) Cash used in investing activities, as adjusted $ (8,637 ) Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , which requires companies leasing assets to recognize on their balance sheet a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term on contracts longer than one year. The new guidance is effective for fiscal years beginning after December 15, 2018, using a modified retrospective approach, with early adoption permitted. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842):Targeted Improvements , which includes two main provisions. The first is an additional optional transition method to adopt the new leasing standard at the adoption date through recognition of a cumulative-effect adjustment to the opening balance of retaining earnings in the period of adoption. The second provides lessors with a practical expedient, by class of underlying asset, to not separate non-lease components from the associated lease component and, instead, to account for those components as a single component, if certain criteria are met. The Partnership has established an implementation team to execute a multi-phase plan to adopt the requirements of the new standard. The team is in the process of finalizing its conclusions on how the guidance will be applied to all identified leases. The team is also evaluating the expanded disclosures required by the new standard and reviewing our system capabilities, processes and internal controls over financial reporting to ensure the appropriate information will be available for these disclosures. We will adopt the new guidance in the first quarter of 2019.

Revenue

Revenue	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue	2. REVENUE We produce and sell thermal coal primarily to large electric utility customers with coal-fired power plants, typically under long-term contracts. Our customers are generally in close proximity through mine-mouth power plants and strategically located rail and barge transportation. Lesser amounts of revenue are generated from royalties from oil and gas leases and sales of various mining byproducts. Under ASC 606, revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration we expect to receive in exchange for those goods or services. We measure revenue based on the consideration specified in the contract, and revenue is recognized when the performance obligations in the contract are satisfied. A performance obligation is a promise in a contract to transfer a distinct service to the customer. The transaction price of a contract is allocated to each distinct performance obligation and recognized as revenue when or as the customer receives the benefit of the performance obligation. For all of our coal sales contracts, performance obligations consist of the delivery of each ton of coal to the customer as our promise is to sell multiple distinct units of a commodity at a point in time. The transaction price principally consists of fixed consideration in the form of a base price per ton of coal with additional variable consideration comprised of adjustments to the base price based on quality measurements. Certain long-term contracts contain additional variable consideration comprised of various index-based adjustments, adjustments based on changes in underlying production costs and reimbursements of various costs such as royalties and taxes. Disaggregated Revenues The following table presents our revenues for the three and six months ended June 30, 2018 and 2017 disaggregated by type of revenue (in thousands): Three Months Ended June 30, Six Months Ended June 30, Type of Revenue 2018 2017 2018 2017 Coal sales $ 60,032 $ 79,817 $ 126,741 $ 152,924 Other revenues 4,263 1,234 5,361 2,932 Total $ 64,295 $ 81,051 $ 132,102 $ 155,856 Contract Balances Contract assets and contract liabilities are the result of timing differences between revenue recognition, billings and cash collections. We recognize contract assets in those instances where billing occurs subsequent to revenue recognition and our right to invoice the customer is conditioned on something other than the passage of time. There were no contract assets included in the Consolidated Balance Sheets (unaudited) as of June 30, 2018 and December 31, 2017, respectively. We recognize contract liabilities in those instances where billing occurs prior to revenue recognition, which occurs for certain contracts with tiered pricing in which the per ton contract price has exceeded per ton revenue to date, or when we have received consideration prior to satisfaction of performance obligations. The following table presents the activity in our contract liabilities for the six months ended June 30, 2018 (in thousands): Contract Liabilities (1) : Balance as of December 31, 2017 $ 3,141 Additions 1,441 Transfers to Revenues (2,545 ) Balance as of June 30, 2018 $ 2,037 _________________________ (1) Comprised entirely of current balances of $2.0 million and $3.1 million reported within Deferred revenue in the Consolidated Balance Sheets (unaudited) as of June 30, 2018 and December 31, 2017, respectively. Remaining Performance Obligations The following table presents our estimated revenues allocated to remaining performance obligations for contracted revenue that has not yet been recognized, representing our “contractually committed” revenues as of June 30, 2018 that we will invoice or transfer from contract liabilities and be recognized in future periods (in thousands): Estimated Revenues Six months ended December 31, 2018 $ 83,853 2019 73,340 2020 69,680 2021 51,727 2022 — Thereafter — Total $ 278,600 Our contractually committed revenue, for purposes of the table above, is limited to the transaction price for long-term coal sales contracts which have minimum tonnage commitments. Our contractually committed revenue amounts generally exclude, based on the following practical expedients that we elected to apply, (i) variable consideration within contracts in which such variable consideration is allocated entirely to wholly unsatisfied performance obligations; and (ii) remaining performance obligations for contracts with an original expected duration of one year or less. Additional revenues are expected to be recognized based on our short-term coal sales contracts, long-term coal sales contracts with no minimum tonnage commitments and long-term coal sales contracts with customer options in addition to minimum tonnage commitments.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Inventories	3. INVENTORIES Inventories consisted of the following: June 30, 2018 December 31, 2017 (In thousands) Coal stockpiles $ 3,539 $ 4,642 Materials and supplies 10,420 10,569 Reserve for obsolete inventory (283 ) (284 ) Total $ 13,676 $ 14,927

Restricted Investments

Restricted Investments	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Restricted Investments	4. RESTRICTED INVESTMENTS For all of its restricted investments accounts, the Partnership can select from limited fixed-income investment options for the funds and receive the investment returns on these investments. Funds in the restricted investments accounts are not available to meet the Partnership’s general cash needs. These investments include available-for-sale debt securities, which are reported at fair value with unrealized gains and losses excluded from earnings and reported in Accumulated other comprehensive income in the Consolidated Balance Sheets. The carrying value and estimated fair value of restricted investments were as follows: June 30, 2018 December 31, 2017 (In thousands) Cash and cash equivalents $ 8,036 $ 7,754 Available-for-sale debt securities 27,775 29,485 $ 35,811 $ 37,239 Available-for-Sale Debt Securities The cost basis, gross unrealized holding gains and losses and fair value of available-for-sale debt securities were as follows: June 30, 2018 December 31, 2017 (In thousands) Cost basis $ 27,859 $ 29,405 Gross unrealized holding gains 330 409 Gross unrealized holding losses (414 ) (329 ) Fair value $ 27,775 $ 29,485

Impairment Charges

Impairment Charges	6 Months Ended
	Jun. 30, 2018
Restructuring and Related Activities [Abstract]
Impairment Charges	5. LOSS ON IMPAIRMENT For the three and six months ended June 30, 2018 , the Partnership recorded an asset impairment charge to various assets in the amounts of $77.7 million in Loss on impairment in the Consolidated Statements of Operations (unaudited). The Partnership determined that indicators of impairment existed with respect to the following: • AEP Generation Resources Inc. (“AEP”) declined the Partnership’s bid to supply coal to AEP’s Conesville Power Plant Units 5 and 6 for periods subsequent to the expiration of the parties' current contract which expires on December 31, 2018. Coal sales under Oxford’s current coal supply contract to AEP’s Conesville Power Plant Units 5 and 6 represented a substantial portion of the Partnership's revenues generated from the Ohio mines for the year ended December 31, 2017. The Partnership performed a recoverability analysis as of June 30, 2018 and determined that the net undiscounted cash flows were less than the carrying values for the Ohio mines' long-lived assets groups. As a result, the Partnership estimated the fair value of the long-lived asset groups using a discounted cash flow analysis using marketplace participant assumptions which constituted Level 3 fair value inputs. The discounted cash flow analysis is dependent on a number of significant management estimates about future performance including sales volumes and prices, which are based on projected revenues based on expected economic conditions, costs to produce, capital spending, working capital changes and the weighted average cost of capital. The estimates of costs to produce include labor, fuel, explosives, supplies and other major components of mining. The Partnership estimated the fair value of certain property, plant and equipment and intangible assets using the market approach. To the extent that the carrying values of the long-lived asset groups exceeded the respective fair values, the Partnership recorded an asset impairment charge, as can be seen by asset type in the table below for the three and six months ended June 30, 2018 . Asset Impairment Charges (In thousands) Land, mineral rights, property, plant and equipment, net $ 50,717 Advanced coal royalties 3,145 Intangible assets, net of accumulated amortization of $7.2 million at June 30, 2018 23,767 Other assets 46 $ 77,675 _____________________ (1) Consists of the current portion of Advanced coal royalties.

Debt and Lines of Credit

Debt and Lines of Credit	6 Months Ended
	Jun. 30, 2018
Disclosure Text Block [Abstract]
Debt and Lines of Credit	6. DEBT AND LINES OF CREDIT Debt consisted of the following: June 30, 2018 December 31, 2017 (In thousands) Term Loan $ 315,945 $ 312,734 Capital lease obligations 11,477 13,478 Other 265 375 Total debt outstanding 327,687 326,587 Less debt issuance costs (1,392 ) (2,754 ) Less current installments, net of debt issuance costs (318,950 ) (314,228 ) Total debt outstanding, less current installments $ 7,345 $ 9,605 The following table presents remaining aggregate contractual debt maturities of all long-term debt: June 30, 2018 (In thousands) 2018 $ 318,084 2019 4,174 2020 1,766 2021 1,664 2022 1,999 Thereafter — Total debt $ 327,687 Term Loan Pursuant to the financing agreement (as amended, the “2014 Financing Agreement”), dated as of December 31, 2014, by and among Oxford Mining Company, LLC, the Partnership and each of its subsidiaries, lenders from time to time party thereto, and U.S. Bank National Association, as administrative agent, we entered into a term loan (“Term Loan”) which matures on December 31, 2018 and pays interest on a quarterly basis at a variable rate equal to the 3-month London Interbank Offered Rate (“LIBOR”) at each period end ( 2.33% as of June 30, 2018 ), subject to a floor of 0.75% , plus 8.50% or the reference rate, as defined in the 2014 Financing Agreement. As of June 30, 2018 , the Term Loan had a cash interest rate of 10.83% . The Term Loan is a primary obligation of Oxford Mining Company, LLC, a wholly owned subsidiary of the Partnership, is guaranteed by the Partnership and its subsidiaries, and is secured by substantially all of the Partnership’s and its subsidiaries’ assets. The 2014 Financing Agreement also provides for Paid-In-Kind Interest (“PIK Interest”) at a variable rate between 1.00% and 3.00% based on our consolidated total net leverage ratio, as defined in the 2014 Financing Agreement. As of June 30, 2018 and December 31, 2017 , the Term Loan had a PIK Interest rate of 3.00% . The rate of PIK Interest is recalculated on a quarterly basis with the PIK Interest added quarterly to the then-outstanding principal amount of the Term Loan. PIK Interest under the 2014 Financing Agreement was $2.4 million and $4.8 million for the three and six months ended June 30, 2018 , respectively, and $2.3 million and $4.6 million for the three and six months ended June 30, 2017 , respectively. The outstanding Term Loan amount as of June 30, 2018 represents the principal balance of $285.8 million , plus PIK Interest of $30.2 million . The 2014 Financing Agreement requires mandatory prepayment of principal with proceeds from the receipt of oil and gas royalties and asset sales. During the three and six months ended June 30, 2018 , respectively, we paid down $0.3 million and $0.8 million of the Term Loan with such proceeds. The 2014 Financing Agreement limits cumulative cash distributions to an aggregate amount not to exceed $15.0 million (“Restricted Distributions”), if we have: (i) a consolidated total net leverage ratio of greater than 3.75 , or a fixed charge coverage ratio of less than 1.00 (as such ratios are defined in the 2014 Financing Agreement), or (ii) liquidity of less than $7.5 million , after giving effect to such cash distribution and applying our availability under the Revolver. As of June 30, 2018 , our consolidated total net leverage ratio is in excess of 3.75 , our fixed charge coverage ratio is less than 1.00 and we have utilized the full $15.0 million limit on Restricted Distributions. Covenant Compliance The Partnership does not currently have liquidity or access to additional capital sufficient to pay off the Term Loan by its December 31, 2018 maturity date. This condition gives rise to substantial doubt as to the Partnership’s ability to continue as a going concern within one year after the date that these financial statements were issued. Certain affirmative covenants in our 2014 Financing Agreement provide that an audit opinion on our consolidated financial statements that includes an explanatory paragraph referencing our conclusion that substantial doubt exists as to the Partnership's ability to continue as a going concern constitutes an event of default. The audit report included in our 2017 Form 10-K contained such an explanatory paragraph. On March 1, 2018, we entered into a waiver and amendment number three to the 2014 Financing Agreement that waived any such event of default arising from the inclusion of a going concern explanatory paragraph in the audit report included in our 2017 Form 10-K. Prior to the expiration of the aforementioned waiver on May 15, 2018, we entered into a series of amendments that ultimately continued to waive any such event of default through September 8, 2018 (“Waiver”) or the occurrence of any other event of default that has not been waived as part of the Waiver. Accordingly, on expiration of the Waiver, the lenders could accelerate the maturity date of the Term Loan, making it immediately due and payable. For more detail please refer to Note 1. Basis Of Presentation "Going Concern, Liquidity and Management’s Plan." Revolver On October 23, 2015, the Partnership and its subsidiaries entered into a Loan and Security Agreement (the “Revolver”) with the lenders party thereto and Canadian Imperial Bank of Commerce (formerly known as The PrivateBank and Trust Company). The Revolver expired on its December 31, 2017 maturity date and management elected not to replace or extend it. Capital Lease Obligations The Partnership engages in leasing transactions for office equipment and equipment utilized in its mining operations. The Partnership did not enter into any new capital leases during the six months ended June 30, 2018 .

Distribution of Available Cash

Distribution of Available Cash	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Distribution of Available Cash	7. DISTRIBUTIONS OF AVAILABLE CASH Our 2014 Financing Agreement restricts us from making cash distributions in excess of $15.0 million in the aggregate when certain ratios and liquidity requirements are not met. As of June 30, 2018 , both of these ratios were not met, and we do not foresee them being met in the near future. As of June 30, 2018 , we have made $15.0 million in Restricted Distributions and, accordingly, cannot make further distributions unless we either refinance or modify our Term Loan or meet the required ratios noted in Note 6. Debt And Lines Of Credit . Pursuant to the Partnership’s Fourth Amended and Restated Agreement of Limited Partnership, as amended (the “Partnership Agreement”), we distribute 100% of our available cash within 45 days after the end of each quarter to unitholders of record and to our GP, subject to the conditions and limitations within the 2014 Financing Agreement. Available cash is determined at the end of each quarter and is generally defined in the Partnership Agreement, as all cash and cash equivalents on hand at the end of each quarter less reserves established by our GP in its reasonable discretion for future cash requirements. These reserves are retained to provide for the conduct of our business, the payment of debt principal and interest, to provide funds for future distributions for any one or more of the next four quarters, and to comply with applicable law or any loan agreement to which the Partnership or any of its subsidiaries are a party. Our available cash may also include, if our GP so determines, all or any portion of the cash on hand on the date of determination of available cash for the quarter resulting from working capital borrowings made subsequent to the end of such quarter. We made cash distributions as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Limited partner common units $ — $ 171 $ — $ 334 General partner units — 5 — 10 Warrants — 22 — 44

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	8. FAIR VALUE MEASUREMENTS Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Valuation techniques used must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy, as defined below, gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. • Level 1, defined as observable inputs such as quoted prices in active markets for identical assets. Level 1 assets include available-for-sale debt securities generally valued based on independent third-party market prices. • Level 2, 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. • Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. The book values of cash and cash equivalents, receivables and accounts payable reflected in the Consolidated Balance Sheets (unaudited) approximate the fair value of these instruments due to the short duration to their maturities. See Note 4. Restricted Investments for further disclosures related to the Partnership's fair value estimates. In connection with our refinancing in June 2013, certain of the second lien lenders and lender affiliates received warrants entitling them to purchase common units. Prior to the expiration of all outstanding warrants in June 2018, the warrants had been measured at fair value at each balance sheet date. Long-term debt fair value estimates are based on observed prices for securities with an active trading market when available (Level 2) and otherwise using discount rate estimates based on interest rates (Level 3). As of June 30, 2018 , the Partnership valued the Term Loan with Level 3 fair values. The estimated fair values of the Partnership’s debt with fixed and variable interest rates are as follows: Fixed Interest Rate Variable Interest Rate Carrying Value Fair Value Carrying Value Fair Value (In thousands) June 30, 2018 $ 11,741 $ 11,741 $ 314,554 $ 70,862 December 31, 2017 13,853 13,853 309,980 144,536

Unit-based Compensation

Unit-based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Unit-based Compensation	9. UNIT-BASED COMPENSATION Historically, we have granted employees and non-employee directors restricted common units under our Long-Term Incentive Plan (“LTIP”). However, we do not anticipate granting any units during the year ended December 31, 2018. We recognized compensation expense from unit-based arrangements as shown in the following table: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Recognition of fair value of restricted common units over the vesting period $ — $ 39 $ 52 $ 81 The unvested restricted common unit awards had an initial vesting date of March 2, 2018. However, on March 1, 2018 the grant was modified and the vesting date for all awards was extended to December 15, 2018. As all related compensation expense was recognized as of the modification date and the modification did not result in an increase in fair value of the awards, no additional expense was recognized. A summary of restricted common unit award activity for the six months ended June 30, 2018 is as follows: Units Weighted Average Grant-Date Fair Value Unamortized Compensation Expense (In thousands) Unvested balance at December 31, 2017 82,240 $ 3.04 Granted — — Vested and issued — — Unvested balance at June 30, 2018 82,240 $ 3.04 $ —

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. COMMITMENTS AND CONTINGENCIES Coal Sales Contracts We are committed under long-term contracts to sell coal that meets certain quality requirements at specified prices. Many of these prices are subject to cost pass-through or cost adjustment provisions that mitigate some risk from rising costs. Quantities sold under some of these contracts may vary from year to year within certain limits at the option of the customer or us. As of June 30, 2018 , the remaining terms of our long-term contracts range from one to eight years. Litigation There have been no material changes in our litigation since December 31, 2017 . For additional information, refer to Note 18. Commitments and Contingencie s to the consolidated financial statements of our 2017 Form 10-K. Guarantees Our GP and the Partnership guarantee certain obligations of our subsidiaries. We believe that these guarantees may result in a material liability to the guarantors, and, consequentially, have a material adverse effect on our financial position, liquidity or operations.

Partners' Capital and Convertib

Partners' Capital and Convertible Units	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Partners' Capital and Convertible Units	11. PARTNERS' CAPITAL AND CONVERTIBLE UNITS Our capital accounts are comprised of approximately 0.15% beneficial general partner interests and 99.85% limited partner interests as of June 30, 2018 . Our limited partners have limited rights of ownership as provided for under our Partnership Agreement and the right to participate in our distributions. Our GP manages our operations and participates in our distributions, including certain incentive distributions pursuant to the incentive distribution rights, which are nonvoting limited partner interests held by our GP. Pursuant to our Partnership Agreement, our GP participates in losses and distributions based on its interest. The GP’s participation in the allocation of losses and distributions is not limited and therefore, such participation can result in a deficit to its capital account. Allocation of losses and distributions, including distributions for previous transactions between entities under common control, has resulted in a deficit to certain limited partners’ capital accounts included in our Consolidated Balance Sheets (unaudited). Series A Convertible Units In connection with the Kemmerer Drop (as defined and described in Note 2. Acquisitions to the consolidated financial statements for our 2017 Form 10-K) and the issuance of the Series A Convertible Units (the "Series A Units"), the Partnership entered into an amendment (the “Amendment”) to our Partnership Agreement. The Amendment established the terms of the Series A Units and any additional Series A Units that may be issued in kind as a distribution (the “Series A PIK Units”), and provided that each Series A Unit will have the right to share in distributions from us on a pro-rata basis with the common units. All or any portion of each distribution payable in respect of the Series A Units (the “Series A Convertible Unit Distribution”) may, at our election, be paid in Series A PIK Units. To the extent any portion of the Series A Convertible Unit Distribution is paid in Series A PIK Units for any quarter, the distribution to the holders of incentive distribution rights shall be reduced by that portion of the distribution that is attributable to the payment of those Series A PIK Units, as further described in the Amendment. The Series A Units and the Series A PIK Units will convert on a one -for-one basis, at the earlier of the date on which we first make a regular quarterly cash distribution with respect to any quarter to holders of common units in an amount at least equal to $0.22 per common unit or upon a change of control. The Series A Units have the same voting rights as if they were outstanding common units and will vote together with the common units as a single class. In addition, the Series A Units are entitled to vote as a separate class on any matters that materially adversely affect the rights or preferences of the Series A Units in relation to other classes of partnership interests or as required by law. Series B Convertible Units On October 28, 2016, we issued 4,512,500 Series B Convertible Units (the “Series B Units”) to WCC in exchange for WCC’s 4,512,500 common units (the "Exchange"). Upon issuance of the Series B Units in the Exchange, WCC’s common units were canceled. The Series B Units do not share in distributions with the common units and are convertible at the option of the holder on a one -for-one basis into common units on the day after the record date for a cash distribution on the common units in which the Partnership is unable to make such a distribution without exceeding its restricted payment basket under the 2014 Financing Agreement (as defined in Note 6. Debt And Lines Of Credit ). This date occurred on November 15, 2017 and the holder of the Series B Units has not yet converted these Series B Units into common units. The Series B Units will convert automatically upon a change of control or a dissolution or liquidation of the Partnership. The Series B Units have the same voting rights as if they were outstanding common units and will vote together with the common units as a single class. In addition, the Series B Units are entitled to vote as a separate class on any matters that materially adversely affect the rights or preferences of the Series B Units in relation to other classes of partnership interests or as required by law. Concurrently with the Exchange, we entered into a second amendment to the Partnership Agreement, which established the terms of the Series B Units. Liquidation Units The liquidation units have no distribution or voting rights, other than in connection with liquidation. For tax purposes, liquidation units are allocated additional taxable income but no additional taxable loss compared to other unit classes. Warrants In June 2013, in connection with a prior credit facility, certain lenders and lender affiliates received warrants entitling them to purchase 166,557 common units at $0.12 per unit. The warrants participated in distributions whether or not exercised. All outstanding warrants expired in June 2018. Net Income (Loss) Attributable to Limited Partner Common Units Net income (loss) is allocated to the limited partner units, Series A Units, Series B Units and general partner units in accordance with their respective ownership percentages, after giving effect to distributions and declared distributions on Series A Units, warrants and general partner units, including incentive distribution rights. Basic and diluted limited partners’ net income (loss) per limited partner common unit is calculated by dividing limited partners’ interest in net income (loss) by the weighted average number of limited partner common units outstanding during the period. We determined basic and diluted limited partners’ net loss per limited partner common unit as follows (in thousands, except per unit amounts): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net loss attributable to the Partnership $ (93,759 ) $ (2,352 ) $ (106,637 ) $ (11,167 ) Less: Paid and declared distributions on Series A convertible units — 2,200 — 4,362 Series A convertible units share of undistributed loss (69,864 ) (3,504 ) (79,463 ) (11,726 ) Series B convertible units share of undistributed loss (18,490 ) (964 ) (21,029 ) (3,265 ) Paid and declared distributions on general partner units — 5 — 10 General partner units share of undistributed loss (140 ) (8 ) (158 ) (26 ) Paid and declared distributions on warrants — 22 — 44 Undistributed net loss attributable to limited partners $ (5,265 ) $ (103 ) $ (5,987 ) $ (566 ) Weighted average number of limited partner common units outstanding used in computation of limited partners' net loss per common unit (basic and diluted) 1,285 1,285 1,285 1,264 Net loss per limited partner common unit, basic and diluted $ (4.10 ) $ (0.08 ) $ (4.66 ) $ (0.45 )

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (loss)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	12. ACCUMULATED OTHER COMPREHENSIVE INCOME The following table reflects the changes in accumulated other comprehensive income by component: Accumulated Other Comprehensive Income (In thousands) Balance at December 31, 2017 $ 80 Other comprehensive loss before reclassification (271 ) Amounts reclassified from accumulated other comprehensive income 107 Balance at June 30, 2018 $ (84 ) The following table reflects the reclassifications out of accumulated other comprehensive income for the three and six months ended June 30, 2018 : Amount Reclassified From Accumulated Other Comprehensive Income Details About Accumulated Other Comprehensive Income Components Three Months Ended June 30, 2018 Six Months Ended June 30, 2018 Affected Line Item in the Statement Where Net Loss is Presented (In thousands) Realized gains on available-for-sale debt securities $ 16 $ 107 Other income

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	13. RELATED PARTY TRANSACTIONS The Board of the GP and its Conflicts Committee review our related party transactions that involve a potential conflict of interest between a general partner and WMLP or its subsidiaries or another partner to determine that such transactions reflect market-clearing terms and conditions customary in the coal industry. As a result of these reviews, the Board and the Conflicts Committee approved each of the transactions described below that had such potential conflict of interest as fair and reasonable to us and our limited partners. Effective January 1, 2015, the Partnership and the GP, which is a wholly owned subsidiary of WCC, entered into an administrative and operational services agreement (the “Services Agreement”). The Services Agreement is terminable by either party upon 120 days’ written notice. The current term of the Services Agreement expires on June 1, 2018, and automatically renews for successive one -year periods unless terminated earlier upon 120-days’ written notice. On January 31, 2018, we received a letter from WCC providing 120 days’ written notice that it was reserving its rights with respect to its continued provision of services to the GP under the Services Agreement, noting that WCC would “continue to pursue value-maximizing transactions for all relevant stakeholders” and noting that WCC would be willing to continue to provide services to the GP and us under certain circumstances. On February 22, 2018, we responded to that letter questioning whether a valid notice of termination of the Services Agreement was provided, addressing the continued deployment of the mine-related employees, noting our intention to seek alternative service providers and preserving our options with respect to the ongoing negotiations over WCC’s provisions of services to the GP and us under the Services Agreement. As previously disclosed in our Quarterly Report on Form 10-Q for the three months ended March 31, 2018, if an agreement with respect to the continued provision of such services had not been reached with WCC by June 1, 2018, we could have initiated a legal dispute with WCC regarding whether the January 31, 2018 reservation of rights letter constituted a valid termination notice under the Services Agreement. As of the date of this filing, no legal dispute has arisen and the parties remain in constructive discussions with respect to WCC’s continued provision of administrative and operational services to us. Under the terms of the Services Agreement, the GP provides services through its, or an affiliate's, employees and is reimbursed for all related costs incurred on our behalf. Pursuant to the Services Agreement, the Partnership engaged the GP to continue providing services such as general administrative and management, engineering, operations (including mining operations), geological, corporate development, real property, marketing, and other services to the Partnership. Administrative services include without limitation legal, finance and accounting, treasury, insurance administration and claims processing, risk management, health, safety and environmental, information technology, human resources, credit, payroll, internal audit and tax. During the three and six months ended June 30, 2018 , respectively, we paid the GP approximately $16.2 million and $34.7 million , respectively, for these services performed under the Services Agreement primarily related to employee costs. Further, under the Services Agreement, the Partnership pays the GP a fixed annual management fee of $2.2 million for certain executive and administrative services, and reimburses the GP at cost for other expenses and expenditures. This fixed annual management fee has not been prepaid and is currently being expensed as incurred. Expense related to this annual management fee, included in Selling and administrative in the Consolidated Statements of Operations (unaudited), was $0.5 million and $1.1 million for the three and six months ended June 30, 2018 and 2017 , respectively. Pursuant to the Services Agreement, the primary reimbursements to our GP were for costs related to payroll. Reimbursable costs under the Services Agreement totaling $2.1 million and $1.3 million were included in accounts payable as of June 30, 2018 and December 31, 2017 , respectively. On January 9, 2017, the Partnership acquired surface coal reserves (“Johnson Run”) through conveyance of leases and recoupable advance royalty payments from Buckingham Coal Company, LLC, ("BCC") a wholly owned subsidiary of WCC, for $1.7 million , of which $1.5 million was deemed a distribution as the transaction was between entities under common control. During the three and six months ended June 30, 2017 , respectively, we sold coal to a subsidiary of WCC, which generated $8.3 million and $12.1 million in revenues. No such coal sales occurred during the three months and six months ended June 30, 2018 . Further, as of December 31, 2017 , accounts receivable related to the coal sales to the subsidiary of WCC totaled $3.8 million and were included in Receivables in the Consolidated Balance Sheet (unaudited) for that period. No accounts receivable related to these revenues was outstanding as of June 30, 2018 .

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Information	14. SEGMENT INFORMATION We operate in one business segment. We operate surface coal mines in Ohio and Wyoming, selling thermal coal to utilities, industrial customers, municipalities and other coal-related entities primarily in the Midwest and Wyoming. All of our operations have similar economic characteristics including but not limited to coal quality, geology, coal marketing opportunities, mining and transportation methods and regulatory issues. Our operating and executive management makes its decisions based on consolidated reports. Our Ohio operating subsidiaries share customers and a particular customer may receive coal from any one of such Ohio operating subsidiaries. We also lease or sublease coal reserves to others through our Ohio Operations in exchange for a per ton royalty rate.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	15. SUBSEQUENT EVENTS The Partnership has evaluated subsequent events in accordance with ASC 855, Subsequent Events , through the filing date of this Quarterly Report, and determined that no events have occurred that have not been disclosed elsewhere in the notes to the consolidated financial statements (unaudited) that would require adjustments to disclosures in the consolidated financial statements (unaudited).

Basis of Presentation (Policies

Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers (Topic 606) (“new revenue standard”), which supersedes all previously existing revenue recognition guidance. Under this guidance, an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard allows for initial application to be performed retrospectively to each period presented or as a cumulative effect adjustment as of the date of adoption. During 2016, the FASB clarified the implementation guidance on principal versus agent, identifying performance obligations and licensing, practical expedients, and made technical corrections on various topics. The Partnership adopted the new revenue standard effective January 1, 2018 using the full retrospective method. The adoption of this standard did not have a material impact to the Partnership's consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“new cash flows standard”), which requires all entities that have restricted cash or restricted cash equivalents to explain the changes during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents in the Consolidated Statements of Cash Flows. As a result, amounts generally described as restricted cash and restricted cash equivalents that are included in other financial statement captions of the Consolidated Balance Sheets should be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts shown on the Consolidated Statements of Cash Flows. The ASU should be adopted using a retrospective transition method to each period presented. The Partnership adopted the new cash flows standard effective January 1, 2018 and applied the ASU retrospectively to the periods presented in the Partnership’s Consolidated Statements of Cash Flows (unaudited). As a result, net cash used in investing activities for the six months ended June 30, 2017 was adjusted to exclude the change in restricted cash as follows: Six Months Ended June 30, 2017 (In thousands) Cash used in investing activities, as previously reported $ (7,204 ) Less: Purchases of restricted investments (1,433 ) Cash used in investing activities, as adjusted $ (8,637 ) Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , which requires companies leasing assets to recognize on their balance sheet a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term on contracts longer than one year. The new guidance is effective for fiscal years beginning after December 15, 2018, using a modified retrospective approach, with early adoption permitted.

Basis of Presentation Basis of

Basis of Presentation Basis of Presentation (Tables)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of New Accounting Pronouncements	As a result, net cash used in investing activities for the six months ended June 30, 2017 was adjusted to exclude the change in restricted cash as follows: Six Months Ended June 30, 2017 (In thousands) Cash used in investing activities, as previously reported $ (7,204 ) Less: Purchases of restricted investments (1,433 ) Cash used in investing activities, as adjusted $ (8,637 )

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table presents our revenues for the three and six months ended June 30, 2018 and 2017 disaggregated by type of revenue (in thousands): Three Months Ended June 30, Six Months Ended June 30, Type of Revenue 2018 2017 2018 2017 Coal sales $ 60,032 $ 79,817 $ 126,741 $ 152,924 Other revenues 4,263 1,234 5,361 2,932 Total $ 64,295 $ 81,051 $ 132,102 $ 155,856
Activity in Contract Liabilities	The following table presents the activity in our contract liabilities for the six months ended June 30, 2018 (in thousands): Contract Liabilities (1) : Balance as of December 31, 2017 $ 3,141 Additions 1,441 Transfers to Revenues (2,545 ) Balance as of June 30, 2018 $ 2,037 _________________________ (1) Comprised entirely of current balances of $2.0 million and $3.1 million reported within Deferred revenue in the Consolidated Balance Sheets (unaudited) as of June 30, 2018 and December 31, 2017, respectively.
Remaining Performance Obligations	The following table presents our estimated revenues allocated to remaining performance obligations for contracted revenue that has not yet been recognized, representing our “contractually committed” revenues as of June 30, 2018 that we will invoice or transfer from contract liabilities and be recognized in future periods (in thousands): Estimated Revenues Six months ended December 31, 2018 $ 83,853 2019 73,340 2020 69,680 2021 51,727 2022 — Thereafter — Total $ 278,600

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consisted of the following: June 30, 2018 December 31, 2017 (In thousands) Coal stockpiles $ 3,539 $ 4,642 Materials and supplies 10,420 10,569 Reserve for obsolete inventory (283 ) (284 ) Total $ 13,676 $ 14,927

Restricted Investments (Tables)

Restricted Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Carrying Value and Fair Value of Restricted Investments	The carrying value and estimated fair value of restricted investments were as follows: June 30, 2018 December 31, 2017 (In thousands) Cash and cash equivalents $ 8,036 $ 7,754 Available-for-sale debt securities 27,775 29,485 $ 35,811 $ 37,239
Summary of Cost, Unrealized Gains and Losses, and Fair Value	The cost basis, gross unrealized holding gains and losses and fair value of available-for-sale debt securities were as follows: June 30, 2018 December 31, 2017 (In thousands) Cost basis $ 27,859 $ 29,405 Gross unrealized holding gains 330 409 Gross unrealized holding losses (414 ) (329 ) Fair value $ 27,775 $ 29,485

Impairment Charges (Tables)

Impairment Charges (Tables)	6 Months Ended
	Jun. 30, 2018
Restructuring and Related Activities [Abstract]
Asset Impairment Charges	To the extent that the carrying values of the long-lived asset groups exceeded the respective fair values, the Partnership recorded an asset impairment charge, as can be seen by asset type in the table below for the three and six months ended June 30, 2018 . Asset Impairment Charges (In thousands) Land, mineral rights, property, plant and equipment, net $ 50,717 Advanced coal royalties 3,145 Intangible assets, net of accumulated amortization of $7.2 million at June 30, 2018 23,767 Other assets 46 $ 77,675 _____________________ (1) Consists of the current portion of Advanced coal royalties.

Debt and Lines of Credit (Table

Debt and Lines of Credit (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure Text Block [Abstract]
Schedule of Long-Term Debt	Debt consisted of the following: June 30, 2018 December 31, 2017 (In thousands) Term Loan $ 315,945 $ 312,734 Capital lease obligations 11,477 13,478 Other 265 375 Total debt outstanding 327,687 326,587 Less debt issuance costs (1,392 ) (2,754 ) Less current installments, net of debt issuance costs (318,950 ) (314,228 ) Total debt outstanding, less current installments $ 7,345 $ 9,605
Schedule of Maturities of Long-term Debt	The following table presents remaining aggregate contractual debt maturities of all long-term debt: June 30, 2018 (In thousands) 2018 $ 318,084 2019 4,174 2020 1,766 2021 1,664 2022 1,999 Thereafter — Total debt $ 327,687

Distribution of Available Cash

Distribution of Available Cash Distribution of Available Cash (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Distribution of Available Cash	We made cash distributions as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Limited partner common units $ — $ 171 $ — $ 334 General partner units — 5 — 10 Warrants — 22 — 44

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments	The estimated fair values of the Partnership’s debt with fixed and variable interest rates are as follows: Fixed Interest Rate Variable Interest Rate Carrying Value Fair Value Carrying Value Fair Value (In thousands) June 30, 2018 $ 11,741 $ 11,741 $ 314,554 $ 70,862 December 31, 2017 13,853 13,853 309,980 144,536

Unit-based Compensation (Tables

Unit-based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Recognized Compensation Expense	We recognized compensation expense from unit-based arrangements as shown in the following table: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Recognition of fair value of restricted common units over the vesting period $ — $ 39 $ 52 $ 81
Summary of Restricted Common Unit Award Activity	A summary of restricted common unit award activity for the six months ended June 30, 2018 is as follows: Units Weighted Average Grant-Date Fair Value Unamortized Compensation Expense (In thousands) Unvested balance at December 31, 2017 82,240 $ 3.04 Granted — — Vested and issued — — Unvested balance at June 30, 2018 82,240 $ 3.04 $ —

Partners' Capital and Convert32

Partners' Capital and Convertible Units (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings (Losses) per Unit	We determined basic and diluted limited partners’ net loss per limited partner common unit as follows (in thousands, except per unit amounts): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net loss attributable to the Partnership $ (93,759 ) $ (2,352 ) $ (106,637 ) $ (11,167 ) Less: Paid and declared distributions on Series A convertible units — 2,200 — 4,362 Series A convertible units share of undistributed loss (69,864 ) (3,504 ) (79,463 ) (11,726 ) Series B convertible units share of undistributed loss (18,490 ) (964 ) (21,029 ) (3,265 ) Paid and declared distributions on general partner units — 5 — 10 General partner units share of undistributed loss (140 ) (8 ) (158 ) (26 ) Paid and declared distributions on warrants — 22 — 44 Undistributed net loss attributable to limited partners $ (5,265 ) $ (103 ) $ (5,987 ) $ (566 ) Weighted average number of limited partner common units outstanding used in computation of limited partners' net loss per common unit (basic and diluted) 1,285 1,285 1,285 1,264 Net loss per limited partner common unit, basic and diluted $ (4.10 ) $ (0.08 ) $ (4.66 ) $ (0.45 )

Accumulated Other Comprehensi33

Accumulated Other Comprehensive Income (loss) (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Income (Loss)	The following table reflects the changes in accumulated other comprehensive income by component: Accumulated Other Comprehensive Income (In thousands) Balance at December 31, 2017 $ 80 Other comprehensive loss before reclassification (271 ) Amounts reclassified from accumulated other comprehensive income 107 Balance at June 30, 2018 $ (84 )
Reclassifications out of Accumulated Other Comprehensive Income (Loss)	The following table reflects the reclassifications out of accumulated other comprehensive income for the three and six months ended June 30, 2018 : Amount Reclassified From Accumulated Other Comprehensive Income Details About Accumulated Other Comprehensive Income Components Three Months Ended June 30, 2018 Six Months Ended June 30, 2018 Affected Line Item in the Statement Where Net Loss is Presented (In thousands) Realized gains on available-for-sale debt securities $ 16 $ 107 Other income

Basis o Presentation (Details)

Basis o Presentation (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Current installments of long-term debt	$ 318,950		$ 314,228
Net Cash Provided by (Used in) Investing Activities	(1,105)	$ (8,637)
Purchases of restricted investments	(4,395)	(8,854)
Term Loan [Member]
Debt Instrument [Line Items]
Current installments of long-term debt	$ 315,945
As Previously Reported [Member]
Debt Instrument [Line Items]
Net Cash Provided by (Used in) Investing Activities		(7,204)
Accounting Standards Update 2016-18 [Member]
Debt Instrument [Line Items]
Purchases of restricted investments		$ (1,433)

Revenue - Disaggregated Revenue

Revenue - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total	$ 64,295	$ 81,051	$ 132,102	$ 155,856
Coal sales [Member]
Disaggregation of Revenue [Line Items]
Revenue, Coal Services	60,032	79,817	126,741	152,924
Other revenues [Member]
Disaggregation of Revenue [Line Items]
Sales Revenue, Services, Other	$ 4,263	$ 1,234	$ 5,361	$ 2,932

Revenue - Activity in Contract

Revenue - Activity in Contract Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Movement in Deferred Revenue [Roll Forward]
Balance as of December 31, 2017	$ 3,141
Additions	1,441
Transfers to Revenues	(2,545)
June 30, 2018	2,037
Deferred revenue	$ 2,037	$ 3,141

Revenue - Remaining Performance

Revenue - Remaining Performance Obligations (Details) $ in Thousands	Jun. 30, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 83,853
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	73,340
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	69,680
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	51,727
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 278,600

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Coal stockpiles	$ 3,539	$ 4,642
Materials and supplies	10,420	10,569
Reserve for obsolete inventory	(283)	(284)
Total	$ 13,676	$ 14,927

Restricted Investments - Carryi

Restricted Investments - Carrying Value and Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 8,036		$ 7,148
Available-for-sale debt securities	27,775	$ 29,485
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	8,036	7,754
Available-for-sale debt securities	27,775	29,485
Restricted Cash and Investments	$ 35,811	$ 37,239

Restricted Investments - Value

Restricted Investments - Value of Available for Sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Cost basis	$ 27,859	$ 29,405
Gross unrealized holding gains	330	409
Gross unrealized holding losses	(414)	(329)
Available-for-sale debt securities	$ 27,775	$ 29,485

Impairment Charges (Details)

Impairment Charges (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Concentration Risk [Line Items]
Loss on impairment	$ 77,675,000	$ 0	$ 77,675,000	$ 0
Accumulated amortization					$ 6,200,000
Land, Mineral Rights, Property, Plant and Equipment, Net [Member]
Concentration Risk [Line Items]
Loss on impairment			50,717,000
Advanced Coal Royalties [Member]
Concentration Risk [Line Items]
Loss on impairment			3,145,000
Intangible assets, net of accumulated amortization of $7.2 million at June 30, 2018 [Member]
Concentration Risk [Line Items]
Loss on impairment			23,767,000
Other Assets [Member]
Concentration Risk [Line Items]
Loss on impairment			$ 46,000

Debt and Lines of Credit - Sche

Debt and Lines of Credit - Schedule (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt	$ 327,687	$ 326,587
Less debt issuance costs	(1,392)	(2,754)
Less current installments, net of debt issuance costs	(318,950)	(314,228)
Total debt outstanding, less current installments	7,345	9,605
Capital lease obligations [Member]
Debt Instrument [Line Items]
Long-term debt	11,477	13,478
Other [Member]
Debt Instrument [Line Items]
Long-term debt	265	375
Term Loan [Member]
Debt Instrument [Line Items]
Long-term debt		$ 312,734
Less current installments, net of debt issuance costs	$ (315,945)

Debt and Lines of Credit - Debt

Debt and Lines of Credit - Debt Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Maturities of Long-term Debt [Abstract]
2,018	$ 318,084
2,019	4,174
2,020	1,766
2,021	1,664
2,022	1,999
Thereafter	0
Long-term Debt	$ 327,687	$ 326,587

Debt and Lines of Credit - Cred

Debt and Lines of Credit - Credit Facilities (Details)	Dec. 31, 2014	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)	Jul. 31, 2015USD ($)
Line of Credit Facility [Line Items]
Principal balance		$ 327,687,000		$ 327,687,000		$ 326,587,000
Repayments of debt				$ 3,845,000	$ 2,620,000
Term Loan [Member]
Line of Credit Facility [Line Items]
Principal balance						$ 312,734,000
Financing Agreement 2014 [Member]
Line of Credit Facility [Line Items]
Maximum capacity to make distributions							$ 15,000,000
Consolidated Total Net Leverage ratio (more than)		3.75		3.75			3.75
Fixed Charge Coverage ratio (less than)		1		1			1
Minimum liquidity requirement							$ 7,500,000
Financing Agreement 2014 [Member] | Secured Debt [Member]
Line of Credit Facility [Line Items]
Interest rate, effective percentage		10.83%		10.83%
Fixed portion of the effective rate				8.50%
PIK interest rate		3.00%		3.00%		3.00%
Paid-in-kind interest		$ 2,400,000	$ 2,300,000	$ 4,800,000	4,600,000
Principal balance		285,800,000		285,800,000
PIK interest payable		$ 30,200,000		$ 30,200,000
Financing Agreement 2014 [Member] | Secured Debt [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate, paid-in-kind	1.00%
Financing Agreement 2014 [Member] | Secured Debt [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate, paid-in-kind	3.00%
Financing Agreement 2014 [Member] | Secured Debt [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Interest rate, effective percentage		2.33%		2.33%
Basis spread on variable rate				0.75%
First Lien Financing Agreement [Member] | Term Loan [Member]
Line of Credit Facility [Line Items]
Repayments of debt		$ 300,000			$ 800,000
2014 Financing Agreement and Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Payments of capital distribution				$ 15,000,000

Distribution of Available Cas45

Distribution of Available Cash (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Class of Stock [Line Items]
Distribution of available cash (percent)			100.00%
Post-quarter period for distribution of available cash			45 days
Warrant [Member]
Class of Stock [Line Items]
Quarterly distribution to unit holders	$ 0	$ 22	$ 0	$ 44
Limited Partner [Member] | Common units [Member]
Class of Stock [Line Items]
Quarterly distribution to unit holders	0	171	0	334
General Partner [Member]
Class of Stock [Line Items]
Quarterly distribution to unit holders	0	$ 5	0	$ 10
2014 Financing Agreement and Revolving Credit Facility [Member]
Class of Stock [Line Items]
Debt covenant, cash distribution limit when certain ratios and liquidity requirements are not met	$ 15,000
Payments of capital distribution			$ 15,000

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Value and Fair Value of Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fixed-rate debt, carrying value	$ 11,741	$ 13,853
Fixed-rate debt, fair value	11,741	13,853
Variable-rate debt, carrying value	314,554	309,980
Variable-rate debt, fair value	$ 70,862	$ 144,536

Unit-based Compensation - Sched

Unit-based Compensation - Schedule of Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognition of fair value of restricted common units over the vesting period	$ 0	$ 39	$ 52	$ 81

Unit-based Compensation - Summa

Unit-based Compensation - Summary of Restricted Common Units (Details) - Restricted Stock Units (RSUs) [Member] $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested at the beginning of the period (in units) | shares	82,240
Granted (in units) | shares	0
Vested (in units) | shares	0
Non-vested at the end of the period (in units) | shares	82,240
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Non-vested at the beginning of the period (in dollars per unit) | $ / shares	$ 3.04
Granted (in dollars per unit) | $ / shares	0
Vested (in dollars per unit) | $ / shares	0
Non-vested at the end of the period (in dollars per unit) | $ / shares	$ 3.04
Unamortized Compensation Expense (In thousands) | $	$ 0

Commitments and Contingencies (

Commitments and Contingencies (Details)	6 Months Ended
	Jun. 30, 2018
Minimum [Member]
Loss Contingencies [Line Items]
Remaining terms of long-term contract	1 year
Maximum [Member]
Loss Contingencies [Line Items]
Remaining terms of long-term contract	8 years

Partners' Capital and Convert50

Partners' Capital and Convertible Units - Additional Information (Details)	6 Months Ended
	Jun. 30, 2018$ / sharesshares	Oct. 28, 2016shares
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
General partner interest (percent)	0.15%
Limited partner interest (percent)	99.85%
Liquidation units	166,557
Series A Convertible Units [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Partnership unit, conversion ratio into common units	1
Minimum quarterly distribution, amount per common unit (in USD per unit) | $ / shares	$ 0.22
Series B Convertible Units [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Partnership unit, conversion ratio into common units	1
Partnership units issued to WCC (in units)		4,512,500
Common units [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Limited partnership units converted (in units)		4,512,500
Warrant [Member] | Fair Value, Inputs, Level 1 [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Fair value assumption, exercise price per unit | $ / shares	$ 0.12

Partners' Capital and Convert51

Partners' Capital and Convertible Units - Computation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Preferred Units [Line Items]
Net loss attributable to the Partnership	$ (93,759)	$ (2,352)	$ (106,637)	$ (11,167)
Paid and declared distributions on Series A convertible units	0	2,200	0	4,362
Series A convertible units share of undistributed loss	69,864	3,504	79,463	11,726
Series B convertible units share of undistributed loss	(18,490)	(964)	(21,029)	(3,265)
Paid and declared distributions on general partner units	0	5	0	10
General partner units share of undistributed loss	(140)	(8)	(158)	(26)
Paid and declared distributions on Series B convertible units	0	22	0	44
Undistributed net loss attributable to limited partners	$ (5,265)	$ (103)	$ (5,987)	$ (566)
Common units [Member]
Preferred Units [Line Items]
Weighted average units outstanding basic and diluted (in units)	1,285	1,285	1,285	1,264
Limited Partners' net loss per common unit (basic and diluted) (in dollars per share)	$ (4.10)	$ (0.08)	$ (4.66)	$ (0.45)

Accumulated Other Comprehensi52

Accumulated Other Comprehensive Income (loss) - Changes by Components (Details) - Accumulated Other Comprehensive Income (Loss) [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 80
Other comprehensive loss before reclassification	(271)
Amounts reclassified from accumulated other comprehensive income	107
Ending balance	$ (84)

Accumulated Other Comprehensi53

Accumulated Other Comprehensive Income (loss) - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income	$ (11,286)	$ (9,987)	$ (22,168)	$ (20,085)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income	$ 16		$ 107

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	Jan. 09, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Notice period for terminating service agreement				120 days
Automatic renewal of service agreement, renewal term				1 year
Administrative fees		$ 16,200		$ 34,700
Annual management fee expense		2,200
Management fee expense		500	$ 500	1,100	$ 1,100
Accounts payable, related parties, current		2,100		2,100		$ 1,300
Acquisition of coal reserves				0	1,526
Payments of distribution to entity under common control				0	388
Buckingham Coal Company, LLC [Member]
Related Party Transaction [Line Items]
Acquisition of coal reserves	$ 1,700
Payments of distribution to entity under common control	$ 1,500
Subsidiary of Common Parent [Member] | Coal Revenue [Member]
Related Party Transaction [Line Items]
Revenue from related parties		0	$ 8,300	0	$ 12,100
Receivables - Trade [Member]
Related Party Transaction [Line Items]
Accounts receivable, related parties		$ 0		$ 0		$ 3,800

Segment Information (Details)

Segment Information (Details)	6 Months Ended
	Jun. 30, 2018segment
Segment Reporting [Abstract]
Number of operating segments	1