Natural Resource Partners (NRP) 10-Q 8 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 01, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Period End Date	Mar. 31, 2019
Document Fiscal Period Focus	Q1
Trading Symbol	NRP
Entity Registrant Name	NATURAL RESOURCE PARTNERS LP
Entity Central Index Key	0001171486
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Common Stock, Shares Outstanding		12,261,199

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 112,374	$ 101,839
Restricted cash	17,333	104,191
Accounts receivable, net	37,023	32,058
Prepaid expenses and other	4,141	3,462
Current assets of discontinued operations	998	993
Total current assets	171,869	242,543
Land	24,008	24,008
Plant and equipment, net	893	984
Mineral rights, net	739,570	743,112
Intangible assets, net	41,754	42,513
Equity in unconsolidated investment	249,936	247,051
Long-term contracts receivable	38,464	38,945
Other assets	5,677	2,491
Total assets	1,272,171	1,341,647
Current liabilities:
Accounts payable	1,797	2,414
Accrued liabilities	6,200	12,347
Accrued interest	4,312	14,345
Current portion of deferred revenue	4,614	3,509
Current portion of long-term debt, net	46,024	115,184
Current liabilities of discontinued operations	727	947
Total current liabilities	63,674	148,746
Deferred revenue	52,473	49,044
Long-term debt, net	541,677	557,574
Other non-current liabilities	4,720	1,150
Total liabilities	662,544	756,514
Commitments and contingencies	0	0
Class A Convertible Preferred Units (250,000 units issued and outstanding at $1,000 par value per unit; liquidation preference of $1,500 per unit)	164,587	164,587
Partners’ capital:
Common unitholders’ interest (12,261,199 and 12,249,469 units issued and outstanding at March 31, 2019 and December 31, 2018, respectively)	378,140	355,113
General partner’s interest	5,476	5,014
Warrant holders’ interest	66,816	66,816
Accumulated other comprehensive loss	(2,457)	(3,462)
Total partners’ capital	447,975	423,481
Non-controlling interest	(2,935)	(2,935)
Total capital	445,040	420,546
Total liabilities and capital	$ 1,272,171	$ 1,341,647

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common units outstanding (in shares)	12,261,199	12,249,469
Common units issued (in shares)	12,261,199	12,249,469
Preferred Units, Issued	250,000	250,000
Preferred units outstanding (in shares)	250,000	250,000
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
		Mar. 31, 2019	Mar. 31, 2018
Revenues		$ 66,785	$ 59,478
Gain on asset sales		256	651
Total revenues and other income		67,041	60,129
Operating expenses
Operating and maintenance expenses		8,360	6,215
Depreciation, depletion and amortization		4,392	5,100
General and administrative expenses		4,350	4,336
Asset impairments		0	242
Total operating expenses		17,102	15,893
Income from operations		49,939	44,236
Other expense, net
Interest expense, net		(14,174)	(17,950)
Net income from continuing operations		35,765	26,286
Loss from discontinued operations		(46)	(1,948)
Net income		35,719	24,338
Net income attributable to NRP	[1]	35,719	24,338
Income attributable to preferred unitholders		(7,500)	(7,500)
Net income attributable to common unitholders and general partner		28,219	16,838
Net income attributable to common unitholders		27,655	16,501
Net income attributable to the general partner		$ 564	$ 337
Income from continuing operations per common unit
Basic (in dollars per share)		$ 2.26	$ 1.50
Diluted (in dollars per share)		1.75	1.16
Net income per common unit
Basic (in dollars per share)		2.26	1.35
Diluted (in dollars per share)		$ 1.75	$ 1.08
Comprehensive income (loss) from unconsolidated investment and other		$ 1,005	$ (1,125)
Comprehensive income		36,724	23,213
Coal Royalty and Other
Revenues		49,502	44,474
Soda Ash
Revenues		11,682	9,621
Transportation and processing services revenues | Coal Royalty and Other
Revenues		$ 5,601	$ 5,383
[1]	Net income includes $7.5 million attributable to Preferred Unitholders that accumulated during the period, of which $7.35 million is allocated to the common unitholders and $0.15 million is allocated to the general partner

Consolidated Statements of Part

Consolidated Statements of Partners' Capital - 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	24,338	[1]	487	[1]	$ 23,851	[1]			24,338	[1]	0
Distributions to unitholders													$ (5,505)		$ (112)	$ (5,617)	$ (5,617)	$ (7,765)	$ (155)	$ (7,610)	$ (7,765)
Issuance of unit-based awards (units)					14
Issuance of unit-based awards	410				$ 410				410
Unit-based awards amortization and vesting	197				197				197
Comprehensive income from unconsolidated investment and other	(1,117)		8		$ 0			(1,125)	(1,117)		0
Balance, end of period (in shares) at Mar. 31, 2018					12,246
Balance, end of period at Mar. 31, 2018	342,729		3,494		$ 280,251		66,816	(4,438)	346,123		(3,394)
Income attributable to preferred unitholders	7,500											$ 7,350		$ (150)
Balance, beginning of period (in shares) at Dec. 31, 2018					12,249
Balance, beginning of period at Dec. 31, 2018	420,546		5,014		$ 355,113		66,816	(3,462)	423,481		(2,935)
Net income	35,719	[1]	714	[1]	$ 35,005	[1]			35,719	[1]	0
Distributions to unitholders													$ (5,513)		$ (112)	$ (5,625)	$ (5,625)	$ (7,500)	$ (150)	$ (7,350)	$ (7,500)
Issuance of unit-based awards (units)					12
Issuance of unit-based awards	486				$ 486				486
Unit-based awards amortization and vesting	399				399				399
Comprehensive income from unconsolidated investment and other	1,015		10		$ 0			1,005	1,015		0
Balance, end of period (in shares) at Mar. 31, 2019					12,261
Balance, end of period at Mar. 31, 2019	445,040		$ 5,476		$ 378,140		$ 66,816	$ (2,457)	$ 447,975		$ (2,935)
Income attributable to preferred unitholders	$ 7,500											$ 7,350		$ 150
[1]	Net income includes $7.5 million attributable to Preferred Unitholders that accumulated during the period, of which $7.35 million is allocated to the common unitholders and $0.15 million is allocated to the general partner

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net income	$ 35,719	$ 24,338
Adjustments to reconcile net income to net cash provided by operating activities of continuing operations:
Depreciation, depletion and amortization	4,392	5,100
Distributions from unconsolidated investment	9,800	10,153
Equity earnings from unconsolidated investment	(11,682)	(9,621)
Gain on asset sales	256	651
Loss from discontinued operations	46	1,948
Asset impairments	0	242
Unit-based compensation expense	901	687
Amortization of debt issuance costs and other	1,796	1,154
Change in operating assets and liabilities:
Accounts receivable	(4,927)	(10,027)
Accounts payable	(616)	869
Accrued liabilities	(6,164)	(5,042)
Accrued interest	(10,033)	(9,777)
Deferred revenue	4,534	5,361
Other items, net	(678)	2,680
Net cash provided by operating activities of continuing operations	22,832	17,414
Net cash provided by operating activities of discontinued operations	121	2,385
Net cash provided by operating activities	22,953	19,799
Cash flows from investing activities
Distributions from unconsolidated investment in excess of cumulative earnings	0	2,097
Proceeds from sale of assets	256	656
Return of long-term contract receivable	441	487
Net cash provided by investing activities of continuing operations	697	3,240
Net cash used in investing activities of discontinued operations	(390)	(3,413)
Net cash provided by (used in) investing activities	307	(173)
Cash flows from financing activities
Borrowings on revolving credit facility	0	35,000
Repayments of loans	(86,468)	(40,800)
Contributions from (to) discontinued operations	(269)	1,408
Debt issuance costs and other	(10)	226
Net cash used in financing activities of continuing operations	(99,852)	(26,844)
Net cash provided by (used in) financing activities of discontinued operations	269	(1,457)
Net cash used in financing activities	(99,583)	(28,301)
Net decrease in cash, cash equivalents and restricted cash	(76,323)	(8,675)
Cash, cash equivalents and restricted cash of continuing operations at beginning of period	129,707	20,790
Cash, cash equivalents and restricted cash of discontinued operations	0	(362)
Cash, cash equivalents and restricted cash at beginning of period	206,030	29,827
Cash, cash equivalents and restricted cash at end of period	129,707	21,152
Cash paid during the period for interest of continuing operations	23,422	26,023
General Partner
Cash flows from financing activities
Distributions to common unitholders and general partner	(5,625)	(5,617)
Preferred Partner
Cash flows from financing activities
Distributions to common unitholders and general partner	(7,500)	(7,765)
Class A Convertible Preferred Units
Cash flows from financing activities
Distributions, Preferred Stock, Paid-in-Kind, Cash Redemption Payment	$ 0	$ (8,844)

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2019
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, managing and leasing a diversified portfolio of mineral properties in the United States, including interests in coal and other natural resources and owns a non-controlling 49% interest in Ciner Wyoming LLC ("Ciner Wyoming"), a producer of natural soda ash. The Partnership is organized into two operating segments further described in Note 7. Segment Information . 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 Consolidated Balance Sheets, Consolidated Statements of Comprehensive Income and Consolidated 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. Recasting of Certain Prior Period Information As described in Note 4. Discontinued Operations , the Partnership reclassified prior period information for the assets and liabilities, operating results and cash flows of its construction aggregates business as discontinued operations in its consolidated financial statements for all periods presented. Restricted Cash Restricted cash at March 31, 2019 and December 31, 2018 represents the remaining net proceeds from the sale of the Partnership's construction aggregates business that is required to be used to repay debt, make acquisitions or make capital expenditures per the terms of the Partnership's and Opco's debt agreements. In the first quarter of 2019, the Partnership used $86.5 million of restricted cash to repay principal amounts on the Opco Senior Notes, and it intends to use the remaining restricted cash to repay a portion of the 2019 amortization payments on the Opco Senior Notes. Recently Adopted Accounting Standards Leases On January 1, 2019, NRP adopted Accounting Standards Codification (ASC) 842, Leases, and all the related amendments (the “new lease standard” and "ASC 842") and recognized 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 required disclosures designed to give financial statement users information on the amount, timing and uncertainty of cash flows arising from leases. The guidance was adopted on January 1, 2019 using a modified retrospective approach. The Partnership is a lessee in one lease that is accounted for as an operating lease under the new lease standard and the adoption of the new lease standard did not have a material impact to the Partnership's consolidated financial statements. For lease agreements entered into or reassessed after the adoption of Topic 842, the Partnership elected to not combine lease and non-lease components. See Note 3. Leases for more information. Recently Issued Accounting Standards Credit Losses In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326). The new standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The new standard replaces today's "incurred loss" model with an "expected credit loss" model that requires entities to estimate an expected lifetime credit loss on financial assets, including trade accounts receivable. The guidance is effective for annual and interim periods beginning after December 15, 2019 and is to be adopted using a modified retrospective approach. The Partnership is currently evaluating the provisions of this guidance on its consolidated financial statements.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer	Revenues from Contracts with Customers The following table represents the Partnership's Coal Royalty and Other segment revenues by major source: Three Months Ended March 31, (In thousands) 2019 2018 Coal royalty revenues $ 32,131 $ 31,002 Production lease minimum revenues 2,700 2,535 Minimum lease straight-line revenues 3,316 603 Property tax revenues 1,433 1,182 Wheelage revenues 1,415 1,974 Coal overriding royalty revenues 3,975 2,872 Lease amendment revenues 771 — Aggregates royalty revenues 1,464 1,091 Oil and gas royalty revenues 1,719 2,898 Other revenues 578 317 Coal royalty and other revenues (1) $ 49,502 $ 44,474 Transportation and processing services revenues (2) 5,601 5,383 Total Coal royalty and other segment revenues $ 55,103 $ 49,857 (1) Coal royalty and other revenues from contracts with customers as defined under ASC 606. (2) Transportation and processing services revenues from contracts with customers as defined under ASC 606 was $2.9 million and $3.0 million for the three months ended March 31, 2019 and 2018 , respectively. The remaining transportation and processing services revenue of $2.7 million and $2.4 million for the three months ended March 31, 2019 , and 2018 respectively, related to other NRP-owned infrastructure leased to and operated by third party operators accounted for under other guidance. See Note 3. Leases for more information. The following table details the Partnership's Coal Royalty and Other segment receivables and liabilities resulting from contracts with customers: March 31, December 31, (In thousands) 2019 2018 Receivables Accounts receivable, net $ 34,036 $ 29,001 Prepaid expenses and other (1) 3,416 2,483 Contract liabilities Current portion of deferred revenue $ 4,614 $ 3,509 Deferred revenue 52,473 49,044 (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: Three Months Ended March 31, (In thousands) 2019 2018 Balance at end of prior period (current and non-current) $ 52,553 $ 100,605 Cumulative adjustment for change in accounting principle — (65,591 ) Balance at beginning of period (current and non-current) $ 52,553 $ 35,014 Increase due to minimums and lease amendment fees 11,877 9,026 Recognition of previously deferred revenue (7,343 ) (5,591 ) Balance at end of period (current and non-current) $ 57,087 $ 38,449 The Partnership's non-cancelable annual minimum payments due under the lease terms of its coal and aggregates royalty and overriding royalty leases are as follows: Lease Term (1) Weighted Average Remaining Years as of March 31, 2019 Annual Minimum Payments (In thousands) 0 - 5 years 2.8 $ 15,681 5 - 10 years 6.6 13,352 10+ years 13.9 50,135 Total 10.5 $ 79,168 (1) Lease term does not include renewal periods.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases Lessee Accounting Under ASC 842 As of March 31, 2019, the Partnership had one operating lease for an office building that is owned by Western Pocahontas Properties Limited Partnership ("WPPLP"), an affiliate of the Partnership as further discussed in Note 13. Related Party Transactions . On January 1, 2019, the Partnership entered into a new lease of the building with a five -year base term and five additional five -year renewal options. Upon adoption and as of March 31, 2019, the Partnership was reasonably certain to exercise all renewal options included in the lease and capitalized the right-of-use asset and corresponding lease liability on its Consolidated Balance Sheets using the present value of the future lease payments over 30 years. The Partnership's right-of-use asset and lease liability included within Other assets and Other non-current liabilities, respectively, on its Consolidated Balance Sheets totaled $3.5 million at both January 1, 2019 and March 31, 2019, respectively. During the three months ended March 31, 2019, the Partnership incurred $0.1 million in total operating lease expenses included in both Operating and maintenance expenses and General and administrative expenses in its Consolidated Statement of Comprehensive Income. The following table details the maturity analysis of the Partnership's operating lease liability and reconciles the undiscounted cash flows to the operating lease liability included in its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of March 31, 2019 2019 $ 362 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,373 Less: present value adjustment (2) (10,860 ) Total operating lease liability $ 3,513 (1) The remaining lease term of the Partnership's operating lease is 29.75 years. (2) The present value of the operating lease liability on the Partnership's Consolidated Balance Sheet was calculated using a 13.5% discount rate which represents the Partnership's estimated incremental borrowing rate under the lease. As the Partnership's lease does not provide an implicit rate, the Partnership estimated the incremental borrowing rate at the time the lease was entered into by utilizing the rate of the Partnership's secured debt and adjusting it for factors that reflect the profile of borrowing over the 30 -year expected lease term. Lessor Accounting as a Lease Under ASC 842 The Partnership owns transportation and processing infrastructure related to certain of its coal properties, including loadout and other transportation assets at the Partnership's Macoupin property in the Illinois Basin which is operated by Foresight Energy. The infrastructure at the Macoupin property is leased to a subsidiary of Foresight Energy and is accounted for as an operating lease under ASC 842. The lease with Macoupin expires in January 2108. From the inception of this lease in 2009 through January 2039, the lease provides that the Partnership is entitled to variable lease payments in the form of throughput fees determined based on the amount of coal transported and processed utilizing the Partnership's assets. These fees are included in Transportation and processing services revenues in the Partnership's Consolidated Statements of Comprehensive Income and were $1.2 million and $1.1 million in the three months ended March 31, 2019 and 2018, respectively. After January 2039, the lease provides that the Partnership is entitled to an annual rent of $10 thousand per year in place of the variable lease payments. Lessor Accounting as a Financing Transaction Under ASC 310, Receivables The Partnership owns rail loadout and associated infrastructure at the Sugar Camp mine in the Illinois Basin operated by a subsidiary of Foresight Energy LP. The infrastructure at the Sugar Camp mine is leased to a subsidiary of Foresight Energy and is accounted for as a financing transaction (the "Sugar Camp lease"). The Sugar Camp lease expires in 2032 with renewal options for up to 80 additional years. There is no option to purchase the infrastructure at the end of the lease. Minimum payments are $5.0 million per year through the end of the lease term and represent a $1.25 million per quarter deficiency payment. The Partnership is also entitled to variable payments in the form of throughput fees determined based on the amount of coal transported and processed utilizing the Partnership's assets. In the event the Sugar Camp lease is renewed beyond 2032, payments become a fixed $10 thousand per year for the remainder of the renewed term. The following table shows certain amounts related to the Partnership's Sugar Camp lease: (In thousands) March 31, 2019 December 31, 2018 Accounts receivable $ 602 $ 661 Contract receivable (current and long-term) 40,331 40,776 Unearned income 24,252 25,058 Projected remaining payments $ 65,185 $ 66,495 The following table details the maturity analysis of the Partnership's operating lease liability and reconciles the undiscounted cash flows to the operating lease liability included in its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of March 31, 2019 2019 $ 362 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,373 Less: present value adjustment (2) (10,860 ) Total operating lease liability $ 3,513 (1) The remaining lease term of the Partnership's operating lease is 29.75 years. (2) The present value of the operating lease liability on the Partnership's Consolidated Balance Sheet was calculated using a 13.5% discount rate which represents the Partnership's estimated incremental borrowing rate under the lease. As the Partnership's lease does not provide an implicit rate, the Partnership estimated the incremental borrowing rate at the time the lease was entered into by utilizing the rate of the Partnership's secured debt and adjusting it for factors that reflect the profile of borrowing over the 30 -year expected lease term.
Leases	Leases Lessee Accounting Under ASC 842 As of March 31, 2019, the Partnership had one operating lease for an office building that is owned by Western Pocahontas Properties Limited Partnership ("WPPLP"), an affiliate of the Partnership as further discussed in Note 13. Related Party Transactions . On January 1, 2019, the Partnership entered into a new lease of the building with a five -year base term and five additional five -year renewal options. Upon adoption and as of March 31, 2019, the Partnership was reasonably certain to exercise all renewal options included in the lease and capitalized the right-of-use asset and corresponding lease liability on its Consolidated Balance Sheets using the present value of the future lease payments over 30 years. The Partnership's right-of-use asset and lease liability included within Other assets and Other non-current liabilities, respectively, on its Consolidated Balance Sheets totaled $3.5 million at both January 1, 2019 and March 31, 2019, respectively. During the three months ended March 31, 2019, the Partnership incurred $0.1 million in total operating lease expenses included in both Operating and maintenance expenses and General and administrative expenses in its Consolidated Statement of Comprehensive Income. The following table details the maturity analysis of the Partnership's operating lease liability and reconciles the undiscounted cash flows to the operating lease liability included in its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of March 31, 2019 2019 $ 362 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,373 Less: present value adjustment (2) (10,860 ) Total operating lease liability $ 3,513 (1) The remaining lease term of the Partnership's operating lease is 29.75 years. (2) The present value of the operating lease liability on the Partnership's Consolidated Balance Sheet was calculated using a 13.5% discount rate which represents the Partnership's estimated incremental borrowing rate under the lease. As the Partnership's lease does not provide an implicit rate, the Partnership estimated the incremental borrowing rate at the time the lease was entered into by utilizing the rate of the Partnership's secured debt and adjusting it for factors that reflect the profile of borrowing over the 30 -year expected lease term. Lessor Accounting as a Lease Under ASC 842 The Partnership owns transportation and processing infrastructure related to certain of its coal properties, including loadout and other transportation assets at the Partnership's Macoupin property in the Illinois Basin which is operated by Foresight Energy. The infrastructure at the Macoupin property is leased to a subsidiary of Foresight Energy and is accounted for as an operating lease under ASC 842. The lease with Macoupin expires in January 2108. From the inception of this lease in 2009 through January 2039, the lease provides that the Partnership is entitled to variable lease payments in the form of throughput fees determined based on the amount of coal transported and processed utilizing the Partnership's assets. These fees are included in Transportation and processing services revenues in the Partnership's Consolidated Statements of Comprehensive Income and were $1.2 million and $1.1 million in the three months ended March 31, 2019 and 2018, respectively. After January 2039, the lease provides that the Partnership is entitled to an annual rent of $10 thousand per year in place of the variable lease payments. Lessor Accounting as a Financing Transaction Under ASC 310, Receivables The Partnership owns rail loadout and associated infrastructure at the Sugar Camp mine in the Illinois Basin operated by a subsidiary of Foresight Energy LP. The infrastructure at the Sugar Camp mine is leased to a subsidiary of Foresight Energy and is accounted for as a financing transaction (the "Sugar Camp lease"). The Sugar Camp lease expires in 2032 with renewal options for up to 80 additional years. There is no option to purchase the infrastructure at the end of the lease. Minimum payments are $5.0 million per year through the end of the lease term and represent a $1.25 million per quarter deficiency payment. The Partnership is also entitled to variable payments in the form of throughput fees determined based on the amount of coal transported and processed utilizing the Partnership's assets. In the event the Sugar Camp lease is renewed beyond 2032, payments become a fixed $10 thousand per year for the remainder of the renewed term. The following table shows certain amounts related to the Partnership's Sugar Camp lease: (In thousands) March 31, 2019 December 31, 2018 Accounts receivable $ 602 $ 661 Contract receivable (current and long-term) 40,331 40,776 Unearned income 24,252 25,058 Projected remaining payments $ 65,185 $ 66,495
Leases	Leases Lessee Accounting Under ASC 842 As of March 31, 2019, the Partnership had one operating lease for an office building that is owned by Western Pocahontas Properties Limited Partnership ("WPPLP"), an affiliate of the Partnership as further discussed in Note 13. Related Party Transactions . On January 1, 2019, the Partnership entered into a new lease of the building with a five -year base term and five additional five -year renewal options. Upon adoption and as of March 31, 2019, the Partnership was reasonably certain to exercise all renewal options included in the lease and capitalized the right-of-use asset and corresponding lease liability on its Consolidated Balance Sheets using the present value of the future lease payments over 30 years. The Partnership's right-of-use asset and lease liability included within Other assets and Other non-current liabilities, respectively, on its Consolidated Balance Sheets totaled $3.5 million at both January 1, 2019 and March 31, 2019, respectively. During the three months ended March 31, 2019, the Partnership incurred $0.1 million in total operating lease expenses included in both Operating and maintenance expenses and General and administrative expenses in its Consolidated Statement of Comprehensive Income. The following table details the maturity analysis of the Partnership's operating lease liability and reconciles the undiscounted cash flows to the operating lease liability included in its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of March 31, 2019 2019 $ 362 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,373 Less: present value adjustment (2) (10,860 ) Total operating lease liability $ 3,513 (1) The remaining lease term of the Partnership's operating lease is 29.75 years. (2) The present value of the operating lease liability on the Partnership's Consolidated Balance Sheet was calculated using a 13.5% discount rate which represents the Partnership's estimated incremental borrowing rate under the lease. As the Partnership's lease does not provide an implicit rate, the Partnership estimated the incremental borrowing rate at the time the lease was entered into by utilizing the rate of the Partnership's secured debt and adjusting it for factors that reflect the profile of borrowing over the 30 -year expected lease term. Lessor Accounting as a Lease Under ASC 842 The Partnership owns transportation and processing infrastructure related to certain of its coal properties, including loadout and other transportation assets at the Partnership's Macoupin property in the Illinois Basin which is operated by Foresight Energy. The infrastructure at the Macoupin property is leased to a subsidiary of Foresight Energy and is accounted for as an operating lease under ASC 842. The lease with Macoupin expires in January 2108. From the inception of this lease in 2009 through January 2039, the lease provides that the Partnership is entitled to variable lease payments in the form of throughput fees determined based on the amount of coal transported and processed utilizing the Partnership's assets. These fees are included in Transportation and processing services revenues in the Partnership's Consolidated Statements of Comprehensive Income and were $1.2 million and $1.1 million in the three months ended March 31, 2019 and 2018, respectively. After January 2039, the lease provides that the Partnership is entitled to an annual rent of $10 thousand per year in place of the variable lease payments. Lessor Accounting as a Financing Transaction Under ASC 310, Receivables The Partnership owns rail loadout and associated infrastructure at the Sugar Camp mine in the Illinois Basin operated by a subsidiary of Foresight Energy LP. The infrastructure at the Sugar Camp mine is leased to a subsidiary of Foresight Energy and is accounted for as a financing transaction (the "Sugar Camp lease"). The Sugar Camp lease expires in 2032 with renewal options for up to 80 additional years. There is no option to purchase the infrastructure at the end of the lease. Minimum payments are $5.0 million per year through the end of the lease term and represent a $1.25 million per quarter deficiency payment. The Partnership is also entitled to variable payments in the form of throughput fees determined based on the amount of coal transported and processed utilizing the Partnership's assets. In the event the Sugar Camp lease is renewed beyond 2032, payments become a fixed $10 thousand per year for the remainder of the renewed term. The following table shows certain amounts related to the Partnership's Sugar Camp lease: (In thousands) March 31, 2019 December 31, 2018 Accounts receivable $ 602 $ 661 Contract receivable (current and long-term) 40,331 40,776 Unearned income 24,252 25,058 Projected remaining payments $ 65,185 $ 66,495

Discontinued Operations

Discontinued Operations	3 Months Ended
	Mar. 31, 2019
Discontinued Operations [Abstract]
Discontinued Operations	Discontinued Operations In December 2018, the Partnership sold VantaCore Partners LLC, its construction aggregates business, and in July 2016, NRP Oil and Gas LLC ("NRP Oil and Gas") sold its non-operated oil and gas working interest assets. The Partnership's exit from both its construction aggregates business and non-operated oil and gas working interest business represented strategic shifts to reduce debt and focus on its Coal Royalty and Other and Soda Ash business segments. As a result, the Partnership classified the assets and liabilities, operating results and cash flows of these businesses as discontinued operations in its Consolidated Balance Sheets, Consolidated Statements of Comprehensive Income and Consolidated Statements of Cash Flows for all periods presented. The following table presents the carrying amounts of the Partnership's assets and liabilities of discontinued operations in the Consolidated Balance Sheets: March 31, 2019 December 31, 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Total ASSETS Current assets Accounts receivable, net $ 10 $ 988 $ 998 $ 5 $ 988 $ 993 Total assets of discontinued operations $ 10 $ 988 $ 998 $ 5 $ 988 $ 993 LIABILITIES Current liabilities Accounts payable $ 48 $ — $ 48 $ 181 $ — $ 181 Accrued liabilities 679 — 679 766 — 766 Total liabilities of discontinued operations $ 727 $ — $ 727 $ 947 $ — $ 947 The following table presents summarized financial results of the Partnership's discontinued operations in the Consolidated Statements of Comprehensive Income Three Months Ended March 31, 2019 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Oil and Gas Total Revenues and other income Construction aggregates $ — $ — $ — $ 26,424 $ — $ 26,424 Road construction and asphalt paving services — — — 728 — 728 Gain (loss) on asset sales (8 ) — (8 ) 9 — 9 Total revenues and other income $ (8 ) $ — $ (8 ) $ 27,161 $ — $ 27,161 Operating expenses Operating and maintenance expenses $ 27 $ 11 $ 38 $ 26,218 $ 14 $ 26,232 Depreciation, depletion and amortization — — — 2,857 — 2,857 Total operating expenses $ 27 $ 11 $ 38 $ 29,075 $ 14 $ 29,089 Interest expense — — — (20 ) — (20 ) Loss from discontinued operations $ (35 ) $ (11 ) $ (46 ) $ (1,934 ) $ (14 ) $ (1,948 ) Capital expenditures related to the Partnership's discontinued operations were $3.4 million during the three months ended March 31, 2018 .

Common and Preferred Unit Distr

Common and Preferred Unit Distributions	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Common and Preferred Unit Distributions	Common and Preferred Unit Distributions The Partnership makes cash distributions to Common and Preferred unitholders on a quarterly basis, subject to approval by the Board of Directors. NRP recognizes both Common and Preferred distributions on the date the distribution is declared. 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. During the three months ended March 31, 2019 and 2018 , the Partnership declared and paid a distribution of $0.45 per common unit with respect to the quarter ended December 31, 2018 and 2017, respectively. Preferred Unit Distributions Income available to common unitholders and the general partner is reduced by Preferred Unit distributions that accumulated during the period. During the three months ended March 31, 2019 and 2018, the Partnership paid a distribution of $30.00 per Preferred Unit with respect to the quarter ended December 31, 2018 and 2017, respectively. NRP reduced net income attributable to common unitholders and the general partner by $7.5 million during the three months ended March 31, 2019 and 2018, respectively, as a result of accumulated Preferred Unit distributions earned during the period. During the three months ended March 31, 2018, the Partnership redeemed all of the outstanding PIK Units, which resulted in an $8.8 million cash payment during the period.

Net Income Per Common Unit

Net Income Per Common Unit	3 Months Ended
	Mar. 31, 2019
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 non-controlling interest, 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 months ended March 31, 2018 includes the net settlement of Warrants to purchase 1.75 million common units with a strike price of $22.81 but 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 calculation of the dilutive effect of the warrants for the three months ended March 31, 2019 , includes both the net settlement of warrants to purchase 1.75 million common units at a strike price of $22.81 and the net settlement of warrants to purchase 2.25 million common units with a strike price of $34.00 . The following table reconciles the numerator and denominator of the basic and diluted net income per common unit computations and calculates basic and diluted net income per common unit: Three Months Ended (In thousands, except per unit data) 2019 2018 Allocation of net income Net income from continuing operations $ 35,765 $ 26,286 Less: income attributable to preferred unitholders (7,500 ) (7,500 ) Net income from continuing operations attributable to common unitholders and general partner $ 28,265 $ 18,786 Less: net income from continuing operations attributable to the general partner (565 ) (376 ) Net income from continuing operations attributable to common unitholders $ 27,700 $ 18,410 Net loss from discontinued operations $ (46 ) $ (1,948 ) Less: net loss from discontinued operations attributable to the general partner 1 39 Net loss from discontinued operations attributable to common unitholders $ (45 ) $ (1,909 ) Net income $ 35,719 $ 24,338 Less: income attributable to preferred unitholders (7,500 ) (7,500 ) Net income attributable to common unitholders and general partner $ 28,219 $ 16,838 Less: net income attributable to the general partner (564 ) (337 ) Net income attributable to common unitholders $ 27,655 $ 16,501 Basic net income (loss) per common unit Weighted average common units—basic 12,255 12,238 Basic net income from continuing operations per common unit $ 2.26 $ 1.50 Basic net loss from discontinued operations per common unit $ — $ (0.16 ) Basic net income per common unit $ 2.26 $ 1.35 Three Months Ended (In thousands, except per unit data) 2019 2018 Diluted income per common unit Weighted average common units—basic 12,255 12,238 Plus: dilutive effect of Warrants 1,096 424 Plus: dilutive effect of Preferred Units 6,664 9,463 Weighted average common units—diluted 20,015 22,125 Net income from continuing operations $ 35,765 $ 26,286 Less: diluted net income from continuing operations attributable to the general partner (715 ) (526 ) Diluted net income from continuing operations attributable to common unitholders $ 35,050 $ 25,760 Diluted net loss from discontinued operations attributable to common unitholders $ (45 ) $ (1,909 ) Net income $ 35,719 $ 24,338 Less: diluted net income attributable to the general partner (714 ) (487 ) Diluted net income attributable to common unitholders $ 35,005 $ 23,851 Diluted net income from continuing operations per common unit $ 1.75 $ 1.16 Diluted net loss from discontinued operations per common unit $ — $ (0.09 ) Diluted net income per common unit $ 1.75 $ 1.08

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information The Partnership's 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 two operating segments: Coal Royalty and Other —consists primarily of coal royalty and coal-related transportation and processing assets. Other assets include industrial minerals royalty properties, aggregates royalty properties, oil and gas royalty properties and timber. The Partnership's coal reserves are primarily located in Appalachia, the Illinois Basin and the Northern Powder River Basin in the United States. The Partnership's industrial minerals and aggregates 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. 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. In December 2018, the Partnership sold its construction aggregates business which enabled it to further reduce debt and focus on its Coal Royalty and Other and Soda Ash business segments. See Note 4. Discontinued Operations for more information. 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 salaries and benefits, insurance, property taxes, legal and royalty, information technology and shared facilities services and are included in Operating and maintenance expenses on the 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, legal and accounting and other corporate-level activity not specifically allocated to a segment and are included in General and administrative expenses on the Consolidated Statements of Comprehensive Income. The following table summarizes certain financial information for each of the Partnership's business segments: Operating Segments (In thousands) Coal Royalty and Other Soda Ash Corporate and Financing Total Three Months Ended March 31, 2019 Revenues $ 55,103 $ 11,682 $ — $ 66,785 Gain on asset sales 256 — — 256 Operating and maintenance expenses 8,360 — — 8,360 Depreciation, depletion and amortization 4,392 — — 4,392 General and administrative expenses — — 4,350 4,350 Interest expense, net — — 14,174 14,174 Net income (loss) from continuing operations 42,607 11,682 (18,524 ) 35,765 Loss from discontinued operations — — — (46 ) Three Months Ended March 31, 2018 Revenues $ 49,857 $ 9,621 $ — $ 59,478 Gain on asset sales 651 — — 651 Operating and maintenance expenses 6,215 — — 6,215 Depreciation, depletion and amortization 5,100 — — 5,100 General and administrative expenses — — 4,336 4,336 Asset impairment 242 — — 242 Interest expense, net — — 17,950 17,950 Net income (loss) from continuing operations 38,951 9,621 (22,286 ) 26,286 Loss from discontinued operations — — — (1,948 ) As of March 31, 2019 Total assets of continuing operations $ 1,001,385 $ 249,936 $ 19,852 $ 1,271,173 Total assets of discontinued operations — — — 998 As of December 31, 2018 Total assets of continuing operations $ 986,680 $ 247,051 $ 106,923 $ 1,340,654 Total assets of discontinued operations — — — 993

Equity Investment

Equity Investment	3 Months Ended
	Mar. 31, 2019
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 (In thousands) 2019 2018 Balance at beginning of period $ 247,051 $ 245,433 Income allocation to NRP’s equity interests 12,894 10,832 Amortization of basis difference (1,212 ) (1,211 ) Comprehensive income (loss) from unconsolidated investment 1,003 (1,125 ) Distribution (9,800 ) (12,250 ) Balance at end of period $ 249,936 $ 241,679 The following table represents summarized financial information for Ciner Wyoming as derived from the respective unaudited financial statements for the three months ended March 31, 2019 and 2018 , respectively: Three Months Ended (In thousands) 2019 2018 Sales $ 130,436 $ 121,219 Gross profit 34,102 28,222 Net income 26,315 22,107

Mineral Rights, Net

Mineral Rights, Net	3 Months Ended
	Mar. 31, 2019
Extractive Industries [Abstract]
Mineral Rights, Net	Mineral Rights, Net The Partnership’s mineral rights consist of the following: March 31, 2019 December 31, 2018 (In thousands) Cost Accumulated Depletion Net Book Value Cost Accumulated Depletion Net Book Value Coal properties $ 1,164,845 $ (454,129 ) $ 710,716 $ 1,164,845 $ (451,210 ) $ 713,635 Aggregates properties 24,920 (12,349 ) 12,571 24,920 (11,814 ) 13,106 Oil and gas royalty properties 12,395 (7,696 ) 4,699 12,395 (7,632 ) 4,763 Other 13,158 (1,574 ) 11,584 13,158 (1,550 ) 11,608 Total mineral rights, net $ 1,215,318 $ (475,748 ) $ 739,570 $ 1,215,318 $ (472,206 ) $ 743,112 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 $3.5 million and $4.3 million for the three months ended March 31, 2019 and 2018 , respectively.

Intangible Assets, Net

Intangible Assets, Net	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets, Net	Intangible Assets, Net The Partnership's intangible assets consist of above-market coal royalty and related 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 included on its Consolidated Balance Sheets are as follows: March 31, December 31, (In thousands) 2019 2018 Intangible assets at cost $ 81,109 $ 81,109 Less: accumulated amortization (39,355 ) (38,596 ) Total intangible assets, net $ 41,754 $ 42,513 Amortization expense included in Depreciation, depletion and amortization on the Partnership's Consolidated Statements of Comprehensive Income was $0.8 million and $0.7 million for the three months ended March 31, 2019 and 2018 , respectively.

Debt, Net

Debt, Net	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt, Net	Debt, Net The Partnership's debt consists of the following: March 31, December 31, (In thousands) 2019 2018 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 $ — $ — Senior notes 8.38% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2019 $ — $ 21,319 5.05% with semi-annual interest payments in January and July, with annual principal payments in July, due July 2020 13,603 15,290 5.55% with semi-annual interest payments in June and December, with annual principal payments in June, due June 2023 11,823 13,414 4.73% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2023 30,356 37,195 5.82% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 63,834 89,529 8.92% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 20,059 27,185 5.03% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 91,821 107,013 5.18% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 23,536 30,555 Total Opco senior notes $ 255,032 $ 341,500 Total debt at face value $ 600,670 $ 687,138 Net unamortized debt discount (1,167 ) (1,266 ) Net unamortized debt issuance costs (11,802 ) (13,114 ) Total debt, net $ 587,701 $ 672,758 Less: current portion of long-term debt (46,024 ) (115,184 ) Total long-term debt, net $ 541,677 $ 557,574 NRP LP Debt 2022 Senior Notes As of March 31, 2019 and December 31, 2018 , NRP and NRP Finance were in compliance with the terms of the Indenture relating to their 10.500% Senior Notes due 2022 (the "2022 Senior Notes"). In April 2019, NRP and NRP Finance issued $300 million aggregate principal amount of 9.125% senior notes due 2025 ("2025 Senior Notes") and plans to use the net proceeds and cash on hand to fund the redemption of the 2022 Senior Notes in May 2019. See Note 17. Subsequent Events for more information. 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 March 31, 2019 and December 31, 2018 , Opco was in compliance with the terms of the financial covenants contained in its debt agreements. Opco Credit Facility As of March 31, 2019 , the Partnership did not have any borrowings outstanding under Opco’s Third Amended and Restated Credit Agreement, as amended (the "Opco Credit Facility") and had $100 million in available borrowing capacity. In April 2019, the Partnership entered into the Fourth Amendment to the Opco Credit Facility which extended the term of the Opco Credit Facility from April 2020 to April 2023. See Note 17. Subsequent Events for more information. The weighted average interest rate for the borrowings outstanding under the Opco Credit Facility during the three months ended March 31, 2018 was 5.91% . There were no borrowings outstanding under the Opco Credit Facility during the three months ended March 31, 2019 . Debt issuance cost related to the Opco Credit Facility were $1.4 million and $1.7 million at March 31, 2019 and December 31, 2018 , 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 $546.2 million and $548.9 million classified as Mineral rights, net and Plant and equipment, net and on the Partnership’s Consolidated Balance Sheets as of March 31, 2019 and December 31, 2018 , respectively. Opco Senior Notes As of March 31, 2019 and December 31, 2018 , the private placement senior notes ("Opco Senior Notes") had cumulative principal balances of $255.0 million and $341.5 million , respectively. Opco made mandatory principal payments of $86.5 million , which included a $49.3 million pre-payment as a result of the sale of the Partnership's construction aggregates business during the three months ended March 31, 2019 , and $40.8 million during the three months ended March 31, 2018 . 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 March 31, 2019 .

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair Value of Financial Assets and Liabilities The Partnership’s financial assets and liabilities consist of cash and cash equivalents, restricted cash, contracts receivable, debt, Preferred Units and Warrants. The carrying amounts reported on the Consolidated Balance Sheets for cash and cash equivalents and restricted cash 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 months ended March 31, 2019 or 2018 . The Partnership uses available market data and valuation methodologies to estimate the fair value of debt. The following table shows the carrying amount and estimated fair value of the Partnership's debt and contracts receivable: March 31, 2019 December 31, 2018 (In thousands) Carrying Estimated Carrying Estimated Debt: NRP 2022 Senior Notes (1) $ 334,929 $ 364,648 $ 334,024 $ 356,871 Opco Senior Notes (2) 252,772 269,059 338,734 352,599 Opco Revolving Credit Facility (3) — — — — Assets: Contracts receivable (current and long-term) (4) $ 40,331 $ 34,405 $ 40,776 $ 34,704 (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 2022 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 expense, net in the Partnership's Consolidated Statements of Comprehensive Income. The embedded derivatives had zero value as of March 31, 2019 and December 31, 2018 .

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions 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 and General and administrative expenses 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, information technology, 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 and General and administrative 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 (In thousands) 2019 2018 Operating and maintenance expenses $ 1,635 $ 1,675 General and administrative expenses 963 931 During the three months ended March 31, 2019 and 2018 , the Partnership recognized $3.0 million and $0.6 million in Operating and maintenance expenses, respectively, on its Consolidated Statements of Comprehensive Income related to an overriding royalty agreement with WPPLP. The Partnership had Accounts payable on its Consolidated Balance Sheets to QMC of $0.4 million and to WPPLP of $0.8 million as of March 31, 2019 and to QMC of $0.5 million and to WPPLP of $1.4 million as of December 31, 2018 . 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 March 31, 2019 , 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 one of the Partnership’s lessees in Tennessee. During the second quarter of 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 for the three months ended March 31, 2018 .

Major Customers

Major Customers	3 Months Ended
	Mar. 31, 2019
Risks and Uncertainties [Abstract]
Major Customers	Major Customers Revenues from customers that exceeded 10 percent of total revenues for any of the periods presented below are as follows: Three Months Ended March 31, 2019 2018 (In thousands) Revenues Percent Revenues Percent Foresight Energy (1) $ 16,191 24 % $ 12,431 21 % Contura Energy (1) (2) 11,111 17 % 5,505 9 % (1) Revenues from Foresight Energy and Contura Energy are included within the Partnership's Coal Royalty and Other segment. (2) In the fourth quarter of 2018, Contura Energy and Alpha Natural Resources merged. Revenues during the three months ended March 31, 2019 relate to the new consolidated Contura Energy while revenues during the three months ended March 31, 2018 do not include revenues from Alpha Natural Resources.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
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. During the first quarter, NRP was also involved in the matters 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 in the District Court of Harris County, Texas, 157th judicial district. The complaint alleged 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 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.

Unit-Based Compensation

Unit-Based Compensation	3 Months Ended
	Mar. 31, 2019
Unit-Based Compensation [Abstract]
Unit-Based Compensation	Unit-Based Compensation The 2017 LTIP awards granted in the first quarter of 2019 and 2018 were valued using the closing price of NRP's units as of the grant date. The grant date fair value of these awards granted during the three months ended March 31, 2019 and 2018 were $5.2 million and $2.2 million , respectively. Total unit-based compensation expense associated with these awards was $0.9 million and $0.6 million for the three months ended March 31, 2019 and 2018, respectively and is included in General and administrative expenses and Operating and maintenance expenses in the Partnership's Consolidated Statements of Comprehensive Income. The unamortized cost associated with unvested outstanding awards as of March 31, 2019 is $4.8 million , which is to be recognized over a weighted average period of 2.6 years . The unamortized cost associated with unvested outstanding awards as of December 31, 2018 was $1.2 million . A summary of the unit activity in the outstanding grants during 2019 is as follows: (In thousands) Common Units Weighted Average Exercise Price Outstanding at January 1, 2019 55 $ 29.10 Granted 126 $ 41.47 Fully vested and issued (12 ) $ 41.47 Forfeitures (15 ) $ 37.33 Outstanding at March 31, 2019 155 $ 37.45

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The following represents material events that have occurred subsequent to March 31, 2019 through the time of the Partnership’s filing of its Quarterly Report on Form 10-Q with the SEC: Distributions Declared In April 2019, the Board of Directors of GP Natural Resource Partners LLC ("the Board") declared a distribution of $0.45 per common unit with respect to the first quarter of 2019. The Board also declared a cash distribution on NRP's Preferred Units with respect to the first quarter of 2019 totaling $7.5 million . In addition, the Board declared a one-time special cash distribution of $0.85 per common unit. The purpose of this special distribution is to cover the common unitholders’ tax liability resulting from the sale of NRP’s construction aggregates business in December 2018. The common unit distributions declared in April will be paid on May 14, 2019 to common unitholders of record on May 7, 2019. Debt Refinancings Opco Credit Facility Amendment In April 2019, the Partnership entered into the Fourth Amendment (the “Fourth Amendment”) to the Opco Credit Facility. The Fourth Amendment extends the term of the Opco Credit Facility until April 2023. Lender commitments under the Opco Credit Facility remain at $100.0 million . The Credit Facility contains financial covenants requiring Opco to maintain: • A leverage ratio of consolidated indebtedness to EBITDDA (as defined in the Opco Credit Facility) not to exceed 4.0 x; provided, however, that if the Partnership increases its quarterly distribution to its common unitholders above $0.45 per common unit, the maximum leverage ratio under the Opco Credit Facility will permanently decrease from 4.0 x to 3.0 x; and • a fixed charge coverage ratio of consolidated EBITDDA to consolidated fixed charges (consisting of consolidated interest expense and consolidated lease expense) of not less than 3.5 to 1.0. The amended Opco Credit Facility also provides that the Partnership may make a one-time special tax distribution to common unitholders at any time prior to October 18, 2019 without triggering the permanent decrease in the maximum leverage ratio from 4.0 x to 3.0 x. The purpose of the special distribution is to cover the common unitholders’ tax liability resulting from the Partnership's sale of its construction aggregates business in December 2018. As discussed above, a one-time special distribution of $0.85 per common unit was declared by the Board in April 2019. Issuance of 2025 Senior Notes and Redemption of 2022 Senior Notes In April 2019, NRP and NRP Finance issued $300 million aggregate principal amount of 9.125% Senior Notes due 2025 ("2025 Senior Notes") and plans to use the net proceeds and approximately $76 million of cash on hand to fund the redemption of the 2022 Senior Notes. The 2022 Senior Notes will be redeemed on May 11, 2019 at a redemption price equal to 105.250% of the principal amount of the 2022 Senior Notes, plus accrued and unpaid interest. The 2025 Senior Notes were issued under an Indenture dated as of April 29, 2019 (the "2025 Indenture"), bear interest at 9.125% per year, are payable semi-annually on June 30 and December 30 beginning December 30, 2019, and mature on June 30, 2025. NRP and NRP Finance have the option to redeem the 2025 Senior Notes, in whole or in part, at any time on or after October 30, 2021, at the redemption prices (expressed as percentages of principal amount) of 104.563% for the 12-month period beginning October 30, 2021, 102.281% for the 12-month period beginning October 30, 2022, and thereafter at 100.000% , together, in each case, with any accrued and unpaid interest to the date of redemption. Furthermore, before October 30, 2021, NRP may on any one or more occasions redeem up to 35% of the aggregate principal amount of the 2022 Senior Notes with the net proceeds of certain public or private equity offerings at a redemption price of 109.125% of the principal amount of 2025 Senior Notes, plus any accrued and unpaid interest, if any, to the date of redemption, if at least 65% of the aggregate principal amount of the 2025 Senior Notes issued under the 2025 Indenture remains outstanding immediately after such redemption and the redemption occurs within 180 days of the closing date of such equity offering. In the event of a change of control, as defined in the 2025 Indenture, the holders of the 2025 Senior Notes may require us to purchase their 2025 Senior Notes at a purchase price equal to 101% of the principal amount of the 2025 Senior Notes, plus accrued and unpaid interest, if any. The 2025 Senior Notes were issued at par. The 2025 Senior Notes are the senior unsecured obligations of NRP and NRP Finance. The 2025 Senior Notes rank equal in right of payment to all existing and future senior unsecured debt of NRP and NRP Finance and senior in right of payment to any of NRP's subordinated debt. The 2025 Senior Notes are effectively subordinated in right of payment to all future secured debt of NRP and NRP Finance to the extent of the value of the collateral securing such indebtedness and are structurally subordinated in right of payment to all existing and future debt and other liabilities of our subsidiaries, including the Opco Credit Facility and each series of Opco’s existing senior notes. None of NRP's subsidiaries guarantee the 2025 Senior Notes. Financial Statement Impact of Debt Refinancings The debt refinancings are expected to result in other expense of approximately $29 million which consists of an $18 million premium to redeem the 2022 Senior Notes and of an $11 million write-off of unamortized debt issuance and debt discount costs that will be recorded on the income statement in the second quarter of 2019. In addition, the Partnership incurred approximately $6 million of deferred financing fees that will be recorded on the balance sheet in the second quarter of 2019.

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2019
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 Consolidated Balance Sheets, Consolidated Statements of Comprehensive Income and Consolidated 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 Leases On January 1, 2019, NRP adopted Accounting Standards Codification (ASC) 842, Leases, and all the related amendments (the “new lease standard” and "ASC 842") and recognized 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 required disclosures designed to give financial statement users information on the amount, timing and uncertainty of cash flows arising from leases. The guidance was adopted on January 1, 2019 using a modified retrospective approach. The Partnership is a lessee in one lease that is accounted for as an operating lease under the new lease standard and the adoption of the new lease standard did not have a material impact to the Partnership's consolidated financial statements. For lease agreements entered into or reassessed after the adoption of Topic 842, the Partnership elected to not combine lease and non-lease components. See Note 3. Leases for more information. Recently Issued Accounting Standards Credit Losses In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326). The new standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The new standard replaces today's "incurred loss" model with an "expected credit loss" model that requires entities to estimate an expected lifetime credit loss on financial assets, including trade accounts receivable. The guidance is effective for annual and interim periods beginning after December 15, 2019 and is to be adopted using a modified retrospective approach. The Partnership is currently evaluating the provisions of this guidance on its consolidated financial statements.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers by Source	The following table represents the Partnership's Coal Royalty and Other segment revenues by major source: Three Months Ended March 31, (In thousands) 2019 2018 Coal royalty revenues $ 32,131 $ 31,002 Production lease minimum revenues 2,700 2,535 Minimum lease straight-line revenues 3,316 603 Property tax revenues 1,433 1,182 Wheelage revenues 1,415 1,974 Coal overriding royalty revenues 3,975 2,872 Lease amendment revenues 771 — Aggregates royalty revenues 1,464 1,091 Oil and gas royalty revenues 1,719 2,898 Other revenues 578 317 Coal royalty and other revenues (1) $ 49,502 $ 44,474 Transportation and processing services revenues (2) 5,601 5,383 Total Coal royalty and other segment revenues $ 55,103 $ 49,857 (1) Coal royalty and other revenues from contracts with customers as defined under ASC 606. (2) Transportation and processing services revenues from contracts with customers as defined under ASC 606 was $2.9 million and $3.0 million for the three months ended March 31, 2019 and 2018 , respectively. The remaining transportation and processing services revenue of $2.7 million and $2.4 million for the three months ended March 31, 2019 , and 2018 respectively, related to other NRP-owned infrastructure leased to and operated by third party operators accounted for under other guidance. See Note 3. Leases for more information.
Schedule of Receivables and Liabilities from Contracts with Customers	The following table details the Partnership's Coal Royalty and Other segment receivables and liabilities resulting from contracts with customers: March 31, December 31, (In thousands) 2019 2018 Receivables Accounts receivable, net $ 34,036 $ 29,001 Prepaid expenses and other (1) 3,416 2,483 Contract liabilities Current portion of deferred revenue $ 4,614 $ 3,509 Deferred revenue 52,473 49,044
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: Three Months Ended March 31, (In thousands) 2019 2018 Balance at end of prior period (current and non-current) $ 52,553 $ 100,605 Cumulative adjustment for change in accounting principle — (65,591 ) Balance at beginning of period (current and non-current) $ 52,553 $ 35,014 Increase due to minimums and lease amendment fees 11,877 9,026 Recognition of previously deferred revenue (7,343 ) (5,591 ) Balance at end of period (current and non-current) $ 57,087 $ 38,449
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 and overriding royalty leases are as follows: Lease Term (1) Weighted Average Remaining Years as of March 31, 2019 Annual Minimum Payments (In thousands) 0 - 5 years 2.8 $ 15,681 5 - 10 years 6.6 13,352 10+ years 13.9 50,135 Total 10.5 $ 79,168 (1) Lease term does not include renewal periods.

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Lessee, Operating Lease, Liability, Maturity	The following table details the maturity analysis of the Partnership's operating lease liability and reconciles the undiscounted cash flows to the operating lease liability included in its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of March 31, 2019 2019 $ 362 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,373 Less: present value adjustment (2) (10,860 ) Total operating lease liability $ 3,513 (1) The remaining lease term of the Partnership's operating lease is 29.75 years. (2) The present value of the operating lease liability on the Partnership's Consolidated Balance Sheet was calculated using a 13.5% discount rate which represents the Partnership's estimated incremental borrowing rate under the lease. As the Partnership's lease does not provide an implicit rate, the Partnership estimated the incremental borrowing rate at the time the lease was entered into by utilizing the rate of the Partnership's secured debt and adjusting it for factors that reflect the profile of borrowing over the 30 -year expected lease term.
Assets And Liabilities, Lessor	The following table shows certain amounts related to the Partnership's Sugar Camp lease: (In thousands) March 31, 2019 December 31, 2018 Accounts receivable $ 602 $ 661 Contract receivable (current and long-term) 40,331 40,776 Unearned income 24,252 25,058 Projected remaining payments $ 65,185 $ 66,495

Discontinued Operations (Tables

Discontinued Operations (Tables)	3 Months Ended
	Mar. 31, 2019
Discontinued Operations [Abstract]
Financial Results of Discontinued Operations	The following table presents the carrying amounts of the Partnership's assets and liabilities of discontinued operations in the Consolidated Balance Sheets: March 31, 2019 December 31, 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Total ASSETS Current assets Accounts receivable, net $ 10 $ 988 $ 998 $ 5 $ 988 $ 993 Total assets of discontinued operations $ 10 $ 988 $ 998 $ 5 $ 988 $ 993 LIABILITIES Current liabilities Accounts payable $ 48 $ — $ 48 $ 181 $ — $ 181 Accrued liabilities 679 — 679 766 — 766 Total liabilities of discontinued operations $ 727 $ — $ 727 $ 947 $ — $ 947 The following table presents summarized financial results of the Partnership's discontinued operations in the Consolidated Statements of Comprehensive Income Three Months Ended March 31, 2019 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Oil and Gas Total Revenues and other income Construction aggregates $ — $ — $ — $ 26,424 $ — $ 26,424 Road construction and asphalt paving services — — — 728 — 728 Gain (loss) on asset sales (8 ) — (8 ) 9 — 9 Total revenues and other income $ (8 ) $ — $ (8 ) $ 27,161 $ — $ 27,161 Operating expenses Operating and maintenance expenses $ 27 $ 11 $ 38 $ 26,218 $ 14 $ 26,232 Depreciation, depletion and amortization — — — 2,857 — 2,857 Total operating expenses $ 27 $ 11 $ 38 $ 29,075 $ 14 $ 29,089 Interest expense — — — (20 ) — (20 ) Loss from discontinued operations $ (35 ) $ (11 ) $ (46 ) $ (1,934 ) $ (14 ) $ (1,948 )

Net Income Per Common Unit (Tab

Net Income Per Common Unit (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Reconciliation of Net Income to Weighted Average Units Outstanding	The following table reconciles the numerator and denominator of the basic and diluted net income per common unit computations and calculates basic and diluted net income per common unit: Three Months Ended (In thousands, except per unit data) 2019 2018 Allocation of net income Net income from continuing operations $ 35,765 $ 26,286 Less: income attributable to preferred unitholders (7,500 ) (7,500 ) Net income from continuing operations attributable to common unitholders and general partner $ 28,265 $ 18,786 Less: net income from continuing operations attributable to the general partner (565 ) (376 ) Net income from continuing operations attributable to common unitholders $ 27,700 $ 18,410 Net loss from discontinued operations $ (46 ) $ (1,948 ) Less: net loss from discontinued operations attributable to the general partner 1 39 Net loss from discontinued operations attributable to common unitholders $ (45 ) $ (1,909 ) Net income $ 35,719 $ 24,338 Less: income attributable to preferred unitholders (7,500 ) (7,500 ) Net income attributable to common unitholders and general partner $ 28,219 $ 16,838 Less: net income attributable to the general partner (564 ) (337 ) Net income attributable to common unitholders $ 27,655 $ 16,501 Basic net income (loss) per common unit Weighted average common units—basic 12,255 12,238 Basic net income from continuing operations per common unit $ 2.26 $ 1.50 Basic net loss from discontinued operations per common unit $ — $ (0.16 ) Basic net income per common unit $ 2.26 $ 1.35 Three Months Ended (In thousands, except per unit data) 2019 2018 Diluted income per common unit Weighted average common units—basic 12,255 12,238 Plus: dilutive effect of Warrants 1,096 424 Plus: dilutive effect of Preferred Units 6,664 9,463 Weighted average common units—diluted 20,015 22,125 Net income from continuing operations $ 35,765 $ 26,286 Less: diluted net income from continuing operations attributable to the general partner (715 ) (526 ) Diluted net income from continuing operations attributable to common unitholders $ 35,050 $ 25,760 Diluted net loss from discontinued operations attributable to common unitholders $ (45 ) $ (1,909 ) Net income $ 35,719 $ 24,338 Less: diluted net income attributable to the general partner (714 ) (487 ) Diluted net income attributable to common unitholders $ 35,005 $ 23,851 Diluted net income from continuing operations per common unit $ 1.75 $ 1.16 Diluted net loss from discontinued operations per common unit $ — $ (0.09 ) Diluted net income per common unit $ 1.75 $ 1.08

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table summarizes certain financial information for each of the Partnership's business segments: Operating Segments (In thousands) Coal Royalty and Other Soda Ash Corporate and Financing Total Three Months Ended March 31, 2019 Revenues $ 55,103 $ 11,682 $ — $ 66,785 Gain on asset sales 256 — — 256 Operating and maintenance expenses 8,360 — — 8,360 Depreciation, depletion and amortization 4,392 — — 4,392 General and administrative expenses — — 4,350 4,350 Interest expense, net — — 14,174 14,174 Net income (loss) from continuing operations 42,607 11,682 (18,524 ) 35,765 Loss from discontinued operations — — — (46 ) Three Months Ended March 31, 2018 Revenues $ 49,857 $ 9,621 $ — $ 59,478 Gain on asset sales 651 — — 651 Operating and maintenance expenses 6,215 — — 6,215 Depreciation, depletion and amortization 5,100 — — 5,100 General and administrative expenses — — 4,336 4,336 Asset impairment 242 — — 242 Interest expense, net — — 17,950 17,950 Net income (loss) from continuing operations 38,951 9,621 (22,286 ) 26,286 Loss from discontinued operations — — — (1,948 ) As of March 31, 2019 Total assets of continuing operations $ 1,001,385 $ 249,936 $ 19,852 $ 1,271,173 Total assets of discontinued operations — — — 998 As of December 31, 2018 Total assets of continuing operations $ 986,680 $ 247,051 $ 106,923 $ 1,340,654 Total assets of discontinued operations — — — 993

Equity Investment (Tables)

Equity Investment (Tables)	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Summarized Financial Information	Activity related to this investment is as follows: Three Months Ended (In thousands) 2019 2018 Balance at beginning of period $ 247,051 $ 245,433 Income allocation to NRP’s equity interests 12,894 10,832 Amortization of basis difference (1,212 ) (1,211 ) Comprehensive income (loss) from unconsolidated investment 1,003 (1,125 ) Distribution (9,800 ) (12,250 ) Balance at end of period $ 249,936 $ 241,679 The following table represents summarized financial information for Ciner Wyoming as derived from the respective unaudited financial statements for the three months ended March 31, 2019 and 2018 , respectively: Three Months Ended (In thousands) 2019 2018 Sales $ 130,436 $ 121,219 Gross profit 34,102 28,222 Net income 26,315 22,107

Mineral Rights, Net (Tables)

Mineral Rights, Net (Tables)	3 Months Ended
	Mar. 31, 2019
Extractive Industries [Abstract]
Mineral Rights	The Partnership’s mineral rights consist of the following: March 31, 2019 December 31, 2018 (In thousands) Cost Accumulated Depletion Net Book Value Cost Accumulated Depletion Net Book Value Coal properties $ 1,164,845 $ (454,129 ) $ 710,716 $ 1,164,845 $ (451,210 ) $ 713,635 Aggregates properties 24,920 (12,349 ) 12,571 24,920 (11,814 ) 13,106 Oil and gas royalty properties 12,395 (7,696 ) 4,699 12,395 (7,632 ) 4,763 Other 13,158 (1,574 ) 11,584 13,158 (1,550 ) 11,608 Total mineral rights, net $ 1,215,318 $ (475,748 ) $ 739,570 $ 1,215,318 $ (472,206 ) $ 743,112

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The Partnership's intangible assets included on its Consolidated Balance Sheets are as follows: March 31, December 31, (In thousands) 2019 2018 Intangible assets at cost $ 81,109 $ 81,109 Less: accumulated amortization (39,355 ) (38,596 ) Total intangible assets, net $ 41,754 $ 42,513

Debt, Net (Tables)

Debt, Net (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Long-Term Debt	The Partnership's debt consists of the following: March 31, December 31, (In thousands) 2019 2018 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 $ — $ — Senior notes 8.38% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2019 $ — $ 21,319 5.05% with semi-annual interest payments in January and July, with annual principal payments in July, due July 2020 13,603 15,290 5.55% with semi-annual interest payments in June and December, with annual principal payments in June, due June 2023 11,823 13,414 4.73% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2023 30,356 37,195 5.82% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 63,834 89,529 8.92% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 20,059 27,185 5.03% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 91,821 107,013 5.18% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 23,536 30,555 Total Opco senior notes $ 255,032 $ 341,500 Total debt at face value $ 600,670 $ 687,138 Net unamortized debt discount (1,167 ) (1,266 ) Net unamortized debt issuance costs (11,802 ) (13,114 ) Total debt, net $ 587,701 $ 672,758 Less: current portion of long-term debt (46,024 ) (115,184 ) Total long-term debt, net $ 541,677 $ 557,574

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Debt and Contracts Receivable	The following table shows the carrying amount and estimated fair value of the Partnership's debt and contracts receivable: March 31, 2019 December 31, 2018 (In thousands) Carrying Estimated Carrying Estimated Debt: NRP 2022 Senior Notes (1) $ 334,929 $ 364,648 $ 334,024 $ 356,871 Opco Senior Notes (2) 252,772 269,059 338,734 352,599 Opco Revolving Credit Facility (3) — — — — Assets: Contracts receivable (current and long-term) (4) $ 40,331 $ 34,405 $ 40,776 $ 34,704 (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 2022 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)	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
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 (In thousands) 2019 2018 Operating and maintenance expenses $ 1,635 $ 1,675 General and administrative expenses 963 931

Major Customers (Tables)

Major Customers (Tables)	3 Months Ended
	Mar. 31, 2019
Risks and Uncertainties [Abstract]
Major customers	Revenues from customers that exceeded 10 percent of total revenues for any of the periods presented below are as follows: Three Months Ended March 31, 2019 2018 (In thousands) Revenues Percent Revenues Percent Foresight Energy (1) $ 16,191 24 % $ 12,431 21 % Contura Energy (1) (2) 11,111 17 % 5,505 9 % (1) Revenues from Foresight Energy and Contura Energy are included within the Partnership's Coal Royalty and Other segment. (2) In the fourth quarter of 2018, Contura Energy and Alpha Natural Resources merged. Revenues during the three months ended March 31, 2019 relate to the new consolidated Contura Energy while revenues during the three months ended March 31, 2018 do not include revenues from Alpha Natural Resources.

Unit-Based Compensation (Tables

Unit-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2019
Unit-Based Compensation [Abstract]
Summary of Activity in Awards	A summary of the unit activity in the outstanding grants during 2019 is as follows: (In thousands) Common Units Weighted Average Exercise Price Outstanding at January 1, 2019 55 $ 29.10 Granted 126 $ 41.47 Fully vested and issued (12 ) $ 41.47 Forfeitures (15 ) $ 37.33 Outstanding at March 31, 2019 155 $ 37.45

Basis of Presentation - Narrati

Basis of Presentation - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)segment	Mar. 31, 2018USD ($)	Sep. 30, 2018	Jul. 31, 2013	Jan. 31, 2013
Accounting Policies [Abstract]
Number of Operating Segments | segment	2
Senior Notes | Opco
Restricted Cash and Cash Equivalents Items [Line Items]
Principal payments on its senior notes | $	$ 86.5	$ 40.8
Ciner Wyoming
Restricted Cash and Cash Equivalents Items [Line Items]
Percentage of partnership interest owned (percent)	49.00%		49.00%	49.00%	48.51%

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Schedule of Partnerships' Coal Royalty and Other Segment Revenues from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	$ 55,103	$ 49,857
Revenues	66,785	59,478
Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	49,502	44,474
Revenues	49,502	44,474
Coal Royalty and Other | Coal royalty revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	32,131	31,002
Coal Royalty and Other | Production lease minimum revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	2,700	2,535
Coal Royalty and Other | Minimum lease straight-line revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	3,316	603
Coal Royalty and Other | Property tax revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	1,433	1,182
Coal Royalty and Other | Wheelage revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	1,415	1,974
Coal Royalty and Other | Coal overriding royalty revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	3,975	2,872
Coal Royalty and Other | Lease amendment revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	771	0
Coal Royalty and Other | Aggregates royalty revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	1,464	1,091
Coal Royalty and Other | Oil and gas royalty revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	1,719	2,898
Coal Royalty and Other | Other revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	578	317
Coal Royalty and Other | Transportation and processing services revenues
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	2,900	3,000
Revenues	5,601	5,383
Coal Royalty and Other | Transportation and Processing
Disaggregation of Revenue [Line Items]
Lease revenue	$ 2,700	$ 2,400

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Schedule of Receivables and Liabilities from Contracts with Customers (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Current portion of deferred revenue	$ 4,614	$ 3,509
Deferred revenue	52,473	49,044
Coal Royalty
Segment Reporting Information [Line Items]
Accounts receivable, net	34,036	29,001
Prepaid expenses and other	3,416	2,483
Current portion of deferred revenue	4,614	3,509
Deferred revenue	$ 52,473	$ 49,044

Revenue from Contracts with C_5

Revenue from Contracts with Customers Revenue Recognition Deferred Revenue Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Deferred Revenue	$ 57,087	$ 38,449	$ 52,553	$ 52,553	$ 35,014	$ 100,605
Accrued minimum payments due and lease amendment fees due	11,877	9,026
Deferred Revenue, Revenue Recognized	$ (7,343)	$ (5,591)
Accounting Standards Update 2014-09
Deferred Revenue					$ (65,591)

Revenue from Contracts with C_6

Revenue from Contracts with Customers - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Average Remaining Contract Term	10 years 6 months
Total Coal royalty and other segment revenues	$ 55,103	$ 49,857
Annual minimum payments	79,168
Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	49,502	44,474
Production lease minimum revenues | Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	2,700	2,535
Transportation and processing services revenues | Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal royalty and other segment revenues	2,900	3,000
Transportation and Processing | Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Lease revenue	$ 2,700	$ 2,400

Revenue from Contracts with C_7

Revenue from Contracts with Customers - Schedule of Annual Minimums by Current Remaining Contract Term (Details) $ in Thousands	Mar. 31, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	10 years 6 months
Annual minimum payments	$ 79,168
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	2 years 10 months
Annual minimum payments	$ 15,681
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	6 years 7 months
Annual minimum payments	$ 13,352
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	13 years 11 months
Annual minimum payments	$ 50,135

Leases Lessee accounting under

Leases Lessee accounting under ASC 842 - narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
Lessor, Lease, Description [Line Items]
Number of options to extend	5
Length of renewal term	5 years
Operating lease, right-of-use asset	$ 3,500	$ 3,500
Operating lease liability	3,513	$ 3,500
Operating lease expenses	$ 100
Minimum
Lessor, Lease, Description [Line Items]
Base term on lease (in years)	5 years

Leases Operating lease maturity

Leases Operating lease maturity schedule (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating Lease, Weighted Average Remaining Lease Term	29 years 9 months
Lessee, Operating Lease, Discount Rate	13.50%
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2019	$ 362
2020	483
2021	483
2022	483
2023	483
After 2023	12,079
Total lease payments	14,373
Less: present value adjustment	10,860
Total operating lease liability	$ 3,513	$ 3,500
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	30 years

Leases Lessor accounting under

Leases Lessor accounting under 842 - narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2039	Dec. 31, 2032
Lessor, Lease, Description [Line Items]
Throughput fees	$ 1,200	$ 1,100
Lease renewal term	80 years
Annual lease payments	$ 5,000
Quarterly deficiency payment	$ 1,250
Scenario, Forecast
Lessor, Lease, Description [Line Items]
Annual rent amount after lease completion			$ 10
Rental payments due after completion of initial lease term				$ 10

Leases Schedule of lessor lease

Leases Schedule of lessor lease information (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Accounts receivable	$ 602	$ 661
Contract receivable (current and long-term)	40,331	40,776
Unearned income	(24,252)	(25,058)
Projected remaining payments	$ 65,185	$ 66,495

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net - Discontinued Operations	$ 998		$ 993
Total assets of discontinued operations	998		993
Accounts payable - Discontinued Operations	48		181
Accrued Liabilities - Discontinued Operations	679		766
Total liabilities of discontinued operations	727		947
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Construction Aggregates Revenues	0	$ 26,424
Road construction and asphalt paving services	0	728
Gain (loss) on asset sales - Discontinued Operations	(8)	9
Total revenues and other income - Discontinued Operations	(8)	27,161
Operating and maintenance expenses - Discontinued Operations	38	26,232
Depreciation, depletion and amortization - Discontinued Operations	0	2,857
Total operating expenses - Discontinued Operations	38	29,089
Interest expense - Discontinued Operations	0	(20)
Loss from discontinued operations	(46)	(1,948)
Capital Expenditures, Discontinued Operations		3,400
Construction Aggregates
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net - Discontinued Operations	10		5
Total assets of discontinued operations	10		5
Accounts payable - Discontinued Operations	48		181
Accrued Liabilities - Discontinued Operations	679		766
Total liabilities of discontinued operations	727		947
NRP Oil and Gas
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net - Discontinued Operations	988		988
Total assets of discontinued operations	988		988
Accounts payable - Discontinued Operations	0		0
Accrued Liabilities - Discontinued Operations	0		0
Total liabilities of discontinued operations	0		$ 0
Construction Aggregates | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Construction Aggregates Revenues	0	26,424
Road construction and asphalt paving services	0	728
Gain (loss) on asset sales - Discontinued Operations	(8)	9
Total revenues and other income - Discontinued Operations	(8)	27,161
Operating and maintenance expenses - Discontinued Operations	27	26,218
Depreciation, depletion and amortization - Discontinued Operations	0	2,857
Total operating expenses - Discontinued Operations	27	29,075
Interest expense - Discontinued Operations	0	(20)
Loss from discontinued operations	(35)	(1,934)
NRP Oil and Gas | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Construction Aggregates Revenues	0	0
Road construction and asphalt paving services	0	0
Gain (loss) on asset sales - Discontinued Operations	0	0
Total revenues and other income - Discontinued Operations	0	0
Operating and maintenance expenses - Discontinued Operations	11	14
Depreciation, depletion and amortization - Discontinued Operations	0	0
Total operating expenses - Discontinued Operations	11	14
Interest expense - Discontinued Operations	0	0
Loss from discontinued operations	$ (11)	$ (14)

Common and Preferred Unit Dis_2

Common and Preferred Unit Distributions Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Temporary Equity [Line Items]
Income attributable to preferred unitholders	$ 7,500	$ 7,500
Class A Convertible Preferred Units
Temporary Equity [Line Items]
Dividends, Preferred Stock, Paid-in-Kind, Cash Redemption Payment	$ 0	$ 8,844
General Partner
Temporary Equity [Line Items]
General partner's general partner distribution	2.00%
Common unitholders and general partner
Temporary Equity [Line Items]
Distribution per common unit (in dollars per share)	$ 0.45	$ 0.45
Preferred Stock | Preferred Partner
Temporary Equity [Line Items]
Distribution per common unit (in dollars per share)	$ 30	$ 30

Net Income Per Common Unit (Det

Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Allocation of net income
Net income from continuing operations		$ 35,765	$ 26,286
Less: income attributable to preferred unitholders		(7,500)	(7,500)
Net income from continuing operations attributable to common unitholders and general partner		28,265	18,786
Less: net income from continuing operations attributable to the general partner		(565)	(376)
Net income from continuing operations attributable to common unitholders		27,700	18,410
Net loss from discontinued operations		(46)	(1,948)
Less: net loss from discontinued operations attributable to the general partner		1	39
Net loss from discontinued operations attributable to common unitholders		(45)	(1,909)
Net income		35,719	24,338
Net income attributable to common unitholders and general partner		28,219	16,838
Less: net income attributable to the general partner		(564)	(337)
Net income attributable to common unitholders		27,655	16,501
Net income	[1]	$ 35,719	$ 24,338
Basic Income (Loss) per Unit:
Weighted average common units (in shares)		12,255	12,238
Basic net income from continuing operations per common unit		$ 2.26	$ 1.50
Basic net loss from discontinued operations per common unit		0	(0.16)
Basic net income per common unit		$ 2.26	$ 1.35
Diluted income per common unit
Dilutive effect of Warrants (in shares)		1,096	424
Dilutive effect of Preferred Units (in shares)		6,664	9,463
Weighted average common units—diluted (in shares)		20,015	22,125
Less: diluted net income from continuing operations attributable to the general partner		$ (715)	$ (526)
Diluted net income from continuing operations attributable to common unitholders		35,050	25,760
Diluted net loss from discontinued operations attributable to common unitholders		(45)	(1,909)
Less: diluted net income attributable to the general partner		(714)	(487)
Diluted net income attributable to common unitholders		$ 35,005	$ 23,851
Diluted net income per common unit from continuing operations (in dollars per share)		$ 1.75	$ 1.16
Diluted net income (loss) from discontinued operations per common unit (in dollars per share)		0	(0.09)
Diluted net income per common unit (in dollars per share)		$ 1.75	$ 1.08
Warrant Holders | Warrants at $22.81 Strike
Class of Warrant or Right, Warrants Issued		1,750	1,750
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 22.81	$ 22.81
Warrant Holders | Warrants at $34.00 Strike
Class of Warrant or Right, Warrants Issued		2,250	2,250
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 34	$ 34
[1]	Net income includes $7.5 million attributable to Preferred Unitholders that accumulated during the period, of which $7.35 million is allocated to the common unitholders and $0.15 million is allocated to the general partner

Segment Information - Additiona

Segment Information - Additional Information (Details) - segment	3 Months Ended
	Mar. 31, 2019	Sep. 30, 2018	Jul. 31, 2013	Jan. 31, 2013
Segment Reporting Information [Line Items]
Number of Operating Segments	2
Ciner Wyoming
Segment Reporting Information [Line Items]
Percentage of partnership interest owned (percent)	49.00%	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
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 66,785	$ 59,478
Gain on asset sales	256	651
Operating and maintenance expenses	8,360	6,215
Depreciation, depletion and amortization	4,392	5,100
General and administrative expenses	4,350	4,336
Asset impairments	0	242
Interest expense, net	14,174	17,950
Net income (loss) from continuing operations	35,765	26,286
Net loss from discontinued operations	(46)	(1,948)
Total assets	1,272,171		$ 1,341,647
Corporate and Financing
Segment Reporting Information [Line Items]
Revenues	0	0
Gain on asset sales	0	0
Operating and maintenance expenses	0	0
Depreciation, depletion and amortization	0	0
General and administrative expenses	4,350	4,336
Asset impairments		0
Interest expense, net	14,174	17,950
Net income (loss) from continuing operations	(18,524)	(22,286)
Net loss from discontinued operations	0	0
Coal Royalty and Other
Segment Reporting Information [Line Items]
Revenues	49,502	44,474
Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Revenues	55,103	49,857
Gain on asset sales	256	651
Operating and maintenance expenses	8,360	6,215
Depreciation, depletion and amortization	4,392	5,100
General and administrative expenses	0	0
Asset impairments		242
Interest expense, net	0	0
Net income (loss) from continuing operations	42,607	38,951
Net loss from discontinued operations	0	0
Soda Ash
Segment Reporting Information [Line Items]
Revenues	11,682	9,621
Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Revenues	11,682	9,621
Gain on asset sales	0	0
Operating and maintenance expenses	0	0
Depreciation, depletion and amortization	0	0
General and administrative expenses	0	0
Asset impairments		0
Interest expense, net	0	0
Net income (loss) from continuing operations	11,682	9,621
Net loss from discontinued operations	0	$ 0
Continuing Operations
Segment Reporting Information [Line Items]
Total assets	1,271,173		1,340,654
Continuing Operations | Corporate and Financing
Segment Reporting Information [Line Items]
Total assets	19,852		106,923
Continuing Operations | Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Total assets	1,001,385		986,680
Continuing Operations | Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Total assets	249,936		247,051
Discontinued Operations
Segment Reporting Information [Line Items]
Total assets	998		993
Discontinued Operations | Corporate and Financing
Segment Reporting Information [Line Items]
Total assets	0		0
Discontinued Operations | Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Total assets	0		0
Discontinued Operations | Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Total assets	$ 0		$ 0

Equity Investment - Additional

Equity Investment - Additional Information (Detail)	Mar. 31, 2019	Sep. 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%	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
	Mar. 31, 2019	Mar. 31, 2018
Equity Method Investments [Roll Forward]
Balance at beginning of period	$ 247,051
Comprehensive income (loss) from unconsolidated investment	36,724	$ 23,213
Balance at end of period	249,936
Sales	11,682	9,621
Ciner Wyoming
Equity Method Investments [Roll Forward]
Balance at beginning of period	247,051	245,433
Income allocation to NRP’s equity interests	12,894	10,832
Amortization of basis difference	(1,212)	(1,211)
Comprehensive income (loss) from unconsolidated investment	1,003	(1,125)
Distribution	(9,800)	(12,250)
Balance at end of period	249,936	241,679
Sales	130,436	121,219
Gross profit	34,102	28,222
Net income	$ 26,315	$ 22,107

Mineral Rights, Net - Mineral R

Mineral Rights, Net - Mineral Rights (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Cost	$ 1,215,318	$ 1,215,318
Accumulated Depletion	(475,748)	(472,206)
Net Book Value	739,570	743,112
Coal Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Cost	1,164,845	1,164,845
Accumulated Depletion	(454,129)	(451,210)
Net Book Value	710,716	713,635
Aggregates Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Cost	24,920	24,920
Accumulated Depletion	(12,349)	(11,814)
Net Book Value	12,571	13,106
Oil And Gas Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Cost	12,395	12,395
Accumulated Depletion	(7,696)	(7,632)
Net Book Value	4,699	4,763
Other Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Cost	13,158	13,158
Accumulated Depletion	(1,574)	(1,550)
Net Book Value	$ 11,584	$ 11,608

Mineral Rights, Net - Additiona

Mineral Rights, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Extractive Industries [Abstract]
Total depletion and amortization expense on mineral interests	$ 3.5	$ 4.3

Intangible Assets, Net - Intang

Intangible Assets, Net - Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 800	$ 700
Intangible assets at cost	81,109		$ 81,109
Less accumulated amortization	(39,355)		(38,596)
Total intangible assets, net	$ 41,754		$ 42,513

Intangible Assets, Net - Additi

Intangible Assets, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 0.8	$ 0.7

Debt, Net - Debt (Detail)

Debt, Net - Debt (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Apr. 29, 2019	Apr. 03, 2019	Dec. 31, 2018	Mar. 02, 2017
Debt Instrument [Line Items]
Principal balance	$ 600,670,000				$ 687,138,000
Net unamortized debt discount	(1,167,000)				(1,266,000)
Net unamortized debt issuance costs	(11,802,000)				(13,114,000)
Total debt	587,701,000				672,758,000
Less - current portion of long term debt	(46,024,000)				(115,184,000)
Total long-term debt, net	541,677,000				557,574,000
NRP LP | 10.5% senior notes, with semi-annual interest payments in March and September, maturing March 2022
Debt Instrument [Line Items]
Principal balance	$ 345,638,000				345,638,000
NRP LP | Senior Notes Due Two Zero Two Two
Debt Instrument [Line Items]
Rate of senior notes	10.50%
Senior Notes, Face Amount	$ 345,638,000
Opco | Senior Notes
Debt Instrument [Line Items]
Principal balance	255,032,000				341,500,000
Principal payments on its senior notes	86,500,000	$ 40,800,000
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty
Debt Instrument [Line Items]
Floating rate revolving credit facility	100,000,000
Principal balance	0				0
Line of Credit Facility, Remaining Borrowing Capacity	$ 100,000,000
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]
Rate of senior notes	4.91%
Opco | 8.38% senior notes, with semi-annual interest payments in March and September, with annual principal payments in March, maturing in March 2019
Debt Instrument [Line Items]
Rate of senior notes	8.38%
Principal balance	$ 0				21,319,000
Opco | 5.05% senior notes, with semi-annual interest payments in January and July, with annual principal payments in July, maturing in July 2020
Debt Instrument [Line Items]
Rate of senior notes	5.05%
Principal balance	$ 13,603,000				15,290,000
Opco | 5.55% senior notes, with semi-annual interest payments in June and December, with annual principal payments in June, maturing in June 2023
Debt Instrument [Line Items]
Rate of senior notes	5.55%
Principal balance	$ 11,823,000				13,414,000
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
Debt Instrument [Line Items]
Rate of senior notes	4.73%
Principal balance	$ 30,356,000				37,195,000
Opco | 5.82% senior notes, with semi-annual interest payments in March and September, with annual principal payments in March, maturing in March 2024
Debt Instrument [Line Items]
Rate of senior notes	5.82%
Principal balance	$ 63,834,000				89,529,000
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
Debt Instrument [Line Items]
Rate of senior notes	8.92%
Principal balance	$ 20,059,000				27,185,000
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
Debt Instrument [Line Items]
Rate of senior notes	5.03%
Principal balance	$ 91,821,000				107,013,000
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
Debt Instrument [Line Items]
Rate of senior notes	5.18%
Principal balance	$ 23,536,000				30,555,000
Senior Notes due 2022
Debt Instrument [Line Items]
Principal balance	334,929,000				334,024,000
Senior Notes due 2022 | Senior Notes
Debt Instrument [Line Items]
Rate of senior notes						10.50%
Senior Notes Offering Price Two | NRP LP | Senior Notes Due Two Zero Two Two
Debt Instrument [Line Items]
Floating rate revolving credit facility	$ 240,638,000
Senior Note issue percentage	100.00%
Senior Notes Offering Price One | NRP LP | Senior Notes Due Two Zero Two Two
Debt Instrument [Line Items]
Floating rate revolving credit facility	$ 105,000,000
Senior Note issue percentage	98.75%
Revolving Credit Facility | Opco
Debt Instrument [Line Items]
Net unamortized debt issuance costs	$ (1,400,000)				$ (1,700,000)
Subsequent Event | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity				$ 100,000,000
Subsequent Event | Senior Notes due 2025 | Senior Notes
Debt Instrument [Line Items]
Rate of senior notes			9.125%
Senior Notes, Face Amount			$ 300,000,000
Net unamortized debt issuance costs			$ (6,000,000)

Debt, Net - Additional Informat

Debt, Net - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Apr. 03, 2019USD ($)	Dec. 31, 2018USD ($)	Mar. 02, 2017
Debt Instrument [Line Items]
Debt issuance cost capitalized	$ 11,802,000			$ 13,114,000
Principal balance	600,670,000			687,138,000
Senior Notes due 2022
Debt Instrument [Line Items]
Principal balance	334,929,000			334,024,000
Senior Notes due 2022 | Senior Notes
Debt Instrument [Line Items]
Rate of senior notes					10.50%
Opco | Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period		5.91%
Debt issuance cost capitalized	1,400,000			1,700,000
Collateral carrying amount	$ 546,200,000			548,900,000
Opco | 8.38% senior notes, with semi-annual interest payments in March and September, with annual principal payments in March, maturing in March 2019
Debt Instrument [Line Items]
Rate of senior notes	8.38%
Principal balance	$ 0			21,319,000
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
Debt Instrument [Line Items]
Rate of senior notes	8.92%
Principal balance	$ 20,059,000			27,185,000
Opco | Senior Notes
Debt Instrument [Line Items]
Principal balance	255,032,000			341,500,000
Principal payments on its senior notes	86,500,000	$ 40,800,000
Pre-payment of Senior Notes	$ 49,300,000
Partnership leverage ratio	3.75
Additional interest accrue	2.00%
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty
Debt Instrument [Line Items]
Floating rate revolving credit facility	$ 100,000,000
Principal balance	0			$ 0
Line of Credit Facility, Remaining Borrowing Capacity	$ 100,000,000
Subsequent Event | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity			$ 100,000,000

Fair Value Measurements - Contr

Fair Value Measurements - Contracts Receivable and Debt (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Transfers between Levels 1, 2, 3	$ 0	$ 0
Carrying Value	600,670,000		$ 687,138,000
Embedded Derivative, Fair Value of Embedded Derivative Liability	0		0
Receivables, Fair Value Disclosure			40,776,000
Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Receivables, Fair Value Disclosure	34,405,000		34,704,000
Senior Notes due 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	334,929,000		334,024,000
Senior Notes due 2022 | Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	364,648,000		356,871,000
Opco Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	252,772,000		338,734,000
Opco Senior Notes | Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	269,059,000		352,599,000
Opco Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	0		0
Opco Revolving Credit Facility | Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	$ 0		$ 0

Fair Value Measurements - Embed

Fair Value Measurements - Embedded Derivatives (Detail) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Embedded Derivative, Fair Value of Embedded Derivative Liability	$ 0	$ 0

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Quintana Minerals
Related Party Transaction [Line Items]
Accounts payable to related parties	$ 0.4		$ 0.5
Western Pocahontas Properties
Related Party Transaction [Line Items]
Accounts payable to related parties	0.8		$ 1.4
Western Pocahontas Properties Limited Partnership | Affiliated Entity
Related Party Transaction [Line Items]
Operating and maintenance expenses	$ 3	$ 0.6
Corsa
Related Party Transaction [Line Items]
Royalty Income, Nonoperating		$ 0.2

Related Party Transactions - Su

Related Party Transactions - Summary of Reimbursements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Quintana Minerals
Related Party Transaction [Line Items]
Accounts payable to related parties	$ 400		$ 500
Western Pocahontas Properties
Related Party Transaction [Line Items]
Accounts payable to related parties	800		$ 1,400
Western Pocahontas Properties Limited Partnership | Affiliated Entity
Related Party Transaction [Line Items]
Operating and maintenance expenses	3,000	$ 600
Western Pocahontas Properties and Quintana Minerals Corporation | Affiliated Entity
Related Party Transaction [Line Items]
Operating and maintenance expenses	1,635	1,675
General and administrative expenses	$ 963	$ 931

Major Customers (Detail)

Major Customers (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Concentration Risk [Line Items]
Revenues	$ 66,785	$ 59,478
Foresight Energy Lp
Concentration Risk [Line Items]
Revenues	16,191	12,431
Contura Energy
Concentration Risk [Line Items]
Revenues	$ 11,111	$ 5,505
Sales Revenue | Customer Concentration Risk | Foresight Energy Lp
Concentration Risk [Line Items]
Concentration risk, percentage	24.00%	21.00%
Sales Revenue | Customer Concentration Risk | Contura Energy
Concentration Risk [Line Items]
Concentration risk, percentage	17.00%	9.00%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	36 Months Ended
	Dec. 31, 2015	Mar. 31, 2019	Sep. 30, 2018	Jul. 31, 2013	Jan. 31, 2013
Anadarko Holding Company
Commitments And Contingencies [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High					$ 50,000
Ciner Wyoming | Anadarko Holding Company
Commitments And Contingencies [Line Items]
Equity Investment Contingent Consideration Paid	$ 11,500
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%	49.00%	48.51%
Pending Litigation | Minimum | Anadarko Holding Company
Commitments And Contingencies [Line Items]
Minimum deficiency payments		$ 0
Pending Litigation | Maximum | Anadarko Holding Company
Commitments And Contingencies [Line Items]
Minimum deficiency payments		$ 40,000

Unit-Based Compensation (Detail

Unit-Based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Granted, Value, Share-based Compensation, Gross	$ 5.2	$ 2.2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	155		55
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 37.45		$ 29.10
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	126
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 41.47
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number	(12)
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 41.47
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period	15
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 0
Unaccrued Cost Associated With Outstanding Grants And Related Distribution Equivalent Rights	$ 4.8		$ 1.2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	2 years 7 months 20 days
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 0.9	$ 0.6

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) $ / shares in Units, $ in Thousands	May 14, 2019USD ($)$ / shares	May 11, 2019USD ($)	Apr. 29, 2019USD ($)	Apr. 03, 2019USD ($)$ / shares	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Mar. 02, 2017
Subsequent Event [Line Items]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents						$ 129,707	$ 206,030	$ 20,790	$ 26,980
Debt issuance cost capitalized						11,802	$ 13,114
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty
Subsequent Event [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity						$ 100,000
Senior Notes due 2022 | Senior Notes
Subsequent Event [Line Items]
Rate of senior notes										10.50%
Subsequent Event
Subsequent Event [Line Items]
Debt Instrument, Percentage of Principal Eligible for Redemption			35.00%
Distribution per common unit (in dollars per share) | $ / shares	$ 0.45
Dividends, Preferred Stock	$ 7,500
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		$ 76,000
Payment for Debt Extinguishment or Debt Prepayment Cost					$ 29,000
Redemption Premium					18,000
Write off of Deferred Debt Issuance Cost					$ 11,000
Subsequent Event | Opco
Subsequent Event [Line Items]
Ratio Of Ebitda To Consolidated Fixed Charges				3.5
Subsequent Event | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty
Subsequent Event [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity				$ 100,000
Subsequent Event | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Subsequent Event [Line Items]
Partners' Capital, Distribution Amount Per Share | $ / shares				$ 0.45
Subsequent Event | Dividend at or Below $0.45 per Share | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Subsequent Event [Line Items]
Debt Instrument, Covenant, Maximum Leverage Ratio				4
Subsequent Event | Dividend Above $0.45 per Share | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Subsequent Event [Line Items]
Debt Instrument, Covenant, Maximum Leverage Ratio				3
Subsequent Event | Special Tax Distribution
Subsequent Event [Line Items]
Distribution per common unit (in dollars per share) | $ / shares	$ 0.85
Subsequent Event | Senior Notes due 2025 | Senior Notes
Subsequent Event [Line Items]
Debt Instrument Redemption Price Percentage Of Principal Remaining After Redemption			65.00%
Debt Instrument Redemption Price At Change Of Control Event As Percentage Of Principal Amount			101.00%
Senior Notes, Face Amount			$ 300,000
Rate of senior notes			9.125%
Debt issuance cost capitalized			$ 6,000
Subsequent Event | Senior Notes due 2022 | Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Redemption Price, Percentage		105.25%
Subsequent Event | Debt Instrument, Redemption, Period Two | Senior Notes due 2025 | Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Redemption Price, Percentage			104.563%
Subsequent Event | Debt Instrument, Redemption, Period Three | Senior Notes due 2025 | Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Redemption Price, Percentage			102.281%
Subsequent Event | Debt Instrument, Redemption, Period Four | Senior Notes due 2025 | Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Redemption Price, Percentage			100.00%
Subsequent Event | Debt Instrument, Redemption, Period One | Senior Notes due 2025 | Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Redemption Price, Percentage			109.125%

Uncategorized Items - nrp-20190

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 70,466,000
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents	2,847,000
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents	0
General Partner [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	1,409,000
Common Stock [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	69,057,000
Partners Capital Excluding Noncontrolling Interest [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 70,466,000