Natural Resource Partners (NRP) 10-Q 9 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 06, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Period End Date	Jun. 30, 2018
Document Fiscal Period Focus	Q2
Trading Symbol	NRP
Entity Registrant Name	NATURAL RESOURCE PARTNERS LP
Entity Central Index Key	1,171,486
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		12,245,920

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 52,975	$ 29,827
Accounts receivable, net	59,312	47,026
Accounts receivable—affiliates	140	161
Inventory	8,048	7,553
Prepaid expenses and other	4,391	5,838
Current assets of discontinued operations	988	991
Total current assets	125,854	91,396
Land	24,809	25,247
Plant and equipment, net	47,917	46,170
Mineral rights, net	873,716	883,885
Intangible assets, net	47,924	49,554
Equity in unconsolidated investment	245,524	245,433
Long-term contracts receivable	39,878	40,776
Other assets	6,184	6,547
Other assets—affiliate	0	156
Total assets	1,411,806	1,389,164
Current liabilities:
Accounts payable	7,801	6,957
Accounts payable—affiliates	1,453	562
Accrued liabilities	12,848	16,890
Accrued liabilities—affiliates	0	515
Accrued interest	14,609	15,484
Current portion of deferred revenue	2,732	0
Current portion of long-term debt, net	75,188	79,740
Current liabilities of discontinued operations	0	401
Total current liabilities	114,631	120,549
Deferred revenue	17,136	100,605
Long-term debt, net	723,147	729,608
Other non-current liabilities	2,385	2,808
Other non-current liabilities—affiliate	0	346
Total liabilities	857,299	953,916
Commitments and contingencies	0	0
Class A Convertible Preferred Units (250,000 and 258,844 units issued and outstanding at June 30, 2018 and December 31, 2017, respectively, at $1,000 par value per unit; liquidation preference of $1,500 per unit)	164,587	173,431
Partners’ capital:
Common unitholders’ interest (12,245,920 and 12,232,006 units issued and outstanding at June 30, 2018 and December 31, 2017, respectively)	326,125	199,851
General partner’s interest	4,427	1,857
Warrant holders’ interest	66,816	66,816
Accumulated other comprehensive loss	(4,872)	(3,313)
Total partners’ capital	392,496	265,211
Non-controlling interest	(2,576)	(3,394)
Total capital	389,920	261,817
Total liabilities and capital	$ 1,411,806	$ 1,389,164

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common units outstanding (in shares)	12,245,920	12,232,006
Common units issued (in shares)	12,245,920	12,232,006
Preferred Units, Issued	250,000	258,844
Preferred units outstanding (in shares)	250,000	258,844
Preferred unit par value per unit	$ 1,000	$ 1,000
Preferred unit liquidation preference per unit	$ 1,500	$ 1,500

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Revenues and other income
Revenues and other income	$ 110,839	$ 91,570	$ 199,205		$ 180,223
Gain on asset sales, net	210	3,361	870		3,405
Total revenues and other income	111,049	94,931	200,075		183,628
Operating expenses
Operating and maintenance expenses	38,301	31,020	68,269		60,648
Operating and maintenance expenses—affiliates	4,065	2,219	6,530		4,774
Depreciation, depletion and amortization	8,563	8,165	16,520		17,889
Amortization expense—affiliate	0	240	0		1,008
General and administrative	2,414	2,031	5,819		8,109
General and administrative—affiliates	849	852	1,780		1,976
Asset impairments	0	0	242		1,778
Total operating expenses	54,192	44,527	99,160		96,182
Income from operations	56,857	50,404	100,915		87,446
Other income (expense)
Interest expense, net	(17,734)	(20,308)	(35,704)		(43,432)
Debt modification expense	0	(132)	0		(7,939)
Loss on extinguishment of debt	0	(4,107)	0		(4,107)
Other expense, net	(17,734)	(24,547)	(35,704)		(55,478)
Net income from continuing operations	39,123	25,857	65,211		31,968
Income (loss) from discontinued operations	(34)	133	(48)		(74)
Net income	39,089	25,990	65,163	[1]	31,894
Less: net income attributable to non-controlling interest	869	0	869		0
Net income attributable to NRP	38,220	25,990	64,294		31,894
Income attributable to preferred unitholders	(7,500)	(7,538)	(15,000)		(10,038)
Net income attributable to common unitholders and general partner	30,720	18,452	49,294		21,856
Net income attributable to common unitholders	30,105	18,015	48,308		21,419
Net income attributable to the general partner	$ 615	$ 437	$ 986		$ 437
Income from continuing operations per common unit
Basic (in dollars per share)	$ 2.46	$ 1.46	$ 3.95		$ 1.76
Diluted (in dollars per share)	1.75	1.13	2.96		1.64
Net income per common unit
Basic (in dollars per share)	2.46	1.47	3.95		1.75
Diluted (in dollars per share)	$ 1.75	$ 1.13	$ 2.95		$ 1.64
Add: comprehensive loss from unconsolidated investment and other	$ (434)	$ (13)	$ (1,559)		$ (1,145)
Comprehensive income	38,655	25,977	63,604		30,749
Less: comprehensive income attributable to non-controlling interest	869	0	869		0
Comprehensive income attributable to NRP	37,786	25,977	62,735		30,749
Coal Royalty and Other
Revenues and other income
Revenues and other income	48,711	32,768	94,684		67,762
Coal royalty and other—affiliates	188	11,338	425		22,843
Construction Aggregates
Revenues and other income
Revenues and other income	34,233	27,363	60,657		52,846
Soda Ash
Revenues and other income
Revenues and other income	16,529	8,389	26,150		18,683
Transportation and processing services revenue | Coal Royalty and Other
Revenues and other income
Revenues and other income	5,002	4,146	10,385		4,146
Transportation and Processing - Affiliates | Coal Royalty and Other
Revenues and other income
Coal royalty and other—affiliates	0	1,374	0		6,013
Road construction and asphalt paving services | Construction Aggregates
Revenues and other income
Revenues and other income	$ 6,176	$ 6,192	$ 6,904		$ 7,930
[1]	Net income includes $15.0 million attributable to Preferred Unitholders that accumulated during the period, of which $14.7 million is allocated to the common unitholders and $0.3 million is allocated to the general partner.

Consolidated Statements of Part

Consolidated Statements of Partners' Capital - 6 months ended Jun. 30, 2018 - USD ($) shares in Thousands, $ in Thousands	Total		General Partner		Common Unitholders		Warrant Holders	Accumulated Other Comprehensive Income (Loss)	Partners Capital Excluding Noncontrolling Interest		Non-Controlling Interest	Common unitholders	Common unitholdersCommon Unitholders	General Partner	General PartnerGeneral Partner	Common unitholders and general partner	Common unitholders and general partnerPartners Capital Excluding Noncontrolling Interest	Preferred Partner	Preferred PartnerGeneral Partner	Preferred PartnerCommon Unitholders	Preferred PartnerPartners Capital Excluding Noncontrolling Interest
Balance, beginning of period (in shares) at Dec. 31, 2017					12,232
Balance, beginning of period at Dec. 31, 2017	$ 261,817		$ 1,857		$ 199,851		$ 66,816	$ (3,313)	$ 265,211		$ (3,394)
Net income	65,163	[1]	1,286	[1]	$ 63,008	[1]			64,294	[1]	869
Distributions to unitholders													$ (11,015)		$ (225)	$ (11,240)	$ (11,240)	$ (15,265)	$ (305)	$ (14,960)	$ (15,265)
Issuance of unit-based awards (units)					14
Issuance of unit-based awards	410				$ 410				410
Unit-based awards amortization and vesting	333				333				333
Comprehensive loss from unconsolidated investment and other	(1,551)		9		$ 50			(1,559)	(1,500)		(51)
Balance, end of period (in shares) at Jun. 30, 2018					12,246
Balance, end of period at Jun. 30, 2018	389,920		$ 4,427		$ 326,125		$ 66,816	$ (4,872)	$ 392,496		$ (2,576)
Income attributable to preferred unitholders	$ 15,000											$ 14,700		$ 300
[1]	Net income includes $15.0 million attributable to Preferred Unitholders that accumulated during the period, of which $14.7 million is allocated to the common unitholders and $0.3 million is allocated to the general partner.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017
Net income	$ 65,163	[1]	$ 31,894
Adjustments to reconcile net income to net cash provided by operating activities of continuing operations:
Depreciation, depletion and amortization	16,520		17,889
Amortization expense—affiliate	0		1,008
Distributions from unconsolidated investment	22,403		22,112
Equity earnings from unconsolidated investment	(26,150)		(18,683)
Gain on asset sales, net	(870)		(3,405)
Debt modification expense	0		7,939
Loss on extinguishment of debt	0		(4,107)
Loss from discontinued operations	48		74
Asset impairments	242		1,778
Unit-based compensation expense	1,073		3
Amortization of debt issuance costs and other	1,973		3,344
Other—affiliates	(190)		(1,173)
Change in operating assets and liabilities:
Accounts receivable	(8,926)		(4,530)
Accounts receivable—affiliates	21		236
Accounts payable	175		46
Accounts payable—affiliates	890		2
Accrued liabilities	(3,381)		(7,302)
Accrued liabilities—affiliates	(515)		0
Accrued interest	(875)		3,405
Deferred revenue	6,037		4,489
Deferred revenue—affiliates	0		(10,166)
Other items, net	952		2,527
Net cash provided by operating activities of continuing operations	74,590		55,594
Net cash used in operating activities of discontinued operations	(447)		(531)
Net cash provided by operating activities	74,143		55,063
Cash flows from investing activities
Distributions from unconsolidated investment in excess of cumulative earnings	2,097		2,388
Proceeds from sale of assets	911		1,268
Return of long-term contract receivable	1,016		1,207
Return of long-term contract receivable—affiliate	0		804
Acquisition of plant and equipment and other	(5,857)		(4,998)
Net cash provided by (used in) investing activities of continuing operations	(1,833)		669
Net cash provided by investing activities of discontinued operations	0		202
Net cash provided by (used in) investing activities	(1,833)		871
Cash flows from financing activities
Proceeds from issuance of preferred units and warrants, net	0		242,100
Proceeds from issuance of 2022 Senior Notes, net	0		103,688
Borrowings on credit facility	35,000		0
Repayments of loans	(48,072)		(348,292)
Contributions to discontinued operations	(447)		(329)
Debt issuance costs and other	(741)		(40,534)
Net cash used in financing activities of continuing operations	(49,609)		(55,851)
Net cash provided by financing activities of discontinued operations	447		329
Net cash used in financing activities	(49,162)		(55,522)
Net increase in cash and cash equivalents	23,148		412
Cash and cash equivalents at beginning of period	29,827		40,371
Cash and cash equivalents at end of period	52,975		40,783
Cash paid during the period for interest from continuing operations	33,155		34,880
Capital Expenditures Incurred but Not yet Paid	894		0
Issuance of 2022 Senior Notes in exchange for 2018 Senior Notes	0		240,638
General Partner
Cash flows from financing activities
Distributions to common unitholders and general partner	(11,240)		(11,234)
Preferred Partner
Cash flows from financing activities
Distributions to common unitholders and general partner	(15,265)		(1,250)
Class A Convertible Preferred Units
Cash flows from financing activities
Distributions, Preferred Stock, Paid-in-Kind, Cash Redemption Payment	$ (8,844)		$ 0
[1]	Net income includes $15.0 million attributable to Preferred Unitholders that accumulated during the period, of which $14.7 million is allocated to the common unitholders and $0.3 million is allocated to the general partner.

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Nature of Business Natural Resource Partners L.P. (the "Partnership") engages principally in the business of owning, operating, managing and leasing a diversified portfolio of mineral properties in the United States, including interests in coal, natural soda ash from trona, construction aggregates and other natural resources. As used in these Notes to Consolidated Financial Statements, the terms "NRP," "we," "us" and "our" refer to Natural Resource Partners L.P. and its subsidiaries, unless otherwise stated or indicated by context. Principles of Consolidation and Reporting The accompanying unaudited Consolidated Financial Statements of the Partnership have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") for interim financial information and with Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In management's opinion, all necessary adjustments to fairly present the Partnership's results of operations, financial position and cash flows for the periods presented have been made and all such adjustments were of a normal and recurring nature. Certain reclassifications have been made to prior period amounts on the Statements of Comprehensive Income and Statements of Cash Flows to conform with current period presentation. These reclassifications had no impact on previously reported net income or cash flows from operating, investing or financing activities. Recently Adopted Accounting Standards Revenue Recognition. On January 1, 2018, NRP adopted accounting standard ASC 606, Revenue from Contracts with Customers, and all the related amendments (the “new revenue standard” and "ASC 606") to all open contracts using the modified retrospective method. The adoption of the new revenue standard impacted royalty revenue from NRP's coal and aggregates royalty leases as further described below. NRP recognized a $90.3 million cumulative effect of adoption adjustment in the opening balance of partners' capital on January 1, 2018. Prior year information has not been restated and continues to be reported under the accounting standards in effect for those periods. The new revenue standard had no impact on revenues from NRP's Construction Aggregates or Soda Ash operating segments. A majority of NRP’s coal and aggregates royalty revenue continues to be recognized over the lease term based on production. For coal and aggregates royalty leases for which NRP expects consideration from minimum payments to be greater than consideration from production over the lease term, royalty revenue is now recognized straight-line over the lease term based on the minimum payment consideration. The cumulative effects of the changes made to our Consolidated Balance Sheet at January 1, 2018 for the adoption of the new revenue standard were as follows: (In thousands) Balance at December 31, 2017 Adjustments due to ASC 606 Balance at January 1, 2018 Assets Accounts receivable, net $ 47,026 $ 3,479 $ 50,505 Liabilities Current portion of deferred revenue $ — $ 1,973 $ 1,973 Deferred revenue 100,605 (88,747 ) 11,858 Partners’ capital Common unitholders’ interest $ 199,851 $ 88,448 $ 288,299 General partner’s interest 1,857 1,805 3,662 Total partners’ capital 265,211 90,253 355,464 The impact of adoption of the new revenue standard on NRP’s Consolidated Balance Sheet and Consolidated Statements of Comprehensive Income was as follows: As of June 30, 2018 (In thousands) As Reported Balances without Adoption of ASC 606 Effect of Change Assets Accounts receivable, net $ 59,312 $ 55,325 $ 3,987 Total assets 1,411,806 1,407,819 3,987 Liabilities and capital Current portion of deferred revenue $ 2,732 $ — $ 2,732 Deferred revenue 17,136 102,244 (85,108 ) Total liabilities 857,299 939,675 (82,376 ) Partners’ capital Common unitholders’ interest 326,125 241,489 84,636 General partner’s interest 4,427 2,700 1,727 Total partners’ capital 392,496 306,133 86,363 Total liabilities and capital 1,411,806 1,407,819 3,987 For the Three Months Ended June 30, 2018 (In thousands) As Reported Amounts without Adoption of ASC 606 Effect of Change Coal royalty and other revenues $ 48,711 $ 50,710 $ (1,999 ) Net income from continuing operations 39,123 41,315 (2,192 ) Net income 39,089 41,281 (2,192 ) Net income per common unit (basic) 2.46 2.64 (0.18 ) Net income per common unit (diluted) 1.75 1.85 (0.10 ) For the Six Months Ended June 30, 2018 (In thousands) As Reported Amounts without Adoption of ASC 606 Effect of Change Coal royalty and other revenues $ 94,684 $ 98,381 $ (3,697 ) Net income from continuing operations 65,211 69,101 (3,890 ) Net income 65,163 69,053 (3,890 ) Net income per common unit (basic) 3.95 4.26 (0.31 ) Net income per common unit (diluted) 2.95 3.13 (0.18 ) Recently Issued Accounting Standards Leases . In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The new standard requires a lessee to recognize assets and liabilities on the balance sheet for the present value of the rights and obligations created by all leases with terms of more than 12 months. This standard does not apply to leases that explore for or use minerals, oil, natural gas and similar non-regenerative resources, including the intangible right to explore for those natural resources and rights to use the land in which those natural resources are contained. The guidance also requires disclosures designed to give financial statement users information on the amount, timing and uncertainty of cash flows arising from leases. The guidance is effective for annual and interim periods beginning after December 31, 2018 and is to be adopted using a modified retrospective approach. The Partnership is currently evaluating the impact of the provisions of this guidance on its consolidated financial statements.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue from Contracts with Customers Coal Royalty and Other Segment The following table represents the Partnership's Coal Royalty and Other segment revenues (including affiliates) by major source: Three Months Ended Six Months Ended (In thousands) June 30, 2018 Coal royalty revenue $ 31,407 $ 60,098 Production lease minimum revenue 102 527 Minimum lease straight-line revenue 6,769 13,529 Wheelage revenue 1,641 3,615 Coal overriding royalty revenue 3,702 6,574 Aggregates royalty revenue 1,572 2,663 Oil and gas royalty revenue 1,354 4,252 Property tax revenue 1,523 2,705 Other revenue 829 1,146 Coal royalty and other revenues (1) $ 48,899 $ 95,109 Transportation and processing services revenue (2) 5,002 10,385 Total Coal royalty and other segment revenues $ 53,901 $ 105,494 (1) Represents revenue from contracts with customers as defined under ASC 606. (2) Revenue from contracts with customers as defined under ASC 606 was $3.1 million and $6.1 million for the three and six months ended June 30, 2018 , respectively. The remaining transportation and processing services revenue of $1.9 million and $4.3 million for the three and six months ended June 30, 2018 , respectively, relates to other NRP-owned infrastructure leased to and operated by third party operators accounted for under ASC 840, Leases. Coal Royalty and Other segment revenues Royalty-based leases. Approximately two-thirds of our royalty-based leases have initial terms of five to 40 years, with many lessees having the option to extend the lease for additional terms. For these types of leases, the lessees generally make payments to NRP based on the greater of a percentage of the gross sales price or a fixed price per ton of mineral they mine or sell. Most of NRP’s coal and aggregates royalty leases require the lessee to pay annual or quarterly minimum amounts, either made in advance or arrears, which are generally recoupable through actual royalty production over certain time periods that generally range from three to five years. In accordance with previous accounting standards in effect prior to January 1, 2018, NRP recognized all coal and aggregates royalty revenue over the lease term based on coal or aggregates production. The recognition of revenue from minimum payments was deferred until either recoupment occurred or the recoupment period expired. Upon expiration, unrecouped minimums were recognized as revenue. Under the new revenue recognition standard, management has defined NRP's coal and aggregates royalty lease performance obligation as providing the lessee the right to mine and sell NRP's coal or aggregates over the lease term. The Partnership then evaluated the likelihood that consideration NRP received from its coal and aggregates lessees resulting from production would exceed consideration received from minimum payments over the lease term. As a result of this evaluation, revenue recognition from the Partnership's royalty-based leases is based on either production or minimum payments as follows: • Production Leases : Leases for which the Partnership expects that consideration from production will be greater than consideration from minimums over the lease term. Revenue recognition for these leases is recognized as Coal royalty revenue or Aggregates royalty revenue, as applicable, over time based on production. Deferred revenue, resulting from minimum consideration received, is recognized as royalty revenue either when recoupment occurs or as Production lease minimum revenue when either the recoupment period expires or when NRP determines that recoupment is remote (breakage). • Minimum Leases : Leases for which the Partnership expects that consideration from minimums will be greater than consideration from production over the lease term. Revenue recognition for these leases is recognized straight-line over the lease term based on the minimum consideration amount and is recognized in Minimum lease straight-line revenue. Additionally, minimum payments contractually due are accrued and recognized in Accounts receivable, net, with an offset to Deferred revenue, and minimum payments received are recorded as Deferred revenue on NRP 's Consolidated Balance Sheets. The Partnership also has overriding royalty revenue interests in certain oil and gas wells and coal reserves. Revenue from these interests is recognized over time based on when the respective commodities are sold. Wheelage. Revenue related to fees collected per ton to transport foreign coal across property owned by the Partnership that is recognized over time as transportation across our property occurs. Other revenue. Other revenue consists primarily of rental payments and surface damage fees related to certain land owned by the Partnership and is recognized straight-line over time as it is earned. Other revenues also include and property tax revenues, the majority of which are reimbursable by the lessee. Property taxes incurred on the Partnership's properties are recognized on a gross basis over time. Transportation and processing services revenue. The Partnership owns transportation and processing infrastructure that is leased to third parties and collects throughput fees for which it recognizes revenue over time based on the coal tons transported over the beltlines or processed through the facilities. Contract modifications Contract modifications that impact the overall economics of the lease's potential future cash flows are evaluated in accordance with ASC 606. A majority of our contract modifications pertain to our coal and aggregates royalty contracts and include, but are not limited to, extending the lease term, changes to royalty rates, floor prices or minimum payments, assignment of the contract or termination due to the exhaustion of merchantable and mineable reserves. In accordance with the contract modification guidance in paragraphs 606-10-25-12 and 25-13, revenues from contracts that were modified before January 1, 2018 were not retrospectively restated for those modifications and instead reflected the aggregate effect of those modifications when identifying the satisfied and unsatisfied performance obligations, determining the transaction price and allocating the transaction price to the satisfied and unsatisfied performance obligation. Contract Assets and Liabilities The following table details the Partnership's Coal Royalty and Other segment receivables from contracts with customers and contract liabilities: June 30, January 1, (In thousands) 2018 2018 Receivables Total accounts receivable, net (including affiliates) $ 30,448 $ 24,047 Prepaid expenses and other (1) 2,163 2,830 Contract liabilities Current portion of deferred revenue $ 2,732 $ 1,973 Deferred revenue 17,136 11,858 (1) Prepaid expenses and other includes notes receivable from contracts with customers. The following table shows the activity related to the Partnership's Coal Royalty and Other segment deferred revenue: (In thousands) Six Months Ended June 30, 2018 Balance at December 31, 2017 $ 100,605 Cumulative adjustment for change in accounting principle recognized in partners' capital (86,774 ) Balance at January 1, 2018 (current and non-current) $ 13,831 Production leases - revenue impact Recoupments recognized in Coal and aggregates royalty revenue (4,630 ) Production lease minimum revenue (393 ) Minimum leases - revenue impact Minimum lease amortization recognized in Minimum lease straight-line revenue (1,958 ) Contractual minimums due 956 Cash received for minimum payments 12,062 Balance at June 30, 2018 (current and non-current) $ 19,868 The following table shows the Partnership's Coal Royalty and Other segment revenue recognized during the three months ended June 30, 2018 that was included in the deferred revenue balance at the beginning of the period: (In thousands) Production leases - revenue impact Recoupments recognized in Coal and aggregates royalty revenue (2,365 ) Production lease minimum revenue (21 ) Minimum leases - revenue impact Minimum lease amortization recognized in Minimum lease straight-line revenue (1,005 ) Remaining Performance Obligations The Partnership's non-cancelable annual minimum payments due under the lease terms of its coal and aggregates royalty leases are as follows: Weighted Average Remaining Years as of June 30, 2018 Annual Minimum Payments (In thousands) Lease Term (1) 1 - 5 years 0.2 $ 7,888 6 - 10 years 2.4 27,439 10+ years 8.2 44,166 (1) The Partnership applied the practical expedient for disclosing remaining performance obligations for contracts with an expected duration of one year or less, and have excluded those contracts from this disclosure. The Partnership's non-cancelable annual minimum payments on its coal and aggregates royalty leases are recognized as revenue as discussed above. In addition, the Partnership's non-cancelable annual minimum payments due under terms of its coal and aggregates overriding royalty agreements include a $1.8 million annual minimum that expires in 2023 and a $1.0 million minimum that expires upon exhaustion of the mineable and recoverable coal reserves, respectively. Construction Aggregates Segment The Partnership's Construction Aggregates segment revenues from contracts with customers by major source are as follows: Three Months Ended Six Months Ended (In thousands) June 30, 2018 Crushed stone, sand and gravel $ 18,070 $ 31,809 Delivery and fuel income 11,678 21,761 Other revenues 4,485 7,087 Total construction aggregates revenues $ 34,233 $ 60,657 Road construction and asphalt paving services 6,176 6,904 Total construction aggregates segment revenues $ 40,409 $ 67,561 Construction Aggregates segment revenues The majority of the Construction Aggregates segment revenues is recognized at a point in time with the exception of revenue related to construction contracts recognized on the percentage-of-completion method as discussed below. The majority of the Partnership's construction contracts have an original expected duration of one year or less. As such, the Partnership has elected to apply the practical expedient and not disclose remaining performance obligations for contracts with an original expected duration of one year or less. Additional discussion of the Partnership's major sources of Construction Aggregates segment revenue are as follows: Crushed stone, sand and gravel and other revenues. Revenue from the sale of crushed stone, sand, gravel and asphalt is recognized based on a fixed price when title is transferred to the buyer and collectibility of the sales proceeds is reasonably assured (typically occurs when products are picked up or delivered to the customer). Other revenues consist of brokered stone sales and barge and service revenues. Brokered stone sales include aggregates purchases from third party quarries, which are then sold and transported to customers and recorded as revenue at the time of delivery. The purchase price of the aggregates from the third party quarries are recorded as expenses. Barge and service revenues relate to loading and unloading services at marine terminals and are recorded as revenue at the time the service is performed. Delivery and fuel income. Revenue related to pass through delivery and fuel costs the Partnership incurs to deliver its products is recognized on a gross basis and is subsequently reimbursed by the customer. The related costs are recognized when incurred and are included in Operating and maintenance expenses on the Consolidated Statements of Comprehensive Income. Road construction and asphalt paving services revenue. Revenue related to construction contracts is recognized on the percentage-of-completion method, measured by the percentage of total costs incurred to date to the estimated total costs for each contract. The Partnership had $24.7 million and $23.0 million in receivables from Construction Aggregates segment related contracts with customers included in Accounts receivable, net on its Consolidated Balance Sheets as of June 30, 2018 and January 1, 2018, respectively.

Class A Convertible Preferred U

Class A Convertible Preferred Units and Warrants	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Convertible Preferred Units and Warrants	Class A Convertible Preferred Units On March 2, 2017, NRP issued $250 million of Class A Convertible Preferred Units representing limited partner interests in NRP (the "Preferred Units") to certain entities controlled by funds affiliated with The Blackstone Group, L.P. (collectively referred to as "Blackstone") and certain affiliates of GoldenTree Asset Management LP (collectively referred to as "GoldenTree") (together the "Preferred Purchasers") pursuant to a Preferred Unit and Warrant Purchase Agreement. NRP issued 250,000 Preferred Units to the Preferred Purchasers at a price of $1,000 per Preferred Unit (the "Per Unit Purchase Price"), less a 2.5% structuring and origination fee. The Preferred Units entitle the Preferred Purchasers to receive cumulative distributions at a rate of 12% per year, up to one half of which NRP may pay in additional Preferred Units (such additional Preferred Units, the "paid-in-kind units" or "PIK Units"), subject to approval by the Board of Directors. During the six months ended June 30, 2018 , the Partnership redeemed all of the outstanding PIK Units, which resulted in an $8.8 million cash payment during the period. Activity related to the Preferred Units is as follows from December 31, 2017 to June 30, 2018 : (In thousands, except unit data) Units Outstanding Financial Position Balance at December 31, 2017 258,844 $ 173,431 Redemption of PIK Units (8,844 ) (8,844 ) Balance at June 30, 2018 250,000 $ 164,587

Common and Preferred Unit Distr

Common and Preferred Unit Distributions	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Common and Preferred Unit Distributions	Common and Preferred Unit Distributions The Partnership makes cash distributions to common unitholders on a quarterly basis, subject to approval by the Board of Directors. As discussed in Note 3 above, the Partnership also makes distributions to the preferred unitholders. Common Unit Distributions Distributions made on the common units and the general partner's general partner ("GP") interest are made on a pro-rata basis in accordance with their relative percentage interests in the Partnership. The general partner is entitled to receive 2% of such distributions. The following table shows the distributions declared and paid to common unitholders during the six months ended June 30, 2018 and 2017 , respectively: Total Distributions (in thousands) Date Paid Period Covered by Distribution Distribution per Common Unit Common Units GP Interest Total 2018 February 14, 2018 October 1 - December 31, 2017 $ 0.45 $ 5,505 $ 112 $ 5,617 May 14, 2018 January 1 - March 31, 2018 $ 0.45 $ 5,510 $ 113 $ 5,623 2017 February 14, 2017 October 1 - December 31, 2016 $ 0.45 $ 5,503 $ 112 $ 5,615 May 12, 2017 January 1 - March 31, 2017 $ 0.45 $ 5,506 $ 113 $ 5,619 Preferred Unit Distributions The following table shows the distributions declared and paid to Preferred Unitholders during the six months ended June 30, 2018 and 2017 , respectively: Date Paid Period Covered by Distribution Distribution per Preferred Unit Total Distribution Declared (in thousands) 2018 February 7, 2018 October 1 - December 31, 2017 $ 30.00 $ 7,765 May 14, 2018 January 1 - March 31, 2018 $ 30.00 $ 7,500 2017 May 30, 2017 March 2 - March 31, 2017 $ 5.00 $ 2,500 Income available to common unitholders and the general partner is reduced by Preferred Unit distributions that accumulated during the period. During the three and six months ended June 30, 2018 , NRP reduced net income attributable to common unitholders and the general partner by $7.5 million and $15.0 million , respectively, as a result of accumulated Preferred Unit distributions earned during the period. The $7.5 million Preferred Unit distribution earned during the three months ended June 30, 2018 will be paid on August 14, 2018.

Net Income Per Common Unit

Net Income Per Common Unit	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Income Per Common Unit	Net Income Per Common Unit Basic net income per common unit is computed by dividing net income, after considering income attributable to preferred unitholders and the general partner’s general partner interest, by the weighted average number of common units outstanding. Diluted net income per common unit includes the effect of NRP's Preferred Units and Warrants, if the inclusion of these items is dilutive. The dilutive effect of the Preferred Units is calculated using the if-converted method. Under the if-converted method, the Preferred Units are assumed to be converted at the beginning of the period, and the resulting common units are included in the denominator of the diluted net income per unit calculation for the period being presented. Distributions declared in the period and undeclared distributions on the Preferred Units that accumulated during the period are added back to the numerator for purposes of the if-converted calculation. The dilutive effect of the Warrants is calculated using the treasury stock method, which assumes that the proceeds from the exercise of these instruments are used to purchase common units at the average market price for the period. The calculation of the dilutive effect of the Warrants for the three and six months ended June 30, 2018 and 2017 did not include the net settlement of Warrants to purchase 2.25 million common units with a strike price of $34.00 because the impact would have been anti-dilutive. The following table reconciles the numerators and denominators of the basic and diluted net income per common unit computations and calculates basic and diluted net income per common unit: Three Months Ended Six Months Ended (In thousands, except per unit data) 2018 2017 2018 2017 Allocation of net income: Net income from continuing operations $ 39,123 $ 25,857 $ 65,211 $ 31,968 Less: net income attributable to non-controlling interest (869 ) — (869 ) — Less: income attributable to preferred unitholders (7,500 ) (7,538 ) (15,000 ) (10,038 ) Net income from continuing operations attributable to common unitholders and general partner $ 30,754 $ 18,319 $ 49,342 $ 21,930 Less: net income from continuing operations attributable to the general partner (616 ) (434 ) (987 ) (438 ) Net income from continuing operations attributable to common unitholders $ 30,138 $ 17,885 $ 48,355 $ 21,492 Net income (loss) from discontinued operations $ (34 ) $ 133 $ (48 ) $ (74 ) Less: net income (loss) from discontinued operations attributable to the general partner 1 (3 ) 1 1 Net income (loss) from discontinued operations attributable to common unitholders $ (33 ) $ 130 $ (47 ) $ (73 ) Net income $ 39,089 $ 25,990 $ 65,163 $ 31,894 Less: net income attributable to non-controlling interest (869 ) — (869 ) — Less: income attributable to preferred unitholders (7,500 ) (7,538 ) (15,000 ) (10,038 ) Net income attributable to common unitholders and general partner $ 30,720 $ 18,452 $ 49,294 $ 21,856 Less: net income attributable to the general partner (615 ) (437 ) (986 ) (437 ) Net income attributable to common unitholders $ 30,105 $ 18,015 $ 48,308 $ 21,419 Basic income (loss) per common unit: Weighted average common units—basic 12,246 12,232 12,242 12,232 Basic net income from continuing operations per common unit $ 2.46 $ 1.46 $ 3.95 $ 1.76 Basic net income (loss) from discontinued operations per common unit $ — $ 0.01 $ — $ (0.01 ) Basic net income per common unit $ 2.46 $ 1.47 $ 3.95 $ 1.75 Three Months Ended Six Months Ended (In thousands, except per unit data) 2018 2017 2018 2017 Diluted income (loss) per common unit: Weighted average common units—basic 12,246 12,232 12,242 12,232 Plus: dilutive effect of Warrants 522 467 476 361 Plus: dilutive effect of Preferred Units 8,615 9,760 8,615 6,517 Weighted average common units—diluted 21,383 22,459 21,333 19,110 Net income from continuing operations $ 39,123 $ 25,857 $ 65,211 $ 31,968 Less: net income attributable to non-controlling interest (869 ) — (869 ) — Diluted net income from continuing operations attributable to common unitholders and general partner $ 38,254 $ 25,857 $ 64,342 $ 31,968 Less: diluted net income from continuing operations attributable to the general partner (766 ) (586 ) (1,287 ) (639 ) Diluted net income from continuing operations attributable to common unitholders $ 37,488 $ 25,271 $ 63,055 $ 31,329 Diluted net income (loss) from discontinued operations attributable to common unitholders $ (33 ) $ 130 $ (47 ) $ (73 ) Net income $ 39,089 $ 25,990 $ 65,163 $ 31,894 Less: net income attributable to non-controlling interest (869 ) — (869 ) — Diluted net income attributable to common unitholders and general partner $ 38,220 $ 25,990 $ 64,294 $ 31,894 Less: diluted net income attributable to the general partner (765 ) (589 ) (1,286 ) (638 ) Diluted net income attributable to common unitholders $ 37,455 $ 25,401 $ 63,008 $ 31,256 Diluted net income from continuing operations per common unit $ 1.75 $ 1.13 $ 2.96 $ 1.64 Diluted net income (loss) from discontinued operations per common unit $ — $ — $ — $ — Diluted net income per common unit $ 1.75 $ 1.13 $ 2.95 $ 1.64

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information The Partnership's operating segments are strategic business units that offer distinct products and services to different customers in different geographies within the U.S. that are managed accordingly. NRP has the following three operating segments: Coal Royalty and Other —consists primarily of coal royalty and coal-related transportation and processing assets. Other assets include aggregates royalty, industrial mineral royalty, oil and gas royalty and timber. The Partnership's coal reserves are primarily located in Appalachia, the Illinois Basin and the western United States. The Partnership's aggregates and industrial minerals properties are located in a number of states across the United States. The Partnership's oil and gas royalty assets are primarily located in Louisiana and Pennsylvania. Soda Ash —consists of the Partnership's 49% non-controlling equity interest in Ciner Wyoming, a trona ore mining operation and soda ash refinery in the Green River Basin of Wyoming. Ciner Resources LP, the Partnership's operating partner, mines the trona, processes it into soda ash, and distributes the soda ash both domestically and internationally to the glass and chemicals industries. The Partnership receives regular quarterly distributions from Ciner Wyoming. Construction Aggregates —consists of the Partnership's construction aggregates materials business that operates hard rock quarries, an underground limestone mine, sand and gravel plants, asphalt plants and marine terminals. Construction Aggregates operates in Pennsylvania, West Virginia, Tennessee, Kentucky and Louisiana. Direct segment costs and certain other costs incurred at the corporate level that are identifiable and that benefit the Partnership's segments are allocated to the operating segments accordingly. These allocated costs generally include: insurance, taxes, legal, information technology and shared facilities services and are included in Operating and maintenance expenses and Operating and maintenance expenses—affiliates on the Consolidated Statements of Comprehensive Income. Intersegment sales are at prices that approximate market and are eliminated on the Partnership's Consolidated Statements of Comprehensive Income. Corporate and Financing includes functional corporate departments that do not earn revenues. Costs incurred by these departments include interest and financing, corporate headquarters and overhead, centralized treasury and accounting and other corporate-level activity not specifically allocated to a segment and are included in General and administrative expenses and General and administrative expenses—affiliates on the Consolidated Statements of Comprehensive Income. The following table summarizes certain financial information for each of the Partnership's operating segments: Operating Segments (In thousands) Coal Royalty and Other Soda Ash Construction Aggregates Corporate and Financing Total Three Months Ended June 30, 2018 Revenues (including affiliates) $ 53,901 $ 16,529 $ 40,409 $ — $ 110,839 Intersegment revenues (expenses) 74 — (74 ) — — Gain on asset sales, net 168 — 42 — 210 Operating and maintenance expenses 8,117 — 34,249 — 42,366 Depreciation, depletion and amortization 5,376 — 3,187 — 8,563 General and administrative (including affiliates) — — — 3,263 3,263 Other expense, net — — — 17,734 17,734 Net income (loss) from continuing operations 40,650 16,529 2,941 (20,997 ) 39,123 Loss from discontinued operations — — — — (34 ) Three Months Ended June 30, 2017 Revenues (including affiliates) $ 49,626 $ 8,389 $ 33,555 $ — $ 91,570 Intersegment revenues (expenses) 68 — (68 ) — — Gain on asset sales, net 3,184 — 177 — 3,361 Operating and maintenance expenses 5,419 — 27,820 — 33,239 Depreciation, depletion and amortization (including affiliates) 5,375 — 3,030 — 8,405 General and administrative (including affiliates) — — — 2,883 2,883 Other expense, net — — 178 24,369 24,547 Net income (loss) from continuing operations 42,084 8,389 2,636 (27,252 ) 25,857 Income from discontinued operations — — — — 133 Operating Segments (In thousands) Coal Royalty and Other Soda Ash Construction Aggregates Corporate and Financing Total Six Months Ended June 30, 2018 Revenues (including affiliates) $ 105,494 $ 26,150 $ 67,561 $ — $ 199,205 Intersegment revenues (expenses) 115 — (115 ) — — Gain on asset sales, net 819 — 51 — 870 Operating and maintenance expenses 14,332 — 60,467 — 74,799 Depreciation, depletion and amortization 10,476 — 6,044 — 16,520 General and administrative (including affiliates) — — — 7,599 7,599 Asset impairment 242 — — — 242 Other expense, net — — 20 35,684 35,704 Net income (loss) from continuing operations 81,378 26,150 966 (43,283 ) 65,211 Loss from discontinued operations — — — — (48 ) Six Months Ended June 30, 2017 Revenues (including affiliates) $ 100,764 $ 18,683 $ 60,776 $ — $ 180,223 Intersegment revenues (expenses) 130 — (130 ) — — Gain on asset sales, net 3,213 — 192 — 3,405 Operating and maintenance expenses 12,803 — 52,619 — 65,422 Depreciation, depletion and amortization (including affiliates) 12,348 — 6,549 — 18,897 General and administrative (including affiliates) — — — 10,085 10,085 Asset impairment 1,778 — — — 1,778 Other expense, net — — 573 54,905 55,478 Net income (loss) from continuing operations 77,178 18,683 1,097 (64,990 ) 31,968 Loss from discontinued operations — — — — (74 ) As of June 30, 2018 Total assets of continuing operations $ 967,627 $ 245,524 $ 193,721 $ 3,946 $ 1,410,818 Total assets of discontinued operations — — — — 988 As of December 31, 2017 Total assets of continuing operations $ 945,237 $ 245,433 $ 191,374 $ 6,129 $ 1,388,173 Total assets of discontinued operations — — — — 991

Equity Investment

Equity Investment	6 Months Ended
	Jun. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Investment	Equity Investment The Partnership accounts for its 49% investment in Ciner Wyoming using the equity method of accounting. Activity related to this investment is as follows: Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Balance at beginning of period $ 241,679 $ 252,803 $ 245,433 $ 255,901 Income allocation to NRP’s equity interests 17,657 9,274 28,489 20,754 Amortization of basis difference (1,128 ) (885 ) (2,339 ) (2,071 ) Comprehensive loss from unconsolidated investment (434 ) (23 ) (1,559 ) (1,165 ) Distribution (12,250 ) (12,250 ) (24,500 ) (24,500 ) Balance at end of period $ 245,524 $ 248,919 $ 245,524 $ 248,919 The following table represents summarized financial information for Ciner Wyoming as derived from the respective unaudited financial statements for the three and six months ended June 30, 2018 and 2017 , respectively: Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Sales $ 91,882 $ 119,737 $ 213,101 $ 246,309 Gross profit 14,022 24,219 42,244 52,916 Net Income 36,035 18,926 58,142 42,354

Plant and Equipment, Net

Plant and Equipment, Net	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Plant and Equipment	Plant and Equipment, Net The Partnership’s plant and equipment consist of the following: June 30, December 31, (In thousands) 2018 2017 Plant and equipment $ 89,686 $ 84,173 Construction in process 1,383 803 Less accumulated depreciation (43,152 ) (38,806 ) Total plant and equipment, net $ 47,917 $ 46,170 Depreciation expense included in Depreciation, depletion and amortization on the Partnership's Consolidated Statements of Comprehensive Income totaled $2.6 million and $2.5 million for the three months ended June 30, 2018 and 2017 , respectively. Depreciation expense totaled $5.0 million and $5.4 million for the six months ended June 30, 2018 and 2017 , respectively.

Mineral Rights, Net

Mineral Rights, Net	6 Months Ended
	Jun. 30, 2018
Extractive Industries [Abstract]
Mineral Rights	Mineral Rights, Net The Partnership’s mineral rights consist of the following: June 30, 2018 (In thousands) Carrying Value Accumulated Depletion Net Book Value Coal properties $ 1,169,862 $ (444,332 ) $ 725,530 Aggregates properties 150,642 (19,103 ) 131,539 Oil and gas royalty properties 12,395 (7,395 ) 5,000 Other 13,161 (1,514 ) 11,647 Total mineral rights, net $ 1,346,060 $ (472,344 ) $ 873,716 December 31, 2017 (In thousands) Carrying Value Accumulated Depletion Net Book Value Coal properties $ 1,170,104 $ (436,964 ) $ 733,140 Aggregates properties 150,642 (16,836 ) 133,806 Oil and gas royalty properties 12,395 (7,158 ) 5,237 Other 13,168 (1,466 ) 11,702 Total mineral rights, net $ 1,346,309 $ (462,424 ) $ 883,885 Depletion expense related to the Partnership’s mineral rights is included in Depreciation, depletion and amortization on the Partnership's Consolidated Statements of Comprehensive Income and totaled $5.1 million and $5.0 million for the three months ended June 30, 2018 and 2017 , respectively. Depletion expense related to the Partnership’s mineral rights totaled $9.9 million and $11.7 million for the six months ended June 30, 2018 and 2017 , respectively. In April 2018, Foresight Energy LP ("Foresight Energy") made a filing with the SEC indicating its intent to permanently close the Deer Run mine operated by its subsidiary Hillsboro Energy LLC ("Hillsboro") if the coal mining lease is terminated by the Court in connection with the ongoing litigation relating thereto. Refer to Note 15. Commitments and Contingencies —Legal —Foresight Energy Disputes for more information on this litigation. In addition, in its June 30, 2018 Form 10-Q, Foresight Energy disclosed that they recorded an impairment charge of $110.7 million during the three months ended June 30, 2018 related to mineral reserves, buildings and structures, machinery and equipment, and other related assets that Foresight Energy does not expect to generate future positive cash flows at the Deer Run mine. The Partnership has evaluated the impact of this impairment recognized by Foresight Energy on its estimate of future cash flows from its Hillsboro property. To the extent the Partnership is unable to generate sufficient cash flow, the carrying value of the Partnership's reserves could be impaired. However, NRP believes there is no basis for termination of the lease, and the lease will remain in full force and effect unless the Court ultimately declares the lease terminated. Further, NRP believes that the approximately 179 million tons of estimated coal reserves at the Deer Run mine have substantial economic value. As of June 30, 2018 the Partnership has concluded there is no indicator of impairment of the $235 million net book value of the Partnership's reserves at the Deer Run mine. NRP will continue to assess the expected cash flow from this property in future periods.

Intangible Assets, Net

Intangible Assets, Net	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets (Including Affiliate)	Intangible Assets, Net The Partnership's intangible assets primarily consist of above-market coal transportation contracts with subsidiaries of Foresight Energy in which the Partnership receives throughput fees for the handling and transportation of coal. The Partnership's intangible assets also include permits, aggregates-related trade names and other agreements. The Partnership's intangible assets included on its Consolidated Balance Sheets are as follows: June 30, December 31, (In thousands) 2018 2017 Intangible assets $ 86,336 $ 86,336 Less: accumulated amortization (38,412 ) (36,782 ) Total intangible assets, net $ 47,924 $ 49,554 Amortization expense included in Depreciation, depletion and amortization on the Partnership's Consolidated Statements of Comprehensive Income was $0.8 million and $0.6 million for the three months ended June 30, 2018 and 2017 , respectively. Amortization expense included in Depreciation, depletion and amortization on the Partnership's Consolidated Statements of Comprehensive Income was $1.6 million and $0.8 million for the six months ended June 30, 2018 and 2017 , respectively. Amortization expense included in amortization expense—affiliates on the Partnership's Consolidated Statements of Comprehensive Income was $0.2 million and $1.0 million for the three and six months ended June 30, 2017 . As of May 9, 2017, Foresight Energy was no longer deemed to be an affiliate of the Partnership. Refer to Note 13. Related Party Transactions for additional details.

Debt, Net

Debt, Net	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Debt	Debt, Net The Partnership's debt consists of the following: June 30, December 31, (In thousands) 2018 2017 NRP LP debt: 10.500% senior notes, with semi-annual interest payments in March and September, due March 2022, $241 million issued at par and $105 million issued at 98.75% $ 345,638 $ 345,638 Opco debt: Revolving credit facility 95,000 60,000 Senior notes 4.91% with semi-annual interest payments in June and December, with annual principal payments in June, due June 2018 — 4,586 8.38% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2019 21,334 42,670 5.05% with semi-annual interest payments in January and July, with annual principal payments in July, due July 2020 22,946 22,946 5.55% with semi-annual interest payments in June and December, with annual principal payments in June, due June 2023 13,429 16,115 4.73% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2023 44,693 44,693 5.82% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 89,589 104,520 8.92% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 27,200 31,733 5.03% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 120,547 120,547 5.18% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 34,396 34,396 $ 814,772 $ 827,844 Net unamortized debt discount (1,463 ) (1,661 ) Net unamortized debt issuance costs (14,974 ) (16,835 ) Total debt, net $ 798,335 $ 809,348 Less: current portion of long-term debt 75,188 79,740 Total long-term debt, net $ 723,147 $ 729,608 NRP LP Debt 2022 Senior Notes As of June 30, 2018 and December 31, 2017 , NRP and NRP Finance were in compliance with the terms of their debt agreements. Opco Debt All of Opco’s debt is guaranteed by its wholly owned subsidiaries and is secured by certain of the assets of Opco and its wholly owned subsidiaries other than NRP Trona LLC. As of June 30, 2018 and December 31, 2017 , Opco was in compliance with the terms of the financial covenants contained in its debt agreements. Opco Credit Facility Opco’s Third Amended and Restated Credit Agreement, as amended (the "Opco Credit Facility"), matures on April 30, 2020. As of June 30, 2018 , Opco had $95.0 million of indebtedness outstanding and $55.0 million in available borrowing capacity under the Opco Credit Facility. The commitments under the Opco Credit Facility will be reduced from $150 million to $100 million at December 31, 2018 and remaining at $100 million through maturity in April 2020. The weighted average interest rates for the borrowings outstanding under the Opco Credit Facility for the three months ended June 30, 2018 was 6.18% . There were no outstanding borrowings during the three months ended June 30, 2017. The weighted average interest rates for the borrowings outstanding under the Opco Credit Facility for six months ended June 30, 2018 and 2017 were 6.08% and 5.22% , respectively. Debt issue cost related to the Opco credit facility were $3.1 million and $4.6 million at June 30, 2018 and December 31, 2017 , respectively, and have been capitalized and included in Other assets on the Partnership's Consolidated Balance Sheets. The Opco Credit Facility is collateralized and secured by liens on certain of Opco’s assets with carrying values of $642.6 and $649.7 million classified as Land, Plant and equipment and Mineral rights on the Partnership’s Consolidated Balance Sheet as of June 30, 2018 and December 31, 2017 , respectively. Opco Senior Notes As of June 30, 2018 and December 31, 2017 , the private placement senior notes ("Opco Senior Notes") had cumulative principal balances of $374.1 million and $422.2 million , respectively. Opco made mandatory principal payments of $48.1 million during the six months ended June 30, 2018 and June 30, 2017 , respectively. The 8.38% and 8.92% Opco Senior Notes also provide that in the event that Opco’s leverage ratio of consolidated indebtedness to consolidated EBITDDA (as defined in the Note Purchase Agreements) exceeds 3.75 to 1.00 at the end of any fiscal quarter, then in addition to all other interest accruing on these notes, additional interest in the amount of 2.00% per annum shall accrue on the notes for the two succeeding quarters and for as long thereafter as the leverage ratio remains above 3.75 to 1.00. Opco has not exceeded the 3.75 to 1.00 ratio at the end of any fiscal quarter through June 30, 2018 .

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair Value of Financial Instruments The Partnership’s financial instruments consist of cash and cash equivalents, accounts receivable, contracts receivable, accounts payable, debt, Preferred Units and warrants. The carrying amounts reported on the Consolidated Balance Sheets for cash and cash equivalents, accounts receivable and accounts payable approximate fair value due to their short-term nature. There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy during the three and six months ended June 30, 2018 or 2017 . The Partnership uses available market data and valuation methodologies to estimate the fair value of debt. The fair value of debt is the estimated amount the Partnership would have to pay a third party to assume the debt, including a credit spread for the difference between the issue rate and the period end market rate. The credit spread is the Partnership's default or repayment risk. The following table shows the carrying amount and estimated fair value of the Partnership's debt and contracts receivable: June 30, 2018 December 31, 2017 (In thousands) Carrying Estimated Carrying Estimated Debt: NRP 2022 Senior Notes (1) $ 332,214 $ 372,857 $ 330,404 $ 366,376 Opco Senior Notes (2) 371,121 403,597 418,944 447,538 Opco Revolving Credit Facility (3) 95,000 95,000 60,000 60,000 Assets: Contracts receivable, current and long-term (4) $ 42,061 $ 29,491 $ 43,826 $ 30,517 (1) The Level 1 fair value is based upon quotations obtained for identical instruments on the closing trading prices near period end. (2) Due to no observable quoted prices on these instruments, the Level 3 fair value is estimated by management using quotations obtained for the NRP Senior Notes on the closing trading prices near period end. (3) The Level 3 fair value approximates the outstanding borrowing amount because the interest rates are variable and reflective of market rates and the terms of the credit facility allow the Partnership to repay this debt at any time without penalty. (4) The Level 3 fair value is determined based on the present value of future cash flow projections related to the underlying assets. NRP has embedded derivatives in the Preferred Units related to certain conversion options, redemption features and the change of control provision that are accounted for separately from the Preferred Units as assets and liabilities at fair value on the Partnership's Consolidated Balance Sheets. Level 3 valuation of the embedded derivatives are based on numerous factors including the likelihood of the event occurring. The embedded derivatives are revalued quarterly, and changes in their fair value would be recorded in other income (expense) in the Partnership's Consolidated Statements of Comprehensive Income. The embedded derivatives had zero value as of June 30, 2018 and December 31, 2017 .

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Cline Affiliates and Foresight Energy L.P. Mr. Chris Cline, both individually and through another affiliate, Adena Minerals, LLC ("Adena"), owned a 31% interest in NRP (GP) LP, NRP's general partner ("NRP GP"), through May 9, 2017. On May 9, 2017, Adena sold its 31% limited partner interest in NRP GP to Great Northern Properties Limited Partnership (“GNPLP”) and Western Pocahontas Properties Limited Partnership ("WPPLP") (the “Adena Sale”). GNPLP and WPPLP are companies controlled by Corbin J. Robertson, the Chairman and Chief Executive Officer of GP Natural Resource Partners LLC (the general partner of NRP GP) (“GP LLC”). Upon closing of this transaction, NRP no longer considers the various companies affiliated with Chris Cline, including Foresight Energy to be affiliates of NRP. As a result, all transactions (including revenues, expenses and cash flows) after May 9, 2017 with the various companies affiliated with Chris Cline are considered to be third party transactions. Revenues and expenses related to transactions with Foresight Energy are included in the Partnership's Consolidated Statements of Comprehensive Income as follows: Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Revenues Coal royalty and other $ 8,022 $ 643 $ 15,070 $ 643 Coal royalty and other—affiliates — 10,051 — 21,203 Transportation and processing services 4,968 4,146 10,351 4,146 Transportation and processing services—affiliate — 1,374 — 6,013 Expenses Operating and maintenance expense $ 411 $ 285 $ 812 $ 285 Operating and maintenance expense—affiliates — 117 — 452 Coal Royalty and Other Revenues Various subsidiaries of Foresight Energy lease coal reserves from the Partnership. In addition, NRP owns a contractual overriding royalty interest at Foresight Energy's Sugar Camp mine in the Illinois Basin which provides for payments based upon production from specific tons at Foresight Energy's Sugar Camp operations on certain reserves owned by another affiliate of Chris Cline. This overriding royalty is accounted for as a financing arrangement. Revenues related to these transactions are included in Coal royalty and other revenues in the Partnership's Consolidated Statements of Comprehensive Income. Transportation and Processing Services Revenues and Expenses The Partnership owns transportation and processing infrastructure related to certain of its coal properties, including loadout and other transportation assets at Foresight Energy's Williamson and Macoupin mines in the Illinois Basin, for which it collects throughput fees. These fees are are included in Transportation and processing services revenues in the Partnership's Consolidated Statements of Comprehensive Income. NRP is responsible for operating and maintaining the rail load out transportation assets at the Williamson mine and subcontracts the operating responsibilities to a subsidiary of Foresight Energy. Expenses related to these transactions with Foresight Energy are included in Operating and maintenance expenses in the Partnership's Consolidated Statements of Comprehensive Income. In addition, NRP owns rail loadout and associated infrastructure at the Sugar Camp mine, an Illinois Basin mine also operated by a subsidiary of Foresight Energy LP. While the Partnership owns coal reserves at the Williamson and Macoupin mines, it does not own coal reserves at the Sugar Camp mine. The infrastructure at the Sugar Camp mine is leased to third parties and NRP collects throughput fees, which are included in Transportation and processing services revenues in the Partnership's Consolidated Statements of Comprehensive Income. NRP's Sugar Camp rail load out lease with a subsidiary of Foresight Energy is accounted for as a financing lease. The following table shows certain amounts related to NRP's Sugar Camp rail load out facility financing lease: June 30, December 31, (In thousands) 2018 2017 Projected remaining payments $ 68,977 $ 71,452 Unearned income 26,695 28,366 Reimbursements to Affiliates of our General Partner The Partnership’s general partner does not receive any management fee or other compensation for its management of NRP. However, in accordance with the partnership agreement, the general partner and its affiliates are reimbursed for services provided to the Partnership and for expenses incurred on the Partnership’s behalf. Employees of Quintana Minerals Corporation ("QMC") and WPPLP, affiliates of the Partnership, provide their services to manage the Partnership's business. QMC and WPPLP charge the Partnership the portion of their employee salary and benefits costs related to their employee services provided to NRP. These QMC and WPPLP employee management service costs are presented as Operating and maintenance expenses—affiliates and General and administrative—affiliates on the Partnership's Consolidated Statements of Comprehensive Income. NRP also reimburses overhead costs incurred by its affiliates to manage the Partnership's business. These overhead costs include certain rent, legal, accounting, treasury, information technology, insurance, administration of employee benefits and other corporate services incurred by or on behalf of the Partnership’s general partner and its affiliates and are presented as Operating and maintenance expenses—affiliates and General and administrative—affiliates on the Partnership's Consolidated Statements of Comprehensive Income. Direct general and administrative expenses charged to the Partnership by QMC and WPPLP are included in the Partnership's Consolidated Statement of Comprehensive Income as follows: Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Operating and maintenance expenses—affiliates $ 1,727 $ 1,799 $ 3,634 $ 3,965 General and administrative—affiliates 849 852 1,780 1,976 During the three months ended June 30, 2018 and 2017 , the Partnership recognized $2.3 million and $0.3 million in Operating and maintenance expenses—affiliates, respectively, on its Consolidated Statements of Comprehensive Income related to a non-participating production royalty payable to WPPLP pursuant to a conveyance agreement entered into in 2007 in which coal royalty revenues received from a third party by NRP are passed back to WPPLP. These charges were $2.9 million and $0.4 million during the six months ended June 30, 2018 and 2017 , respectively. At December 31, 2017 , the Partnership had Other assets—affiliate from WPPLP on its Consolidated Balance Sheets related to a non-production royalty receivable from WPPLP for overriding royalty interest of $0.2 million . The Partnership had Accounts payable—affiliates on its Consolidated Balance Sheets to QMC of $0.4 million and WPPLP of $1.1 million as of June 30, 2018 and to QMC of $0.4 million and WPPLP of $0.1 million as of December 31, 2017 . Quintana Capital Group GP, Ltd. Corbin J. Robertson, Jr. is a principal in Quintana Capital Group GP, Ltd. ("Quintana Capital"), which controls several private equity funds focused on investments in the energy business. In connection with the formation of Quintana Capital, the Partnership adopted a formal conflicts policy that establishes the opportunities that will be pursued by the Partnership and those that will be pursued by Quintana Capital. The governance documents of Quintana Capital’s affiliated investment funds reflect the guidelines set forth in the Partnership's conflicts policy. At June 30, 2018 , a fund controlled by Quintana Capital owned a substantial interest in Corsa Coal Corp. ("Corsa"), a coal mining company traded on the TSX Venture Exchange that was of the Partnership’s lessees in Tennessee. During the three months ended June 30, 2018 , Corsa assigned its lease with NRP to a third party and is no longer deemed a related party. Coal related revenues from Corsa totaled $0.2 million and $0.4 million for the three months ended June 30, 2018 and 2017 , respectively. Coal related revenues from Corsa totaled $0.4 million and $0.7 million for the six months ended June 30, 2018 and 2017 , respectively. At June 30, 2018 and December 31, 2017 , the Partnership had Accounts receivable—affiliates totaling $0.1 million and $0.2 million from Corsa on its Consolidated Balance Sheets, respectively. Quinwood Coal Company Royalty In May 2017, a subsidiary of Alpha Natural Resources assigned two coal leases with us to Quinwood Coal Company ("Quinwood"), and entity wholly-owned by Corbin J. Robertson III. In connection with this lease assignment, Quinwood forfeited the historical recoupable balance related to this property. As a result, NRP recognized $0.9 million of deferred minimum payments received in prior periods from a subsidiary of Alpha as Coal royalty and other—affiliates revenue on its Consolidated Statements of Comprehensive Income during the three and six months ended June 30, 2017, respectively.

Major Customers

Major Customers	6 Months Ended
	Jun. 30, 2018
Risks and Uncertainties [Abstract]
Major Customers	Major Customers Revenues from customers that exceeded 10 percent of total revenues and other income for any of the periods presented below are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Revenues Percent Revenues Percent Revenues Percent Revenues Percent Foresight Energy $ 12,990 11.7 % $ 16,255 17.1 % $ 25,421 12.7 % $ 32,046 17.5 % Revenues from Foresight Energy are included within the Partnership's Coal Royalty and Other segment.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal NRP is involved, from time to time, in various legal proceedings arising in the ordinary course of business. While the ultimate results of these proceedings cannot be predicted with certainty, Partnership management believes these claims will not have a material effect on the Partnership’s financial position, liquidity or operations. NRP is also currently involved in the legal proceedings described below. Anadarko Contingent Consideration Payment Dispute In January 2013, NRP acquired a non-controlling 48.51% general partner interest in OCI Wyoming, L.P. ("OCI LP") and all of the preferred stock and a portion of the common stock of OCI Wyoming Co. ("OCI Co") (which in turn owned a 1% limited partner interest in OCI LP) from Anadarko Holding Company and its subsidiary, Big Island Trona Company (together, "Anadarko"). The remaining general partner interest in OCI LP and common stock of OCI Co were owned by subsidiaries of OCI Chemical Corporation. The acquisition agreement provided for additional contingent consideration of up to $50 million to be paid by NRP if certain performance criteria were met at OCI LP as defined in the purchase and sale agreement in any of the years 2013, 2014 or 2015. For those years, NRP paid an aggregate of $11.5 million to Anadarko in full satisfaction of these contingent consideration payment obligations. In July 2013, pursuant to a series of transactions in connection with an initial public offering by a subsidiary of OCI Chemical Corporation, the ownership structure in OCI LP was simplified. In connection with such reorganization, NRP exchanged the stock of OCI Co for a limited partner interest in OCI LP. Following the reorganization, NRP's interest in OCI LP increased to 49% , consisting of both limited and general partner interests. The restructuring did not have any impact on the operations, revenues, management or control of OCI LP. In July 2017, Anadarko filed a lawsuit against Opco and NRP Trona LLC alleging that the transactions conducted in 2013 triggered an acceleration of NRP's obligation under the purchase agreement with Anadarko to pay additional contingent consideration in full and demanded immediate payment of such amount, together with interest, court costs and attorneys’ fees. NRP does not believe the reorganization transactions triggered an obligation to pay any additional contingent consideration, and is vigorously defending this lawsuit. However, the ultimate outcome cannot be predicted with certainty given the early stage of this matter, and the Partnership estimates a possible range of loss between $0 , if it prevails, and approximately $40 million plus interest, court costs and attorneys’ fees if Anadarko prevails and is awarded the full damages it seeks. Foresight Energy Disputes In November 2015, NRP filed a lawsuit against Hillsboro and has subsequently named Foresight Energy and certain of its other subsidiaries in that lawsuit. The lawsuit alleges, among other items, breach of contract by Hillsboro resulting from a wrongful declaration of force majeure at Hillsboro’s Deer Run mine, as well as alter-ego and tortious interference claims against Foresight Energy. In late March 2015, elevated carbon monoxide readings were detected at the Deer Run mine, and coal production at the mine was idled. In July 2015, Hillsboro declared a force majeure event under its lease with us, and Hillsboro has failed to make its contractually obligated minimum quarterly payments of $7.5 million since then. NRP believes the force majeure declaration by Hillsboro has no merit and is vigorously pursuing recovery against Hillsboro as well as against Foresight Energy and certain of its other subsidiaries. Hillsboro has made a counterclaim seeking a declaration that the lease terminated retroactively effective March 26, 2015. We believe there is no basis for termination of the lease, as substantial merchantable and mineable coal reserves remain at the Deer Run mine, and the lease will remain in full force and effect unless the Court ultimately declares the lease terminated. Hillsboro has failed to make $91.0 million of required quarterly minimum payments to NRP to date, and such amount will continue to increase by $7.5 million for each quarter with respect to which payment is not made. Additionally, approximately $15 million of interest on the unpaid amounts has accrued through July 31, 2018. A bench trial is currently set for October 22, 2018. In April 2016, NRP filed a lawsuit against Macoupin Energy, LLC ("Macoupin"), a subsidiary of Foresight Energy, in Macoupin County, Illinois. The lawsuit alleges that Macoupin has failed to comply with the terms of its coal mining, rail loadout and rail loop leases by incorrectly recouping previously paid minimum royalties. As a result, Macoupin owes NRP approximately $10.1 million in improperly recouped minimum royalties through June 30, 2018 .

Unit-Based Compensation Unit-Ba

Unit-Based Compensation Unit-Based Compensation	6 Months Ended
	Jun. 30, 2018
Unit-Based Compensation [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	Unit-Based Compensation 2017 Long-Term Incentive Plan In December 2017, the 2017 Long-Term Incentive Plan (the “2017 LTIP”) was approved and it became effective in January 2018. The 2017 LTIP authorizes 800,000 common units that are available for delivery by the Partnership pursuant to awards under the plan. The term is 10 years from the date of Board approval or, if earlier, the date the 2017 LTIP is terminated by the Board or the committee appointed by the Board to administer the 2017 LTIP, or the date all available common units available have been delivered. Common units delivered pursuant to the 2017 LTIP will consist, in whole or part, of (i) common units acquired in the open market, (ii) common units acquired from the Partnership (including newly issued units), any of our affiliates or any other person or (iii) any combination of the foregoing. Employees, consultants and non-employee directors of the Partnership, the General Partner, GP LLC and their affiliates are generally eligible to receive awards under the 2017 LTIP. The 2017 LTIP provides for the issuance of a variety of equity-based grants, including grants of (i) options, (ii) unit appreciation rights, (iii) restricted units, (iv) phantom units, (v) cash awards, (vi) performance awards, (vii) distribution equivalent rights, and (viii) other unit-based awards. The plan is administered by the Compensation, Nominating and Governance Committee of the Board, which will determine the terms and conditions of awards granted under the 2017 LTIP. The Partnership recognizes forfeitures for any awards issued under this plan as they occur. In connection with the phantom unit awards, the Compensation, Nominating and Governance Committee also granted tandem Distribution Equivalent Rights ("DERs"), which entitle the holders to receive distributions equal to the distributions paid on the Partnership’s common units between the date the units are granted and the vesting date. The DERs are payable in cash upon vesting but may be subject to forfeiture if the grantee ceases employment prior to vesting. Unit-Based Awards Unit-based awards under the 2017 LTIP are generally issued to certain employees and non-employee directors of the Partnership. Awards granted to employees vest at the end of a three year period and awards granted to non-employee directors are immediately vested. Directors are given the option to take immediate issuance of the vested awards or defer such issuance until a later date. Upon deferral of issuance, such units will continue to accumulate DERs until issuance. A summary of the activity during six months ended June 30, 2018 is as follows: (In thousands) Common Units Weighted Average Exercise Price Outstanding at January 1, 2018 — $ — Granted 75 $ 29.16 Fully vested and issued (14 ) $ 29.44 Forfeitures — $ — Outstanding at June 30, 2018 61 $ 29.10 The awards granted in the first quarter of 2018 were valued using the closing price of NRP's units as of the grant date. The grant date fair value of the 2017 LTIP awards granted during the period was $2.2 million , including awards granted to board members with a grant date fair value of $0.6 million which immediately vested and of which $0.4 million were issued. Total unit-based compensation expense associated with these awards was $0.2 million for the three months ended June 30, 2018 and $0.8 million for the six months ended June 30, 2018 and is included in General and administrative expense and Operating and maintenance expense in the Partnership's Consolidated Statements of Comprehensive Income. The unamortized cost associated with unvested outstanding awards as of June 30, 2018 is $1.4 million , which is to be recognized over a weighted-average period of 2.6 years .

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The following represents material events that have occurred subsequent to June 30, 2018 through the time of the Partnership’s filing of its Quarterly Report on Form 10-Q with the SEC: Distributions Declared On July 26, 2018, the Board of Directors of GP Natural Resource Partners LLC declared a distribution of $0.45 per common unit to be paid by the Partnership on August 14, 2018 to common unitholders of record on August 7, 2018. In addition, the Board declared a distribution on NRP's 12.0% Class A Convertible Preferred Units with respect to the second quarter totaling $7.5 million in cash.

Basis of Presentation (Policies

Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Principles of Consolidation Reporting	Principles of Consolidation and Reporting The accompanying unaudited Consolidated Financial Statements of the Partnership have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") for interim financial information and with Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In management's opinion, all necessary adjustments to fairly present the Partnership's results of operations, financial position and cash flows for the periods presented have been made and all such adjustments were of a normal and recurring nature. Certain reclassifications have been made to prior period amounts on the Statements of Comprehensive Income and Statements of Cash Flows to conform with current period presentation. These reclassifications had no impact on previously reported net income or cash flows from operating, investing or financing activities.
Recently Issued Accounting Standards	Recently Adopted Accounting Standards Revenue Recognition. On January 1, 2018, NRP adopted accounting standard ASC 606, Revenue from Contracts with Customers, and all the related amendments (the “new revenue standard” and "ASC 606") to all open contracts using the modified retrospective method. The adoption of the new revenue standard impacted royalty revenue from NRP's coal and aggregates royalty leases as further described below. NRP recognized a $90.3 million cumulative effect of adoption adjustment in the opening balance of partners' capital on January 1, 2018. Prior year information has not been restated and continues to be reported under the accounting standards in effect for those periods. The new revenue standard had no impact on revenues from NRP's Construction Aggregates or Soda Ash operating segments. A majority of NRP’s coal and aggregates royalty revenue continues to be recognized over the lease term based on production. For coal and aggregates royalty leases for which NRP expects consideration from minimum payments to be greater than consideration from production over the lease term, royalty revenue is now recognized straight-line over the lease term based on the minimum payment consideration. The cumulative effects of the changes made to our Consolidated Balance Sheet at January 1, 2018 for the adoption of the new revenue standard were as follows: (In thousands) Balance at December 31, 2017 Adjustments due to ASC 606 Balance at January 1, 2018 Assets Accounts receivable, net $ 47,026 $ 3,479 $ 50,505 Liabilities Current portion of deferred revenue $ — $ 1,973 $ 1,973 Deferred revenue 100,605 (88,747 ) 11,858 Partners’ capital Common unitholders’ interest $ 199,851 $ 88,448 $ 288,299 General partner’s interest 1,857 1,805 3,662 Total partners’ capital 265,211 90,253 355,464 The impact of adoption of the new revenue standard on NRP’s Consolidated Balance Sheet and Consolidated Statements of Comprehensive Income was as follows: As of June 30, 2018 (In thousands) As Reported Balances without Adoption of ASC 606 Effect of Change Assets Accounts receivable, net $ 59,312 $ 55,325 $ 3,987 Total assets 1,411,806 1,407,819 3,987 Liabilities and capital Current portion of deferred revenue $ 2,732 $ — $ 2,732 Deferred revenue 17,136 102,244 (85,108 ) Total liabilities 857,299 939,675 (82,376 ) Partners’ capital Common unitholders’ interest 326,125 241,489 84,636 General partner’s interest 4,427 2,700 1,727 Total partners’ capital 392,496 306,133 86,363 Total liabilities and capital 1,411,806 1,407,819 3,987 For the Three Months Ended June 30, 2018 (In thousands) As Reported Amounts without Adoption of ASC 606 Effect of Change Coal royalty and other revenues $ 48,711 $ 50,710 $ (1,999 ) Net income from continuing operations 39,123 41,315 (2,192 ) Net income 39,089 41,281 (2,192 ) Net income per common unit (basic) 2.46 2.64 (0.18 ) Net income per common unit (diluted) 1.75 1.85 (0.10 ) For the Six Months Ended June 30, 2018 (In thousands) As Reported Amounts without Adoption of ASC 606 Effect of Change Coal royalty and other revenues $ 94,684 $ 98,381 $ (3,697 ) Net income from continuing operations 65,211 69,101 (3,890 ) Net income 65,163 69,053 (3,890 ) Net income per common unit (basic) 3.95 4.26 (0.31 ) Net income per common unit (diluted) 2.95 3.13 (0.18 ) Recently Issued Accounting Standards Leases . In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The new standard requires a lessee to recognize assets and liabilities on the balance sheet for the present value of the rights and obligations created by all leases with terms of more than 12 months. This standard does not apply to leases that explore for or use minerals, oil, natural gas and similar non-regenerative resources, including the intangible right to explore for those natural resources and rights to use the land in which those natural resources are contained. The guidance also requires disclosures designed to give financial statement users information on the amount, timing and uncertainty of cash flows arising from leases. The guidance is effective for annual and interim periods beginning after December 31, 2018 and is to be adopted using a modified retrospective approach. The Partnership is currently evaluating the impact of the provisions of this guidance on its consolidated financial statements.

Basis of Presentation Basis of

Basis of Presentation Basis of Presentation (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Schedule of Effect of Adoption of New Accounting Policy	The cumulative effects of the changes made to our Consolidated Balance Sheet at January 1, 2018 for the adoption of the new revenue standard were as follows: (In thousands) Balance at December 31, 2017 Adjustments due to ASC 606 Balance at January 1, 2018 Assets Accounts receivable, net $ 47,026 $ 3,479 $ 50,505 Liabilities Current portion of deferred revenue $ — $ 1,973 $ 1,973 Deferred revenue 100,605 (88,747 ) 11,858 Partners’ capital Common unitholders’ interest $ 199,851 $ 88,448 $ 288,299 General partner’s interest 1,857 1,805 3,662 Total partners’ capital 265,211 90,253 355,464 The impact of adoption of the new revenue standard on NRP’s Consolidated Balance Sheet and Consolidated Statements of Comprehensive Income was as follows: As of June 30, 2018 (In thousands) As Reported Balances without Adoption of ASC 606 Effect of Change Assets Accounts receivable, net $ 59,312 $ 55,325 $ 3,987 Total assets 1,411,806 1,407,819 3,987 Liabilities and capital Current portion of deferred revenue $ 2,732 $ — $ 2,732 Deferred revenue 17,136 102,244 (85,108 ) Total liabilities 857,299 939,675 (82,376 ) Partners’ capital Common unitholders’ interest 326,125 241,489 84,636 General partner’s interest 4,427 2,700 1,727 Total partners’ capital 392,496 306,133 86,363 Total liabilities and capital 1,411,806 1,407,819 3,987 For the Three Months Ended June 30, 2018 (In thousands) As Reported Amounts without Adoption of ASC 606 Effect of Change Coal royalty and other revenues $ 48,711 $ 50,710 $ (1,999 ) Net income from continuing operations 39,123 41,315 (2,192 ) Net income 39,089 41,281 (2,192 ) Net income per common unit (basic) 2.46 2.64 (0.18 ) Net income per common unit (diluted) 1.75 1.85 (0.10 ) For the Six Months Ended June 30, 2018 (In thousands) As Reported Amounts without Adoption of ASC 606 Effect of Change Coal royalty and other revenues $ 94,684 $ 98,381 $ (3,697 ) Net income from continuing operations 65,211 69,101 (3,890 ) Net income 65,163 69,053 (3,890 ) Net income per common unit (basic) 3.95 4.26 (0.31 ) Net income per common unit (diluted) 2.95 3.13 (0.18 )

Revenue from Contracts with C26

Revenue from Contracts with Customers (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers by Source	The Partnership's Construction Aggregates segment revenues from contracts with customers by major source are as follows: Three Months Ended Six Months Ended (In thousands) June 30, 2018 Crushed stone, sand and gravel $ 18,070 $ 31,809 Delivery and fuel income 11,678 21,761 Other revenues 4,485 7,087 Total construction aggregates revenues $ 34,233 $ 60,657 Road construction and asphalt paving services 6,176 6,904 Total construction aggregates segment revenues $ 40,409 $ 67,561 The following table represents the Partnership's Coal Royalty and Other segment revenues (including affiliates) by major source: Three Months Ended Six Months Ended (In thousands) June 30, 2018 Coal royalty revenue $ 31,407 $ 60,098 Production lease minimum revenue 102 527 Minimum lease straight-line revenue 6,769 13,529 Wheelage revenue 1,641 3,615 Coal overriding royalty revenue 3,702 6,574 Aggregates royalty revenue 1,572 2,663 Oil and gas royalty revenue 1,354 4,252 Property tax revenue 1,523 2,705 Other revenue 829 1,146 Coal royalty and other revenues (1) $ 48,899 $ 95,109 Transportation and processing services revenue (2) 5,002 10,385 Total Coal royalty and other segment revenues $ 53,901 $ 105,494 (1) Represents revenue from contracts with customers as defined under ASC 606. (2) Revenue from contracts with customers as defined under ASC 606 was $3.1 million and $6.1 million for the three and six months ended June 30, 2018 , respectively. The remaining transportation and processing services revenue of $1.9 million and $4.3 million for the three and six months ended June 30, 2018 , respectively, relates to other NRP-owned infrastructure leased to and operated by third party operators accounted for under ASC 840, Leases.
Schedule of Receivables and Liabilities from Contracts with Customers	The following table details the Partnership's Coal Royalty and Other segment receivables from contracts with customers and contract liabilities: June 30, January 1, (In thousands) 2018 2018 Receivables Total accounts receivable, net (including affiliates) $ 30,448 $ 24,047 Prepaid expenses and other (1) 2,163 2,830 Contract liabilities Current portion of deferred revenue $ 2,732 $ 1,973 Deferred revenue 17,136 11,858 (1) Prepaid expenses and other includes notes receivable from contracts with customers.
Activity Related to Partners' Coal Royalty and Other Segment Deferred Revenue	The following table shows the activity related to the Partnership's Coal Royalty and Other segment deferred revenue: (In thousands) Six Months Ended June 30, 2018 Balance at December 31, 2017 $ 100,605 Cumulative adjustment for change in accounting principle recognized in partners' capital (86,774 ) Balance at January 1, 2018 (current and non-current) $ 13,831 Production leases - revenue impact Recoupments recognized in Coal and aggregates royalty revenue (4,630 ) Production lease minimum revenue (393 ) Minimum leases - revenue impact Minimum lease amortization recognized in Minimum lease straight-line revenue (1,958 ) Contractual minimums due 956 Cash received for minimum payments 12,062 Balance at June 30, 2018 (current and non-current) $ 19,868 The following table shows the Partnership's Coal Royalty and Other segment revenue recognized during the three months ended June 30, 2018 that was included in the deferred revenue balance at the beginning of the period: (In thousands) Production leases - revenue impact Recoupments recognized in Coal and aggregates royalty revenue (2,365 ) Production lease minimum revenue (21 ) Minimum leases - revenue impact Minimum lease amortization recognized in Minimum lease straight-line revenue (1,005 )
Schedule of Annual Minimums by Current Remaining Contract Term	The Partnership's non-cancelable annual minimum payments due under the lease terms of its coal and aggregates royalty leases are as follows: Weighted Average Remaining Years as of June 30, 2018 Annual Minimum Payments (In thousands) Lease Term (1) 1 - 5 years 0.2 $ 7,888 6 - 10 years 2.4 27,439 10+ years 8.2 44,166 (1) The Partnership applied the practical expedient for disclosing remaining performance obligations for contracts with an expected duration of one year or less, and have excluded those contracts from this disclosure.

Class A Convertible Preferred27

Class A Convertible Preferred Units Temporary equity (Tables) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Temporary Equity Disclosure [Abstract]
Temporary Equity [Table Text Block]			Activity related to the Preferred Units is as follows from December 31, 2017 to June 30, 2018 : (In thousands, except unit data) Units Outstanding Financial Position Balance at December 31, 2017 258,844 $ 173,431 Redemption of PIK Units (8,844 ) (8,844 ) Balance at June 30, 2018 250,000 $ 164,587
Temporary Equity [Line Items]
Income attributable to preferred unitholders	$ 7,500	$ 7,538	$ 15,000	$ 10,038
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance			173,431
Ending balance	$ 164,587		$ 164,587

Common and Preferred Unit Dis28

Common and Preferred Unit Distributions (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Distributions Paid	The following table shows the distributions declared and paid to common unitholders during the six months ended June 30, 2018 and 2017 , respectively: Total Distributions (in thousands) Date Paid Period Covered by Distribution Distribution per Common Unit Common Units GP Interest Total 2018 February 14, 2018 October 1 - December 31, 2017 $ 0.45 $ 5,505 $ 112 $ 5,617 May 14, 2018 January 1 - March 31, 2018 $ 0.45 $ 5,510 $ 113 $ 5,623 2017 February 14, 2017 October 1 - December 31, 2016 $ 0.45 $ 5,503 $ 112 $ 5,615 May 12, 2017 January 1 - March 31, 2017 $ 0.45 $ 5,506 $ 113 $ 5,619 Preferred Unit Distributions The following table shows the distributions declared and paid to Preferred Unitholders during the six months ended June 30, 2018 and 2017 , respectively: Date Paid Period Covered by Distribution Distribution per Preferred Unit Total Distribution Declared (in thousands) 2018 February 7, 2018 October 1 - December 31, 2017 $ 30.00 $ 7,765 May 14, 2018 January 1 - March 31, 2018 $ 30.00 $ 7,500 2017 May 30, 2017 March 2 - March 31, 2017 $ 5.00 $ 2,500

Net Income Per Common Unit (Tab

Net Income Per Common Unit (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Reconciliation of Net Income to Weighted Average Units Outstanding	The following table reconciles the numerators and denominators of the basic and diluted net income per common unit computations and calculates basic and diluted net income per common unit: Three Months Ended Six Months Ended (In thousands, except per unit data) 2018 2017 2018 2017 Allocation of net income: Net income from continuing operations $ 39,123 $ 25,857 $ 65,211 $ 31,968 Less: net income attributable to non-controlling interest (869 ) — (869 ) — Less: income attributable to preferred unitholders (7,500 ) (7,538 ) (15,000 ) (10,038 ) Net income from continuing operations attributable to common unitholders and general partner $ 30,754 $ 18,319 $ 49,342 $ 21,930 Less: net income from continuing operations attributable to the general partner (616 ) (434 ) (987 ) (438 ) Net income from continuing operations attributable to common unitholders $ 30,138 $ 17,885 $ 48,355 $ 21,492 Net income (loss) from discontinued operations $ (34 ) $ 133 $ (48 ) $ (74 ) Less: net income (loss) from discontinued operations attributable to the general partner 1 (3 ) 1 1 Net income (loss) from discontinued operations attributable to common unitholders $ (33 ) $ 130 $ (47 ) $ (73 ) Net income $ 39,089 $ 25,990 $ 65,163 $ 31,894 Less: net income attributable to non-controlling interest (869 ) — (869 ) — Less: income attributable to preferred unitholders (7,500 ) (7,538 ) (15,000 ) (10,038 ) Net income attributable to common unitholders and general partner $ 30,720 $ 18,452 $ 49,294 $ 21,856 Less: net income attributable to the general partner (615 ) (437 ) (986 ) (437 ) Net income attributable to common unitholders $ 30,105 $ 18,015 $ 48,308 $ 21,419 Basic income (loss) per common unit: Weighted average common units—basic 12,246 12,232 12,242 12,232 Basic net income from continuing operations per common unit $ 2.46 $ 1.46 $ 3.95 $ 1.76 Basic net income (loss) from discontinued operations per common unit $ — $ 0.01 $ — $ (0.01 ) Basic net income per common unit $ 2.46 $ 1.47 $ 3.95 $ 1.75 Three Months Ended Six Months Ended (In thousands, except per unit data) 2018 2017 2018 2017 Diluted income (loss) per common unit: Weighted average common units—basic 12,246 12,232 12,242 12,232 Plus: dilutive effect of Warrants 522 467 476 361 Plus: dilutive effect of Preferred Units 8,615 9,760 8,615 6,517 Weighted average common units—diluted 21,383 22,459 21,333 19,110 Net income from continuing operations $ 39,123 $ 25,857 $ 65,211 $ 31,968 Less: net income attributable to non-controlling interest (869 ) — (869 ) — Diluted net income from continuing operations attributable to common unitholders and general partner $ 38,254 $ 25,857 $ 64,342 $ 31,968 Less: diluted net income from continuing operations attributable to the general partner (766 ) (586 ) (1,287 ) (639 ) Diluted net income from continuing operations attributable to common unitholders $ 37,488 $ 25,271 $ 63,055 $ 31,329 Diluted net income (loss) from discontinued operations attributable to common unitholders $ (33 ) $ 130 $ (47 ) $ (73 ) Net income $ 39,089 $ 25,990 $ 65,163 $ 31,894 Less: net income attributable to non-controlling interest (869 ) — (869 ) — Diluted net income attributable to common unitholders and general partner $ 38,220 $ 25,990 $ 64,294 $ 31,894 Less: diluted net income attributable to the general partner (765 ) (589 ) (1,286 ) (638 ) Diluted net income attributable to common unitholders $ 37,455 $ 25,401 $ 63,008 $ 31,256 Diluted net income from continuing operations per common unit $ 1.75 $ 1.13 $ 2.96 $ 1.64 Diluted net income (loss) from discontinued operations per common unit $ — $ — $ — $ — Diluted net income per common unit $ 1.75 $ 1.13 $ 2.95 $ 1.64

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table summarizes certain financial information for each of the Partnership's operating segments: Operating Segments (In thousands) Coal Royalty and Other Soda Ash Construction Aggregates Corporate and Financing Total Three Months Ended June 30, 2018 Revenues (including affiliates) $ 53,901 $ 16,529 $ 40,409 $ — $ 110,839 Intersegment revenues (expenses) 74 — (74 ) — — Gain on asset sales, net 168 — 42 — 210 Operating and maintenance expenses 8,117 — 34,249 — 42,366 Depreciation, depletion and amortization 5,376 — 3,187 — 8,563 General and administrative (including affiliates) — — — 3,263 3,263 Other expense, net — — — 17,734 17,734 Net income (loss) from continuing operations 40,650 16,529 2,941 (20,997 ) 39,123 Loss from discontinued operations — — — — (34 ) Three Months Ended June 30, 2017 Revenues (including affiliates) $ 49,626 $ 8,389 $ 33,555 $ — $ 91,570 Intersegment revenues (expenses) 68 — (68 ) — — Gain on asset sales, net 3,184 — 177 — 3,361 Operating and maintenance expenses 5,419 — 27,820 — 33,239 Depreciation, depletion and amortization (including affiliates) 5,375 — 3,030 — 8,405 General and administrative (including affiliates) — — — 2,883 2,883 Other expense, net — — 178 24,369 24,547 Net income (loss) from continuing operations 42,084 8,389 2,636 (27,252 ) 25,857 Income from discontinued operations — — — — 133 Operating Segments (In thousands) Coal Royalty and Other Soda Ash Construction Aggregates Corporate and Financing Total Six Months Ended June 30, 2018 Revenues (including affiliates) $ 105,494 $ 26,150 $ 67,561 $ — $ 199,205 Intersegment revenues (expenses) 115 — (115 ) — — Gain on asset sales, net 819 — 51 — 870 Operating and maintenance expenses 14,332 — 60,467 — 74,799 Depreciation, depletion and amortization 10,476 — 6,044 — 16,520 General and administrative (including affiliates) — — — 7,599 7,599 Asset impairment 242 — — — 242 Other expense, net — — 20 35,684 35,704 Net income (loss) from continuing operations 81,378 26,150 966 (43,283 ) 65,211 Loss from discontinued operations — — — — (48 ) Six Months Ended June 30, 2017 Revenues (including affiliates) $ 100,764 $ 18,683 $ 60,776 $ — $ 180,223 Intersegment revenues (expenses) 130 — (130 ) — — Gain on asset sales, net 3,213 — 192 — 3,405 Operating and maintenance expenses 12,803 — 52,619 — 65,422 Depreciation, depletion and amortization (including affiliates) 12,348 — 6,549 — 18,897 General and administrative (including affiliates) — — — 10,085 10,085 Asset impairment 1,778 — — — 1,778 Other expense, net — — 573 54,905 55,478 Net income (loss) from continuing operations 77,178 18,683 1,097 (64,990 ) 31,968 Loss from discontinued operations — — — — (74 ) As of June 30, 2018 Total assets of continuing operations $ 967,627 $ 245,524 $ 193,721 $ 3,946 $ 1,410,818 Total assets of discontinued operations — — — — 988 As of December 31, 2017 Total assets of continuing operations $ 945,237 $ 245,433 $ 191,374 $ 6,129 $ 1,388,173 Total assets of discontinued operations — — — — 991

Equity Investment (Tables)

Equity Investment (Tables)	6 Months Ended
	Jun. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Summarized Financial Information	Activity related to this investment is as follows: Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Balance at beginning of period $ 241,679 $ 252,803 $ 245,433 $ 255,901 Income allocation to NRP’s equity interests 17,657 9,274 28,489 20,754 Amortization of basis difference (1,128 ) (885 ) (2,339 ) (2,071 ) Comprehensive loss from unconsolidated investment (434 ) (23 ) (1,559 ) (1,165 ) Distribution (12,250 ) (12,250 ) (24,500 ) (24,500 ) Balance at end of period $ 245,524 $ 248,919 $ 245,524 $ 248,919 The following table represents summarized financial information for Ciner Wyoming as derived from the respective unaudited financial statements for the three and six months ended June 30, 2018 and 2017 , respectively: Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Sales $ 91,882 $ 119,737 $ 213,101 $ 246,309 Gross profit 14,022 24,219 42,244 52,916 Net Income 36,035 18,926 58,142 42,354

Plant and Equipment, Net (Table

Plant and Equipment, Net (Tables)	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Plant and Equipment	The Partnership’s plant and equipment consist of the following: June 30, December 31, (In thousands) 2018 2017 Plant and equipment $ 89,686 $ 84,173 Construction in process 1,383 803 Less accumulated depreciation (43,152 ) (38,806 ) Total plant and equipment, net $ 47,917 $ 46,170

Mineral Rights, Net (Tables)

Mineral Rights, Net (Tables)	6 Months Ended
	Jun. 30, 2018
Extractive Industries [Abstract]
Mineral Rights	The Partnership’s mineral rights consist of the following: June 30, 2018 (In thousands) Carrying Value Accumulated Depletion Net Book Value Coal properties $ 1,169,862 $ (444,332 ) $ 725,530 Aggregates properties 150,642 (19,103 ) 131,539 Oil and gas royalty properties 12,395 (7,395 ) 5,000 Other 13,161 (1,514 ) 11,647 Total mineral rights, net $ 1,346,060 $ (472,344 ) $ 873,716 December 31, 2017 (In thousands) Carrying Value Accumulated Depletion Net Book Value Coal properties $ 1,170,104 $ (436,964 ) $ 733,140 Aggregates properties 150,642 (16,836 ) 133,806 Oil and gas royalty properties 12,395 (7,158 ) 5,237 Other 13,168 (1,466 ) 11,702 Total mineral rights, net $ 1,346,309 $ (462,424 ) $ 883,885

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The Partnership's intangible assets included on its Consolidated Balance Sheets are as follows: June 30, December 31, (In thousands) 2018 2017 Intangible assets $ 86,336 $ 86,336 Less: accumulated amortization (38,412 ) (36,782 ) Total intangible assets, net $ 47,924 $ 49,554

Debt, Net (Tables)

Debt, Net (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Long-Term Debt	The Partnership's debt consists of the following: June 30, December 31, (In thousands) 2018 2017 NRP LP debt: 10.500% senior notes, with semi-annual interest payments in March and September, due March 2022, $241 million issued at par and $105 million issued at 98.75% $ 345,638 $ 345,638 Opco debt: Revolving credit facility 95,000 60,000 Senior notes 4.91% with semi-annual interest payments in June and December, with annual principal payments in June, due June 2018 — 4,586 8.38% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2019 21,334 42,670 5.05% with semi-annual interest payments in January and July, with annual principal payments in July, due July 2020 22,946 22,946 5.55% with semi-annual interest payments in June and December, with annual principal payments in June, due June 2023 13,429 16,115 4.73% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2023 44,693 44,693 5.82% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 89,589 104,520 8.92% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 27,200 31,733 5.03% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 120,547 120,547 5.18% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 34,396 34,396 $ 814,772 $ 827,844 Net unamortized debt discount (1,463 ) (1,661 ) Net unamortized debt issuance costs (14,974 ) (16,835 ) Total debt, net $ 798,335 $ 809,348 Less: current portion of long-term debt 75,188 79,740 Total long-term debt, net $ 723,147 $ 729,608

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Contractual Override, Note Receivable and Long-Term Debt	The following table shows the carrying amount and estimated fair value of the Partnership's debt and contracts receivable: June 30, 2018 December 31, 2017 (In thousands) Carrying Estimated Carrying Estimated Debt: NRP 2022 Senior Notes (1) $ 332,214 $ 372,857 $ 330,404 $ 366,376 Opco Senior Notes (2) 371,121 403,597 418,944 447,538 Opco Revolving Credit Facility (3) 95,000 95,000 60,000 60,000 Assets: Contracts receivable, current and long-term (4) $ 42,061 $ 29,491 $ 43,826 $ 30,517 (1) The Level 1 fair value is based upon quotations obtained for identical instruments on the closing trading prices near period end. (2) Due to no observable quoted prices on these instruments, the Level 3 fair value is estimated by management using quotations obtained for the NRP Senior Notes on the closing trading prices near period end. (3) The Level 3 fair value approximates the outstanding borrowing amount because the interest rates are variable and reflective of market rates and the terms of the credit facility allow the Partnership to repay this debt at any time without penalty. (4) The Level 3 fair value is determined based on the present value of future cash flow projections related to the underlying assets.

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	Revenues and expenses related to transactions with Foresight Energy are included in the Partnership's Consolidated Statements of Comprehensive Income as follows: Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Revenues Coal royalty and other $ 8,022 $ 643 $ 15,070 $ 643 Coal royalty and other—affiliates — 10,051 — 21,203 Transportation and processing services 4,968 4,146 10,351 4,146 Transportation and processing services—affiliate — 1,374 — 6,013 Expenses Operating and maintenance expense $ 411 $ 285 $ 812 $ 285 Operating and maintenance expense—affiliates — 117 — 452 The following table shows certain amounts related to NRP's Sugar Camp rail load out facility financing lease: June 30, December 31, (In thousands) 2018 2017 Projected remaining payments $ 68,977 $ 71,452 Unearned income 26,695 28,366
Summary of Reimbursements	Direct general and administrative expenses charged to the Partnership by QMC and WPPLP are included in the Partnership's Consolidated Statement of Comprehensive Income as follows: Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Operating and maintenance expenses—affiliates $ 1,727 $ 1,799 $ 3,634 $ 3,965 General and administrative—affiliates 849 852 1,780 1,976

Major Customers (Tables)

Major Customers (Tables)	6 Months Ended
	Jun. 30, 2018
Risks and Uncertainties [Abstract]
Major customers	Revenues from customers that exceeded 10 percent of total revenues and other income for any of the periods presented below are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Revenues Percent Revenues Percent Revenues Percent Revenues Percent Foresight Energy $ 12,990 11.7 % $ 16,255 17.1 % $ 25,421 12.7 % $ 32,046 17.5 % Revenues from Foresight Energy are included within the Partnership's Coal Royalty and Other segment.

Unit-Based Compensation (Tables

Unit-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
Unit-Based Compensation [Abstract]
Summary of Activity in Awards	A summary of the activity during six months ended June 30, 2018 is as follows: (In thousands) Common Units Weighted Average Exercise Price Outstanding at January 1, 2018 — $ — Granted 75 $ 29.16 Fully vested and issued (14 ) $ 29.44 Forfeitures — $ — Outstanding at June 30, 2018 61 $ 29.10

Basis of Presentation - Narrati

Basis of Presentation - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital	$ 392,496		$ 392,496		$ 355,464	$ 265,211
Net Income	38,220	$ 25,990	64,294	$ 31,894
Effect of Change | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital	$ 86,363		$ 86,363		$ 90,253

Basis of Presentation - Summary

Basis of Presentation - Summary of Effect of New Accounting Pronouncement on Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	$ 59,312	$ 50,505	$ 47,026
Current portion of deferred revenue	2,732	1,973	0
Deferred revenue	17,136	11,858	100,605
Common unitholders’ interest	326,125	288,299	199,851
General partner’s interest	4,427	3,662	1,857
Cumulative effect of adoption of accounting standard (See Note 2)		90,253
Partners' Capital	392,496	355,464	265,211
Amounts without Adoption of ASC 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	55,325		47,026
Current portion of deferred revenue	0		0
Deferred revenue	102,244		100,605
Common unitholders’ interest	241,489		199,851
General partner’s interest	2,700		1,857
Partners' Capital	306,133		$ 265,211
Accounting Standards Update 2014-09 | Effect of Change
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	3,987	3,479
Current portion of deferred revenue	2,732	1,973
Deferred revenue	(85,108)	(88,747)
Common unitholders’ interest	84,636	88,448
General partner’s interest	1,727	1,805
Partners' Capital	$ 86,363	$ 90,253

Basis of Presentation - Summa42

Basis of Presentation - Summary of Effect of New Accounting Pronouncement on Statement of Comprehensive Income and Balance Sheet (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
(In thousands)
Coal royalty and other revenues	$ 110,839	$ 91,570	$ 199,205		$ 180,223
Operating and maintenance expenses	38,301	31,020	68,269		60,648
Net income from continuing operations	39,123	25,857	65,211		31,968
Net income	$ 39,089	$ 25,990	$ 65,163	[1]	$ 31,894
Net income per common unit (basic)	$ 2.46	$ 1.47	$ 3.95		$ 1.75
Net income per common unit (diluted)	$ 1.75	$ 1.13	$ 2.95		$ 1.64
(In thousands)
Accounts receivable, net	$ 59,312		$ 59,312			$ 50,505	$ 47,026
Total assets	1,411,806		1,411,806				1,389,164
Current portion of deferred revenue	2,732		2,732			1,973	0
Deferred revenue	17,136		17,136			11,858	100,605
Total liabilities	857,299		857,299				953,916
Common unitholders’ interest	326,125		326,125			288,299	199,851
General partner’s interest	4,427		4,427			3,662	1,857
Total partners’ capital	392,496		392,496			355,464	265,211
Total liabilities and capital	1,411,806		1,411,806				1,389,164
Amounts without Adoption of ASC 606
(In thousands)
Coal royalty and other revenues	50,710		98,381
Net income from continuing operations	41,315		69,101
Net income	$ 41,281		$ 69,053
Net income per common unit (basic)	$ 2.64		$ 4.26
Net income per common unit (diluted)	$ 1.85		$ 3.13
(In thousands)
Accounts receivable, net	$ 55,325		$ 55,325				47,026
Total assets	1,407,819		1,407,819
Current portion of deferred revenue	0		0				0
Deferred revenue	102,244		102,244				100,605
Total liabilities	939,675		939,675
Common unitholders’ interest	241,489		241,489				199,851
General partner’s interest	2,700		2,700				1,857
Total partners’ capital	306,133		306,133				$ 265,211
Total liabilities and capital	1,407,819		1,407,819
Accounting Standards Update 2014-09 | Effect of Change
(In thousands)
Coal royalty and other revenues	(1,999)		(3,697)
Net income from continuing operations	(2,192)		(3,890)
Net income	$ (2,192)		$ (3,890)
Net income per common unit (basic)	$ (0.18)		$ (0.31)
Net income per common unit (diluted)	$ (0.10)		$ (0.18)
(In thousands)
Accounts receivable, net	$ 3,987		$ 3,987			3,479
Total assets	3,987		3,987
Current portion of deferred revenue	2,732		2,732			1,973
Deferred revenue	(85,108)		(85,108)			(88,747)
Total liabilities	(82,376)		(82,376)
Common unitholders’ interest	84,636		84,636			88,448
General partner’s interest	1,727		1,727			1,805
Total partners’ capital	86,363		86,363			$ 90,253
Total liabilities and capital	3,987		3,987
Coal Royalty and Other
(In thousands)
Coal royalty and other revenues	$ 48,711	$ 32,768	$ 94,684		$ 67,762
[1]	Net income includes $15.0 million attributable to Preferred Unitholders that accumulated during the period, of which $14.7 million is allocated to the common unitholders and $0.3 million is allocated to the general partner.

Revenue from Contracts with C43

Revenue from Contracts with Customers - Schedule of Partnerships' Coal Royalty and Other Segment Revenues from Contracts with Customers (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	$ 53,901,000		$ 105,494,000
Revenue, Net	110,839,000	$ 91,570,000	199,205,000	$ 180,223,000
Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	48,899,000		95,109,000
Revenue, Net	48,711,000	32,768,000	94,684,000	67,762,000
Coal Royalty and Other | Coal royalty revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	31,407,000		60,098,000
Coal Royalty and Other | Production lease minimum revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	102,000		527,000
Coal Royalty and Other | Minimum lease straight-line revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	6,769,000		13,529,000
Coal Royalty and Other | Wheelage revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	1,641,000		3,615,000
Coal Royalty and Other | Coal overriding royalty revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	3,702,000		6,574,000
Coal Royalty and Other | Aggregates royalty revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	1,572,000		2,663,000
Coal Royalty and Other | Oil and gas royalty revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	1,354,000		4,252,000
Coal Royalty and Other | Property tax revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	1,523,000		2,705,000
Coal Royalty and Other | Other revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	829,000		1,146,000
Coal Royalty and Other | Transportation and processing services revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	3,100,000		6,051,043
Revenue, Net	5,002,000	$ 4,146,000	10,385,000	$ 4,146,000
Coal Royalty and Other | Transportation and Processing
Disaggregation of Revenue [Line Items]
Lease revenue	$ 1,900,000		$ 4,300,000

Revenue from Contracts with C44

Revenue from Contracts with Customers - Narrative (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Jul. 31, 2013	Jan. 31, 2013
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	$ 53,901,000	$ 105,494,000
Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	48,899,000	95,109,000
Construction Aggregates
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	34,233,000	$ 60,657,000
Minimum
Disaggregation of Revenue [Line Items]
Lease term		5 years
Recoupable period		3 years
Maximum
Disaggregation of Revenue [Line Items]
Lease term		40 years
Recoupable period		5 years
Operating Segments | Construction Aggregates
Disaggregation of Revenue [Line Items]
Trade Accounts Receivable	$ 24,700,000	$ 24,700,000	$ 23,000,000
Ciner Wyoming
Disaggregation of Revenue [Line Items]
Noncontrolling interest (percent)	49.00%	49.00%		49.00%	48.51%
Royalty Leases
Disaggregation of Revenue [Line Items]
Minimum lease payments due 2023	$ 1,800,000	$ 1,800,000
Minimum lease payments expiring upon exhaustion	1,000,000	1,000,000
Production lease minimum revenue | Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	102,000	527,000
Transportation and processing services revenue | Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	3,100,000	6,051,043
Transportation and Processing | Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Lease revenue	$ 1,900,000	$ 4,300,000

Revenue from Contracts with C45

Revenue from Contracts with Customers - Schedule of Receivables and Liabilities from Contracts with Customers (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Total accounts receivable, net (including affiliates)	$ 30,448	$ 24,047
Prepaid expenses and other	2,163	2,830
Current portion of deferred revenue	2,732	1,973	$ 0
Deferred revenue	$ 17,136	$ 11,858	$ 100,605

Revenue from Contracts with C46

Revenue from Contracts with Customers - Activity Related to Partners' Coal Royalty and Other Segment Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jan. 01, 2018
Disaggregation of Revenue [Line Items]
Balance beginning of period		$ 100,605
Deferred revenue	$ 19,868	100,605	$ 13,831
Production lease minimum revenue	(21)	(393)
Recoupments recognized in Coal and aggregates royalty revenue	(2,365)	(4,630)
Minimum lease amortization recognized in Minimum lease straight-line revenue	(1,005)	(1,958)
Contractual minimums due		956
Cash received for minimum payments		12,062
Balance end of period	19,868	19,868
Total Coal royalty and other segment revenues	53,901	105,494
Accounting Standards Update 2014-09
Disaggregation of Revenue [Line Items]
Deferred revenue			$ (86,774)
Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	48,899	95,109
Coal Royalty and Other | Minimum lease straight-line revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	$ 6,769	$ 13,529

Revenue from Contracts with C47

Revenue from Contracts with Customers - Schedule of Annual Minimums by Current Remaining Contract Term (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	2 months
Annual Minimum Payments	$ 7,888
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	2 years 5 months
Annual Minimum Payments	$ 27,439
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	8 years 2 months
Annual Minimum Payments	$ 44,166

Revenue from Contracts with C48

Revenue from Contracts with Customers - Schedule of Segment Revenue from Customers by Major Source (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 Coal royalty and other segment revenues	$ 53,901		$ 105,494
Gain on asset sales, net	210	$ 3,361	870	$ 3,405
Construction Aggregates
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	34,233		60,657
Total construction aggregates segment revenues	40,409		67,561
Construction Aggregates | Crushed stone, sand and gravel
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	18,070		31,809
Construction Aggregates | Delivery and fuel income
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	11,678		21,761
Construction Aggregates | Other revenue
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	4,485		$ 7,087
Construction Aggregates | Road construction and asphalt paving services
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	$ 6,176

Class A Convertible Preferred49

Class A Convertible Preferred Units and Warrants - Preferred Units and Warrants Issued (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 02, 2017	Jun. 30, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Preferred Units, net		$ 164,587	$ 173,431
Warrant holders’ interest		$ 66,816	$ 66,816
Preferred Units, Issued		250,000	258,844
Preferred unit par value per unit		$ 1,000	$ 1,000
Preferred Stock
Class of Stock [Line Items]
Transaction price, gross	$ 250,000
Class A Convertible Preferred Units
Class of Stock [Line Items]
Preferred Units, Issued	250,000
Preferred unit par value per unit	$ 1,000
Preferred Units, Origination Fee, Percent	2.50%
Preferred Stock, Dividend Rate, Percentage		12.00%

Class A Convertible Preferred50

Class A Convertible Preferred Units and Warrants - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 02, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Class of Stock [Line Items]
Preferred Units, Issued		250,000		258,844
Preferred unit purchase price		$ 1,000		$ 1,000
Class A Convertible Preferred Units
Class of Stock [Line Items]
Distributions, Preferred Stock, Paid-in-Kind, Cash Redemption Payment		$ 8,844	$ 0
Preferred Units, Issued	250,000
Preferred unit purchase price	$ 1,000
Preferred Units, Origination Fee, Percent	2.50%
Preferred Stock, Dividend Rate, Percentage		12.00%
Warrants at $34.00 Strike [Member] | Warrant Holders
Class of Stock [Line Items]
Class of Warrant or Right, Warrants Issued		2,250,000
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 34
Preferred Stock
Class of Stock [Line Items]
Transaction price, gross	$ 250,000

Class A Convertible Preferred51

Class A Convertible Preferred Units and Warrants - Financial Position (Details) - USD ($) shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Class of Stock [Line Items]
Preferred Units, net	$ 164,587		$ 173,431
Preferred Partner | Preferred Stock
Class of Stock [Line Items]
Preferred Units outstanding	250,000		258,844
Preferred Units, net	$ 164,587		$ 173,431
Class A Convertible Preferred Units
Class of Stock [Line Items]
Distributions, Preferred Stock, Paid-in-Kind, Cash Redemption Payment	$ (8,844)	$ 0

Common and Preferred Unit Dis52

Common and Preferred Unit Distributions Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Temporary Equity [Line Items]
Income attributable to preferred unitholders	$ (7,500)	$ (7,538)	$ (15,000)	$ (10,038)
Class A Convertible Preferred Units
Temporary Equity [Line Items]
Preferred Stock, Dividend Rate, Percentage			12.00%
General Partner
Temporary Equity [Line Items]
General partner's general partner distribution			2.00%

Common and Preferred Unit Dis53

Common and Preferred Unit Distributions Schedule of Distributions Paid (Details) - USD ($) $ / shares in Units, $ in Thousands	May 14, 2018	Feb. 14, 2018	May 30, 2017	May 12, 2017	Feb. 14, 2017	Jun. 30, 2018	Jun. 30, 2017
Common unitholders and general partner
Distribution per common unit (in dollars per share)	$ 0.45	$ 0.45		$ 0.45	$ 0.45
Total distributions paid	$ 5,623	$ 5,617		$ 5,619	$ 5,615	$ 11,240
Common unitholders
Distributions to common unitholders and general partner	(5,510)	(5,505)		(5,506)	(5,503)
Preferred Partner
Distributions to common unitholders and general partner						(15,265)	$ (1,250)
Total distributions paid						15,265
General Partner
Distributions to common unitholders and general partner						$ (11,240)	$ (11,234)
Distributions paid to general partners	$ 113	$ 112		$ 113	$ 112
Preferred Stock | Preferred Partner
Distribution per common unit (in dollars per share)	$ 30	$ 30	$ 5
Total Distribution Declared (in thousands)	$ 7,500	$ 7,765	$ 2,500

Net Income Per Common Unit (Det

Net Income Per Common Unit (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
Allocation of net income:
Net income from continuing operations	$ 39,123	$ 25,857	$ 65,211		$ 31,968
Less: net income attributable to non-controlling interest	(869)	0	(869)		0
Less: income attributable to preferred unitholders	(7,500)	(7,538)	(15,000)		(10,038)
Net income from continuing operations attributable to common unitholders and general partner	30,754	18,319	49,342		21,930
Less: net income from continuing operations attributable to the general partner	(616)	(434)	(987)		(438)
Net income from continuing operations attributable to common unitholders	30,138	17,885	48,355		21,492
Net income (loss) from discontinued operations	(34)	133	(48)		(74)
Less: net income (loss) from discontinued operations attributable to the general partner	1	(3)	1		1
Net income (loss) from discontinued operations attributable to common unitholders	(33)	130	(47)		(73)
Net income	39,089	25,990	65,163	[1]	31,894
Net income attributable to common unitholders and general partner	30,720	18,452	49,294		21,856
Less: net income attributable to the general partner	(615)	(437)	(986)		(437)
Net income attributable to common unitholders	30,105	18,015	48,308		21,419
Net Income	38,220	25,990	64,294		31,894
Diluted net income attributable to common unitholders and general partner	38,220	25,990	64,294		31,894
Diluted net income from continuing operations attributable to common unitholders and general partner	$ 38,254	$ 25,857	$ 64,342		$ 31,968
Basic Income (Loss) per Unit:
Weighted average common units (in shares)	12,246	12,232	12,242		12,232
Basic net income from continuing operations per common unit	$ 2.46	$ 1.46	$ 3.95		$ 1.76
Basic net income (loss) from discontinued operations per common unit	0	0.01	0		(0.01)
Basic net income per common unit	$ 2.46	$ 1.47	$ 3.95		$ 1.75
Diluted income (loss) per common unit:
Dilutive effect of Warrants (in shares)	522	467	476		361
Dilutive effect of Preferred Units (in shares)	8,615	9,760	8,615		6,517
Weighted average common units—diluted (in shares)	21,383	22,459	21,333		19,110
Less: diluted net income from continuing operations attributable to the general partner	$ (766)	$ (586)	$ (1,287)		$ (639)
Diluted net income from continuing operations attributable to common unitholders	37,488	25,271	63,055		31,329
Diluted net income (loss) from discontinued operations attributable to common unitholders	(33)	130	(47)		(73)
Less: diluted net income attributable to the general partner	(765)	(589)	(1,286)		(638)
Diluted net income attributable to common unitholders	$ 37,455	$ 25,401	$ 63,008		$ 31,256
Diluted net income per common unit from continuing operations (in dollars per share)	$ 1.75	$ 1.13	$ 2.96		$ 1.64
Diluted net income (loss) from discontinued operations per common unit (in dollars per share)	0	0	0		0
Diluted net income per common unit (in dollars per share)	1.75	$ 1.13	$ 2.95		$ 1.64
Warrant Holders | Warrants at $34.00 Strike [Member]
Class of Warrant or Right, Warrants Issued			2,250
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 34		$ 34
[1]	Net income includes $15.0 million attributable to Preferred Unitholders that accumulated during the period, of which $14.7 million is allocated to the common unitholders and $0.3 million is allocated to the general partner.

Segment Information - Additiona

Segment Information - Additional Information (Details) - segment	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2013	Jan. 31, 2013
Segment Reporting Information [Line Items]
Number of operating segments	3
Ciner Wyoming
Segment Reporting Information [Line Items]
Percentage of partnership interest owned (percent)	49.00%	49.00%	48.51%

Segment Information - Schedule

Segment Information - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues and other income	$ 110,839	$ 91,570	$ 199,205	$ 180,223
Gain on asset sales, net	210	3,361	870	3,405
Operating and maintenance expenses (including affiliates)	42,366	33,239	74,799	65,422
Depreciation, depletion and amortization	8,563	8,405	16,520	18,897
General and administrative (including affiliates)	3,263	2,883	7,599	10,085
Asset impairments	0	0	242	1,778
Other expense, net	17,734	24,547	35,704	55,478
Net income (loss) from continuing operations	39,123	25,857	65,211	31,968
Net income (loss) from discontinued operations	(34)	133	(48)	(74)
Total assets	1,411,806		1,411,806		$ 1,389,164
Corporate and Financing
Segment Reporting Information [Line Items]
Revenues and other income	0	0	0	0
Gain on asset sales, net	0	0	0	0
Operating and maintenance expenses (including affiliates)	0	0	0	0
Depreciation, depletion and amortization	0	0	0	0
General and administrative (including affiliates)	3,263	2,883	7,599	10,085
Asset impairments			0	0
Other expense, net	(17,734)	24,369	35,684	54,905
Net income (loss) from continuing operations	(20,997)	(27,252)	(43,283)	(64,990)
Net income (loss) from discontinued operations	0	0	0	0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues and other income	0	0	0	0
Coal Royalty and Other
Segment Reporting Information [Line Items]
Revenues and other income	48,711	32,768	94,684	67,762
Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income	53,901	49,626	105,494	100,764
Gain on asset sales, net	168	3,184	819	3,213
Operating and maintenance expenses (including affiliates)	8,117	5,419	14,332	12,803
Depreciation, depletion and amortization	5,376	5,375	10,476	12,348
General and administrative (including affiliates)	0	0	0	0
Asset impairments			242	1,778
Other expense, net	0	0	0	0
Net income (loss) from continuing operations	40,650	42,084	81,378	77,178
Net income (loss) from discontinued operations	0	0	0	0
Coal Royalty and Other | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues and other income	74	68	115	130
Soda Ash
Segment Reporting Information [Line Items]
Revenues and other income	16,529	8,389	26,150	18,683
Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income	16,529	8,389	26,150	18,683
Gain on asset sales, net	0	0	0	0
Operating and maintenance expenses (including affiliates)	0	0	0	0
Depreciation, depletion and amortization	0	0	0	0
General and administrative (including affiliates)	0	0	0	0
Asset impairments			0	0
Other expense, net	0	0	0	0
Net income (loss) from continuing operations	16,529	8,389	26,150	18,683
Net income (loss) from discontinued operations	0	0	0	0
Soda Ash | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues and other income	0	0	0	0
Construction Aggregates
Segment Reporting Information [Line Items]
Revenues and other income	34,233	27,363	60,657	52,846
Construction Aggregates | Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income	40,409	33,555	67,561	60,776
Gain on asset sales, net	42	177	51	192
Operating and maintenance expenses (including affiliates)	34,249	27,820	60,467	52,619
Depreciation, depletion and amortization	3,187	3,030	6,044	6,549
General and administrative (including affiliates)	0	0	0	0
Asset impairments			0	0
Other expense, net	0	(178)	(20)	(573)
Net income (loss) from continuing operations	2,941	2,636	966	1,097
Net income (loss) from discontinued operations	0	0	0	0
Construction Aggregates | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues and other income	(74)	$ (68)	(115)	$ (130)
Continuing Operations
Segment Reporting Information [Line Items]
Total assets	1,410,818		1,410,818		1,388,173
Continuing Operations | Corporate and Financing
Segment Reporting Information [Line Items]
Total assets	3,946		3,946		6,129
Continuing Operations | Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Total assets	967,627		967,627		945,237
Continuing Operations | Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Total assets	245,524		245,524		245,433
Continuing Operations | Construction Aggregates | Operating Segments
Segment Reporting Information [Line Items]
Total assets	193,721		193,721		191,374
Discontinued Operations
Segment Reporting Information [Line Items]
Total assets	988		988		991
Discontinued Operations | Corporate and Financing
Segment Reporting Information [Line Items]
Total assets	0		0		0
Discontinued Operations | Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Total assets	0		0		0
Discontinued Operations | Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Total assets	0		0		0
Discontinued Operations | Construction Aggregates | Operating Segments
Segment Reporting Information [Line Items]
Total assets	$ 0		$ 0		$ 0

Equity Investment - Additional

Equity Investment - Additional Information (Detail)	Jun. 30, 2018	Jul. 31, 2013	Jan. 31, 2013
Ciner Wyoming
Schedule of Equity Method Investments [Line Items]
Percentage of partnership interest owned (percent)	49.00%	49.00%	48.51%

Equity Investment - Schedule o

Equity Investment - Schedule of Summarized Financial Information of Unaudited Financial Statements (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity Method Investments [Roll Forward]
Balance at beginning of period			$ 245,433
Comprehensive loss from unconsolidated investment	$ 38,655	$ 25,977	63,604	$ 30,749
Balance at end of period	245,524		245,524
Net Income	38,220	25,990	64,294	31,894
Ciner Wyoming
Equity Method Investments [Roll Forward]
Balance at beginning of period	241,679	252,803	245,433	255,901
Income allocation to NRP’s equity interests	17,657	9,274	28,489	20,754
Amortization of basis difference	1,128	885	2,339	2,071
Comprehensive loss from unconsolidated investment	(434)	(23)	(1,559)	(1,165)
Cash Dividends Paid to Parent Company by Unconsolidated Subsidiaries	(12,250)	(12,250)	(24,500)	(24,500)
Balance at end of period	245,524	248,919	245,524	248,919
Sales	91,882	119,737	213,101	246,309
Gross profit	14,022	24,219	42,244	52,916
Net Income	$ 36,035	$ 18,926	$ 58,142	$ 42,354

Plant and Equipment, Net - Plan

Plant and Equipment, Net - Plant and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Plant and equipment	$ 89,686	$ 84,173
Construction in process	1,383	803
Less accumulated depreciation	(43,152)	(38,806)
Total plant and equipment, net	$ 47,917	$ 46,170

Plant and Equipment, Net - Addi

Plant and Equipment, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Line Items]
Depreciation expense on plant and equipment	$ 2.6	$ 2.5	$ 5	$ 5.4

Mineral Rights, Net - Mineral R

Mineral Rights, Net - Mineral Rights (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	$ 1,346,060	$ 1,346,309
Accumulated Depletion	(472,344)	(462,424)
Net Book Value	873,716	883,885
Coal Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	1,169,862	1,170,104
Accumulated Depletion	(444,332)	(436,964)
Net Book Value	725,530	733,140
Aggregate Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	150,642	150,642
Accumulated Depletion	(19,103)	(16,836)
Net Book Value	131,539	133,806
Oil And Gas Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	12,395	12,395
Accumulated Depletion	(7,395)	(7,158)
Net Book Value	5,000	5,237
Other Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	13,161	13,168
Accumulated Depletion	(1,514)	(1,466)
Net Book Value	11,647	$ 11,702
Hillsboro Property [Member] | Coal Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Net Book Value	$ 235,000

Mineral Rights, Net - Additiona

Mineral Rights, Net - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Total depletion and amortization expense on mineral interests	$ 5,100	$ 5,000	$ 9,900	$ 11,700
Asset impairments	0	$ 0	242	$ 1,778
Mineral rights, net	873,716		873,716		$ 883,885
Coal Mineral Rights
Mineral rights, net	725,530		725,530		733,140
Oil And Gas Mineral Rights
Mineral rights, net	5,000		5,000		5,237
Other Mineral Rights
Mineral rights, net	$ 11,647		$ 11,647		$ 11,702
Hillsboro Property [Member] | Coal Mineral Rights
Mineral Rights, Tons	179,000		179,000
Asset impairments			$ 0
Mineral rights, net	$ 235,000		$ 235,000
Foresight Energy Lp
Asset impairments	$ 110,700

Intangible Assets, Net - Intang

Intangible Assets, Net - Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 86,336	$ 86,336
Less accumulated amortization	(38,412)	(36,782)
Total intangible assets, net	$ 47,924	$ 49,554

Intangible Assets, Net - Additi

Intangible Assets, Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Intangible Assets [Line Items]
Amortization expense—affiliate	$ 0	$ 240	$ 0	$ 1,008
Amortization expense	$ 800	$ 600	$ 1,600	$ 800

Debt, Net - Debt (Detail)

Debt, Net - Debt (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal balance	$ 814,772,000	$ 827,844,000
Net unamortized debt discount	(1,463,000)	(1,661,000)
Net unamortized debt issuance costs	(14,974,000)	(16,835,000)
Total debt	798,335,000	809,348,000
Less - current portion of long term debt	75,188,000	79,740,000
Total long-term debt, net	723,147,000	729,608,000
NRP LP | 10.5% senior notes, with semi-annual interest payments in March and September, maturing March 2022 [Member]
Debt Instrument [Line Items]
Principal balance	$ 345,638,000	345,638,000
NRP LP | Senior Notes Due Two Zero Two Two [Member]
Debt Instrument [Line Items]
Interest rate	10.50%
Senior Notes, Face Amount	$ 345,638,000
NRP LP | Senior Notes Due October Two Zero One Eight [Member]
Debt Instrument [Line Items]
Interest rate	9.125%
Senior Notes, Face Amount	$ 425,000,000
Opco | Senior Notes
Debt Instrument [Line Items]
Principal balance	374,100,000	422,200,000
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty [Member]
Debt Instrument [Line Items]
Floating rate revolving credit facility	150,000,000
Principal balance	95,000,000	60,000,000
Line of Credit Facility, Remaining Borrowing Capacity	$ 55,000,000
Opco | 4.91% senior notes, with semi-annual interest payments in June and December, with annual principal payments in June, maturing in June 2018
Debt Instrument [Line Items]
Interest rate	4.91%
Principal balance	$ 0	4,586,000
Opco | 8.38% senior notes, with semi-annual interest payments in March and September, with annual principal payments in March, maturing in March 2019 [Member]
Debt Instrument [Line Items]
Interest rate	8.38%
Principal balance	$ 21,334,000	42,670,000
Opco | 5.05% senior notes, with semi-annual interest payments in January and July, with annual principal payments in July, maturing in July 2020 [Member]
Debt Instrument [Line Items]
Interest rate	5.05%
Principal balance	$ 22,946,000	22,946,000
Opco | 5.55% senior notes, with semi-annual interest payments in June and December, with annual principal payments in June, maturing in June 2023 [Member]
Debt Instrument [Line Items]
Interest rate	5.55%
Principal balance	$ 13,429,000	16,115,000
Opco | 4.73% senior notes, with semi-annual interest payments in June and December, with scheduled principal payments beginning December 2014, maturing in December 2023 [Member]
Debt Instrument [Line Items]
Interest rate	4.73%
Principal balance	$ 44,693,000	44,693,000
Opco | 5.82% senior notes, with semi-annual interest payments in March and September, with annual principal payments in March, maturing in March 2024 [Member]
Debt Instrument [Line Items]
Interest rate	5.82%
Principal balance	$ 89,589,000	104,520,000
Opco | 8.92% senior notes, with semi-annual interest payments in March and September, with scheduled principal payments beginning March 2014, maturing in March 2024 [Member]
Debt Instrument [Line Items]
Interest rate	8.92%
Principal balance	$ 27,200,000	31,733,000
Opco | 5.03% senior notes, with semi-annual interest payments in June and December, with scheduled principal payments beginning December 2014, maturing in December 2026 [Member]
Debt Instrument [Line Items]
Interest rate	5.03%
Principal balance	$ 120,547,000	120,547,000
Opco | 5.18% senior notes, with semi-annual interest payments in June and December, with scheduled principal payments beginning December 2014, maturing in December 2026 [Member]
Debt Instrument [Line Items]
Interest rate	5.18%
Principal balance	$ 34,396,000	$ 34,396,000
Opco | Utility Local Improvement Obligation Due March Two Zero Two One [Member]
Debt Instrument [Line Items]
Interest rate	5.31%
Senior Notes Offering Price Two [Member] | NRP LP | Senior Notes Due Two Zero Two Two [Member]
Debt Instrument [Line Items]
Floating rate revolving credit facility	$ 240,638,000
Senior Note issue percentage	100.00%
Senior Notes Offering Price Two [Member] | NRP LP | Senior Notes Due October Two Zero One Eight [Member]
Debt Instrument [Line Items]
Floating rate revolving credit facility	$ 125,000,000
Senior Note issue percentage	99.50%
Senior Notes Offering Price One [Member] | NRP LP | Senior Notes Due Two Zero Two Two [Member]
Debt Instrument [Line Items]
Floating rate revolving credit facility	$ 105,000,000
Senior Note issue percentage	98.75%
Senior Notes Offering Price One [Member] | NRP LP | Senior Notes Due October Two Zero One Eight [Member]
Debt Instrument [Line Items]
Floating rate revolving credit facility	$ 300,000,000
Senior Note issue percentage	99.007%

Debt, Net - Additional Informat

Debt, Net - Additional Information (Detail)	3 Months Ended	6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Debt issuance cost capitalized	$ 14,974,000	$ 14,974,000			$ 16,835,000
Principal balance	814,772,000	814,772,000			827,844,000
Senior Notes due 2022
Debt Instrument [Line Items]
Principal balance	$ 332,214,000	$ 332,214,000			330,404,000
NRP LP | 9.125% senior notes, with semi-annual interest payments in April and October, maturing October 2018
Debt Instrument [Line Items]
Rate of senior notes	9.125%	9.125%
Senior Notes, Face Amount	$ 425,000,000	$ 425,000,000
NRP LP | Senior Notes Offering Price One [Member] | 9.125% senior notes, with semi-annual interest payments in April and October, maturing October 2018
Debt Instrument [Line Items]
Floating rate revolving credit facility	$ 300,000,000	$ 300,000,000
Senior Note issue percentage	99.007%	99.007%
Opco | Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period	6.18%	6.08%	5.22%
Debt issuance cost capitalized	$ 3,100,000	$ 3,100,000			4,600,000
Collateral carrying amount	$ 642,600,000	$ 642,600,000			649,700,000
Opco | 8.38% senior notes, with semi-annual interest payments in March and September, with annual principal payments in March, maturing in March 2019 [Member]
Debt Instrument [Line Items]
Rate of senior notes	8.38%	8.38%
Principal balance	$ 21,334,000	$ 21,334,000			42,670,000
Opco | 8.92% senior notes, with semi-annual interest payments in March and September, with scheduled principal payments beginning March 2014, maturing in March 2024 [Member]
Debt Instrument [Line Items]
Rate of senior notes	8.92%	8.92%
Principal balance	$ 27,200,000	$ 27,200,000			31,733,000
Opco | Senior Notes
Debt Instrument [Line Items]
Principal balance	$ 374,100,000	374,100,000			422,200,000
Principal payments on its senior notes		$ 48,100,000	$ 48,100,000
Partnership leverage ratio		3.75
Additional interest accrue	2.00%	2.00%
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty [Member]
Debt Instrument [Line Items]
Floating rate revolving credit facility	$ 150,000,000	$ 150,000,000
Principal balance	95,000,000	95,000,000			$ 60,000,000
Line of Credit Facility, Remaining Borrowing Capacity	$ 55,000,000	$ 55,000,000
Opco | Scenario, Forecast [Member] | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty [Member]
Debt Instrument [Line Items]
Floating rate revolving credit facility				$ 100,000,000

Fair Value Measurements - Contr

Fair Value Measurements - Contracts Receivable and Debt (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3	$ 0	$ 0	$ 0	$ 0
Carrying Value	814,772,000		814,772,000		$ 827,844,000
Contracts receivable—affiliate, current and long-term	42,061,000		42,061,000		43,826,000
Embedded Derivative, Fair Value of Embedded Derivative Liability	0		0		0
Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contracts receivable—affiliate, current and long-term	29,491,000		29,491,000		30,517,000
Senior Notes due 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	332,214,000		332,214,000		330,404,000
Senior Notes due 2022 | Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	372,857,000		372,857,000		366,376,000
Opco Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	371,121,000		371,121,000		418,944,000
Opco Senior Notes | Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	403,597,000		403,597,000		447,538,000
Opco Revolving Credit Facility And Term Loan Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	95,000,000		95,000,000		60,000,000
Opco Revolving Credit Facility And Term Loan Facility | Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	$ 95,000,000		$ 95,000,000		$ 60,000,000

Fair Value Measurements - Embed

Fair Value Measurements - Embedded Derivatives (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Equity [Abstract]
Embedded Derivative, Fair Value of Embedded Derivative Liability	$ 0	$ 0

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($) $ in Thousands	May 09, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Operating and maintenance expenses—affiliates		$ 4,065	$ 2,219	$ 6,530	$ 4,774
Amount payable to related parties		1,453		1,453		$ 562
Accounts receivable—affiliates		140		$ 140		161
Cline Affiliates
Related Party Transaction [Line Items]
Rate of interest in the partnerships general partner	31.00%			31.00%
Operating and maintenance expenses—affiliates		0	117	$ 0	452
Quintana Minerals [Member]
Related Party Transaction [Line Items]
Amount payable to related parties		400		400		400
Western Pocahontas Properties [Member]
Related Party Transaction [Line Items]
Amount payable to related parties		1,100		1,100		100
Western Pocahontas Properties Limited Partnership [Member] | Affiliated Entity
Related Party Transaction [Line Items]
Operating and maintenance expenses—affiliates		2,300	300	2,900	400
Other assets—affiliate						200
Corsa
Related Party Transaction [Line Items]
Royalty Revenue from Coal		200	400	400	700
Accounts receivable—affiliates		$ 100		100		$ 200
Quinwood Coal Company [Member]
Related Party Transaction [Line Items]
Deferred Revenue, Revenue Recognized			$ 900	$ 0	$ 900

Related Party Transactions - Sc

Related Party Transactions - Schedule of Related Party Transactions (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Related Party Transaction [Line Items]
Revenue, Net	$ 110,839,000	$ 91,570,000	$ 199,205,000	$ 180,223,000
Operating Expenses	54,192,000	44,527,000	99,160,000	96,182,000
Operating and maintenance expenses—affiliates	4,065,000	2,219,000	6,530,000	4,774,000
Cline Affiliates
Related Party Transaction [Line Items]
Operating Expenses	411,000	285,000	812,000	285,000
Operating and maintenance expenses—affiliates	0	117,000	0	452,000
Coal Sales | Foresight Energy Lp
Related Party Transaction [Line Items]
Revenues	8,022,000	643,000	15,070,000	643,000
Coal royalty and other—affiliates	0	10,051,000	0	21,203,000
Transportation and Processing | Foresight Energy Lp
Related Party Transaction [Line Items]
Revenue, Net	4,968,000		10,351,000
Transportation and Processing - Affiliates | Foresight Energy Lp
Related Party Transaction [Line Items]
Coal royalty and other—affiliates	0	1,374,000	0	6,013,000
Coal Royalty and Other
Related Party Transaction [Line Items]
Coal royalty and other—affiliates	188,000	11,338,000	425,000	22,843,000
Revenue, Net	48,711,000	32,768,000	94,684,000	67,762,000
Coal Royalty and Other | Transportation and processing services revenue
Related Party Transaction [Line Items]
Revenue, Net	5,002,000	4,146,000	10,385,000	4,146,000
Coal Royalty and Other | Transportation and Processing - Affiliates
Related Party Transaction [Line Items]
Coal royalty and other—affiliates	$ 0	$ 1,374,000	$ 0	$ 6,013,000

Related Party Transactions - 71

Related Party Transactions - Schedule of Sugar Camp Transactions (Details) - Sugar Camp - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Projected remaining payments	$ 68,977	$ 71,452
Unearned income	$ 26,695	$ 28,366

Related Party Transactions - Su

Related Party Transactions - Summary of Reimbursements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Related Party Transaction [Line Items]
Operating and maintenance expenses—affiliates	$ 4,065	$ 2,219	$ 6,530	$ 4,774
General and administrative—affiliates	849	852	1,780	1,976
Western Pocahontas Properties and Quintana Minerals Corporation [Member] | Affiliated Entity
Related Party Transaction [Line Items]
Operating and maintenance expenses—affiliates	$ 1,727	$ 1,799	$ 3,634	$ 3,965

Major Customers (Detail)

Major Customers (Detail) - Foresight Energy Lp - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Concentration Risk [Line Items]
Revenues	$ 12,990	$ 16,255	$ 25,421	$ 32,046
Sales Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	11.70%	17.10%	12.70%	17.50%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	6 Months Ended	36 Months Ended
	Jun. 30, 2018	Dec. 31, 2015	Jul. 31, 2013	Jan. 31, 2013
Lawsuit Against Macoupin Energy, LLC
Commitments And Contingencies [Line Items]
Damages sought, value	$ 10,100,000
Anadarko Holding Company
Commitments And Contingencies [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High				$ 50,000,000
Ciner Wyoming | Anadarko Holding Company
Commitments And Contingencies [Line Items]
Equity Investment Contingent Consideration Paid		$ 11,500,000
OCI LP | Ciner Wyoming
Commitments And Contingencies [Line Items]
Percentage of partnership interest owned (percent)				1.00%
Ciner Wyoming
Commitments And Contingencies [Line Items]
Percentage of partnership interest owned (percent)	49.00%		49.00%	48.51%
Pending Litigation [Member] | Lawsuit Against Hillsboro Energy LLC
Commitments And Contingencies [Line Items]
Minimum quarterly deficiency payments	$ 7,500,000
Loss Contingency, Loss in Period, Interest	15,200,000
Loss Contingency, Loss in Period	91,000,000
Pending Litigation [Member] | Minimum | Anadarko Holding Company
Commitments And Contingencies [Line Items]
Minimum deficiency payments	0
Pending Litigation [Member] | Maximum | Anadarko Holding Company
Commitments And Contingencies [Line Items]
Minimum deficiency payments	$ 40,000,000

Unit-Based Compensation (Detail

Unit-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	800,000	800,000
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	61,000	61,000	0
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 29.10	$ 29.10	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		75,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price		$ 29.16
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number	(14,000)	(14,000)
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 29.44	$ 29.44
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period		0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price		$ 0
Stock Granted, Value, Share-based Compensation, Gross		$ 2.2
Allocated Share-based Compensation Expense	$ 0.2	0.8
Unaccrued Cost Associated With Outstanding Grants And Related Distribution Equivalent Rights	$ 1.4	$ 1.4
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term		2 years 6 months 24 days
Board Members [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Granted, Value, Share-based Compensation, Gross		$ 0.6
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Issued in Period, Fair Value		$ 0.4

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jul. 26, 2018	Jun. 30, 2018
Subsequent Event [Member]
Subsequent Event [Line Items]
Distribution per common unit (in dollars per share)	$ 0.45
Dividends, Preferred Stock	$ 7.5
Class A Convertible Preferred Units
Subsequent Event [Line Items]
Preferred Stock, Dividend Rate, Percentage		12.00%

Uncategorized Items - nrp-20180

Label	Element	Value
General Partner [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 1,805,000
Common Stock [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	88,448,000
Partners Capital Excluding Noncontrolling Interest [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 90,253,000