Natural Resource Partners (NRP) 10-Q 8 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Aug. 01, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Entity Current Reporting Status	Yes
Document Fiscal Year Focus	2019
Document Period End Date	Jun. 30, 2019
Document Fiscal Period Focus	Q2
Interactive Data Current	Yes
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	false
Shell Company	false
Entity Common Stock, Shares Outstanding		12,261,199

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 70,850	$ 101,839
Restricted cash	14,925	104,191
Accounts receivable, net	28,553	32,058
Prepaid expenses and other	5,963	3,462
Current assets of discontinued operations	984	993
Total current assets	121,275	242,543
Land	24,008	24,008
Plant and equipment, net	825	984
Mineral rights, net	736,413	743,112
Intangible assets, net	41,008	42,513
Equity in unconsolidated investment	251,135	247,051
Long-term contracts receivable	37,973	38,945
Other assets	6,806	2,491
Total assets	1,219,443	1,341,647
Current liabilities:
Accounts payable	1,211	2,414
Accrued liabilities	6,856	12,347
Accrued interest	7,201	14,345
Current portion of deferred revenue	6,579	3,509
Current portion of long-term debt, net	46,040	115,184
Current liabilities of discontinued operations	658	947
Total current liabilities	68,545	148,746
Deferred revenue	43,290	49,044
Long-term debt, net	498,029	557,574
Other non-current liabilities	4,731	1,150
Total liabilities	614,595	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 June 30, 2019 and December 31, 2018, respectively)	374,275	355,113
General partner’s interest	5,387	5,014
Warrant holders’ interest	66,816	66,816
Accumulated other comprehensive loss	(3,282)	(3,462)
Total partners’ capital	443,196	423,481
Non-controlling interest	(2,935)	(2,935)
Total capital	440,261	420,546
Total liabilities and capital	$ 1,219,443	$ 1,341,647

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues	$ 81,223	$ 69,451	$ 148,008	$ 128,929
Gain on asset sales	246	168	502	819
Total revenues and other income	81,469	69,619	148,510	129,748
Operating expenses
Operating and maintenance expenses	12,459	8,117	20,819	14,332
Depreciation, depletion and amortization	3,970	5,376	8,362	10,476
General and administrative expenses	4,196	3,263	8,546	7,599
Asset impairments	0	0	0	242
Total operating expenses	20,625	16,756	37,727	32,649
Income from operations	60,844	52,863	110,783	97,099
Other expenses, net
Interest expense, net	(12,456)	(17,734)	(26,630)	(35,684)
Loss on extinguishment of debt	(29,282)	0	(29,282)	0
Total other expenses, net	(41,738)	(17,734)	(55,912)	(35,684)
Net income from continuing operations	19,106	35,129	54,871	61,415
Income from discontinued operations	245	2,981	199	1,033
Net income	19,351	38,110	55,070	62,448
Net income attributable to non-controlling interest	0	(869)	0	(869)
Net income attributable to NRP	19,351	37,241	55,070	61,579
Income attributable to preferred unitholders	(7,500)	(7,500)	(15,000)	(15,000)
Net income attributable to common unitholders and general partner	11,851	29,741	40,070	46,579
Net income attributable to common unitholders	11,614	29,146	39,269	45,647
Net income attributable to the general partner	$ 237	$ 595	$ 801	$ 932
Income from continuing operations per common unit
Basic (in dollars per share)	$ 0.93	$ 2.14	$ 3.19	$ 3.65
Diluted (in dollars per share)	0.85	1.57	2.58	2.78
Net income per common unit
Basic (in dollars per share)	0.95	2.38	3.20	3.73
Diluted (in dollars per share)	$ 0.87	$ 1.71	$ 2.59	$ 2.83
Comprehensive income (loss) from unconsolidated investment and other	$ (825)	$ (434)	$ 180	$ (1,559)
Comprehensive income	18,526	37,676	55,250	60,889
Comprehensive income attributable to non-controlling interest	0	(869)	0	(869)
Comprehensive income attributable to NRP	18,526	36,807	55,250	60,020
Coal Royalty and Other
Revenues	64,616	47,920	114,118	92,394
Soda Ash
Revenues	11,333	16,529	23,015	26,150
Transportation and processing services revenues | Coal Royalty and Other
Revenues	$ 5,274	$ 5,002	$ 10,875	$ 10,385

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 Loss	Partners' Capital Excluding Non-Controlling Interest		Non-Controlling Interest	Common unitholders	Common unitholdersCommon Unitholders	Common unitholders and general partner	Common unitholders and general partnerPartners' Capital Excluding Non-Controlling Interest	General Partner	General PartnerGeneral Partner	Preferred Partner	Preferred PartnerGeneral Partner	Preferred PartnerCommon Unitholders	Preferred PartnerPartners' Capital Excluding Non-Controlling 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		487	$ 23,851			24,338	[1]
Net income	24,338							0
Distributions to unitholders										$ (5,505)	$ (5,617)	$ (5,617)		$ (112)	$ (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, 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	61,579
Net income	62,448
Balance, end of period (in shares) at Jun. 30, 2018			12,246
Balance, end of period at Jun. 30, 2018	367,418	3,977	$ 304,073	66,816	(4,872)	369,994		(2,576)
Income attributable to preferred unitholders	15,000
Balance, beginning of period (in shares) at Mar. 31, 2018			12,246
Balance, beginning of period at Mar. 31, 2018	342,729	3,494	$ 280,251	66,816	(4,438)	346,123		(3,394)
Net income	37,241	745	36,496			37,241	[1]
Net income	38,110							869
Distributions to unitholders										(5,510)	(5,623)	(5,623)		(113)	(7,500)	(150)	(7,350)	(7,500)
Unit-based awards amortization and vesting	136		136			136
Comprehensive income from unconsolidated investment and other	(434)	1	$ 50		(434)	(383)		(51)
Balance, end of period (in shares) at Jun. 30, 2018			12,246
Balance, end of period at Jun. 30, 2018	367,418	3,977	$ 304,073	66,816	(4,872)	369,994		(2,576)
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		714	$ 35,005			35,719	[1]
Net income	35,719							0
Distributions to unitholders										(5,513)	(5,625)	(5,625)		(112)	(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
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	55,070
Net income	55,070
Balance, end of period (in shares) at Jun. 30, 2019			12,261
Balance, end of period at Jun. 30, 2019	440,261	5,387	$ 374,275	66,816	(3,282)	443,196		(2,935)
Income attributable to preferred unitholders	15,000
Balance, beginning of period (in shares) at Mar. 31, 2019			12,261
Balance, beginning of period at Mar. 31, 2019	445,040	5,476	$ 378,140	66,816	(2,457)	447,975		(2,935)
Net income	19,351	387	18,964			19,351	[1]
Net income	19,351							0
Distributions to unitholders										$ (15,939)	$ (16,265)	$ (16,265)		$ (326)	$ (7,500)	$ (150)	$ (7,350)	$ (7,500)
Unit-based awards amortization and vesting	460		460			460
Comprehensive income from unconsolidated investment and other	(825)	0	$ 0		(825)	(825)		0
Balance, end of period (in shares) at Jun. 30, 2019			12,261
Balance, end of period at Jun. 30, 2019	440,261	$ 5,387	$ 374,275	$ 66,816	$ (3,282)	$ 443,196		$ (2,935)
Income attributable to preferred unitholders	$ 7,500
[1]	Common Unitholders General Partner Warrant Holders AccumulatedOtherComprehensive Loss Partners' Capital Excluding Non-Controlling Interest Non-Controlling Interest Total Capital (In thousands)Units Amounts Balance at December 31, 201812,249 $355,113 $5,014 $66,816 $(3,462) $423,481 $(2,935) $420,546Net income (1)— 35,005 714 — — 35,719 — 35,719Distributions to common unitholders and general partner— (5,513) (112) — — (5,625) — (5,625)Distributions to preferred unitholders— (7,350) (150) — — (7,500) — (7,500)Issuance of unit-based awards12 486 — — — 486 — 486Unit-based awards amortization and vesting— 399 — — — 399 — 399Comprehensive income from unconsolidated investment and other— — 10 — 1,005 1,015 — 1,015Balance at March 31, 201912,261 $378,140 $5,476 $66,816 $(2,457) $447,975 $(2,935) $445,040Net income (1)— 18,964 387 — — 19,351 — 19,351Distributions to common unitholders and general partner— (15,939) (326) — — (16,265) — (16,265)Distributions to preferred unitholders— (7,350) (150) — — (7,500) — (7,500)Unit-based awards amortization and vesting— 460 — — — 460 — 460Comprehensive loss from unconsolidated investment and other— — — — (825) (825) — (825)Balance at June 30, 201912,261 $374,275 $5,387 $66,816 $(3,282) $443,196 $(2,935) $440,261 (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	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Net income	$ 55,070	$ 62,448
Adjustments to reconcile net income to net cash provided by operating activities of continuing operations:
Depreciation, depletion and amortization	8,362	10,476
Distributions from unconsolidated investment	19,110	22,403
Equity earnings from unconsolidated investment	(23,015)	(26,150)
Gain on asset sales	(502)	(819)
Loss on extinguishment of debt	29,282	0
Income from discontinued operations	(199)	(1,033)
Asset impairments	0	242
Unit-based compensation expense	1,376	990
Amortization of debt issuance costs and other	2,151	2,815
Change in operating assets and liabilities:
Accounts receivable	3,584	(7,043)
Accounts payable	(1,177)	863
Accrued liabilities	(5,522)	(3,287)
Accrued interest	(7,144)	(875)
Deferred revenue	(2,684)	9,006
Other items, net	(2,501)	1,271
Net cash provided by operating activities of continuing operations	76,191	71,307
Net cash provided by operating activities of discontinued operations	355	2,836
Net cash provided by operating activities	76,546	74,143
Cash flows from investing activities
Distributions from unconsolidated investment in excess of cumulative earnings	0	2,097
Proceeds from sale of assets	503	826
Return of long-term contract receivable	892	1,016
Net cash provided by investing activities of continuing operations	1,395	3,939
Net cash used in investing activities of discontinued operations	(434)	(5,772)
Net cash provided by (used in) investing activities	961	(1,833)
Cash flows from financing activities
Debt borrowings	300,000	35,000
Debt repayments	(434,470)	(48,072)
Contributions to discontinued operations	(79)	(2,250)
Debt issuance costs and other	26,402	226
Net cash used in financing activities of continuing operations	(197,841)	(50,897)
Net cash provided by financing activities of discontinued operations	79	1,735
Net cash used in financing activities	(197,762)	(49,162)
Net increase (decrease) in cash, cash equivalents and restricted cash	(120,255)	23,148
Cash, cash equivalents and restricted cash of continuing operations at beginning of period	206,030	26,980
Cash and cash equivalents of discontinued operations at beginning of period	0	(2,847)
Cash, cash equivalents and restricted cash at beginning of period	206,030	29,827
Cash, cash equivalents and restricted cash at end of period	85,775	51,329
Less: cash and cash equivalents of discontinued operations at end of period	0	(1,646)
Cash, cash equivalents and restricted cash of continuing operations at end of period	85,775	52,975
Cash paid during the period for interest of continuing operations	33,045	33,155
General Partner
Cash flows from financing activities
Distributions to common unitholders and general partner	(21,890)	(11,240)
Preferred Partner
Cash flows from financing activities
Distributions to common unitholders and general partner	(15,000)	(15,265)
Class A Convertible Preferred Units
Cash flows from financing activities
Redemption of preferred units paid-in-kind	$ 0	$ (8,844)

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 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 trona ore mining and soda ash production business. The Partnership is organized into two operating segments further described in Note 6. 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 total assets, total liabilities, partners' capital, net income or cash flows from operating, investing or financing activities. Recasting of Certain Prior Period Information As described in Note 3. 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 June 30, 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 six months of 2019, the Partnership used $88.8 million of restricted cash to repay principal amounts on Opco's private placement senior notes (the "Opco Senior Notes") and it intends to use the remaining $14.9 million of restricted cash to repay a portion of the remaining 2019 principal 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 its Consolidated 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 by NRP 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 ASC 842, the Partnership elected to not combine lease and non-lease components. See Note 16. 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 continuing to evaluate the provisions of this guidance on its consolidated financial statements, but based on its analysis to date, the Partnership does not expect this standard to have a material effect on its consolidated financial statements.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	6 Months Ended
	Jun. 30, 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 June 30, Six Months Ended June 30, (In thousands) 2019 2018 2019 2018 Coal royalty revenues $ 30,703 $ 34,762 $ 62,834 $ 65,764 Production lease minimum revenues 15,879 2,006 18,579 4,541 Minimum lease straight-line revenues 3,854 569 7,170 1,172 Property tax revenues 1,377 1,523 2,810 2,705 Wheelage revenues 1,945 1,609 3,360 3,583 Coal overriding royalty revenues 3,999 3,702 7,974 6,574 Lease amendment revenues 4,414 — 5,185 — Aggregates royalty revenues 1,237 1,572 2,701 2,663 Oil and gas royalty revenues 482 1,354 2,201 4,252 Other revenues 726 823 1,304 1,140 Coal royalty and other revenues (1) $ 64,616 $ 47,920 $ 114,118 $ 92,394 Transportation and processing services revenues (2) 5,274 5,002 10,875 10,385 Total Coal Royalty and Other segment revenues $ 69,890 $ 52,922 $ 124,993 $ 102,779 (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 $2.6 million and $3.1 million for the three months ended June 30, 2019 and 2018 , respectively, and $5.6 million and $6.1 million for the six months ended June 30, 2019 and 2018 , respectively. The remaining transportation and processing services revenues of $2.6 million and $1.9 million for the three months ended June 30, 2019 , and 2018 , respectively, and $5.3 million and $4.3 million for the six months ended June 30, 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 16. Leases for more information. The following table details the Partnership's Coal Royalty and Other segment receivables and liabilities resulting from contracts with customers: June 30, December 31, (In thousands) 2019 2018 Receivables Accounts receivable, net $ 25,438 $ 29,001 Prepaid expenses and other (1) 5,445 2,483 Contract liabilities Current portion of deferred revenue $ 6,579 $ 3,509 Deferred revenue 43,290 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: Six Months Ended June 30, (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 29,776 17,954 Recognition of previously deferred revenue (32,460 ) (10,873 ) Balance at end of period (current and non-current) $ 49,869 $ 42,095 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 (in thousands): Lease Term (1) Weighted Average Remaining Years as of June 30, 2019 Annual Minimum Payments (2) 0 - 5 years 2.4 $ 12,589 5 - 10 years 8.0 2,176 10+ years 13.1 47,452 Total 10.8 $ 62,217 (1) Lease term does not include renewal periods. (2) Annual minimum payments do not include $5.0 million from a coal lease that is accounted for as a financing transaction. See Note 16. Leases for additional information.

Discontinued Operations

Discontinued Operations	6 Months Ended
	Jun. 30, 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, the Partnership 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: June 30, 2019 December 31, 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Total ASSETS Current assets Accounts receivable, net $ (4 ) $ 988 $ 984 $ 5 $ 988 $ 993 Total assets of discontinued operations $ (4 ) $ 988 $ 984 $ 5 $ 988 $ 993 LIABILITIES Current liabilities Accounts payable $ 42 $ — $ 42 $ 181 $ — $ 181 Accrued liabilities 616 — 616 766 — 766 Total liabilities of discontinued operations $ 658 $ — $ 658 $ 947 $ — $ 947 The following tables present summarized financial results of the Partnership's discontinued operations in the Consolidated Statements of Comprehensive Income: Three Months Ended June 30, 2019 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Oil and Gas Total Revenues and other income Construction aggregates $ — $ — $ — $ 34,233 $ — $ 34,233 Road construction and asphalt paving services — — — 6,176 — 6,176 Oil and gas — — — — (2 ) (2 ) Gain on asset sales 246 — 246 42 — 42 Total revenues and other income $ 246 $ — $ 246 $ 40,451 $ (2 ) $ 40,449 Operating expenses Operating and maintenance expenses $ — $ 1 $ 1 $ 34,249 $ 32 $ 34,281 Depreciation, depletion and amortization — — — 3,187 — 3,187 Total operating expenses $ — $ 1 $ 1 $ 37,436 $ 32 $ 37,468 Income (loss) from discontinued operations $ 246 $ (1 ) $ 245 $ 3,015 $ (34 ) $ 2,981 Six Months Ended June 30, 2019 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Oil and Gas Total Revenues and other income Construction aggregates $ — $ — $ — $ 60,657 $ — $ 60,657 Road construction and asphalt paving services — — — 6,904 — 6,904 Oil and gas — — — — (2 ) (2 ) Gain on asset sales 238 — 238 51 — 51 Total revenues and other income $ 238 $ — $ 238 $ 67,612 $ (2 ) $ 67,610 Operating expenses Operating and maintenance expenses $ 27 $ 12 $ 39 $ 60,467 $ 46 $ 60,513 Depreciation, depletion and amortization — — — 6,044 — 6,044 Total operating expenses $ 27 $ 12 $ 39 $ 66,511 $ 46 $ 66,557 Interest expense — — — (20 ) — (20 ) Income (loss) from discontinued operations $ 211 $ (12 ) $ 199 $ 1,081 $ (48 ) $ 1,033 Capital expenditures related to the Partnership's discontinued operations were $5.9 million during the six months ended June 30, 2018 .

Common and Preferred Unit Distr

Common and Preferred Unit Distributions	6 Months Ended
	Jun. 30, 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 of GP Natural Resource Partners LLC (the "Board of Directors"). NRP recognizes both common unit and preferred unit distributions on the date the distribution is declared. 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. Income available to common unitholders and the general partner is reduced by Preferred Unit distributions that accumulated during the period. NRP reduced net income attributable to common unitholders and the general partner by $7.5 million during the three months ended June 30, 2019 and 2018 , respectively, and $15.0 million during the six months ended June 30, 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, which is not included in the table below. The following table shows the distributions declared and paid to common and preferred unitholders during the six months ended June 30, 2019 and 2018 , respectively: Common Units Preferred Units Date Paid Period Covered by Distribution Distribution per Unit Total Distribution (1) (In thousands) Distribution per Unit Total Distribution (In thousands) 2019 February 2019 October 1 - December 31, 2018 $ 0.45 $ 5,625 $ 30.00 $ 7,500 May 2019 January 1 - March 31, 2019 0.45 5,630 30.00 7,500 May 2019 (2) Special Distribution 0.85 10,635 — — 2018 February 2018 October 1 - December 31, 2017 $ 0.45 $ 5,617 $ 30.00 $ 7,500 May 2018 January 1 - March 31, 2018 0.45 5,623 30.00 7,500 (1) Totals include the amount paid to NRP's general partner in accordance with the general partner's 2% general partner interest. (2) The special distribution of $0.85 per common unit was made to cover the common unitholders’ tax liability resulting from the sale of NRP’s construction aggregates business in December 2018.

Net Income Per Common Unit

Net Income Per Common Unit	6 Months Ended
	Jun. 30, 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, Warrants, and unvested unit-based awards 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 calculation of diluted net income per common unit for the three months ended June 30, 2019 does not include the assumed conversion of the Preferred Units because the impact would have been anti-dilutive. The calculation of diluted net income per common unit for the three months ended June 30, 2018 and six months ended June 30, 2019 and 2018 includes the assumed conversion of the Preferred Units. The dilutive effect of the Warrants is calculated using the treasury stock method, which assumes that the proceeds from the exercise of these instruments are used to purchase common units at the average market price for the period. The calculation of the dilutive effect of the Warrants for the three and six months ended June 30, 2018 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 diluted net income per common unit for the three and six months ended June 30, 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 Six Months Ended (In thousands, except per unit data) 2019 2018 2019 2018 Allocation of net income Net income from continuing operations $ 19,106 $ 35,129 $ 54,871 $ 61,415 Less: net income attributable to non-controlling interest — (869 ) — (869 ) Less: income attributable to preferred unitholders (7,500 ) (7,500 ) (15,000 ) (15,000 ) Net income from continuing operations attributable to common unitholders and general partner $ 11,606 $ 26,760 $ 39,871 $ 45,546 Less: net income from continuing operations attributable to the general partner (232 ) (535 ) (797 ) (911 ) Net income from continuing operations attributable to common unitholders $ 11,374 $ 26,225 $ 39,074 $ 44,635 Net income from discontinued operations $ 245 $ 2,981 $ 199 $ 1,033 Less: net income from discontinued operations attributable to the general partner (5 ) (60 ) (4 ) (21 ) Net income from discontinued operations attributable to common unitholders $ 240 $ 2,921 $ 195 $ 1,012 Net income $ 19,351 $ 38,110 $ 55,070 $ 62,448 Less: net income attributable to non-controlling interest — (869 ) — (869 ) Less: income attributable to preferred unitholders (7,500 ) (7,500 ) (15,000 ) (15,000 ) Net income attributable to common unitholders and general partner $ 11,851 $ 29,741 $ 40,070 $ 46,579 Less: net income attributable to the general partner (237 ) (595 ) (801 ) (932 ) Net income attributable to common unitholders $ 11,614 $ 29,146 $ 39,269 $ 45,647 Basic net income per common unit Weighted average common units—basic 12,261 12,246 12,258 12,242 Basic net income from continuing operations per common unit $ 0.93 $ 2.14 $ 3.19 $ 3.65 Basic net income from discontinued operations per common unit $ 0.02 $ 0.24 $ 0.02 $ 0.08 Basic net income per common unit $ 0.95 $ 2.38 $ 3.20 $ 3.73 Three Months Ended Six Months Ended (In thousands, except per unit data) 2019 2018 2019 2018 Diluted income per common unit Weighted average common units—basic 12,261 12,246 12,258 12,242 Plus: dilutive effect of Preferred Units — 8,615 7,443 8,615 Plus: dilutive effect of Warrants 1,087 522 1,091 476 Plus: dilutive effect of unvested unit-based awards 40 — 36 — Weighted average common units—diluted 13,388 21,383 20,828 21,333 Net income from continuing operations $ 19,106 $ 35,129 $ 54,871 $ 61,415 Less: net income attributable to non-controlling interest — (869 ) — (869 ) Less: income attributable to preferred unitholders (7,500 ) — — — Diluted net income from continuing operations attributable to common unitholders and general partner $ 11,606 $ 34,260 $ 54,871 $ 60,546 Less: diluted net income from continuing operations attributable to the general partner (232 ) (685 ) (1,097 ) (1,211 ) Diluted net income from continuing operations attributable to common unitholders $ 11,374 $ 33,575 $ 53,774 $ 59,335 Diluted net income from discontinued operations attributable to common unitholders $ 240 $ 2,921 $ 195 $ 1,012 Net income $ 19,351 $ 38,110 $ 55,070 $ 62,448 Less: net income attributable to non-controlling interest — (869 ) — (869 ) Less: income attributable to preferred unitholders (7,500 ) — — — Diluted net income attributable to common unitholders and general partner $ 11,851 $ 37,241 $ 55,070 $ 61,579 Less: diluted net income attributable to the general partner (237 ) (745 ) (1,101 ) (1,232 ) Diluted net income attributable to common unitholders $ 11,614 $ 36,496 $ 53,969 $ 60,347 Diluted net income from continuing operations per common unit $ 0.85 $ 1.57 $ 2.58 $ 2.78 Diluted net income from discontinued operations per common unit $ 0.02 $ 0.14 $ 0.01 $ 0.05 Diluted net income per common unit $ 0.87 $ 1.71 $ 2.59 $ 2.83

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 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 properties and coal-related transportation and processing assets. Other assets include industrial mineral 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 and soda ash production business located 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 3. 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, royalty, information technology and shared facilities services and are included in Operating and maintenance expenses on the Partnership's Consolidated Statements of Comprehensive Income. Corporate and Financing includes functional corporate departments that do not earn revenues. Costs incurred by these departments include interest and financing, corporate headquarters and overhead, centralized treasury, legal and accounting and other corporate-level activity not specifically allocated to a segment and are included in General and administrative expenses on the Partnership's 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 June 30, 2019 Revenues $ 69,890 $ 11,333 $ — $ 81,223 Gain on asset sales 246 — — 246 Operating and maintenance expenses 12,459 — — 12,459 Depreciation, depletion and amortization 3,970 — — 3,970 General and administrative expenses — — 4,196 4,196 Other expenses, net — — 41,738 41,738 Net income (loss) from continuing operations 53,707 11,333 (45,934 ) 19,106 Income from discontinued operations — — — 245 Three Months Ended June 30, 2018 Revenues $ 52,922 $ 16,529 $ — $ 69,451 Gain on asset sales 168 — — 168 Operating and maintenance expenses 8,117 — — 8,117 Depreciation, depletion and amortization 5,376 — — 5,376 General and administrative expenses — — 3,263 3,263 Other expenses, net — — 17,734 17,734 Net income (loss) from continuing operations 39,597 16,529 (20,997 ) 35,129 Income from discontinued operations — — — 2,981 Operating Segments (In thousands) Coal Royalty and Other Soda Ash Corporate and Financing Total Six Months Ended June 30, 2019 Revenues $ 124,993 $ 23,015 $ — $ 148,008 Gain on asset sales 502 — — 502 Operating and maintenance expenses 20,819 — — 20,819 Depreciation, depletion and amortization 8,362 — — 8,362 General and administrative expenses — — 8,546 8,546 Other expenses, net — — 55,912 55,912 Net income (loss) from continuing operations 96,314 23,015 (64,458 ) 54,871 Income from discontinued operations — — — 199 Six Months Ended June 30, 2018 Revenues $ 102,779 $ 26,150 $ — $ 128,929 Gain on asset sales 819 — — 819 Operating and maintenance expenses 14,332 — — 14,332 Depreciation, depletion and amortization 10,476 — — 10,476 General and administrative expenses — — 7,599 7,599 Asset impairments 242 — — 242 Other expenses, net — — 35,684 35,684 Net income (loss) from continuing operations 78,548 26,150 (43,283 ) 61,415 Income from discontinued operations — — — 1,033 As of June 30, 2019 Total assets of continuing operations $ 949,198 $ 251,135 $ 18,126 $ 1,218,459 Total assets of discontinued operations — — — 984 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	6 Months Ended
	Jun. 30, 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 Six Months Ended (In thousands) 2019 2018 2019 2018 Balance at beginning of period $ 249,936 $ 241,679 $ 247,051 $ 245,433 Income allocation to NRP’s equity interests 12,549 17,657 25,443 28,489 Amortization of basis difference (1,216 ) (1,128 ) (2,428 ) (2,339 ) Comprehensive income (loss) from unconsolidated investment (824 ) (434 ) 179 (1,559 ) Distribution (9,310 ) (12,250 ) (19,110 ) (24,500 ) Balance at end of period $ 251,135 $ 245,524 $ 251,135 $ 245,524 The following table represents summarized financial information for Ciner Wyoming as derived from their unaudited financial statements: Three Months Ended Six Months Ended (In thousands) 2019 2018 2019 2018 Sales $ 129,794 $ 91,882 $ 260,230 $ 213,101 Gross profit 32,533 14,022 66,635 42,244 Net income 25,610 36,035 51,925 58,142

Mineral Rights, Net

Mineral Rights, Net	6 Months Ended
	Jun. 30, 2019
Extractive Industries [Abstract]
Mineral Rights, Net	Mineral Rights, Net The Partnership’s mineral rights consist of the following: June 30, 2019 December 31, 2018 (In thousands) Cost Accumulated Depletion Net Book Value Cost Accumulated Depletion Net Book Value Coal properties $ 1,148,176 $ (456,817 ) $ 691,359 $ 1,164,845 $ (451,210 ) $ 713,635 Aggregates properties 41,589 (12,729 ) 28,860 24,920 (11,814 ) 13,106 Oil and gas royalty properties 12,395 (7,759 ) 4,636 12,395 (7,632 ) 4,763 Other 13,157 (1,599 ) 11,558 13,158 (1,550 ) 11,608 Total mineral rights, net $ 1,215,317 $ (478,904 ) $ 736,413 $ 1,215,318 $ (472,206 ) $ 743,112 Depletion expense related to the Partnership’s mineral rights is included in Depreciation, depletion and amortization on its Consolidated Statements of Comprehensive Income and totaled $3.2 million and $4.5 million for the three months ended June 30, 2019 and 2018 , respectively, and $6.7 million and $8.8 million for the six months ended June 30, 2019 and 2018 , respectively.

Intangible Assets, Net

Intangible Assets, Net	6 Months Ended
	Jun. 30, 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 LP ("Foresight Energy") in which the Partnership receives throughput fees for the transportation and processing of coal. The Partnership's intangible assets included on its Consolidated Balance Sheets are as follows: June 30, December 31, (In thousands) 2019 2018 Intangible assets at cost $ 81,109 $ 81,109 Less: accumulated amortization (40,101 ) (38,596 ) Total intangible assets, net $ 41,008 $ 42,513 Amortization expense included in Depreciation, depletion and amortization on the Partnership's Consolidated Statements of Comprehensive Income was $0.7 million and $0.8 million for the three months ended June 30, 2019 and 2018 , respectively and $1.5 million for the six months ended June 30, 2019 and 2018 .

Debt, Net

Debt, Net	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Debt, Net	Debt, Net The Partnership's debt consists of the following: June 30, December 31, (In thousands) 2019 2018 NRP LP debt: 9.125% senior notes, with semi-annual interest payments in June and December, due June 2025 issued at par ("2025 Senior Notes") $ 300,000 $ — 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% ("2022 Senior Notes") — 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 9,458 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 $ 252,667 $ 341,500 Total debt at face value $ 552,667 $ 687,138 Net unamortized debt discount — (1,266 ) Net unamortized debt issuance costs (8,598 ) (13,114 ) Total debt, net $ 544,069 $ 672,758 Less: current portion of long-term debt (46,040 ) (115,184 ) Total long-term debt, net $ 498,029 $ 557,574 NRP LP Debt 2025 Senior Notes In April 2019, NRP and NRP Finance issued the 2025 Senior Notes and used the $300 million proceeds and $76 million of cash on hand to fund the redemption of the 2022 Senior Notes. 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. The Partnership incurred $6.6 million of debt issuance costs related to the 2025 Senior Notes which are presented netted against the debt principal on the Partnership's Consolidated Balance Sheet at June 30, 2019 . 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 2025 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. As of June 30, 2019 , NRP and NRP Finance were in compliance with the terms of the Indenture relating to their 2025 Senior Notes. 2022 Senior Notes During the three months ended June 30, 2019, the Partnership redeemed the 2022 Senior Notes at a redemption price equal to 105.250% of the principal amount of the 2022 Senior Notes, plus accrued and unpaid interest. In connection with the early redemption, the Partnership paid an $18.1 million call premium and also wrote off $10.4 million of unamortized debt issuance costs and debt discount. These expenses are included in Loss on extinguishment of debt on the Partnership's Consolidated Statements of Comprehensive Income. Opco Debt All of Opco’s debt is guaranteed by its wholly owned subsidiaries and is secured by certain of the assets of Opco and its wholly owned subsidiaries other than NRP Trona LLC. As of June 30, 2019 and December 31, 2018 , Opco was in compliance with the terms of the financial covenants contained in its debt agreements. Opco Credit Facility In April 2019, the Partnership entered into the Fourth Amendment (the “Fourth Amendment”) to the Opco Credit Facility (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 Opco 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. As of June 30, 2019 , the Partnership did not have any borrowings outstanding under the Opco Credit Facility and had $100 million in available borrowing capacity. The weighted average interest rates for the borrowings outstanding under the Opco Credit Facility during the three and six months ended June 30, 2018 were 6.18% and 6.08% , respectively. There were no borrowings outstanding under the Opco Credit Facility during the three and six months ended June 30, 2019 . Debt issuance cost related to the Opco Credit Facility were $2.2 million and $1.7 million at June 30, 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 $543.4 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 June 30, 2019 and December 31, 2018 , respectively. Opco Senior Notes As of June 30, 2019 and December 31, 2018 , the Opco Senior Notes had cumulative principal balances of $252.7 million and $341.5 million , respectively. Opco made mandatory principal payments of $88.8 million , which included a $49.3 million pre-payment as a result of the sale of the Partnership's construction aggregates business, during the six months ended June 30, 2019 , and $48.1 million during the six months ended June 30, 2018 . The 8.92% Opco Senior Notes also provides that in the event that Opco’s leverage ratio of consolidated indebtedness to consolidated EBITDDA (as defined in the Note Purchase Agreements) exceeds 3.75 to 1.00 at the end of any fiscal quarter, then in addition to all other interest accruing on these notes, additional interest in the amount of 2.00% per annum shall accrue on the notes for the two succeeding quarters and for as long thereafter as the leverage ratio remains above 3.75 to 1.00. Opco has not exceeded the 3.75 to 1.00 ratio at the end of any fiscal quarter through June 30, 2019 .

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 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 and six months ended June 30, 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: June 30, 2019 December 31, 2018 (In thousands) Carrying Estimated Carrying Estimated Debt: NRP 2025 Senior Notes (1) $ 293,556 $ 309,000 $ — $ — NRP 2022 Senior Notes (1) — — 334,024 356,871 Opco Senior Notes (2) 250,513 260,247 338,734 352,599 Opco Credit Facility (3) — — — — Assets: Contracts receivable (current and long-term) (4) $ 39,878 $ 34,099 $ 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 2025 or 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 on the Partnership's Consolidated Statements of Comprehensive Income. The embedded derivatives had zero value as of June 30, 2019 and December 31, 2018 .

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 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 Western Pocahontas Properties Limited Partnership ("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 Six Months Ended (In thousands) 2019 2018 2019 2018 Operating and maintenance expenses $ 1,573 $ 1,459 $ 3,208 $ 3,134 General and administrative expenses 886 849 1,849 1,780 During the three months ended June 30, 2019 and 2018 , the Partnership recognized $0.5 million and $2.3 million in Operating and maintenance expenses, respectively, on its Consolidated Statements of Comprehensive Income related to an overriding royalty agreement with WPPLP. These charges were $3.5 million and $2.9 million during the six months ended June 30, 2019 and 2018 , respectively. At June 30, 2019 , the Partnership had $0.4 million of Other assets on its Consolidated Balance Sheet related to a prepaid royalty for this agreement and at December 31, 2018 the Partnership had $1.4 million of Accounts payable to WPPLP for this agreement. The Partnership had Accounts payable on its Consolidated Balance Sheets to QMC of $0.4 million and $0.5 million as of June 30, 2019 and December 31, 2018 , respectively. Quintana Capital Group GP, Ltd. Corbin J. Robertson, Jr. is a principal in Quintana Capital Group GP, Ltd. ("Quintana Capital"), which controls several private equity funds focused on investments in the energy business. In connection with the formation of Quintana Capital, the Partnership adopted a formal conflicts policy that establishes the opportunities that will be pursued by the Partnership and those that will be pursued by Quintana Capital. The governance documents of Quintana Capital’s affiliated investment funds reflect the guidelines set forth in the Partnership's conflicts policy. At June 30, 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 and $0.4 million for the three and six months ended June 30, 2018 , respectively.

Major Customers

Major Customers	6 Months Ended
	Jun. 30, 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 June 30, Six Months Ended June 30, 2019 2018 2019 2018 (In thousands) Revenues Percent Revenues Percent Revenues Percent Revenues Percent Foresight Energy (1) $ 16,038 20 % $ 12,990 19 % $ 32,229 22 % $ 25,421 20 % Contura Energy (1) (2) 12,614 16 % 5,915 9 % 23,725 16 % 11,382 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 and six months ended June 30, 2019 relate to the combined company, while revenues during the three and six months ended June 30, 2018 do not include revenues from Alpha Natural Resources.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 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 second 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. A trial in this matter is currently set to commence in September 2019.

Unit-Based Compensation

Unit-Based Compensation	6 Months Ended
	Jun. 30, 2019
Unit-Based Compensation [Abstract]
Unit-Based Compensation	Unit-Based Compensation The Partnership's unit-based awards granted in 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 six months ended June 30, 2019 and 2018 were $5.4 million and $2.2 million , respectively. Total unit-based compensation expense associated with these awards was $0.4 million and $0.2 million for the three months ended June 30, 2019 and 2018 , respectively, and $1.3 million and $0.8 million for the six months ended June 30, 2019 and 2018 , respectively and is included in General and administrative expenses and Operating and maintenance expenses on the Partnership's Consolidated Statements of Comprehensive Income. The unamortized cost associated with unvested outstanding awards as of June 30, 2019 is $4.5 million , which is to be recognized over a weighted average period of 2.5 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 129 $ 41.41 Fully vested and issued (12 ) $ 41.47 Forfeitures (15 ) $ 37.33 Outstanding at June 30, 2019 157 $ 37.48

Leases

Leases	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Leases	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 on its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of June 30, 2019 2019 $ 242 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,253 Less: present value adjustment (2) (10,742 ) Total operating lease liability $ 3,511 (1) The remaining lease term of the Partnership's operating lease is 29.5 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 Lessee Accounting Under ASC 842 As of June 30, 2019 , the Partnership had one operating lease for an office building that is owned by WPPLP. 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 June 30, 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 Sheet 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 June 30, 2019 . During the three and six months ended June 30, 2019 , the Partnership incurred total operating lease expenses of $0.1 million and $0.2 million , respectively, included in both Operating and maintenance expenses and General and administrative expenses on 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 on its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of June 30, 2019 2019 $ 242 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,253 Less: present value adjustment (2) (10,742 ) Total operating lease liability $ 3,511 (1) The remaining lease term of the Partnership's operating lease is 29.5 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 on the Partnership's Consolidated Statements of Comprehensive Income and were $1.3 million and $1.0 million in the three months ended June 30, 2019 and 2018 , respectively, and $2.5 million and $2.1 million in the six months ended June 30, 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. 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. 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) June 30, 2019 December 31, 2018 Accounts receivable $ 605 $ 661 Contract receivable (current and long-term) 39,878 40,776 Unearned income 23,455 25,058 Projected remaining payments $ 63,938 $ 66,495
Leases	Leases Lessee Accounting Under ASC 842 As of June 30, 2019 , the Partnership had one operating lease for an office building that is owned by WPPLP. 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 June 30, 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 Sheet 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 June 30, 2019 . During the three and six months ended June 30, 2019 , the Partnership incurred total operating lease expenses of $0.1 million and $0.2 million , respectively, included in both Operating and maintenance expenses and General and administrative expenses on 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 on its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of June 30, 2019 2019 $ 242 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,253 Less: present value adjustment (2) (10,742 ) Total operating lease liability $ 3,511 (1) The remaining lease term of the Partnership's operating lease is 29.5 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 on the Partnership's Consolidated Statements of Comprehensive Income and were $1.3 million and $1.0 million in the three months ended June 30, 2019 and 2018 , respectively, and $2.5 million and $2.1 million in the six months ended June 30, 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. 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. 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) June 30, 2019 December 31, 2018 Accounts receivable $ 605 $ 661 Contract receivable (current and long-term) 39,878 40,776 Unearned income 23,455 25,058 Projected remaining payments $ 63,938 $ 66,495
Leases	Leases Lessee Accounting Under ASC 842 As of June 30, 2019 , the Partnership had one operating lease for an office building that is owned by WPPLP. 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 June 30, 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 Sheet 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 June 30, 2019 . During the three and six months ended June 30, 2019 , the Partnership incurred total operating lease expenses of $0.1 million and $0.2 million , respectively, included in both Operating and maintenance expenses and General and administrative expenses on 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 on its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of June 30, 2019 2019 $ 242 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,253 Less: present value adjustment (2) (10,742 ) Total operating lease liability $ 3,511 (1) The remaining lease term of the Partnership's operating lease is 29.5 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 on the Partnership's Consolidated Statements of Comprehensive Income and were $1.3 million and $1.0 million in the three months ended June 30, 2019 and 2018 , respectively, and $2.5 million and $2.1 million in the six months ended June 30, 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. 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. 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) June 30, 2019 December 31, 2018 Accounts receivable $ 605 $ 661 Contract receivable (current and long-term) 39,878 40,776 Unearned income 23,455 25,058 Projected remaining payments $ 63,938 $ 66,495

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The following represents material events that have occurred subsequent to June 30, 2019 through the time of the Partnership’s filing of its Quarterly Report on Form 10-Q with the SEC: Distributions Declared In July 2019, the Board of Directors declared a distribution of $0.45 per common unit with respect to the second quarter of 2019. The Board of Directors also declared a cash distribution on NRP's Preferred Units with respect to the second quarter of 2019 totaling $7.5 million .

Basis of Presentation (Policies

Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 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 total assets, total liabilities, partners' capital, net income or cash flows from operating, investing or financing activities.
Recasting of Certain Prior Period Information	Recasting of Certain Prior Period Information As described in Note 3. 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.
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 its Consolidated 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 by NRP 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 ASC 842, the Partnership elected to not combine lease and non-lease components. See Note 16. 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 continuing to evaluate the provisions of this guidance on its consolidated financial statements, but based on its analysis to date, the Partnership does not expect this standard to have a material effect on its consolidated financial statements.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	6 Months Ended
	Jun. 30, 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 June 30, Six Months Ended June 30, (In thousands) 2019 2018 2019 2018 Coal royalty revenues $ 30,703 $ 34,762 $ 62,834 $ 65,764 Production lease minimum revenues 15,879 2,006 18,579 4,541 Minimum lease straight-line revenues 3,854 569 7,170 1,172 Property tax revenues 1,377 1,523 2,810 2,705 Wheelage revenues 1,945 1,609 3,360 3,583 Coal overriding royalty revenues 3,999 3,702 7,974 6,574 Lease amendment revenues 4,414 — 5,185 — Aggregates royalty revenues 1,237 1,572 2,701 2,663 Oil and gas royalty revenues 482 1,354 2,201 4,252 Other revenues 726 823 1,304 1,140 Coal royalty and other revenues (1) $ 64,616 $ 47,920 $ 114,118 $ 92,394 Transportation and processing services revenues (2) 5,274 5,002 10,875 10,385 Total Coal Royalty and Other segment revenues $ 69,890 $ 52,922 $ 124,993 $ 102,779 (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 $2.6 million and $3.1 million for the three months ended June 30, 2019 and 2018 , respectively, and $5.6 million and $6.1 million for the six months ended June 30, 2019 and 2018 , respectively. The remaining transportation and processing services revenues of $2.6 million and $1.9 million for the three months ended June 30, 2019 , and 2018 , respectively, and $5.3 million and $4.3 million for the six months ended June 30, 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 16. 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: June 30, December 31, (In thousands) 2019 2018 Receivables Accounts receivable, net $ 25,438 $ 29,001 Prepaid expenses and other (1) 5,445 2,483 Contract liabilities Current portion of deferred revenue $ 6,579 $ 3,509 Deferred revenue 43,290 49,044 (1) Prepaid expenses and other includes notes receivable from contracts with customers.
Activity Related to Partners' Coal Royalty and Other Segment Deferred Revenue	The following table shows the activity related to the Partnership's Coal Royalty and Other segment deferred revenue: Six Months Ended June 30, (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 29,776 17,954 Recognition of previously deferred revenue (32,460 ) (10,873 ) Balance at end of period (current and non-current) $ 49,869 $ 42,095
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 (in thousands): Lease Term (1) Weighted Average Remaining Years as of June 30, 2019 Annual Minimum Payments (2) 0 - 5 years 2.4 $ 12,589 5 - 10 years 8.0 2,176 10+ years 13.1 47,452 Total 10.8 $ 62,217 (1) Lease term does not include renewal periods. (2) Annual minimum payments do not include $5.0 million from a coal lease that is accounted for as a financing transaction. See Note 16. Leases for additional information.

Discontinued Operations (Tables

Discontinued Operations (Tables)	6 Months Ended
	Jun. 30, 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: June 30, 2019 December 31, 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Total ASSETS Current assets Accounts receivable, net $ (4 ) $ 988 $ 984 $ 5 $ 988 $ 993 Total assets of discontinued operations $ (4 ) $ 988 $ 984 $ 5 $ 988 $ 993 LIABILITIES Current liabilities Accounts payable $ 42 $ — $ 42 $ 181 $ — $ 181 Accrued liabilities 616 — 616 766 — 766 Total liabilities of discontinued operations $ 658 $ — $ 658 $ 947 $ — $ 947 The following tables present summarized financial results of the Partnership's discontinued operations in the Consolidated Statements of Comprehensive Income: Three Months Ended June 30, 2019 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Oil and Gas Total Revenues and other income Construction aggregates $ — $ — $ — $ 34,233 $ — $ 34,233 Road construction and asphalt paving services — — — 6,176 — 6,176 Oil and gas — — — — (2 ) (2 ) Gain on asset sales 246 — 246 42 — 42 Total revenues and other income $ 246 $ — $ 246 $ 40,451 $ (2 ) $ 40,449 Operating expenses Operating and maintenance expenses $ — $ 1 $ 1 $ 34,249 $ 32 $ 34,281 Depreciation, depletion and amortization — — — 3,187 — 3,187 Total operating expenses $ — $ 1 $ 1 $ 37,436 $ 32 $ 37,468 Income (loss) from discontinued operations $ 246 $ (1 ) $ 245 $ 3,015 $ (34 ) $ 2,981 Six Months Ended June 30, 2019 2018 (In thousands) Construction Aggregates NRP Total Construction Aggregates NRP Oil and Gas Total Revenues and other income Construction aggregates $ — $ — $ — $ 60,657 $ — $ 60,657 Road construction and asphalt paving services — — — 6,904 — 6,904 Oil and gas — — — — (2 ) (2 ) Gain on asset sales 238 — 238 51 — 51 Total revenues and other income $ 238 $ — $ 238 $ 67,612 $ (2 ) $ 67,610 Operating expenses Operating and maintenance expenses $ 27 $ 12 $ 39 $ 60,467 $ 46 $ 60,513 Depreciation, depletion and amortization — — — 6,044 — 6,044 Total operating expenses $ 27 $ 12 $ 39 $ 66,511 $ 46 $ 66,557 Interest expense — — — (20 ) — (20 ) Income (loss) from discontinued operations $ 211 $ (12 ) $ 199 $ 1,081 $ (48 ) $ 1,033

Common and Preferred Unit Dis_2

Common and Preferred Unit Distributions (Tables)	6 Months Ended
	Jun. 30, 2019
Equity [Abstract]
Distributions declared and paid	The following table shows the distributions declared and paid to common and preferred unitholders during the six months ended June 30, 2019 and 2018 , respectively: Common Units Preferred Units Date Paid Period Covered by Distribution Distribution per Unit Total Distribution (1) (In thousands) Distribution per Unit Total Distribution (In thousands) 2019 February 2019 October 1 - December 31, 2018 $ 0.45 $ 5,625 $ 30.00 $ 7,500 May 2019 January 1 - March 31, 2019 0.45 5,630 30.00 7,500 May 2019 (2) Special Distribution 0.85 10,635 — — 2018 February 2018 October 1 - December 31, 2017 $ 0.45 $ 5,617 $ 30.00 $ 7,500 May 2018 January 1 - March 31, 2018 0.45 5,623 30.00 7,500 (1) Totals include the amount paid to NRP's general partner in accordance with the general partner's 2% general partner interest. (2) The special distribution of $0.85 per common unit was made to cover the common unitholders’ tax liability resulting from the sale of NRP’s construction aggregates business in December 2018.

Net Income Per Common Unit (Tab

Net Income Per Common Unit (Tables)	6 Months Ended
	Jun. 30, 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 Six Months Ended (In thousands, except per unit data) 2019 2018 2019 2018 Allocation of net income Net income from continuing operations $ 19,106 $ 35,129 $ 54,871 $ 61,415 Less: net income attributable to non-controlling interest — (869 ) — (869 ) Less: income attributable to preferred unitholders (7,500 ) (7,500 ) (15,000 ) (15,000 ) Net income from continuing operations attributable to common unitholders and general partner $ 11,606 $ 26,760 $ 39,871 $ 45,546 Less: net income from continuing operations attributable to the general partner (232 ) (535 ) (797 ) (911 ) Net income from continuing operations attributable to common unitholders $ 11,374 $ 26,225 $ 39,074 $ 44,635 Net income from discontinued operations $ 245 $ 2,981 $ 199 $ 1,033 Less: net income from discontinued operations attributable to the general partner (5 ) (60 ) (4 ) (21 ) Net income from discontinued operations attributable to common unitholders $ 240 $ 2,921 $ 195 $ 1,012 Net income $ 19,351 $ 38,110 $ 55,070 $ 62,448 Less: net income attributable to non-controlling interest — (869 ) — (869 ) Less: income attributable to preferred unitholders (7,500 ) (7,500 ) (15,000 ) (15,000 ) Net income attributable to common unitholders and general partner $ 11,851 $ 29,741 $ 40,070 $ 46,579 Less: net income attributable to the general partner (237 ) (595 ) (801 ) (932 ) Net income attributable to common unitholders $ 11,614 $ 29,146 $ 39,269 $ 45,647 Basic net income per common unit Weighted average common units—basic 12,261 12,246 12,258 12,242 Basic net income from continuing operations per common unit $ 0.93 $ 2.14 $ 3.19 $ 3.65 Basic net income from discontinued operations per common unit $ 0.02 $ 0.24 $ 0.02 $ 0.08 Basic net income per common unit $ 0.95 $ 2.38 $ 3.20 $ 3.73 Three Months Ended Six Months Ended (In thousands, except per unit data) 2019 2018 2019 2018 Diluted income per common unit Weighted average common units—basic 12,261 12,246 12,258 12,242 Plus: dilutive effect of Preferred Units — 8,615 7,443 8,615 Plus: dilutive effect of Warrants 1,087 522 1,091 476 Plus: dilutive effect of unvested unit-based awards 40 — 36 — Weighted average common units—diluted 13,388 21,383 20,828 21,333 Net income from continuing operations $ 19,106 $ 35,129 $ 54,871 $ 61,415 Less: net income attributable to non-controlling interest — (869 ) — (869 ) Less: income attributable to preferred unitholders (7,500 ) — — — Diluted net income from continuing operations attributable to common unitholders and general partner $ 11,606 $ 34,260 $ 54,871 $ 60,546 Less: diluted net income from continuing operations attributable to the general partner (232 ) (685 ) (1,097 ) (1,211 ) Diluted net income from continuing operations attributable to common unitholders $ 11,374 $ 33,575 $ 53,774 $ 59,335 Diluted net income from discontinued operations attributable to common unitholders $ 240 $ 2,921 $ 195 $ 1,012 Net income $ 19,351 $ 38,110 $ 55,070 $ 62,448 Less: net income attributable to non-controlling interest — (869 ) — (869 ) Less: income attributable to preferred unitholders (7,500 ) — — — Diluted net income attributable to common unitholders and general partner $ 11,851 $ 37,241 $ 55,070 $ 61,579 Less: diluted net income attributable to the general partner (237 ) (745 ) (1,101 ) (1,232 ) Diluted net income attributable to common unitholders $ 11,614 $ 36,496 $ 53,969 $ 60,347 Diluted net income from continuing operations per common unit $ 0.85 $ 1.57 $ 2.58 $ 2.78 Diluted net income from discontinued operations per common unit $ 0.02 $ 0.14 $ 0.01 $ 0.05 Diluted net income per common unit $ 0.87 $ 1.71 $ 2.59 $ 2.83

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 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 June 30, 2019 Revenues $ 69,890 $ 11,333 $ — $ 81,223 Gain on asset sales 246 — — 246 Operating and maintenance expenses 12,459 — — 12,459 Depreciation, depletion and amortization 3,970 — — 3,970 General and administrative expenses — — 4,196 4,196 Other expenses, net — — 41,738 41,738 Net income (loss) from continuing operations 53,707 11,333 (45,934 ) 19,106 Income from discontinued operations — — — 245 Three Months Ended June 30, 2018 Revenues $ 52,922 $ 16,529 $ — $ 69,451 Gain on asset sales 168 — — 168 Operating and maintenance expenses 8,117 — — 8,117 Depreciation, depletion and amortization 5,376 — — 5,376 General and administrative expenses — — 3,263 3,263 Other expenses, net — — 17,734 17,734 Net income (loss) from continuing operations 39,597 16,529 (20,997 ) 35,129 Income from discontinued operations — — — 2,981 Operating Segments (In thousands) Coal Royalty and Other Soda Ash Corporate and Financing Total Six Months Ended June 30, 2019 Revenues $ 124,993 $ 23,015 $ — $ 148,008 Gain on asset sales 502 — — 502 Operating and maintenance expenses 20,819 — — 20,819 Depreciation, depletion and amortization 8,362 — — 8,362 General and administrative expenses — — 8,546 8,546 Other expenses, net — — 55,912 55,912 Net income (loss) from continuing operations 96,314 23,015 (64,458 ) 54,871 Income from discontinued operations — — — 199 Six Months Ended June 30, 2018 Revenues $ 102,779 $ 26,150 $ — $ 128,929 Gain on asset sales 819 — — 819 Operating and maintenance expenses 14,332 — — 14,332 Depreciation, depletion and amortization 10,476 — — 10,476 General and administrative expenses — — 7,599 7,599 Asset impairments 242 — — 242 Other expenses, net — — 35,684 35,684 Net income (loss) from continuing operations 78,548 26,150 (43,283 ) 61,415 Income from discontinued operations — — — 1,033 As of June 30, 2019 Total assets of continuing operations $ 949,198 $ 251,135 $ 18,126 $ 1,218,459 Total assets of discontinued operations — — — 984 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)	6 Months Ended
	Jun. 30, 2019
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Summarized Financial Information	Activity related to this investment is as follows: Three Months Ended Six Months Ended (In thousands) 2019 2018 2019 2018 Balance at beginning of period $ 249,936 $ 241,679 $ 247,051 $ 245,433 Income allocation to NRP’s equity interests 12,549 17,657 25,443 28,489 Amortization of basis difference (1,216 ) (1,128 ) (2,428 ) (2,339 ) Comprehensive income (loss) from unconsolidated investment (824 ) (434 ) 179 (1,559 ) Distribution (9,310 ) (12,250 ) (19,110 ) (24,500 ) Balance at end of period $ 251,135 $ 245,524 $ 251,135 $ 245,524 The following table represents summarized financial information for Ciner Wyoming as derived from their unaudited financial statements: Three Months Ended Six Months Ended (In thousands) 2019 2018 2019 2018 Sales $ 129,794 $ 91,882 $ 260,230 $ 213,101 Gross profit 32,533 14,022 66,635 42,244 Net income 25,610 36,035 51,925 58,142

Mineral Rights, Net (Tables)

Mineral Rights, Net (Tables)	6 Months Ended
	Jun. 30, 2019
Extractive Industries [Abstract]
Mineral Rights	The Partnership’s mineral rights consist of the following: June 30, 2019 December 31, 2018 (In thousands) Cost Accumulated Depletion Net Book Value Cost Accumulated Depletion Net Book Value Coal properties $ 1,148,176 $ (456,817 ) $ 691,359 $ 1,164,845 $ (451,210 ) $ 713,635 Aggregates properties 41,589 (12,729 ) 28,860 24,920 (11,814 ) 13,106 Oil and gas royalty properties 12,395 (7,759 ) 4,636 12,395 (7,632 ) 4,763 Other 13,157 (1,599 ) 11,558 13,158 (1,550 ) 11,608 Total mineral rights, net $ 1,215,317 $ (478,904 ) $ 736,413 $ 1,215,318 $ (472,206 ) $ 743,112

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	6 Months Ended
	Jun. 30, 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: June 30, December 31, (In thousands) 2019 2018 Intangible assets at cost $ 81,109 $ 81,109 Less: accumulated amortization (40,101 ) (38,596 ) Total intangible assets, net $ 41,008 $ 42,513

Debt, Net (Tables)

Debt, Net (Tables)	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Long-Term Debt	The Partnership's debt consists of the following: June 30, December 31, (In thousands) 2019 2018 NRP LP debt: 9.125% senior notes, with semi-annual interest payments in June and December, due June 2025 issued at par ("2025 Senior Notes") $ 300,000 $ — 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% ("2022 Senior Notes") — 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 9,458 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 $ 252,667 $ 341,500 Total debt at face value $ 552,667 $ 687,138 Net unamortized debt discount — (1,266 ) Net unamortized debt issuance costs (8,598 ) (13,114 ) Total debt, net $ 544,069 $ 672,758 Less: current portion of long-term debt (46,040 ) (115,184 ) Total long-term debt, net $ 498,029 $ 557,574

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 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: June 30, 2019 December 31, 2018 (In thousands) Carrying Estimated Carrying Estimated Debt: NRP 2025 Senior Notes (1) $ 293,556 $ 309,000 $ — $ — NRP 2022 Senior Notes (1) — — 334,024 356,871 Opco Senior Notes (2) 250,513 260,247 338,734 352,599 Opco Credit Facility (3) — — — — Assets: Contracts receivable (current and long-term) (4) $ 39,878 $ 34,099 $ 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 2025 or 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)	6 Months Ended
	Jun. 30, 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 Six Months Ended (In thousands) 2019 2018 2019 2018 Operating and maintenance expenses $ 1,573 $ 1,459 $ 3,208 $ 3,134 General and administrative expenses 886 849 1,849 1,780

Major Customers (Tables)

Major Customers (Tables)	6 Months Ended
	Jun. 30, 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 June 30, Six Months Ended June 30, 2019 2018 2019 2018 (In thousands) Revenues Percent Revenues Percent Revenues Percent Revenues Percent Foresight Energy (1) $ 16,038 20 % $ 12,990 19 % $ 32,229 22 % $ 25,421 20 % Contura Energy (1) (2) 12,614 16 % 5,915 9 % 23,725 16 % 11,382 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 and six months ended June 30, 2019 relate to the combined company, while revenues during the three and six months ended June 30, 2018 do not include revenues from Alpha Natural Resources.

Unit-Based Compensation (Tables

Unit-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 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 129 $ 41.41 Fully vested and issued (12 ) $ 41.47 Forfeitures (15 ) $ 37.33 Outstanding at June 30, 2019 157 $ 37.48

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 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 on its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of June 30, 2019 2019 $ 242 2020 483 2021 483 2022 483 2023 483 After 2023 12,079 Total lease payments (1) $ 14,253 Less: present value adjustment (2) (10,742 ) Total operating lease liability $ 3,511 (1) The remaining lease term of the Partnership's operating lease is 29.5 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) June 30, 2019 December 31, 2018 Accounts receivable $ 605 $ 661 Contract receivable (current and long-term) 39,878 40,776 Unearned income 23,455 25,058 Projected remaining payments $ 63,938 $ 66,495

Basis of Presentation - Narrati

Basis of Presentation - Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)segment	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018	Jul. 31, 2013	Jan. 31, 2013
Accounting Policies [Abstract]
Number of operating segments | segment	2
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 14,925		$ 104,191
Senior Notes | Opco
Restricted Cash and Cash Equivalents Items [Line Items]
Principal payments on its senior notes	$ 88,800	$ 48,100
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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	$ 69,890	$ 52,922	$ 124,993	$ 102,779
Revenues	81,223	69,451	148,008	128,929
Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	64,616	47,920	114,118	92,394
Revenues	64,616	47,920	114,118	92,394
Coal Royalty and Other | Coal royalty revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	30,703	34,762	62,834	65,764
Coal Royalty and Other | Production lease minimum revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	15,879	2,006	18,579	4,541
Coal Royalty and Other | Minimum lease straight-line revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	3,854	569	7,170	1,172
Coal Royalty and Other | Property tax revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	1,377	1,523	2,810	2,705
Coal Royalty and Other | Wheelage revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	1,945	1,609	3,360	3,583
Coal Royalty and Other | Coal overriding royalty revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	3,999	3,702	7,974	6,574
Coal Royalty and Other | Lease amendment revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	4,414	0	5,185	0
Coal Royalty and Other | Aggregates royalty revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	1,237	1,572	2,701	2,663
Coal Royalty and Other | Oil and gas royalty revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	482	1,354	2,201	4,252
Coal Royalty and Other | Other revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	726	823	1,304	1,140
Coal Royalty and Other | Transportation and processing services revenues
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	2,600	3,100	5,600	6,100
Revenues	5,274	5,002	10,875	10,385
Coal Royalty and Other | Transportation and processing revenues
Disaggregation of Revenue [Line Items]
Lease revenue	$ 2,600	$ 1,900	$ 5,300	$ 4,300

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Schedule of Receivables and Liabilities from Contracts with Customers (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Current portion of deferred revenue	$ 6,579	$ 3,509
Deferred revenue	43,290	49,044
Coal Royalty
Segment Reporting Information [Line Items]
Accounts receivable, net	25,438	29,001
Prepaid expenses and other	5,445	2,483
Current portion of deferred revenue	6,579	3,509
Deferred revenue	$ 43,290	$ 49,044

Revenue from Contracts with C_5

Revenue from Contracts with Customers Revenue Recognition Deferred Revenue Rollforward (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Deferred Revenue	$ 49,869	$ 42,095	$ 52,553	$ 52,553	$ 35,014	$ 100,605
Increase due to minimums and lease amendment fees	29,776	17,954
Recognition of previously deferred revenue	$ (32,460)	$ (10,873)
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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Average Remaining Contract Term	10 years 9 months 6 days		10 years 9 months 6 days
Total Coal Royalty and Other segment revenues	$ 69,890	$ 52,922	$ 124,993	$ 102,779
Annual minimum payments	62,217		62,217
Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	64,616	47,920	114,118	92,394
Production lease minimum revenues | Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	15,879	2,006	18,579	4,541
Transportation and processing services revenues | Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total Coal Royalty and Other segment revenues	2,600	3,100	5,600	6,100
Transportation and processing revenues | Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Lease revenue	$ 2,600	$ 1,900	$ 5,300	$ 4,300

Revenue from Contracts with C_7

Revenue from Contracts with Customers - Schedule of Annual Minimums by Current Remaining Contract Term (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	10 years 9 months 6 days
Annual minimum payments	$ 62,217
Annual lease payments	$ 5,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	2 years 5 months 2 days
Annual minimum payments	$ 12,589
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	7 years 11 months 28 days
Annual minimum payments	$ 2,176
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Average Remaining Contract Term	13 years 1 month 8 days
Annual minimum payments	$ 47,452

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net - Discontinued Operations	$ 984		$ 984		$ 993
Total assets of discontinued operations	984		984		993
Accounts payable - Discontinued Operations	42		42		181
Accrued liabilities - Discontinued Operations	616		616		766
Total liabilities of discontinued operations	658		658		947
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Construction aggregates revenues	0	$ 34,233	0	$ 60,657
Road construction and asphalt paving services	0	6,176	0	6,904
Oil and gas revenues	0	(2)	0	(2)
Gain (loss) on asset sales - Discontinued Operations	246	42	238	51
Total revenues and other income - Discontinued Operations	246	40,449	238	67,610
Operating and maintenance expenses - Discontinued Operations	1	34,281	39	60,513
Depreciation, depletion and amortization - Discontinued Operations	0	3,187	0	6,044
Total operating expenses - Discontinued Operations	1	37,468	39	66,557
Interest expense - Discontinued Operations			0	(20)
Income (loss) from discontinued operations	245	2,981	199	1,033
Capital Expenditures, Discontinued Operations				5,900
Construction Aggregates
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net - Discontinued Operations	(4)		(4)		5
Total assets of discontinued operations	(4)		(4)		5
Accounts payable - Discontinued Operations	42		42		181
Accrued liabilities - Discontinued Operations	616		616		766
Total liabilities of discontinued operations	658		658		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		988
Total assets of discontinued operations	988		988		988
Accounts payable - Discontinued Operations	0		0		0
Accrued liabilities - Discontinued Operations	0		0		0
Total liabilities of discontinued operations	0		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	34,233	0	60,657
Road construction and asphalt paving services	0	6,176	0	6,904
Oil and gas revenues	0	0	0	0
Gain (loss) on asset sales - Discontinued Operations	246	42	238	51
Total revenues and other income - Discontinued Operations	246	40,451	238	67,612
Operating and maintenance expenses - Discontinued Operations	0	34,249	27	60,467
Depreciation, depletion and amortization - Discontinued Operations	0	3,187	0	6,044
Total operating expenses - Discontinued Operations	0	37,436	27	66,511
Interest expense - Discontinued Operations			0	(20)
Income (loss) from discontinued operations	246	3,015	211	1,081
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	0	0
Road construction and asphalt paving services	0	0	0	0
Oil and gas revenues	0	(2)	0	(2)
Gain (loss) on asset sales - Discontinued Operations	0	0	0	0
Total revenues and other income - Discontinued Operations	0	(2)	0	(2)
Operating and maintenance expenses - Discontinued Operations	1	32	12	46
Depreciation, depletion and amortization - Discontinued Operations	0	0	0	0
Total operating expenses - Discontinued Operations	1	32	12	46
Interest expense - Discontinued Operations			0	0
Income (loss) from discontinued operations	$ (1)	$ (34)	$ (12)	$ (48)

Common and Preferred Unit Dis_3

Common and Preferred Unit Distributions Narrative (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Temporary Equity [Line Items]
Income attributable to preferred unitholders	$ 7,500	$ 7,500	$ 7,500	$ 7,500	$ 15,000	$ 15,000
Class A Convertible Preferred Units
Temporary Equity [Line Items]
Cash payment for redeemed paid-in-kind units				$ 8,800	$ 0	$ 8,844
General Partner
Temporary Equity [Line Items]
General partner's general partner distribution					2.00%

Common and Preferred Unit Dis_4

Common and Preferred Unit Distributions Distributions declared and paid (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018
Common Units
Class of Stock [Line Items]
Distribution per Unit	$ 0.45	$ 0.45	$ 0.45	$ 0.45
Total distributions, common units	$ 16,265	$ 5,625	$ 5,623	$ 5,617
Preferred Units
Class of Stock [Line Items]
Total distributions, common units	$ 7,500	$ 7,500	$ 7,500	$ 7,765
Preferred Units | Preferred Stock
Class of Stock [Line Items]
Distribution per Unit	$ 30,000	$ 30,000	$ 30,000	$ 30,000
Total distributions, preferred units	$ 7,500	$ 7,500	$ 7,500	$ 7,500
Cash Distribution | Common Units
Class of Stock [Line Items]
Total distributions, common units	$ 5,630
Special Tax Distribution
Class of Stock [Line Items]
Distribution per Unit	$ 0.85
Total distributions, common units	$ 10,635

Net Income Per Common Unit (Det

Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Allocation of net income
Net income from continuing operations	$ 19,106		$ 35,129		$ 54,871	$ 61,415
Less: net income attributable to non-controlling interest	0		(869)		0	(869)
Less: income attributable to preferred unitholders	(7,500)	$ (7,500)	(7,500)	$ (7,500)	(15,000)	(15,000)
Net income from continuing operations attributable to common unitholders and general partner	11,606		26,760		39,871	45,546
Less: net income from continuing operations attributable to the general partner	(232)		(535)		(797)	(911)
Net income from continuing operations attributable to common unitholders	11,374		26,225		39,074	44,635
Net income from discontinued operations	245		2,981		199	1,033
Less: net income from discontinued operations attributable to the general partner	(5)		(60)		(4)	(21)
Net income from discontinued operations attributable to common unitholders	240		2,921		195	1,012
Net income	19,351	$ 35,719	38,110	$ 24,338	55,070	62,448
Net income attributable to common unitholders and general partner	11,851		29,741		40,070	46,579
Less: net income attributable to the general partner	(237)		(595)		(801)	(932)
Net income attributable to common unitholders	11,614		29,146		39,269	45,647
Net income	$ 19,351		$ 37,241		$ 55,070	$ 61,579
Basic Income (Loss) per Unit:
Weighted average common units (in shares)	12,261		12,246		12,258	12,242
Basic net income from continuing operations per common unit	$ 0.93		$ 2.14		$ 3.19	$ 3.65
Basic net income from discontinued operations per common unit	0.02		0.24		0.02	0.08
Basic net income per common unit	$ 0.95		$ 2.38		$ 3.20	$ 3.73
Diluted income per common unit
Dilutive effect of Preferred Units (in shares)	0		8,615		7,443	8,615
Dilutive effect of Warrants (in shares)	1,087		522		1,091	476
Dilutive effect of unvested common unit awards (in shares)	40		0		36	0
Weighted average common units—diluted (in shares)	13,388		21,383		20,828	21,333
Less: income attributable to preferred unitholders	$ (7,500)		$ 0		$ 0	$ 0
Diluted net income from continuing operations attributable to common unitholders and general partner	11,606		34,260		54,871	60,546
Less: diluted net income from continuing operations attributable to the general partner	(232)		(685)		(1,097)	(1,211)
Diluted net income from continuing operations attributable to common unitholders	11,374		33,575		53,774	59,335
Diluted net income from discontinued operations attributable to common unitholders	240		2,921		195	1,012
Less: diluted net income attributable to the general partner	(237)		745		(1,101)	(1,232)
Diluted net income attributable to common unitholders and general partner	11,851		37,241		55,070	61,579
Diluted net income attributable to common unitholders	$ 11,614		$ 36,496		$ 53,969	$ 60,347
Diluted net income per common unit from continuing operations (in dollars per share)	$ 0.85		$ 1.57		$ 2.58	$ 2.78
Diluted net income (loss) from discontinued operations per common unit (in dollars per share)	0.02		0.14		0.01	0.05
Diluted net income per common unit (in dollars per share)	$ 0.87		1.71		$ 2.59	$ 2.83
Warrant Holders | Warrants at $22.81 Strike
Class of Warrant or Right, Warrants Issued	1,750				1,750	1,750
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 22.81		22.81		$ 22.81	$ 22.81
Warrant Holders | Warrants at $34.00 Strike
Class of Warrant or Right, Warrants Issued	2,250				2,250	2,250
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 34		$ 34		$ 34	$ 34

Segment Information - Additiona

Segment Information - Additional Information (Details) - segment	6 Months Ended
	Jun. 30, 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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 81,223	$ 69,451	$ 148,008	$ 128,929
Gain on asset sales	246	168	502	819
Operating and maintenance expenses	12,459	8,117	20,819	14,332
Depreciation, depletion and amortization	3,970	5,376	8,362	10,476
General and administrative expenses	4,196	3,263	8,546	7,599
Asset impairments	0	0	0	242
Other expenses, net	41,738	17,734	55,912	35,684
Net income (loss) from continuing operations	19,106	35,129	54,871	61,415
Net income from discontinued operations	245	2,981	199	1,033
Total assets	1,219,443		1,219,443		$ 1,341,647
Corporate and Financing
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Gain on asset sales	0	0	0	0
Operating and maintenance expenses	0	0	0	0
Depreciation, depletion and amortization	0	0	0	0
General and administrative expenses	4,196	3,263	8,546	7,599
Asset impairments				0
Other expenses, net	41,738	17,734	55,912	35,684
Net income (loss) from continuing operations	(45,934)	(20,997)	(64,458)	(43,283)
Net income from discontinued operations	0	0	0	0
Coal Royalty and Other
Segment Reporting Information [Line Items]
Revenues	64,616	47,920	114,118	92,394
Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Revenues	69,890	52,922	124,993	102,779
Gain on asset sales	246	168	502	819
Operating and maintenance expenses	12,459	8,117	20,819	14,332
Depreciation, depletion and amortization	3,970	5,376	8,362	10,476
General and administrative expenses	0	0	0	0
Asset impairments				242
Other expenses, net	0	0	0	0
Net income (loss) from continuing operations	53,707	39,597	96,314	78,548
Net income from discontinued operations	0	0	0	0
Soda Ash
Segment Reporting Information [Line Items]
Revenues	11,333	16,529	23,015	26,150
Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Revenues	11,333	16,529	23,015	26,150
Gain on asset sales	0	0	0	0
Operating and maintenance expenses	0	0	0	0
Depreciation, depletion and amortization	0	0	0	0
General and administrative expenses	0	0	0	0
Asset impairments				0
Other expenses, net	0	0	0	0
Net income (loss) from continuing operations	11,333	16,529	23,015	26,150
Net income from discontinued operations	0	$ 0	0	$ 0
Continuing Operations
Segment Reporting Information [Line Items]
Total assets	1,218,459		1,218,459		1,340,654
Continuing Operations | Corporate and Financing
Segment Reporting Information [Line Items]
Total assets	18,126		18,126		106,923
Continuing Operations | Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Total assets	949,198		949,198		986,680
Continuing Operations | Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Total assets	251,135		251,135		247,051
Discontinued Operations
Segment Reporting Information [Line Items]
Total assets	984		984		993
Discontinued Operations | Corporate and Financing
Segment Reporting Information [Line Items]
Total assets	0		0		0
Discontinued Operations | Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Total assets	0		0		0
Discontinued Operations | Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Total assets	$ 0		$ 0		$ 0

Equity Investment - Additional

Equity Investment - Additional Information (Detail)	Jun. 30, 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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Equity Method Investments [Roll Forward]
Balance at beginning of period			$ 247,051
Comprehensive income (loss) from unconsolidated investment	$ 18,526	$ 37,676	55,250	$ 60,889
Balance at end of period	251,135		251,135
Sales			23,015	26,150
Ciner Wyoming
Equity Method Investments [Roll Forward]
Balance at beginning of period	249,936	241,679	247,051	245,433
Income allocation to NRP’s equity interests	12,549	17,657	25,443	28,489
Amortization of basis difference	(1,216)	(1,128)	(2,428)	(2,339)
Comprehensive income (loss) from unconsolidated investment	(824)	(434)	179	(1,559)
Distribution	(9,310)	(12,250)	(19,110)	(24,500)
Balance at end of period	251,135	245,524	251,135	245,524
Sales	129,794	91,882	260,230	213,101
Gross profit	32,533	14,022	66,635	42,244
Net income	$ 25,610	$ 36,035	$ 51,925	$ 58,142

Mineral Rights, Net - Mineral R

Mineral Rights, Net - Mineral Rights (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Depletion and amortization expense on coal and other mineral rights	$ 3,200	$ 4,500	$ 6,700	$ 8,800
Cost	1,215,317		1,215,317		$ 1,215,318
Accumulated Depletion	(478,904)		(478,904)		(472,206)
Net Book Value	736,413		736,413		743,112
Coal Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Cost	1,148,176		1,148,176		1,164,845
Accumulated Depletion	(456,817)		(456,817)		(451,210)
Net Book Value	691,359		691,359		713,635
Aggregates Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Cost	41,589		41,589		24,920
Accumulated Depletion	(12,729)		(12,729)		(11,814)
Net Book Value	28,860		28,860		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		12,395
Accumulated Depletion	(7,759)		(7,759)		(7,632)
Net Book Value	4,636		4,636		4,763
Other Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Cost	13,157		13,157		13,158
Accumulated Depletion	(1,599)		(1,599)		(1,550)
Net Book Value	$ 11,558		$ 11,558		$ 11,608

Mineral Rights, Net - Additiona

Mineral Rights, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Extractive Industries [Abstract]
Depletion and amortization expense on coal and other mineral rights	$ 3.2	$ 4.5	$ 6.7	$ 8.8

Intangible Assets, Net - Intang

Intangible Assets, Net - Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets at cost	$ 81,109		$ 81,109		$ 81,109
Less accumulated amortization	(40,101)		(40,101)		(38,596)
Total intangible assets, net	41,008		41,008		$ 42,513
Amortization expense	$ 700	$ 800	$ 1,500	$ 1,500

Intangible Assets, Net - Additi

Intangible Assets, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 0.7	$ 0.8	$ 1.5	$ 1.5

Debt, Net - Debt (Detail)

Debt, Net - Debt (Detail) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Principal balance	$ 552,667,000	$ 687,138,000
Net unamortized debt discount	0	(1,266,000)
Net unamortized debt issuance costs	(8,598,000)	(13,114,000)
Total debt, net	544,069,000	672,758,000
Less - current portion of long term debt	(46,040,000)	(115,184,000)
Total long-term debt, net	498,029,000	557,574,000
NRP LP | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025
Debt Instrument [Line Items]
Principal balance	$ 300,000,000	0
Rate of senior notes	9.125%
NRP LP | 10.5% senior notes, with semi-annual interest payments in March and September, maturing March 2022
Debt Instrument [Line Items]
Principal balance	$ 0	$ 345,638,000
Rate of senior notes		10.50%
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Debt Instrument [Line Items]
Principal balance	0
Floating rate revolving credit facility	100,000,000
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty
Debt Instrument [Line Items]
Principal balance		$ 0
Opco | Senior Notes
Debt Instrument [Line Items]
Principal balance	252,667,000	341,500,000
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]
Principal balance	$ 0	21,319,000
Rate of senior notes	8.38%
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]
Principal balance	$ 13,603,000	15,290,000
Rate of senior notes	5.05%
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]
Principal balance	$ 9,458,000	13,414,000
Rate of senior notes	5.55%
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]
Principal balance	$ 30,356,000	37,195,000
Rate of senior notes	4.73%
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]
Principal balance	$ 63,834,000	89,529,000
Rate of senior notes	5.82%
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]
Principal balance	$ 20,059,000	27,185,000
Rate of senior notes	8.92%
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]
Principal balance	$ 91,821,000	107,013,000
Rate of senior notes	5.03%
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]
Principal balance	$ 23,536,000	30,555,000
Rate of senior notes	5.18%
Senior Notes Offering Price Two | NRP LP | 10.5% senior notes, with semi-annual interest payments in March and September, maturing March 2022
Debt Instrument [Line Items]
Principal balance		$ 105,000,000
Senior Note issue percentage		100.00%
Senior Notes Offering Price One | NRP LP | 10.5% senior notes, with semi-annual interest payments in March and September, maturing March 2022
Debt Instrument [Line Items]
Principal balance		$ 240,638,000
Senior Note issue percentage		98.75%
Revolving Credit Facility | Opco
Debt Instrument [Line Items]
Net unamortized debt issuance costs	$ (2,200,000)	$ (1,700,000)

Debt, Net - Additional Informat

Debt, Net - Additional Information (Detail)	Apr. 29, 2019USD ($)	Jun. 30, 2019USD ($)$ / shares	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)$ / shares	Jun. 30, 2018USD ($)	May 11, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Principal balance		$ 552,667,000		$ 552,667,000			$ 687,138,000
Cash on hand		85,775,000	$ 51,329,000	85,775,000	$ 51,329,000	$ 76,000,000	206,030,000	$ 26,980,000
Debt issuance cost capitalized		8,598,000		8,598,000			13,114,000
Percentage of principal eligible for redemption	35.00%
Redemption premium		18,100,000
Write off of Deferred Debt Issuance Cost		10,400,000
9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Rate of senior notes	9.125%
Debt issuance cost capitalized	$ 6,600,000
Redemption price percentage of principal remaining after redemption	65.00%
Redemption price at change of control event as percentage of principal amount	101.00%
NRP LP | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025
Debt Instrument [Line Items]
Principal balance		$ 300,000,000		$ 300,000,000			0
Rate of senior notes		9.125%		9.125%
Opco | Revolving Credit Facility
Debt Instrument [Line Items]
Debt issuance cost capitalized		$ 2,200,000		$ 2,200,000			1,700,000
Weighted average interest rate			6.18%		6.08%
Collateral carrying amount		543,400,000		543,400,000			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]
Principal balance		$ 0		$ 0			21,319,000
Rate of senior notes		8.38%		8.38%
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]
Principal balance		$ 20,059,000		$ 20,059,000			27,185,000
Rate of senior notes		8.92%		8.92%
Opco | Senior Notes
Debt Instrument [Line Items]
Principal balance		$ 252,667,000		$ 252,667,000			$ 341,500,000
Principal payments on its senior notes				88,800,000	$ 48,100,000
Pre-payment of Senior Notes				$ 49,300,000
Partnership leverage ratio				3.75
Additional interest accrue		2.00%		2.00%
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Debt Instrument [Line Items]
Principal balance		$ 0		$ 0
Lender commitments under Opco credit facility		$ 100,000,000		$ 100,000,000
Distribution per share (in dollars per share) | $ / shares		$ 0.45		$ 0.45
Ratio Of Ebitda to consolidated fixed charges				3.5
Floating rate revolving credit facility		$ 100,000,000		$ 100,000,000
Dividend at or Below $0.45 per Share | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Debt Instrument [Line Items]
Maximum leverage ratio				4
Dividend Above $0.45 per Share | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Debt Instrument [Line Items]
Maximum leverage ratio				3
Debt Instrument, Redemption, Period Two | 10.5% senior notes, with semi-annual interest payments in March and September, maturing March 2022 | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal	105.25%
Debt Instrument, Redemption, Period Two | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal	104.563%
Debt Instrument, Redemption, Period Three | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal	102.281%
Debt Instrument, Redemption, Period Four | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal	100.00%
Debt Instrument, Redemption, Period One | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal	109.125%

Fair Value Measurements - Contr

Fair Value Measurements - Contracts Receivable and Debt (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Transfers between Levels 1, 2, 3	$ 0	$ 0	$ 0	$ 0
Carrying Value	544,069,000		544,069,000		$ 672,758,000
Contracts receivable (current and long-term)	39,878,000		39,878,000		40,776,000
Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contracts receivable (current and long-term)	34,099,000		34,099,000		34,704,000
Senior Notes due 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	293,556,000		293,556,000		0
Senior Notes due 2025 | Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	309,000,000		309,000,000		0
Senior Notes due 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	0		0		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	0		0		356,871,000
Opco Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	250,513,000		250,513,000		338,734,000
Opco Senior Notes | Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	260,247,000		260,247,000		352,599,000
Opco Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	0		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		$ 0

Fair Value Measurements - Embed

Fair Value Measurements - Embedded Derivatives (Detail) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Equity [Abstract]
Fair value of embedded derivatives	$ 0	$ 0

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Quintana Minerals
Related Party Transaction [Line Items]
Accounts payable to related parties	$ 0.4		$ 0.4		$ 0.5
Western Pocahontas Properties
Related Party Transaction [Line Items]
Accounts payable to related parties					$ 1.4
Western Pocahontas Properties Limited Partnership | Affiliated Entity
Related Party Transaction [Line Items]
Operating and maintenance expenses	0.5	$ 2.3	3.5	$ 2.9
Other related party assets	$ 0.4		$ 0.4
Corsa
Related Party Transaction [Line Items]
Revenue from related parties		$ 0.2		$ 0.4

Related Party Transactions - Su

Related Party Transactions - Summary of Reimbursements (Details) - Affiliated Entity - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Western Pocahontas Properties Limited Partnership
Related Party Transaction [Line Items]
Operating and maintenance expenses	$ 500	$ 2,300	$ 3,500	$ 2,900
Western Pocahontas Properties and Quintana Minerals Corporation
Related Party Transaction [Line Items]
Operating and maintenance expenses	1,573	1,459	3,208	3,134
General and administrative expenses	$ 886	$ 849	$ 1,849	$ 1,780

Major Customers (Detail)

Major Customers (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Concentration Risk [Line Items]
Revenues	$ 81,223	$ 69,451	$ 148,008	$ 128,929
Foresight Energy Lp
Concentration Risk [Line Items]
Revenues	16,038	12,990	32,229	25,421
Contura Energy
Concentration Risk [Line Items]
Revenues	$ 12,614	$ 5,915	$ 23,725	$ 11,382
Sales Revenue | Customer Concentration Risk | Foresight Energy Lp
Concentration Risk [Line Items]
Percent	20.00%	19.00%	22.00%	20.00%
Sales Revenue | Customer Concentration Risk | Contura Energy
Concentration Risk [Line Items]
Percent	16.00%	9.00%	16.00%	9.00%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	36 Months Ended
	Dec. 31, 2015	Jun. 30, 2019	Sep. 30, 2018	Jul. 31, 2013	Jan. 31, 2013
Anadarko Holding Company
Commitments And Contingencies [Line Items]
Contingent consideration to be paid by NRP					$ 50,000
Ciner Wyoming | Anadarko Holding Company
Commitments And Contingencies [Line Items]
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 ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Granted, Value, Share-based Compensation, Gross			$ 5.4	$ 2.2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term			2 years 6 months
Unaccrued Cost Associated With Outstanding Grants And Related Distribution Equivalent Rights	$ 4.5		$ 4.5		$ 1.2
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 0.4	$ 0.2	$ 1.3	$ 0.8

Unit-Based Compensation Summary

Unit-Based Compensation Summary of unit based activity (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2019$ / sharesshares
Common Units
Outstanding at beginning of period | shares	55
Granted | shares	129
Fully vested and issued | shares	(12)
Forfeitures | shares	(15)
Outstanding at the end of period | shares	157
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding at beginning of period | $ / shares	$ 37.48
Granted | $ / shares	41.41
Fully vested and issued | $ / shares	41.47
Forfeitures | $ / shares	37.33
Outstanding at the end of period | $ / shares	$ 29.10

Leases Lessee accounting under

Leases Lessee accounting under ASC 842 - narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jan. 01, 2019
Lessor, Lease, Description [Line Items]
Number of options to extend		5
Length of renewal term	5 years	5 years
Operating lease, right-of-use asset	$ 3,500	$ 3,500	$ 3,500
Operating lease liability	3,511	3,511	$ 3,500
Operating lease expenses	$ 100	$ 200
Operating Lease, Weighted Average Remaining Lease Term	29 years 6 months	29 years 6 months
Minimum
Lessor, Lease, Description [Line Items]
Base term on lease (in years)	5 years	5 years

Leases Operating lease maturity

Leases Operating lease maturity schedule (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating Lease, Weighted Average Remaining Lease Term	29 years 6 months
Lessee, Operating Lease, Discount Rate	13.50%
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2019	$ 242
2020	483
2021	483
2022	483
2023	483
After 2023	12,079
Total lease payments	14,253
Less: present value adjustment	(10,742)
Total operating lease liability	$ 3,511	$ 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		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2039	Dec. 31, 2032
Lessor, Lease, Description [Line Items]
Throughput fees	$ 1,300	$ 1,000	$ 2,500	$ 2,100
Lease renewal term	80 years		80 years
Annual lease payments			$ 5,000
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	Jun. 30, 2019	Dec. 31, 2018
Leases [Abstract]
Accounts receivable	$ 605	$ 661
Contract receivable (current and long-term)	39,878	40,776
Unearned income	23,455	25,058
Projected remaining payments	$ 63,938	$ 66,495

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - Subsequent Event $ / shares in Units, $ in Millions	Aug. 14, 2019USD ($)$ / shares
Subsequent Event [Line Items]
Distribution per Unit | $ / shares	$ 0.45
Preferred unit dividends | $	$ 7.5

Uncategorized Items - nrp-20190

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 70,466,000
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