Sisecam Resources (SIRE) 10-K 8 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Mar. 01, 2019	Jun. 30, 2018
Document and Entity Information
Entity Registrant Name	Ciner Resources LP.
Entity Central Index Key	1,575,051
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 134.5
Common Units
Document and Entity Information
Entity Common Stock, Shares Outstanding		19,744,301
General Partner
Document and Entity Information
Entity Common Stock, Shares Outstanding		399,000

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 10.2	$ 30.2
Accounts receivable -affiliates	70.1	98.3
Accounts receivable, net	36.9	34.2
Inventory	22.3	19.8
Other current assets	2	1.8
Total current assets	141.5	184.3
Property, plant and equipment, net	266.7	249.3
Other non-current assets	26.4	19.6
Total assets	434.6	453.2
Current liabilities:
Current portion of long-term debt	0	11.4
Accounts payable	17.6	14.5
Due to affiliates	2.6	3
Accrued expenses	44.4	27.7
Total current liabilities	64.6	56.6
Long-term debt	99	138
Other non-current liabilities	10.9	10.4
Total liabilities	174.5	205
Commitments and Contingencies (See Note 14)
Equity:
General partner unitholders - Ciner Resource Partners LLC (0.4 units issued and outstanding at December 31, 2018 and December 31, 2017)	3.9	3.8
Accumulated other comprehensive loss	(3.8)	(3.7)
Partners’ capital attributable to Ciner Resources LP	153.9	148.4
Non-controlling interest	106.2	99.8
Total equity	260.1	248.2
Total liabilities and partners’ equity	434.6	453.2
Common Units
Equity:
Common unitholders - Public and Ciner Holdings (19.7 units issued and outstanding at December 31, 2018 and December 31, 2017)	$ 153.8	$ 148.3

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares shares in Millions	Dec. 31, 2018	Dec. 31, 2017
General partner units issued (in shares)	0.4	0.4
General partners units outstanding (in shares)	0.4	0.4
Common Units
Common units issued (in shares)	19.7	19.7
Common units outstanding (in shares)	19.7	19.7

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net sales:
Sales - affiliates	$ 253.3	$ 304.5	$ 271.2
Sales - others	233.4	192.8	204
Total net sales	486.7	497.3	475.2
Cost of products sold:
Cost of products sold (excludes depreciation, depletion and amortization expense set forth separately below)	215.9	211	216
Depreciation, depletion and amortization expense	28.4	27.1	26.1
Total cost of products sold	383.4	383.8	361.7
Gross profit	103.3	113.5	113.5
Operating expenses:
Selling, general and administrative expenses—affiliates	17.6	16.9	18.7
Selling, general and administrative expenses—others	6.9	5.5	4.6
Impairment and loss on disposal of assets, net	0	1.6	0.3
Litigation settlement gain	(27.5)	0	0
Total operating expenses	(3)	24	23.6
Operating income	106.3	89.5	89.9
Other income/(expenses):
Interest income	1.9	1.7	0
Interest expense	(5.1)	(4.6)	(3.6)
Other - net	(0.1)	(0.2)	0
Total other expense, net	(3.3)	(3.1)	(3.6)
Net income	103	86.4	86.3
Net income attributable to non-controlling interest	53.1	44.8	44.9
Net income attributable to Ciner Resources LP	49.9	41.6	41.4
Other comprehensive income/(loss):
Income (loss) on derivative financial instruments	(0.2)	(4)	0.9
Comprehensive income	102.8	82.4	87.2
Comprehensive income attributable to non-controlling interest	53	42.9	45.3
Comprehensive income attributable to Ciner Resources LP	$ 49.8	$ 39.5	$ 41.9
Net income per limited partner unit:
Net income per limited partner unit (basic) (in dollars per share)	$ 2.48	$ 2.08	$ 2.08
Net income per limited partner unit (diluted) (in dollars per share)	$ 2.48	$ 2.07	$ 2.08
Limited partner units outstanding:
Total weighted average limited partner units outstanding (basic) (in shares)	19.7	19.6	19.6
Weighted average limited partner units outstanding (diluted) (in shares)	19.7	19.7	19.6
Cargo and Freight [Member]
Cost of products sold:
Cost of products sold (excludes depreciation, depletion and amortization expense set forth separately below)	$ 139.1	$ 145.7	$ 119.6

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 103	$ 86.4	$ 86.3
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization expense	28.7	27.5	26.5
Impairment and loss on disposal of assets, net	0	1.6	0.3
Equity-based compensation expense	1.8	1.3	0.6
Other non-cash items	0.3	0.3	0.4
Changes in operating assets and liabilities:
Accounts receivable - net	(2.7)	0.2	0.4
Accounts receivable - affiliates	28.2	(37.7)	2.4
Inventory	(3)	0.5	7
Other current and other non-current assets	(0.2)	(0.2)	0.2
Increase/(decrease) in:
Accounts payable	2.4	1.7	1.1
Due to affiliates	(0.4)	(1.2)	(0.4)
Accrued expenses and other liabilities	4.1	(1.1)	3.5
Net cash provided by operating activities	162.2	79.3	128.3
Cash flows from investing activities:
Capital expenditures	(39.4)	(24.7)	(25.3)
Net cash used in investing activities	(39.4)	(24.7)	(25.3)
Cash flows from financing activities:
Borrowings on Ciner Wyoming credit facility	104	88.5	15
Repayments on Ciner Wyoming credit facility	(143)	(28.5)	(27)
Repayments on other long-term debt	(11.4)	(8.6)	0
Debt issuance costs	0	(1.1)	0
Common units surrendered for taxes	(0.3)	0	0
Distributions to non-controlling interest	(46.6)	(49)	(46.6)
Net cash used in financing activities	(142.8)	(44.1)	(103.7)
Net increase/(decrease) in cash and cash equivalents	(20)	10.5	(0.7)
Cash and cash equivalents at beginning of year	30.2	19.7	20.4
Cash and cash equivalents at end of year	10.2	30.2	19.7
Supplemental disclosure of cash flow information:
Interest paid during the year	5.1	4.1	3.2
Supplemental disclosure of non-cash investing activities:
Capital expenditures on account	14	1	3.9
Common Units
Cash flows from financing activities:
Distributions	(44.6)	(44.5)	(22.2)
Subordinated Unitholders
Cash flows from financing activities:
Distributions	0	0	(22)
General Partner
Cash flows from financing activities:
Distributions	$ (0.9)	$ (0.9)	$ (0.9)

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Partnership unitsCommon Units	Partnership unitsSubordinated Unitholders	Partnership unitsGeneral Partner	Accumulated Other Comprehensive Loss	Partners’ Capital Attributable to Ciner Resources LP Equity	Noncontrolling Interests
Beginning balance at Dec. 31, 2015	$ 263.2	$ 110.8	$ 43.3	$ 4	$ (2.1)	$ 156	$ 107.2
Increase (decrease) in shareholders' equity
Net income	86.3	25.2	15.4	0.8		41.4	44.9
Other comprehensive income/(loss)	0.9				0.5	0.5	0.4
Equity-based compensation plan activity	0.5	0.5				0.5
Distributions	(91.7)	(22.2)	(22)	(0.9)		(45.1)	(46.6)
Conversion of subordinated units to common units	0	36.7	(36.7)			0
Ending balance at Dec. 31, 2016	259.2	151	0	3.9	(1.6)	153.3	105.9
Increase (decrease) in shareholders' equity
Net income	86.4	40.8		0.8		41.6	44.8
Other comprehensive income/(loss)	(4)				(2.1)	(2.1)	(1.9)
Equity-based compensation plan activity	1	1				1
Distributions	(94.4)	(44.5)		(0.9)		(45.4)	(49)
Ending balance at Dec. 31, 2017	248.2	148.3	0	3.8	(3.7)	148.4	99.8
Increase (decrease) in shareholders' equity
Net income	103	48.9		1		49.9	53.1
Other comprehensive income/(loss)	(0.2)				(0.1)	(0.1)	(0.1)
Equity-based compensation plan activity	1.2	1.2				1.2
Distributions	(92.1)	(44.6)		(0.9)		(45.5)	(46.6)
Ending balance at Dec. 31, 2018	$ 260.1	$ 153.8	$ 0	$ 3.9	$ (3.8)	$ 153.9	$ 106.2

GENERAL

GENERAL	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
GENERAL	GENERAL Nature of Operations As used in this Report, the terms “Ciner Resources LP,” “the “Partnership,” “CINR,” “we,” “us,” or “our” may refer to Ciner Resources LP, formerly OCI Resources LP, a publicly traded Delaware limited partnership formed in April 2013 by Ciner Wyoming Holding Co. (“Ciner Holdings” or ), formerly OCI Wyoming Holding Co. Ciner Holdings, a wholly-owned subsidiary of Ciner Resources Corporation (“Ciner Corp”), formerly OCI Chemical Corporation, wholly-owned Ciner Resource Partners LLC (our “general partner” or “Ciner GP”), formerly OCI Resource Partners LLC. Ciner Corp is a direct wholly-owned subsidiary of Ciner Enterprises Inc. (“Ciner Enterprises”), which is directly wholly-owned by WE Soda Ltd. (“WE Soda”), which is directly wholly-owned by KEW Soda Ltd. (“KEW Soda”), which is directly wholly-owned by Akkan Enerji ve Madencilik Anonim Şirketi (“Akkan”), which in turn is directly wholly-owned by Turgay Ciner, the Chairman of the Ciner Group, a Turkish conglomerate of companies engaged in energy and mining (including soda ash mining), media and shipping markets. Ciner Wyoming LLC (“Ciner Wyoming”), formerly OCI Wyoming LLC, is in the business of mining trona ore to produce soda ash, and a majority-owned subsidiary of the Partnership. The Partnership’s operations consist solely of its investment in Ciner Wyoming. The Partnership owns a controlling interest comprised of 51.0% membership interest in Ciner Wyoming. All our soda ash processed is sold to various domestic and European customers, and to Ciner Ic ve Dis Ticaret Anonim Sirketi (“CIDT”) and American Natural Soda Ash Corporation (“ANSAC”) which are affiliates for export sales. During 2018, there were no sales to CIDT, an affiliate for export sales, as the previous contract concluded in the 2017 year. All mining and processing activities of Ciner Wyoming take place in one facility located in the Green River Basin of Wyoming. NRP Trona LLC, a wholly owned subsidiary of Natural Resource Partners L.P. (“NRP”), currently owns a 49.0% membership interest in Ciner Wyoming. On February 22, 2018, Akkan transferred its direct 100% ownership in Ciner Enterprises to KEW Soda, a UK company, which transferred such ownership to WE Soda, a UK company. WE Soda is 100% owned by KEW Soda, and KEW Soda is wholly owned by Akkan. This reorganization is a part of Ciner Group’s strategy to combine the global soda ash business under a common structure in the UK.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Significant Accounting Policies The accompanying consolidated financial statements of the Partnership and its subsidiary have been prepared in conformity with U.S. generally accepted accounting principles and reflect all adjustments, consisting of normal recurring accruals, which are necessary for fair presentation of the results of operations, financial position and cash flows for the periods presented. All significant intercompany transactions, balances, revenue and expenses have been eliminated in consolidation and unless otherwise noted, the financial information for the Partnership is presented before non-controlling interest. Non-Controlling Interests In connection with the conversion of Ciner Wyoming from a Delaware limited partnership (“LP”) to a Delaware limited liability company (“LLC”), in June 2014, NRP’s general partner interest and limited partnership interest were converted into a single-class of membership interests in Ciner Wyoming, which currently consists of a 49.0% membership interest in Ciner Wyoming. Prior to the conversion of Ciner Wyoming from a Delaware LP to a Delaware LLC, non-controlling interests in the consolidated financial statements of the Partnership consisted of a 39.37% general partner interest and a 9.63% limited partner interest in Ciner Wyoming owned by NRP. Use of Estimates The preparation of consolidated financial statements, in accordance with accounting principles generally accepted in the United States of America, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the dates of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Revenue Recognition On May 28, 2014 the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers (Topic 606), that requires companies to recognize revenue when a customer obtains control rather than when companies have transferred substantially all risks and rewards of a good or service. The Partnership has applied the provisions of this ASC and notes that our adoption of ASC 606 does not materially change the amount or timing of revenues recognized by us, nor does it materially affect our financial position. The majority of our revenues generated are recognized upon delivery and transfer of title to the product to our customers. The time at which delivery and transfer of title occurs, for the majority of our contracts with customers, is the point when the product leaves our facility, thereby rendering our performance obligation fulfilled. Additionally, the Partnership has made an accounting policy election to account for shipping and handling activities as fulfillment costs. The Partnership adopted this ASC effective January 1, 2018, as permitted by the ASC, using the modified retrospective method and we have not made any adjustment to opening retained earnings. Freight Costs The Partnership includes freight costs billed to customers for shipments administered by the Partnership in gross sales. The related freight costs along with cost of products sold are deducted from gross sales to determine gross profit. Cash and Cash Equivalents The Partnership considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Cash equivalents consist primarily of money market deposit accounts. Accounts Receivable Accounts receivable are carried at the original invoice amount less an estimate for doubtful receivables. We generally do not require collateral against outstanding accounts receivable. The allowance for doubtful accounts is based on specifically identified amounts that the Partnership believes to be uncollectible. An additional allowance is recorded based on certain percentages of aged receivables, which are determined based on management’s assessment of the general financial conditions affecting the Partnership’s customer base. We determined that no allowance for doubtful accounts was required against receivables from affiliates as of December 31, 2018 and 2017 . If actual collection experience changes, revisions to the allowance may be required. Accounts receivable are written off when deemed uncollectible. Recoveries of accounts receivable previously written off are recorded when received. During the years ended 2018 , 2017 and 2016 , there were no significant accounts receivable bad debt expenses, write-offs or recoveries. Inventory Inventory is carried at the lower of cost or market. Cost is determined using the first-in, first-out method for raw material and finished goods inventory and the weighted average cost method for stores inventory. Costs include raw materials, direct labor and manufacturing overhead. Market is based on current replacement cost for raw materials and net realizable value for stores inventory and finished goods. • Raw material inventory includes material, chemicals and natural resources being used in the mining and refining process. • Finished goods inventory is the finished product soda ash. • Stores inventory includes parts, materials and operating supplies which are typically consumed in the production of soda ash and currently available for future use. Inventory expected to be consumed within the year is classified as current assets and remainder is classified as non-current assets. Property, Plant, and Equipment Property, plant, and equipment are stated at cost less accumulated depreciation. Depreciation is computed over the estimated useful lives of depreciable assets, using the straight-line method. The estimated useful lives applied to depreciable assets are as follows: Useful Lives Land improvements 10 years Depletable land 15-60 years Buildings and building improvements 10-30 years Computer hardware 3-5 years Machinery and equipment 5-20 years Furniture and fixtures 10 years The Partnership’s policy is to evaluate property, plant, and equipment for impairment whenever events or changes in circumstances indicate that its carrying amount may not be recoverable. An indicator of potential impairment would include situations when the estimated future undiscounted cash flows are less than the carrying value. The amount of any impairment then recognized would be calculated as the difference between estimated fair value and the carrying value of the asset. Derivative Instruments and Hedging Activities The Partnership may enter into derivative contracts from time to time to manage exposure to the risk of exchange rate changes on its foreign currency transactions, the risk of changes in natural gas prices, and the risk of the variability in interest rates on borrowings. Gains and losses on derivative contracts qualifying for hedge accounting are reported as a component of the underlying transactions. The Partnership follows hedge accounting for its hedging activities. All derivative instruments are recorded on the balance sheet at their fair values. The accounting for changes in the fair value of a derivative depends on the intended use of the derivative and the resulting designation. The Partnership designates its derivatives based upon criteria established for hedge accounting under generally accepted accounting principles. For a derivative designated as a fair value hedge, the gain or loss is recognized in earnings in the period of change together with the offsetting gain or loss on the hedged item attributed to the risk being hedged. For a derivative designated as a cash flow hedge, the effective portion of the derivative’s gain or loss is initially reported as a component of accumulated other comprehensive income (loss) and subsequently reclassified into earnings when the hedged exposure affects earnings. Any significant ineffective portion of the gain or loss is reported in earnings immediately. For derivatives not designated as hedges, the gain or loss is reported in earnings in the period of change. The natural gas physical forward contracts are accounted for under the normal purchases and normal sales scope exception. Income Tax We are organized as a pass-through entity for federal income tax purposes and therefore are not subject to federal or certain state income taxes. As a result, our partners are responsible for federal income taxes based on their respective share of taxable income. Net income for financial statement purposes may differ significantly from taxable income reportable to unitholders as a result of differences between the tax basis and financial reporting basis of assets and liabilities and the taxable income allocation requirements under the partnership agreement. Reclamation Costs The Partnership is obligated to return the land beneath its refinery and tailings ponds to its natural condition upon completion of operations and is required to return the land beneath its rail yard to its natural condition upon termination of the various lease agreements. The Partnership accounts for its land reclamation liability as an asset retirement obligation, which requires that obligations associated with the retirement of a tangible long-lived asset be recorded as a liability when those obligations are incurred, with the amount of the liability initially measured at fair value. Upon initially recognizing a liability for an asset retirement obligation, an entity must capitalize the cost by recognizing an increase in the carrying amount of the related long-lived asset. Over time, the liability is accreted to its present value each period, and the capitalized cost is depreciated over the estimated useful life of the related asset. Upon settlement of the liability, an entity either settles the obligation for its recorded amount or incurs a gain or loss upon settlement. The estimated original liability calculated in 1996 for the refinery and tailing ponds was calculated based on the estimated useful life of the mine, which was 80 years , and on external and internal estimates as to the cost to restore the land in the future and state regulatory requirements. During 2018 , 2017 and 2016 , the remaining life was 60 , 66 and 67 years, respectively. In 2019 , the mining reserve will be amortized over a remaining life of 59 years. The decline in estimated mining reserves estimated remaining life is based on the results of a recent independent mine reserve analysis conducted as of December 31, 2017. The independent mine reserve analysis is routine and performed approximately every three years. The liability was discounted using a weighted average credit-adjusted risk-free rates of approximately 6% and is being accreted throughout the estimated life of the related assets to equal the total estimated costs with a corresponding charge being recorded to cost of products sold. During 2011 , the Partnership constructed a rail yard to facilitate loading and switching of rail cars. The Partnership is required to restore the land on which the rail yard is constructed to its natural conditions. The original estimated liability for restoring the rail yard to its natural condition was calculated based on the land lease life of 30 years and on external and internal estimates as to the cost to restore the land in the future. The liability is discounted using a credit-adjusted risk-free rate of 4.25% and is being accreted throughout the estimated life of the related assets to equal the total estimated costs with a corresponding charge being recorded to cost of products sold. Fair Value of Financial Instruments Fair value is determined using a valuation hierarchy, generally by reference to an active trading market, quoted market prices or model-derived valuations for the same or similar financial instruments. See Note 17, “Fair Value Measurements,” for more information. Equity-Based Compensation We recognize compensation expense related to equity-based awards, with service conditions, granted to employees based on the estimated fair value of the awards on the date of grant, net of estimated forfeitures. The grant date fair value of the equity-based awards is generally recognized on a straight-line basis over the requisite service period, which is generally the vesting period of the respective awards. Equity-based awards with market conditions are fair valued using a Monte Carlo Simulation model. See Note 12, “Equity-Based Compensation,” for additional information. Subsequent Events We have evaluated subsequent events through the filing of this Annual Report on Form 10-K. See Note 19, “Subsequent Events” for additional information. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The update amends existing standards for accounting for leases by lessees, with accounting for leases by lessors remaining largely unchanged from current guidance. The update requires that lessees recognize a lease liability and a right of use asset for all leases (with the exception of short-term leases) at the commencement date of the lease and disclose key information about leasing arrangements. For leases less than 12 months, an entity is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight-line basis over the lease term. The Partnership will make this election upon adoption. In preparation for the new requirements, the Partnership has completed its evaluation of the lease agreements. The Partnership will adopt ASC 842 effective January 1, 2019 using a modified transition approach under which prior comparative periods will not be adjusted, as permitted by the guidance. The Partnership has determined that the adoption of the new standard will not have a material impact on the balance sheet or statement of operations because the Partnership has no material long term leases that are subject to ASC 842. Ciner Corp was determined to be the ultimate lessee for rail car lease agreements under ASC 842, and the Partnership will continue to incur an allocation of rent expense in relation to the use of rail cars leased by Ciner Corp. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (ASC Topic 815) – Targeted Improvements to Accounting for Hedging Activities. This ASU aims to improve the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements. In addition, this ASU makes certain targeted improvements to simplify the application of the existing hedge accounting guidance. This ASU is effective for us beginning in the first quarter of 2019, with early application permitted. The Partnership adopted this ASU effective January 1, 2019 and concluded there is no material impact to the Partnership’s consolidated financial statements. In May 2017, the FASB issued ASU 2017-09–Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. ASU 2017-09 provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. The Partnership adopted this ASU effective January 1, 2018 and concluded there is no material impact to the Partnership’s consolidated financial statements.

NET INCOME PER UNIT AND CASH DI

NET INCOME PER UNIT AND CASH DISTRIBUTION	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
NET INCOME PER UNIT AND CASH DISTRIBUTION	NET INCOME PER UNIT AND CASH DISTRIBUTION Allocation of Net Income Net income per unit applicable to limited partners is computed by dividing limited partners’ interest in net income attributable to Ciner Corp, after deducting the general partner’s interest and any incentive distributions, by the weighted average number of outstanding common and subordinated units. Our net income is allocated to the general partner and limited partners in accordance with their respective partnership percentages, after giving effect to priority income allocations for incentive distributions, if any, to our general partner, pursuant to our partnership agreement. Earnings in excess of distributions are allocated to the general partner and limited partners based on their respective ownership interests. Payments made to our unitholders are determined in relation to actual distributions declared and are not based on the net income allocations used in the calculation of net income per unit. In addition to the common units, we have also identified the general partner interest and incentive distribution rights (“IDRs”) as participating securities and use the two-class method when calculating the net income per unit applicable to limited partners, which is based on the weighted-average number of common units outstanding during the period. Anti-dilutive units outstanding were immaterial for all periods presented. The net income attributable to common and subordinated unitholders and the weighted average units for calculating basic and diluted net income per common and subordinated units were as follows: Year Ended December 31, (In millions, except per unit data) 2018 2017 2016 Net income attributable to Ciner Resources LP $ 49.9 $ 41.6 $ 41.4 Less: General partner’s interest in net income 1.0 0.8 0.8 Limited partners’ interest in net income $ 48.9 $ 40.8 $ 40.6 Weighted average limited partner units outstanding: Common - Public and Ciner Holdings (basic) 19.7 19.6 12.3 Subordinated - Ciner Holdings (basic) — — 7.3 Total weighted average limited partner units outstanding (basic) 19.7 19.6 19.6 Common - Public and Ciner Holdings (diluted) 19.7 19.7 12.3 Subordinated - Ciner Holdings (diluted) — — 7.3 Total weighted average limited partner units outstanding (diluted) 19.7 19.7 19.6 Net income per limited partner unit: Common - Public and Ciner Holdings (basic) $ 2.48 $ 2.08 $ 2.06 Subordinated - Ciner Holdings (basic) $ — $ — $ 2.11 Net income per limited partner units (basic) $ 2.48 $ 2.08 $ 2.08 Common - Public and Ciner Holdings (diluted) $ 2.48 $ 2.07 $ 2.06 Subordinated - Ciner Holdings (diluted) $ — $ — $ 2.11 Net income per limited partner units (diluted) $ 2.48 $ 2.07 $ 2.08 The calculation of limited partners’ interest in net income is as follows: Year Ended December 31, (In millions, except per unit data) 2018 2017 2016 Net income attributable to common unitholders: Distributions (1) $ 44.6 $ 44.5 $ 27.9 (Distributions in excess of net income)/undistributed earnings 4.3 (3.7 ) (2.7 ) Common unitholders’ interest in net income $ 48.9 $ 40.8 $ 25.2 Net income attributable to subordinated unitholders: Distributions (1) $ — $ — $ 16.6 (Distributions in excess of net income)/undistributed earnings — — (1.2 ) Subordinated unitholders’ interest in net income $ — $ — $ 15.4 (1) Distributions declared per unit for the year 2.268 2.268 2.265 Conversion of subordinated units Upon payment of the quarterly distribution for the third quarter of 2016, the conditions for conversion of the Partnership’s subordinated units were satisfied. Accordingly, effective on November 14, 2016, the Partnership’s 9,775,500 subordinated units converted into common units on a one -for-one basis. For purposes of calculating net income per common and subordinated units, the conversion of the subordinated units were deemed to have occurred on October 1, 2016. Quarterly Distribution On January 31, 2019 , the Partnership declared its fourth quarter 2018 quarterly distribution. The quarterly cash distribution of $0.567 per unit was paid on February 28, 2019 to unitholders of record on February 11, 2019 . Our general partner has considerable discretion in determining the amount of available cash, the amount of distributions and the decision to make any distribution. Although our partnership agreement requires that we distribute all of our available cash quarterly, there is no guarantee that we will make quarterly cash distributions to our unitholders at our current quarterly distribution level, at the minimum quarterly distribution level or at any other rate, and we have no legal obligation to do so. However, our partnership agreement does contain provisions intended to motivate our general partner to make steady, increasing and sustainable distributions over time. General Partner Interest and Incentive Distribution Rights Our partnership agreement provides that our general partner initially will be entitled to 2.0% of all distributions that we make prior to our liquidation. Our general partner has the right, but not the obligation, to contribute up to a proportionate amount of capital to us in order to maintain its 2.0% general partner interest if we issue additional units. Our general partner’s approximate 2.0% interest, and the percentage of our cash distributions to which our general partner is entitled from such approximate 2.0% interest, will be proportionately reduced if we issue additional units in the future (other than the issuance of common units upon a reset of the IDRs), and our general partner does not contribute a proportionate amount of capital to us in order to maintain its approximate 2.0% general partner interest. Our partnership agreement does not require that our general partner fund its capital contribution with cash. It may, instead, fund its capital contribution by contributing to us common units or other property. IDRs represent the right to receive increasing percentages ( 13.0% , 23.0% and 48.0% ) of quarterly distributions from operating surplus after we have achieved the minimum quarterly distribution and the target distribution levels. Our general partner currently holds the IDRs, but may transfer these rights separately from its general partner interest, subject to certain restrictions in our partnership agreement. Percentage Allocations of Distributions from Operating Surplus The following table illustrates the percentage allocations of distributions from operating surplus between the unitholders and our general partner based on the specified target distribution levels. The amounts set forth under the column heading "Marginal Percentage Interest in Distributions" are the percentage interests of our general partner and the unitholders in any distributions from operating surplus we distribute up to and including the corresponding amount in the column "Total Quarterly Distribution per Unit Target Amount." The percentage interests shown for our unitholders and our general partner for the minimum quarterly distribution also apply to quarterly distribution amounts that are less than the minimum quarterly distribution. The percentage interests set forth below for our general partner (1) include a 2.0% general partner interest, (2) assume that our general partner has contributed any additional capital necessary to maintain its 2.0% general partner interest, (3) assume that our general partner has not transferred its incentive distribution rights and (4) assume there are no arrearages on common units. Marginal Percentage Interest in Distributions Total Quarterly Distribution per Unit Target Amount Unitholders General Partner Minimum Quarterly Distribution $0.5000 98.0 % 2.0 % First Target Distribution above $0.5000 up to $0.5750 98.0 % 2.0 % Second Target Distribution above $0.5750 up to $0.6250 85.0 % 15.0 % Third Target Distribution above $0.6250 up to $0.7500 75.0 % 25.0 % Thereafter above $0.7500 50.0 % 50.0 %

ACCOUNTS RECEIVABLE, NET

ACCOUNTS RECEIVABLE, NET	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
ACCOUNTS RECEIVABLE, NET	ACCOUNTS RECEIVABLE, NET Accounts receivable, net consisted of the following as of December 31: (In millions) 2018 2017 Trade receivables $ 31.0 $ 27.5 Other receivables 5.9 6.7 Total $ 36.9 $ 34.2

INVENTORY

INVENTORY	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
INVENTORY	INVENTORY Inventory consisted of the following as of December 31: (In millions) 2018 2017 Raw materials $ 10.9 $ 10.1 Finished goods 5.1 3.2 Stores inventory, current 6.3 6.5 Total $ 22.3 $ 19.8

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	PROPERTY, PLANT, AND EQUIPMENT, NET Property, plant, and equipment, net consisted of the following as of December 31: (In millions) 2018 2017 Land and land improvements $ 0.3 $ 0.3 Depletable land 3.0 3.0 Buildings and building improvements 137.1 135.0 Computer hardware 4.7 5.3 Machinery and equipment 677.7 652.6 Mining reserves 65.3 65.3 Total 888.1 861.5 Less accumulated depreciation, depletion and amortization (667.7 ) (644.7 ) Total net book value 220.4 216.8 Construction in progress 46.3 32.5 Total property, plant, and equipment, net $ 266.7 $ 249.3 Depreciation, depletion and amortization expense on property, plant, and equipment was $28.4 million , $27.1 million and $26.1 million for the years ended December 31, 2018 , 2017 and 2016 , respectively.

OTHER NON-CURRENT ASSETS

OTHER NON-CURRENT ASSETS	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
OTHER NON-CURRENT ASSETS	OTHER NON-CURRENT ASSETS Other non-current assets consisted of the following as of December 31: (In millions) 2018 2017 Stores inventory, non-current $ 19.4 $ 18.6 Internal-use software 6.2 — Deferred financing costs and other 0.8 1.0 Total $ 26.4 $ 19.6 In accordance with ASC 350-40, Internal Use Software, we capitalize certain internal use software development costs associated with creating and enhancing internally developed software related to our enterprise resource planning system that was implemented in 2018 and went live on January 1, 2019. Software development activities generally consist of three stages (i) the research and planning stage, (ii) the application and infrastructure development stage, and (iii) the post-implementation stage. Costs incurred in the planning and post-implementation stages of software development, or other maintenance and development expenses that do not meet the qualification for capitalization are expensed as incurred. Costs incurred in the application and infrastructure development stage, including significant enhancements and upgrades, are capitalized. As a result, we have capitalized $6.2 million of software development costs and zero of accumulated amortization, as an intangible asset within “other non-current assets” in the consolidated balance sheet as of December 31, 2018 . These software development costs are amortized on a straight-line basis over the estimated useful life of five to ten years under depreciation and amortization expense in the consolidated statements of operations. Amortization for these capitalized costs is expected to be $0.6 million per year.

ACCRUED EXPENSES

ACCRUED EXPENSES	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
ACCRUED EXPENSES	ACCRUED EXPENSES Accrued expenses consisted of the following as of December 31: (In millions) 2018 2017 Accrued capital expenditures $ 13.0 $ 1.0 Accrued energy costs 6.6 5.2 Accrued royalty costs 6.5 4.5 Accrued employee compensation & benefits 7.5 6.8 Accrued other taxes 4.7 4.8 Accrued derivatives 1.9 1.9 Other accruals 4.2 3.5 Total $ 44.4 $ 27.7

DEBT

DEBT	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
DEBT	DEBT Long-term debt consisted of the following as of December 31: (In millions) 2018 2017 Variable Rate Demand Revenue Bonds, principal due October 1, 2018, interest payable monthly, bearing an interest rate of 1.82% at December 31, 2017 $ — $ 11.4 Ciner Wyoming Credit Facility, unsecured principal expiring on August 1, 2022, variable interest rate as a weighted average rate of 3.99% at December 31, 2018 and 3.08% at December 31, 2017 99.0 138.0 Total Debt 99.0 $ 149.4 Current portion of long-term debt — 11.4 Total long-term debt $ 99.0 $ 138.0 Aggregate maturities required on long-term debt at December 31, 2018 are due in future years as follows: Amount 2019 $ — 2020 — 2021 — 2022 99.0 2023 — Thereafter — Total $ 99.0 Demand Revenue Bond On October 1, 2018 the Partnership fully extinguished the $11.4 million 2018 Variable Rate Demand Revenue Bonds due on that day. The Bonds were paid in full, including all accrued interest and without penalties. Additionally, the extinguishment of the bonds relieved Ciner Wyoming of maintaining the related standby letters of credit. Ciner Wyoming Credit Facility On August 1, 2017, Ciner Wyoming entered into a Credit Agreement (“Ciner Wyoming Credit Facility”) with each of the lenders listed on the respective signature pages thereof and PNC Bank, National Association, as administrative agent, swing line lender and a Letter of Credit (“ L/C”) issuer. The Ciner Wyoming Credit Facility replaces the former Credit Facility (“Former Ciner Wyoming Credit Facility”), dated as of July 18, 2013, by and among Ciner Wyoming, the lenders party thereto and Bank of America, N.A., as administrative agent, swing line lender and L/C issuer, as amended, which was terminated on August 1, 2017 upon entry into the Ciner Wyoming Credit Facility. This arrangement was accounted for as a modification of debt in accordance with ASC 470-50. The Ciner Wyoming Credit Facility is a $225.0 million senior unsecured revolving credit facility with a syndicate of lenders, which will mature on the fifth anniversary of the closing date of such credit facility. The Ciner Wyoming Credit Facility provides for revolving loans to fund working capital requirements, capital expenditures, to consummate permitted acquisitions and for all other lawful partnership purposes. The Ciner Wyoming Credit Facility has an accordion feature that allows Ciner Wyoming to increase the available revolving borrowings under the facility by up to an additional $75.0 million , subject to Ciner Wyoming receiving increased commitments from existing lenders or new commitments from new lenders and the satisfaction of certain other conditions. In addition, the Ciner Wyoming Credit Facility includes a sublimit up to $20.0 million for same-day swing line advances and a sublimit up to $40.0 million for letters of credit. Ciner Wyoming’s obligations under the Ciner Wyoming Credit Facility are unsecured. The Ciner Wyoming Credit Facility contains various covenants and restrictive provisions that limit (subject to certain exceptions) Ciner Wyoming’s ability to: • make distributions on or redeem or repurchase units; • incur or guarantee additional debt; • make certain investments and acquisitions; • incur certain liens or permit them to exist; • enter into certain types of transactions with affiliates of Ciner Wyoming; • merge or consolidate with another company; and • transfer, sell or otherwise dispose of assets. The Ciner Wyoming Credit Facility also requires quarterly maintenance of a consolidated leverage ratio (as defined in the Ciner Wyoming Credit Facility) of not more than 3.00 to 1.00 and a consolidated interest coverage ratio (as defined in the Ciner Wyoming Credit Facility) of not less than 3.00 to 1.00. The Ciner Wyoming Credit Facility contains events of default customary for transactions of this nature, including (i) failure to make payments required under the Ciner Wyoming Credit Facility, (ii) events of default resulting from failure to comply with covenants and financial ratios in the Ciner Wyoming Credit Facility, (iii) the occurrence of a change of control, (iv) the institution of insolvency or similar proceedings against Ciner Wyoming and (v) the occurrence of a default under any other material indebtedness Ciner Wyoming may have. Upon the occurrence and during the continuation of an event of default, subject to the terms and conditions of the Ciner Wyoming Credit Facility, the administrative agent shall, at the request of the Required Lenders (as defined in the Ciner Wyoming Credit Facility), or may, with the consent of the Required Lenders, terminate all outstanding commitments under the Ciner Wyoming Credit Facility and may declare any outstanding principal of the Ciner Wyoming Credit Facility debt, together with accrued and unpaid interest, to be immediately due and payable. Under the Ciner Wyoming Credit Facility, a change of control is triggered if Ciner Corp and its wholly-owned subsidiaries, directly or indirectly, cease to own all of the equity interests, or cease to have the ability to elect a majority of the board of directors (or similar governing body) of our general partner (or any entity that performs the functions of the Partnership’s general partner). In addition, a change of control would be triggered if the Partnership ceases to own at least 50.1% of the economic interests in Ciner Wyoming or cease to have the ability to elect a majority of the members of Ciner Wyoming’s board of managers. Loans under the Ciner Wyoming Credit Facility bear interest at Ciner Wyoming’s option at either: • a Base Rate, which equals the highest of (i) the federal funds rate in effect on such day plus 0.50% , (ii) the administrative agent’s prime rate in effect on such day or (iii) one-month LIBOR plus 1.0% , in each case, plus an applicable margin; or • Eurodollar Rate plus an applicable margin. The unused portion of the Ciner Wyoming Credit Facility is subject to an unused line fee ranging from 0.225% to 0.300% per annum based on Ciner Wyoming’s then current consolidated leverage ratio. At December 31, 2018 , Ciner Wyoming was in compliance with all financial covenants of the Ciner Wyoming Credit Facility. Ciner Resources Credit Facility On August 1, 2017, the Partnership entered into a Credit Agreement (the “Ciner Resources Credit Facility”) with each of the lenders listed on the respective signature pages thereof and PNC Bank, National Association, as administrative agent, swing line lender and an L/C issuer. The Ciner Resources Credit Facility replaces the former Credit Facility, dated as of July 18, 2013, by and among the Partnership, the lenders party thereto and Bank of America, N.A., as administrative agent, swing line lender and L/C issuer, as amended (the “Former Revolving Credit Facility”), which was terminated on August 1, 2017 upon entry into the Ciner Resources Credit Facility. The Ciner Resources Credit Facility is a $10.0 million senior secured revolving credit facility with a syndicate of lenders, which will mature on the fifth anniversary of the closing date of such credit facility. The Ciner Resources Credit Facility provides for revolving loans to be available to fund distributions on the Partnership’s units and working capital requirements and capital expenditures, to consummate permitted acquisitions and for all other lawful partnership purposes. The Ciner Resources Credit Facility includes a sublimit up to $5.0 million for same-day swing line advances and a sublimit up to $5.0 million for letters of credit. The Partnership’s obligations under the Ciner Resources Credit Facility are guaranteed by each of the Partnership’s material domestic subsidiaries other than Ciner Wyoming LLC (“Ciner Wyoming”). In addition, the Partnership’s obligations under the Ciner Resources Credit Facility are secured by a pledge of substantially all of the Partnership’s assets (subject to certain exceptions), including the membership interests held in Ciner Wyoming by the Partnership. The Ciner Resources Credit Facility contains various covenants and restrictive provisions that limit (subject to certain exceptions) the Partnership’s ability to (and the ability of the Partnership’s subsidiaries, including without limitation, Ciner Wyoming to): • make distributions on or redeem or repurchase units; • incur or guarantee additional debt; • make certain investments and acquisitions; • incur certain liens or permit them to exist; • enter into certain types of transactions with affiliates; • merge or consolidate with another company; and • transfer, sell or otherwise dispose of assets. The Ciner Resources Credit Facility also requires quarterly maintenance of a consolidated leverage ratio (as defined in the Ciner Resources Credit Facility) of not more than 3.00 to 1.00 and a consolidated interest coverage ratio (as defined in the Ciner Resources Credit Facility) of not less than 3.00 to 1.00. In addition, the Ciner Resources Credit Facility contains events of default customary for transactions of this nature, including (i) failure to make payments required under the Ciner Resources Credit Facility, (ii) events of default resulting from failure to comply with covenants and financial ratios, (iii) the occurrence of a change of control, (iv) the institution of insolvency or similar proceedings against the Partnership or its material subsidiaries and (v) the occurrence of a default under any other material indebtedness the Partnership (or any of its subsidiaries) may have, including the Ciner Wyoming Credit Facility. Upon the occurrence and during the continuation of an event of default, subject to the terms and conditions of the Ciner Resources Credit Facility, the lenders may terminate all outstanding commitments under the Ciner Resources Credit Facility and may declare any outstanding principal of the Ciner Resources Credit Facility debt, together with accrued and unpaid interest, to be immediately due and payable. Under the Ciner Resources Credit Facility, a change of control is triggered if Ciner Corp and its wholly-owned subsidiaries, directly or indirectly, cease to own all of the equity interests, or cease to have the ability to elect a majority of the board of directors (or similar governing body) of, Ciner Holdings or Ciner GP (or any entity that performs the functions of the Partnership’s general partner). In addition, a change of control would be triggered if the Partnership ceases to own at least 50.1% of the economic interests in Ciner Wyoming or ceases to have the ability to elect a majority of the members of Ciner Wyoming’s board of managers. Loans under the Ciner Resources Credit Facility bear interest at our option at either: • a Base Rate, which equals the highest of (i) the federal funds rate in effect on such day plus 0.50% , (ii) the administrative agent’s prime rate in effect on such day or (iii) one-month LIBOR plus 1.0% , in each case, plus an applicable margin; or • Eurodollar Rate plus an applicable margin. The unused portion of the Ciner Resources Credit Facility is subject to an unused line fee ranging from 0.225% to 0.300% based on our then current consolidated leverage ratio. At December 31, 2018 , the Partnership has not drawn upon the $10.0 million of availability under this facility. Additionally, at December 31, 2018 , the Partnership was in compliance with all financial covenants of the Ciner Resources Credit Facility. WE Soda and Ciner Enterprises Facilities Agreement On August 1, 2018, Ciner Enterprises, the entity that indirectly owns and controls our General Partner, refinanced its existing credit agreement and entered into a new facilities agreement, to which WE Soda and Ciner Enterprises (as borrowers), and KEW Soda, WE Soda, certain related parties and Ciner Enterprises, Ciner Holdings and Ciner Corp (as original guarantors and together with the borrowers, the “Ciner obligors”), are parties (as amended and restated or otherwise modified, the “Facilities Agreement”), and certain related finance documents. The Facilities Agreement expires on August 1, 2025. Even though neither the Partnership nor Ciner Wyoming is a party or a guarantor under the Facilities Agreement, while any amounts are outstanding under the Facilities Agreement we will be indirectly affected by certain affirmative and restrictive covenants that apply to WE Soda and its subsidiaries (which include us). Besides the customary covenants and restrictions, the Facilities Agreement includes provisions that, without a waiver or amendment approved by lenders whose commitments are more than 66-2/3% of the total commitments under the Facilities Agreement to undertake such action, would (i) prevent transactions with our affiliates that could reasonably be expected to materially and adversely affect the interests of certain finance parties, (ii) restrict the ability to amend our limited partnership agreement or the General Partner’s limited liability company agreement or our other constituency documents if such amendment could reasonably be expected to materially and adversely affect the interests of the lenders to the Facilities Agreement; and (iii) prevent actions that enable certain restrictions or prohibitions on our ability to upstream cash (including via distributions) to the borrowers under the Facilities Agreement. In addition, while the General Partner’s interest is not subject to a lien under the Facilities Agreement, Ciner Enterprises’ ownership in Ciner Holdings, which directly owns the General Partner, is subject to a lien under the Facilities Agreement, which enables the lenders under the Facilities Agreement to foreclose on such collateral and take control of the General Partner if any of WE Soda or KEW Soda or certain of their related parties, or Ciner Enterprises, Ciner Corp or Ciner Holdings is unable to satisfy its respective obligations under the Facilities Agreement.

OTHER NON-CURRENT LIABILITIES

OTHER NON-CURRENT LIABILITIES	12 Months Ended
	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
OTHER NON-CURRENT LIABILITIES	OTHER NON-CURRENT LIABILITIES Other non-current liabilities consisted of the following as of December 31: (In millions) 2018 2017 Reclamation reserve $ 5.4 $ 5.1 Derivative instruments and hedges, fair value liabilities 5.5 5.3 Total $ 10.9 $ 10.4 A reconciliation of the Partnership’s reclamation reserve liability is as follows: (In millions) 2018 2017 Reclamation reserve balance at beginning of year $ 5.1 $ 5.5 Accretion expense 0.3 0.3 Reclamation adjustments (1) $ — $ (0.7 ) Reclamation reserve balance at end of year $ 5.4 $ 5.1 (1) The reclamation adjustments are primarily a result of changes in the self-bond agreement with the Wyoming Department of Environmental Quality. See Note 14 “Commitments and Contingencies” for additional information on our reclamation reserve.

EMPLOYEE COMPENSATION

EMPLOYEE COMPENSATION	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
EMPLOYEE COMPENSATION	EMPLOYEE COMPENSATION The Partnership participates in various benefit plans offered and administered by Ciner Corp and is allocated its portions of the annual costs related thereto. The specific plans are as follows: Retirement Plans - Benefits provided under the pension plan for salaried employees and pension plan for hourly employees (collectively, the “Retirement Plans”) are based upon years of service and average compensation for the highest 60 consecutive months of the employee’s last 120 months of service, as defined. Each plan covers substantially all full-time employees hired before May 1, 2001. Ciner Corp’s pension plans had a net unfunded liability balance of $56.9 million and $57.4 million at December 31, 2018 and December 31, 2017 , respectively. Ciner Corp’s funding policy is to contribute an amount within the range of the minimum required and the maximum tax-deductible contribution. The Partnership’s allocated portion of the pension plan’s net periodic pension costs for the twelve months ended December 31, 2018 , 2017 and 2016 were $0.4 million , $1.4 million and $2.0 million , respectively. The decrease in pension costs during the twelve months ended December 31, 2018 was driven by reduced service costs from retirements and asset gains from the prior year. Savings Plan - The 401(k) retirement plan (the “401(k) Plan”) covers all eligible hourly and salaried employees. Eligibility is limited to all domestic residents and any foreign expatriates who are in the United States indefinitely. The plan permits employees to contribute specified percentages of their compensation, while the Partnership makes contributions based upon specified percentages of employee contributions. Participants hired on or subsequent to May 1, 2001, will receive an additional contribution from the Partnership based on a percentage of the participant’s base pay. Contributions made to the 401(k) Plan for the twelve months ended December 31, 2018 , 2017 and 2016 were $2.8 million , $3.7 million and $1.6 million , respectively. The decrease during the twelve months ended December 31, 2018 was primarily due to the additional profit sharing contributions made during 2017 that did not occur during the current year. Postretirement Benefits - Most of the Partnership’s employees are eligible for postretirement benefits other than pensions if they reach retirement age while still employed. The postretirement benefits are accounted for by Ciner Corp on an accrual basis over an employee’s period of service. The postretirement plan, excluding pensions, are not funded, and Ciner Corp has the right to modify or terminate the plan. The post-retirement plan had a net unfunded liability of $9.9 million and $11.5 million at December 31, 2018 and December 31, 2017 , respectively. The decrease in the obligation as of December 31, 2018 as compared to December 31, 2017 is due to the Ciner Corp amending its postretirement benefit plan during 2017 to increase eligibility requirements at which participants may begin receiving benefits, implementing a subsidy rather than a premium for the benefit plan, and eliminating plan eligibility for individuals hired after December 31, 2016. The result of these changes have resulted in a postretirement (benefit) cost being amortized to the liability recorded at Ciner Corp during the latter half of 2017 and into 2018. The Partnership’s allocated portion of postretirement (benefit) cost for the twelve months ended December 31, 2018 , 2017 and 2016 , were $(2.9) million , $(2.8) million and $1.4 million , respectively.

EQUITY - BASED COMPENSATION

EQUITY - BASED COMPENSATION	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
EQUITY - BASED COMPENSATION	EQUITY - BASED COMPENSATION In July 2013, our general partner established the Ciner Resource Partners LLC 2013 Long-Term Incentive Plan (as amended to date,the “Plan” or “LTIP”). The Plan is intended to provide incentives that will attract and retain valued employees, officers, consultants and non-employee directors by offering them a greater stake in our success and a closer identity with us, and to encourage ownership of our common units by such individuals. The Plan provides for awards in the form of common units, phantom units, distribution equivalent rights (“DERs”), cash awards and other unit-based awards. All employees, officers, consultants and non-employee directors of us and our parents and subsidiaries are eligible to be selected to participate in the Plan. As of December 31, 2018 , subject to further adjustment as provided in the Plan, a total of 0.7 million common units were available for awards under the Plan. Any common units tendered by a participant in payment of the tax liability with respect to an award, including common units withheld from any such award, will not be available for future awards under the Plan. Common units awarded under the Plan may be reserved or made available from our authorized and unissued common units or from common units reacquired (through open market transactions or otherwise). Any common units issued under the Plan through the assumption or substitution of outstanding grants from an acquired company will not reduce the number of common units available for awards under the Plan. If any common units subject to an award under the Plan are forfeited, any common units counted against the number of common units available for issuance pursuant to the Plan with respect to such award will again be available for awards under the Plan. Non-employee Director Awards During the twelve months ended December 31, 2018 , a total of 6,807 common units were granted and fully vested to non-employee directors, and 7,887 were grants during the twelve months ended December 31, 2017 . The grant date average fair value per unit of these awards was $27.55 and $28.53 for the twelve months ended December 31, 2018 and 2017 , respectively. The total fair value of these awards were approximately $0.2 million during the twelve months ended December 31, 2018 and 2017 , respectively. Time Restricted Unit Awards We grant restricted unit awards in the form of common units to certain employees which vest over a specified period of time, usually between one to three years, with vesting based on continued employment as of each applicable vesting date. Award recipients are entitled to distributions subject to the same restrictions as the underlying common unit. The awards are classified as equity awards, and are accounted for at fair value at grant date. The following table presents a summary of activity on the Time Restricted Unit Awards for the years ended December 31: 2018 2017 (Units in whole numbers) Number of Units Grant-Date Average Fair Value per Unit (1) Number of Units Grant-Date Average Fair Value per Unit (1) Unvested at the beginning of year 94,791 $ 27.22 39,170 $ 22.50 Granted (1) 37,914 26.13 80,370 28.41 Vested (42,989 ) 25.73 (13,055 ) 22.50 Forfeited (18,280 ) 27.12 (11,694 ) 24.90 Unvested at the end of the year 71,436 $ 27.56 94,791 $ 27.22 (1) Determined by dividing the aggregate grant date fair value of awards by the number of awards issued. No estimated forfeiture rate was applied to the awards as of December 31, 2018 as all awards granted are expected to vest. Total Return Performance Unit Awards We grant TR Performance Unit Awards to certain employees. The TR Performance Unit Awards represent the right to receive a number of common units at a future date based on the achievement of market-based performance requirements in accordance with the TR Unit Performance Award agreement, and also include Distribution Equivalent Rights (“DERs”). DERs are the right to receive an amount equal to the accumulated cash distributions made during the period with respect to each common unit issued upon vesting. The TR Performance Unit Awards vest at the end of the performance period, usually between two to three years from the date of the grant. Performance is measured on the achievement of a specified level of total return, or TR, relative to the TR of a peer group comprised of other limited partnerships. The potential payout ranges from 0 - 200% of the grant target quantity and is adjusted based on our TR performance relative to the peer group. For purposes of the table below the number of units are included at target quantity. We utilized a Monte Carlo simulation model to estimate the grant date fair value of TR Performance Unit Awards granted to employees. These type of awards, with market conditions, require the input of highly subjective assumptions, including expected volatility and expected distribution yield. Historical and implied volatilities were used in estimating the fair value of these awards. The following table presents a summary of activity on the TR Performance Unit Awards for the years ended December 31: 2018 2017 (Units in whole numbers) Number of Units Grant-Date Average Fair Value per Unit (1) Number of Units Grant-Date Average Fair Value per Unit (1) Unvested at the beginning of year 26,177 $ 42.93 5,787 $ 43.93 Granted 33,994 41.52 22,849 42.73 Forfeited (7,197 ) 41.53 (2,459 ) 43.47 Unvested at the end of the year 52,974 $ 42.22 26,177 $ 42.93 (1) Determined by dividing the aggregate grant date fair value of awards by the number of awards issued. Unrecognized Compensation Expense A summary of the Partnership’s unrecognized compensation expense for its unvested restricted time and performance based units, and the weighted-average periods over which the compensation expense is expected to be recognized are as following: Year Ended Year Ended Unrecognized Compensation Expense (In millions) Weighted Average to be Recognized (In years) Unrecognized Compensation Expense (In millions) Weighted Average to be Recognized (In years) Time-based units $ 1.3 1.60 $ 1.7 2.03 Performance-based units 1.2 1.78 0.8 1.88 Total $ 2.5 $ 2.5

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE LOSS	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE LOSS	ACCUMULATED OTHER COMPREHENSIVE LOSS Accumulated Other Comprehensive loss Accumulated other comprehensive loss, attributable to Ciner Resources LP, includes unrealized gains and losses on derivative financial instruments. Amounts recorded in accumulated other comprehensive loss as of December 31, 2018 , 2017 and 2016 , and changes within the period, consisted of the following: Gains and Losses on Cash Flow Hedges (In millions) Balance at January 1, 2016 $ (2.1 ) Other comprehensive loss before reclassification (0.5 ) Amounts reclassified from accumulated other comprehensive loss $ 1.0 Net current-period other comprehensive income 0.5 Balance at December 31, 2016 $ (1.6 ) Other comprehensive loss before reclassification (2.8 ) Amounts reclassified from accumulated other comprehensive loss 0.7 Net current-period other comprehensive loss (2.1 ) Balance at December 31, 2017 $ (3.7 ) Other comprehensive loss before reclassification (0.6 ) Amounts reclassified from accumulated other comprehensive loss 0.5 Net current period other comprehensive loss (0.1 ) Balance at December 31, 2018 $ (3.8 ) Other Comprehensive Income/(Loss) Other comprehensive income/(loss), including portion attributable to non-controlling interest, is derived from adjustments to reflect the unrealized gains/(loss) on derivative financial instruments. The components of other comprehensive income/(loss) consisted of the following for the years ended December 31: (In millions) 2018 2017 2016 Unrealized gain/(loss) on derivatives: Mark to market adjustment on interest rate swap contracts $ (0.2 ) $ 0.4 $ 0.4 Mark to market adjustment on natural gas forward contracts — (4.4 ) 0.5 Income/(loss) on derivative financial instruments $ (0.2 ) $ (4.0 ) $ 0.9 Reclassifications for the period The components of other comprehensive income/(loss), attributable to Ciner Resources LP, that have been reclassified consisted of the following for the years ended December 31: (In millions) 2018 2017 2016 Affected Line Items on the Consolidated Statements of Operations and Comprehensive Income Details about other comprehensive income/(loss) components: Gains and losses on cash flow hedges: Interest rate swap contracts $ — $ 0.2 $ 0.4 Interest expense Natural gas forward contracts $ 0.5 $ 0.5 $ 0.6 Cost of products sold Total reclassifications for the period $ 0.5 $ 0.7 $ 1.0

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Lease and License Commitments The Partnership leases and licenses mineral rights from the U.S. Bureau of Land Management, the state of Wyoming, Rock Springs Royalty Company, LLC, an affiliate of Anadarko Petroleum, and other private parties. All of these leases and the licnese provide for royalties based upon production volume. The remaining leases provide for minimum lease payments as detailed in the table below. The Partnership has a perpetual right of first refusal with respect to these leases and license and intends to continue renewing the leases as has been its practice. The Partnership entered into a 10 - year rail yard switching and maintenance agreement with a third party, Watco Companies, LLC (“Watco”), on December 1, 2011. Under the agreement, Watco provides rail-switching services at the Partnership’s rail yard. The Partnership’s rail yard is constructed on land leased by Watco from Rock Springs Grazing Association and on land by which Watco holds an easement from Anadarko Land Corp; the Rock Springs Grazing Association land lease is renewable every 5 years for a total period of 30 years , while the Anadarko Land Corp. easement lease is perpetual. The Partnership has an option agreement with Watco to assign these leases to the Partnership at any time during the land lease term. An immaterial annual rental is paid under the easement and lease. The Partnership entered into two track lease agreements, collectively, not to exceed 10 years with Union Pacific for certain rail tracks used in connection with the rail yard. As of December 31, 2018 , the total minimum contractual rental commitments under the Partnership’s various operating leases, including renewal periods, are as follows: (In millions) Leased Land Track Leases Total Minimum Lease Payments 2019 0.10 0.10 0.20 2020 0.10 0.10 0.20 2021 0.10 0.03 0.13 2022 0.10 — 0.10 2023 0.10 — 0.10 Thereafter 1.30 — 1.30 Total $ 1.8 $ 0.2 $ 2.0 Ciner Corp typically enters into operating lease contracts with various lessors for railcars to transport product to customer locations and warehouses. Rail car leases under these contractual commitments range for periods from one to ten years. Ciner Corp's obligation related to these rail car leases are $11.1 million in 2019 , $8.5 million in 2020 , $6.0 million in 2021 , $3.8 million in 2022 , $1.4 million in 2023 and $4.7 million in 2024 and thereafter. Total lease expense allocated to the Partnership from Ciner Corp was approximately $13.9 million , $14.6 million and $14.5 million for the years ended December 31, 2018 , 2017 and 2016 , respectively, and is recorded in cost of products sold. Purchase Commitments We have physical and financial natural gas supply contracts to mitigate volatility in the price of natural gas. As of December 31, 2018 , these contracts totaled approximately $56.0 million for the purchase of a portion of our natural gas requirements over approximately the next five years. The supply purchase agreements have specific commitments of $21.3 million in 2019 , $15.8 million in 2020 , $10.0 million in 2021 , $5.0 million in 2022 and $3.9 million in 2023 . We have a separate contract that expires in 2021 and renews annually thereafter, for transportation of natural gas with an average annual cost of approximately $3.8 million per year. Legal Proceedings From time to time we are party to various claims and legal proceedings related to our business. Although the outcome of these proceedings cannot be predicted with certainty, management does not currently expect any of the legal proceedings we are involved in to have a material effect on our business, financial condition and results of operations. We cannot predict the nature of any future claims or proceedings, nor the ultimate size or outcome of existing claims and legal proceedings and whether any damages resulting from them will be covered by insurance. Litigation Settlement On February 2, 2016, amended on January 3, 2017, Ciner Wyoming filed suit against Rock Springs Royalty Company, LLC (“RSRC”) in the Third Judicial District Court in Sweetwater County, Wyoming, Case No. C-16-77-L, seeking, among other things, to recover approximately $32 million in royalty overpayments. The royalty payments arose under our license with RSRC, an affiliate of Anardarko Petroleum Corporation, to mine sodium minerals from lands located in Sweetwater County, Wyoming (“License”). The License sets the applicable royalty rate based on a most favored nation clause, where either the royalty rate is set at the same royalty rate we pay to other licensors in Sweetwater County for sodium minerals, or, if certain conditions are met, the royalty rate is set by the rate paid by a third party to Anadarko Petroleum Corporation under a separate license. In the lawsuit, we claim that RSRC has, for at least the last ten years, been charging an arbitrarily high royalty rate in contradiction of the License terms. In addition, we sought a modification of the expiration term of the License land-lease between Ciner Wyoming and RSRC to those terms granted to other licensors in accordance with the most favored nation clause. On June 28, 2018, RSRC and Ciner Wyoming signed a Settlement Agreement and Release (the “Settlement Agreement”) which among other things (i) required RSRC to pay Ciner Wyoming $27.5 million which was received on July 2, 2018, and (ii) concurrently amended selected sections of the License land-lease including among other things, (a) extension of the term of the License Agreement to July 18, 2061 and for so long thereafter as Ciner Wyoming continuously conducts operations to mine and remove sodium minerals from the licensed premises in commercial quantities; and (b) revises the production royalty rate for each sale of sodium mineral products produced from ore extracted from the licensed premises at the royalty rate of eight percent ( 8% ) of the net sales of such sodium mineral products. There are no unresolved conditions or uncertainties associated with the Settlement Agreement and management determined the $27.5 million settlement payment was related to the historical overpayment of royalties. Off-Balance Sheet Arrangements We have a self-bond agreement with the Wyoming Department of Environmental Quality under which we commit to pay directly for reclamation costs at our Green River, Wyoming plant site. The amount of the bond was $32.9 million as of December 31, 2018 and December 31, 2017 , which is the amount we would need to pay the State of Wyoming for reclamation costs if we cease mining operations currently. The amount of this self-bond is subject to change upon periodic re-evaluation by the Land Quality Division.

AGREEMENTS AND TRANSACTIONS WIT

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
AGREEMENTS AND TRANSACTIONS WITH AFFILIATES	AGREEMENTS AND TRANSACTIONS WITH AFFILIATES Ciner Corp is the exclusive sales agent for the Partnership and through its membership in ANSAC, Ciner Corp is responsible for promoting and increasing the use and sale of soda ash and other refined or processed sodium products produced. ANSAC operates on a cooperative service-at-cost basis to its members such that typically any annual profit or loss is passed through to the members. In the event an ANSAC member exits or the ANSAC cooperative is dissolved, the exiting members are obligated for their respective portion of the residual net assets or deficit of the cooperative. On November 9, 2018, Ciner Corp delivered a notice to terminate its membership in ANSAC. The termination from ANSAC will be effective as of December 31, 2021. As of December 31, 2018, we have not recognized an asset or liability related to its exit from ANSAC as such an amount is not currently probable or estimable. All actual sales and marketing costs incurred by Ciner Corp are charged directly to the Partnership. Selling, general and administrative expenses also include amounts charged to the Partnership by its affiliates principally consisting of salaries, benefits, office supplies, professional fees, travel, rent and other costs of certain assets used by the Partnership. On October 23, 2015, the Partnership entered into a Services Agreement (the “Services Agreement”), among the Partnership, our general partner and Ciner Corp. Pursuant to the Services Agreement, Ciner Corp has agreed to provide the Partnership with certain corporate, selling, marketing, and general and administrative services, in return for which the Partnership has agreed to pay Ciner Corp an annual management fee and reimburse Ciner Corp for certain third-party costs incurred in connection with providing such services. In addition, under the limited liability company agreement governing Ciner Wyoming, Ciner Wyoming reimburses us for employees who operate our assets and for support provided to Ciner Wyoming. These transactions do not necessarily represent arm's length transactions and may not represent all costs if the Company operated on a standalone basis. The total selling, general and administrative costs charged to the Partnership by affiliates were as follows: Years Ended December 31, (In millions) 2018 2017 2016 Ciner Corp 14.6 14.5 14.9 ANSAC (1) 3.0 2.4 3.8 Total selling, general and administrative expenses - affiliates $ 17.6 $ 16.9 $ 18.7 (1) ANSAC allocates its expenses to its members using a pro rata calculation based on sales. Cost of products sold includes an allocation of Ciner Corp's railcar lease expense (refer to Note 14 “Commitments and Contingencies”) and logistics services charged by ANSAC. For the years ended December 31, 2018 , 2017 and 2016 these ANSAC logistics costs were zero , $19.8 million and $3.3 million , respectively. When we elect to use ANSAC to provide freight services for our other non-ANSAC international sales, ANSAC separately and directly charges the Partnership for such services. During the year ended 2018 we did not use ANSAC for non-ANSAC international sales. The decrease in freight costs charged by ANSAC was due to a decrease in non-ANSAC international sales, to CIDT, during the year ended December 31, 2018 compared to 2017 . There were no sales to CIDT during the year ended December 31, 2018 , as the previous contract concluded in the 2017 year. Net sales to affiliates were as follows: Years Ended December 31, (In millions) 2018 2017 2016 ANSAC $ 253.3 $ 222.2 $ 262.2 CIDT — 82.3 9.0 Total $ 253.3 $ 304.5 $ 271.2 The Partnership had accounts receivable from affiliates and due to affiliates as follows: As of December 31, (In millions) 2018 2017 2018 2017 Accounts receivable from affiliates Due to affiliates ANSAC 48.7 57.7 $ 0.7 $ 1.3 CIDT 7.1 32.9 — — Ciner Resources Corporation 14.3 7.7 1.9 1.7 Total $ 70.1 $ 98.3 $ 2.6 $ 3.0

MAJOR CUSTOMERS AND SEGMENT REP

MAJOR CUSTOMERS AND SEGMENT REPORTING	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
MAJOR CUSTOMERS AND SEGMENT REPORTING	MAJOR CUSTOMERS AND SEGMENT REPORTING Our operations are similar in geography, nature of products we provide, and type of customers we serve. As the Partnership earns substantially all of its revenues through the sale of soda ash mined at a single location, we have concluded that we have one operating segment for reporting purposes. The net sales by geographic area consisted of the following: Years Ended December 31, (In millions) 2018 2017 2016 Domestic $ 233.4 $ 192.8 $ 192.6 International ANSAC 253.3 222.2 262.2 CIDT — 82.3 9.0 Other — — 11.4 Total international 253.3 304.5 282.6 Total net sales $ 486.7 $ 497.3 $ 475.2

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Partnership measures certain financial and non-financial assets and liabilities at fair value on a recurring basis. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. Fair value disclosures are reflected in a three-level hierarchy, maximizing the use of observable inputs and minimizing the use of unobservable inputs. A three-level valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability on the measurement date. The three levels are defined as follows: Ÿ Level 1-inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market. Ÿ Level 2-inputs to the valuation methodology include quoted prices for a similar asset or liability in an active market or model-derived valuations in which all significant inputs are observable for substantially the full term of the asset or liability. Ÿ Level 3-inputs to the valuation methodology are unobservable and significant to the fair value measurement of the asset or liability. Financial instruments consist primarily of cash and cash equivalents, accounts receivable, accounts payable, derivative financial instruments and long-term debt. The carrying amounts of cash and cash equivalents, accounts receivable and accounts payable approximate their fair value because of the nature of such instruments. Our long-term debt and derivative financial instruments are measured at their fair values with Level 2 inputs based on quoted market values for similar but not identical financial instruments. Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis Derivative Financial Instruments We have interest rate swap contracts, designated as cash flow hedges, to mitigate our exposure to possible increases in interest rates. The swap contracts consist of four individual $12.5 million swaps with an aggregate notional value of $50.0 million at December 31, 2018 and have various maturities through 2022. Our previous interest rate swap contracts, with an aggregate notional value of $70.0 million as of December 31, 2017 , expired on July 18, 2018. We enter into natural gas financial forward contracts, designated as cash flow hedges, to mitigate volatility in the price of natural gas related to a portion of the natural gas we consume. These contracts generally have various maturities through 2023 . These contracts had an aggregate notional value of $41.2 million and $37.0 million at December 31, 2018 and December 31, 2017 , respectively. The following table presents the fair value of derivative assets and liability derivatives and the respective locations on our consolidated balance sheets as of December 31, 2018 and December 31, 2017 : Assets Liabilities 2018 2017 2018 2017 (In millions) Balance Sheet Location Fair Value Balance Sheet Location Fair Value Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedges: Interest rate swap contracts - current $ — $ — Accrued Expenses $ 0.3 Accrued Expenses $ — Natural gas forward contracts - current Other Current Assets — — Accrued Expenses 1.6 Accrued Expenses 1.9 Natural gas forward contracts - non-current — — Other non-current liabilities 5.5 Other non-current liabilities 5.3 Total fair value of derivatives designated as hedging instruments $ — $ — $ 7.4 $ 7.2 Financial Assets and Liabilities not Measured at Fair Value The carrying value of our long-term debt materially reflects the fair value of our long-term debt as rates are variable and its key terms are similar to indebtedness with similar amounts, durations and credit risks. See Note 9 “Debt” for additional information on our debt arrangements.

REVENUE

REVENUE	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
REVENUE	REVENUE We have one reportable segment and our revenue is derived from the sale of soda ash which is our sole and primary good and service. We account for revenue in accordance with ASC 606, Revenue from Contracts with Customers, which we adopted on January 1, 2018, using the modified retrospective method. Performance Obligations. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer, and is the unit of account in ASC 606. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. At contract inception, we assess the goods and services promised in contracts with customers and identify performance obligations for each promise to transfer to the customer, a good or service that is distinct. To identify the performance obligations, the Partnership considers all goods and services promised in the contract regardless of whether they are explicitly stated or are implied by customary business practices. From its analysis, the Partnership determined that the sale of soda ash is currently its only performance obligation. Many of our customer volume commitments are short-term and our performance obligations for the sale of soda ash are generally limited to single purchase orders. When performance obligations are satisfied. Substantially all of our revenue is recognized at a point-in-time when control of goods transfers to the customer. Transfer of Goods. The Partnership uses standard shipping terms across each customer contract with very few exceptions. Shipments to customers are made with terms stated as Free on Board (“FOB”) Shipping Point. Control typically transfers when goods are delivered to the carrier for shipment, which is the point at which the customer has the ability to direct the use of and obtain substantially all remaining benefits from the asset. Payment Terms. Our payment terms vary by the type and location of our customers. The term between invoicing and when payment is due is not significant and consistent with typical terms in the industry. Variable Consideration. We recognize revenue as the amount of consideration that we expect to receive in exchange for transferring promised goods or services to customers. We do not adjust the transaction price for the effects of a significant financing component, as the time period between control transfer of goods and services and expected payment is one year or less. At the time of sale, we estimate provisions for different forms of variable consideration (discounts, rebates, and pricing adjustments) based on historical experience, current conditions and contractual obligations, as applicable. The estimated transaction price is typically not subject to significant reversals. We adjust these estimates when the most likely amount of consideration we expect to receive changes, although these changes are typically immaterial. Returns, Refunds and Warranties. In the normal course of business, the Partnership does not accept returns, nor does it typically provide customers with the right to a refund. Freight. In accordance with ASC 606, the Partnership made a policy election to treat freight and related costs that occur after control of the related good transfers to the customer as fulfillment activities instead of separate performance obligations. Therefore freight is recognized at the point in which control of soda ash has transfered to the customer. Revenue disaggregation . In accordance with ASC 606-10-50, the Partnership disaggregates revenue from contracts with customers into geographical regions. The Partnership determined that disaggregating revenue into these categories achieved the disclosure objectives to depict how the nature, timing, amount and uncertainty of revenue and cash flows are affected by economic factors. Refer to Note 16, “Major Customers and Segment Reporting” for revenue disaggregated into geographical regions. Contract Balances . The timing of revenue recognition, billings and cash collections results in billed receivables, unbilled receivables (contract assets), and customer advances and deposits (contract liabilities). Contract Assets. At the point of shipping, the Partnership has an unconditional right to payment that is only dependent on the passage of time. In general, customers are billed and a receivable is recorded as goods are shipped. These billed receivables are reported as “Accounts Receivable, net” on the Consolidated Balance Sheet as of December 31, 2018 . There were no contract assets as of December 31, 2018 or as of the date of adoption of ASC 606. Contract Liabilities. There may be situations where customers are required to prepay for freight and insurance prior to shipment. The Partnership has elected the practical expedient for its treatment of freight and therefore, such prepayments are considered a part of the single obligation to provide soda ash. In such instances, a contract liability for prepaid freight will be recorded. For the twelve months ended December 31, 2018 , there were no customers that required prepaid freight. There were no contract liabilities as of December 31, 2018 or as of the date of adoption of ASC 606. Practical and Expedients Exceptions Incremental costs of obtaining contracts. We generally expense costs related to sales, including sales force salaries and marketing expenses, when incurred because the amortization period would have been one year or less. These costs are recorded within sales and marketing expenses. Unsatisfied performance obligations. We do not disclose the value of unsatisfied performance obligations for contracts with an original expected length of one year or less.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS Distribution Declaration On February 14, 2019 , the members of the Board of Managers of Ciner Wyoming, approved a cash distribution to the members of Ciner Wyoming in the aggregate amount of $20.0 million . This distribution was payable and paid on February 15, 2019 . On January 31, 2019 , the Partnership declared a cash distribution approved by the board of directors of its general partner. The cash distribution for the fourth quarter of 2018 of $0.567 per unit was paid on February 28, 2019 to unitholders of record on February 11, 2019 .

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies The accompanying consolidated financial statements of the Partnership and its subsidiary have been prepared in conformity with U.S. generally accepted accounting principles and reflect all adjustments, consisting of normal recurring accruals, which are necessary for fair presentation of the results of operations, financial position and cash flows for the periods presented. All significant intercompany transactions, balances, revenue and expenses have been eliminated in consolidation and unless otherwise noted, the financial information for the Partnership is presented before non-controlling interest.
Non-controlling interests	Non-Controlling Interests In connection with the conversion of Ciner Wyoming from a Delaware limited partnership (“LP”) to a Delaware limited liability company (“LLC”), in June 2014, NRP’s general partner interest and limited partnership interest were converted into a single-class of membership interests in Ciner Wyoming, which currently consists of a 49.0% membership interest in Ciner Wyoming. Prior to the conversion of Ciner Wyoming from a Delaware LP to a Delaware LLC, non-controlling interests in the consolidated financial statements of the Partnership consisted of a 39.37% general partner interest and a 9.63% limited partner interest in Ciner Wyoming owned by NRP.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements, in accordance with accounting principles generally accepted in the United States of America, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the dates of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Revenue Recognition	Revenue Recognition On May 28, 2014 the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers (Topic 606), that requires companies to recognize revenue when a customer obtains control rather than when companies have transferred substantially all risks and rewards of a good or service. The Partnership has applied the provisions of this ASC and notes that our adoption of ASC 606 does not materially change the amount or timing of revenues recognized by us, nor does it materially affect our financial position. The majority of our revenues generated are recognized upon delivery and transfer of title to the product to our customers. The time at which delivery and transfer of title occurs, for the majority of our contracts with customers, is the point when the product leaves our facility, thereby rendering our performance obligation fulfilled. Additionally, the Partnership has made an accounting policy election to account for shipping and handling activities as fulfillment costs. The Partnership adopted this ASC effective January 1, 2018, as permitted by the ASC, using the modified retrospective method and we have not made any adjustment to opening retained earnings.
Freight Costs	Freight Costs The Partnership includes freight costs billed to customers for shipments administered by the Partnership in gross sales. The related freight costs along with cost of products sold are deducted from gross sales to determine gross profit.
Cash and Cash Equivalents	Cash and Cash Equivalents The Partnership considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Cash equivalents consist primarily of money market deposit accounts.
Accounts Receivable	Accounts Receivable Accounts receivable are carried at the original invoice amount less an estimate for doubtful receivables. We generally do not require collateral against outstanding accounts receivable. The allowance for doubtful accounts is based on specifically identified amounts that the Partnership believes to be uncollectible. An additional allowance is recorded based on certain percentages of aged receivables, which are determined based on management’s assessment of the general financial conditions affecting the Partnership’s customer base.
Inventory	Inventory Inventory is carried at the lower of cost or market. Cost is determined using the first-in, first-out method for raw material and finished goods inventory and the weighted average cost method for stores inventory. Costs include raw materials, direct labor and manufacturing overhead. Market is based on current replacement cost for raw materials and net realizable value for stores inventory and finished goods. • Raw material inventory includes material, chemicals and natural resources being used in the mining and refining process. • Finished goods inventory is the finished product soda ash. • Stores inventory includes parts, materials and operating supplies which are typically consumed in the production of soda ash and currently available for future use. Inventory expected to be consumed within the year is classified as current assets and remainder is classified as non-current assets.
Property, Plant, and Equipment	Property, Plant, and Equipment Property, plant, and equipment are stated at cost less accumulated depreciation. Depreciation is computed over the estimated useful lives of depreciable assets, using the straight-line method. The estimated useful lives applied to depreciable assets are as follows: Useful Lives Land improvements 10 years Depletable land 15-60 years Buildings and building improvements 10-30 years Computer hardware 3-5 years Machinery and equipment 5-20 years Furniture and fixtures 10 years The Partnership’s policy is to evaluate property, plant, and equipment for impairment whenever events or changes in circumstances indicate that its carrying amount may not be recoverable. An indicator of potential impairment would include situations when the estimated future undiscounted cash flows are less than the carrying value. The amount of any impairment then recognized would be calculated as the difference between estimated fair value and the carrying value of the asset.
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities The Partnership may enter into derivative contracts from time to time to manage exposure to the risk of exchange rate changes on its foreign currency transactions, the risk of changes in natural gas prices, and the risk of the variability in interest rates on borrowings. Gains and losses on derivative contracts qualifying for hedge accounting are reported as a component of the underlying transactions. The Partnership follows hedge accounting for its hedging activities. All derivative instruments are recorded on the balance sheet at their fair values. The accounting for changes in the fair value of a derivative depends on the intended use of the derivative and the resulting designation. The Partnership designates its derivatives based upon criteria established for hedge accounting under generally accepted accounting principles. For a derivative designated as a fair value hedge, the gain or loss is recognized in earnings in the period of change together with the offsetting gain or loss on the hedged item attributed to the risk being hedged. For a derivative designated as a cash flow hedge, the effective portion of the derivative’s gain or loss is initially reported as a component of accumulated other comprehensive income (loss) and subsequently reclassified into earnings when the hedged exposure affects earnings. Any significant ineffective portion of the gain or loss is reported in earnings immediately. For derivatives not designated as hedges, the gain or loss is reported in earnings in the period of change. The natural gas physical forward contracts are accounted for under the normal purchases and normal sales scope exception.
Income Tax	Income Tax We are organized as a pass-through entity for federal income tax purposes and therefore are not subject to federal or certain state income taxes. As a result, our partners are responsible for federal income taxes based on their respective share of taxable income. Net income for financial statement purposes may differ significantly from taxable income reportable to unitholders as a result of differences between the tax basis and financial reporting basis of assets and liabilities and the taxable income allocation requirements under the partnership agreement.
Reclamation Costs	Reclamation Costs The Partnership is obligated to return the land beneath its refinery and tailings ponds to its natural condition upon completion of operations and is required to return the land beneath its rail yard to its natural condition upon termination of the various lease agreements. The Partnership accounts for its land reclamation liability as an asset retirement obligation, which requires that obligations associated with the retirement of a tangible long-lived asset be recorded as a liability when those obligations are incurred, with the amount of the liability initially measured at fair value. Upon initially recognizing a liability for an asset retirement obligation, an entity must capitalize the cost by recognizing an increase in the carrying amount of the related long-lived asset. Over time, the liability is accreted to its present value each period, and the capitalized cost is depreciated over the estimated useful life of the related asset. Upon settlement of the liability, an entity either settles the obligation for its recorded amount or incurs a gain or loss upon settlement. The estimated original liability calculated in 1996 for the refinery and tailing ponds was calculated based on the estimated useful life of the mine, which was 80 years , and on external and internal estimates as to the cost to restore the land in the future and state regulatory requirements. During 2018 , 2017 and 2016 , the remaining life was 60 , 66 and 67 years, respectively. In 2019 , the mining reserve will be amortized over a remaining life of 59 years. The decline in estimated mining reserves estimated remaining life is based on the results of a recent independent mine reserve analysis conducted as of December 31, 2017. The independent mine reserve analysis is routine and performed approximately every three years. The liability was discounted using a weighted average credit-adjusted risk-free rates of approximately 6% and is being accreted throughout the estimated life of the related assets to equal the total estimated costs with a corresponding charge being recorded to cost of products sold. During 2011 , the Partnership constructed a rail yard to facilitate loading and switching of rail cars. The Partnership is required to restore the land on which the rail yard is constructed to its natural conditions. The original estimated liability for restoring the rail yard to its natural condition was calculated based on the land lease life of 30 years and on external and internal estimates as to the cost to restore the land in the future. The liability is discounted using a credit-adjusted risk-free rate of 4.25% and is being accreted throughout the estimated life of the related assets to equal the total estimated costs with a corresponding charge being recorded to cost of products sold.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is determined using a valuation hierarchy, generally by reference to an active trading market, quoted market prices or model-derived valuations for the same or similar financial instruments. See Note 17, “Fair Value Measurements,” for more information.
Equity-Based Compensation	Equity-Based Compensation We recognize compensation expense related to equity-based awards, with service conditions, granted to employees based on the estimated fair value of the awards on the date of grant, net of estimated forfeitures. The grant date fair value of the equity-based awards is generally recognized on a straight-line basis over the requisite service period, which is generally the vesting period of the respective awards. Equity-based awards with market conditions are fair valued using a Monte Carlo Simulation model.
Subsequent Events	Subsequent Events We have evaluated subsequent events through the filing of this Annual Report on Form 10-K.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The update amends existing standards for accounting for leases by lessees, with accounting for leases by lessors remaining largely unchanged from current guidance. The update requires that lessees recognize a lease liability and a right of use asset for all leases (with the exception of short-term leases) at the commencement date of the lease and disclose key information about leasing arrangements. For leases less than 12 months, an entity is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight-line basis over the lease term. The Partnership will make this election upon adoption. In preparation for the new requirements, the Partnership has completed its evaluation of the lease agreements. The Partnership will adopt ASC 842 effective January 1, 2019 using a modified transition approach under which prior comparative periods will not be adjusted, as permitted by the guidance. The Partnership has determined that the adoption of the new standard will not have a material impact on the balance sheet or statement of operations because the Partnership has no material long term leases that are subject to ASC 842. Ciner Corp was determined to be the ultimate lessee for rail car lease agreements under ASC 842, and the Partnership will continue to incur an allocation of rent expense in relation to the use of rail cars leased by Ciner Corp. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (ASC Topic 815) – Targeted Improvements to Accounting for Hedging Activities. This ASU aims to improve the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements. In addition, this ASU makes certain targeted improvements to simplify the application of the existing hedge accounting guidance. This ASU is effective for us beginning in the first quarter of 2019, with early application permitted. The Partnership adopted this ASU effective January 1, 2019 and concluded there is no material impact to the Partnership’s consolidated financial statements. In May 2017, the FASB issued ASU 2017-09–Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. ASU 2017-09 provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. The Partnership adopted this ASU effective January 1, 2018 and concluded there is no material impact to the Partnership’s consolidated financial statements.

NET INCOME PER UNIT AND CASH _2

NET INCOME PER UNIT AND CASH DISTRIBUTION (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Calculation of Net Income Per Unit	The net income attributable to common and subordinated unitholders and the weighted average units for calculating basic and diluted net income per common and subordinated units were as follows: Year Ended December 31, (In millions, except per unit data) 2018 2017 2016 Net income attributable to Ciner Resources LP $ 49.9 $ 41.6 $ 41.4 Less: General partner’s interest in net income 1.0 0.8 0.8 Limited partners’ interest in net income $ 48.9 $ 40.8 $ 40.6 Weighted average limited partner units outstanding: Common - Public and Ciner Holdings (basic) 19.7 19.6 12.3 Subordinated - Ciner Holdings (basic) — — 7.3 Total weighted average limited partner units outstanding (basic) 19.7 19.6 19.6 Common - Public and Ciner Holdings (diluted) 19.7 19.7 12.3 Subordinated - Ciner Holdings (diluted) — — 7.3 Total weighted average limited partner units outstanding (diluted) 19.7 19.7 19.6 Net income per limited partner unit: Common - Public and Ciner Holdings (basic) $ 2.48 $ 2.08 $ 2.06 Subordinated - Ciner Holdings (basic) $ — $ — $ 2.11 Net income per limited partner units (basic) $ 2.48 $ 2.08 $ 2.08 Common - Public and Ciner Holdings (diluted) $ 2.48 $ 2.07 $ 2.06 Subordinated - Ciner Holdings (diluted) $ — $ — $ 2.11 Net income per limited partner units (diluted) $ 2.48 $ 2.07 $ 2.08
Calculation of Net Income	The calculation of limited partners’ interest in net income is as follows: Year Ended December 31, (In millions, except per unit data) 2018 2017 2016 Net income attributable to common unitholders: Distributions (1) $ 44.6 $ 44.5 $ 27.9 (Distributions in excess of net income)/undistributed earnings 4.3 (3.7 ) (2.7 ) Common unitholders’ interest in net income $ 48.9 $ 40.8 $ 25.2 Net income attributable to subordinated unitholders: Distributions (1) $ — $ — $ 16.6 (Distributions in excess of net income)/undistributed earnings — — (1.2 ) Subordinated unitholders’ interest in net income $ — $ — $ 15.4 (1) Distributions declared per unit for the year 2.268 2.268 2.265
Percentage Allocations of Distributions From Operating Surplus	The following table illustrates the percentage allocations of distributions from operating surplus between the unitholders and our general partner based on the specified target distribution levels. The amounts set forth under the column heading "Marginal Percentage Interest in Distributions" are the percentage interests of our general partner and the unitholders in any distributions from operating surplus we distribute up to and including the corresponding amount in the column "Total Quarterly Distribution per Unit Target Amount." The percentage interests shown for our unitholders and our general partner for the minimum quarterly distribution also apply to quarterly distribution amounts that are less than the minimum quarterly distribution. The percentage interests set forth below for our general partner (1) include a 2.0% general partner interest, (2) assume that our general partner has contributed any additional capital necessary to maintain its 2.0% general partner interest, (3) assume that our general partner has not transferred its incentive distribution rights and (4) assume there are no arrearages on common units. Marginal Percentage Interest in Distributions Total Quarterly Distribution per Unit Target Amount Unitholders General Partner Minimum Quarterly Distribution $0.5000 98.0 % 2.0 % First Target Distribution above $0.5000 up to $0.5750 98.0 % 2.0 % Second Target Distribution above $0.5750 up to $0.6250 85.0 % 15.0 % Third Target Distribution above $0.6250 up to $0.7500 75.0 % 25.0 % Thereafter above $0.7500 50.0 % 50.0 %

ACCOUNTS RECEIVABLE, NET (Table

ACCOUNTS RECEIVABLE, NET (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of Accounts Receivable	Accounts receivable, net consisted of the following as of December 31: (In millions) 2018 2017 Trade receivables $ 31.0 $ 27.5 Other receivables 5.9 6.7 Total $ 36.9 $ 34.2

INVENTORY (Tables)

INVENTORY (Tables)	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consisted of the following as of December 31: (In millions) 2018 2017 Raw materials $ 10.9 $ 10.1 Finished goods 5.1 3.2 Stores inventory, current 6.3 6.5 Total $ 22.3 $ 19.8

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant, and equipment, net consisted of the following as of December 31: (In millions) 2018 2017 Land and land improvements $ 0.3 $ 0.3 Depletable land 3.0 3.0 Buildings and building improvements 137.1 135.0 Computer hardware 4.7 5.3 Machinery and equipment 677.7 652.6 Mining reserves 65.3 65.3 Total 888.1 861.5 Less accumulated depreciation, depletion and amortization (667.7 ) (644.7 ) Total net book value 220.4 216.8 Construction in progress 46.3 32.5 Total property, plant, and equipment, net $ 266.7 $ 249.3

OTHER NON-CURRENT ASSETS (Table

OTHER NON-CURRENT ASSETS (Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Noncurrent Assets	Other non-current assets consisted of the following as of December 31: (In millions) 2018 2017 Stores inventory, non-current $ 19.4 $ 18.6 Internal-use software 6.2 — Deferred financing costs and other 0.8 1.0 Total $ 26.4 $ 19.6

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following as of December 31: (In millions) 2018 2017 Accrued capital expenditures $ 13.0 $ 1.0 Accrued energy costs 6.6 5.2 Accrued royalty costs 6.5 4.5 Accrued employee compensation & benefits 7.5 6.8 Accrued other taxes 4.7 4.8 Accrued derivatives 1.9 1.9 Other accruals 4.2 3.5 Total $ 44.4 $ 27.7

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Components of Long-term Debt	Long-term debt consisted of the following as of December 31: (In millions) 2018 2017 Variable Rate Demand Revenue Bonds, principal due October 1, 2018, interest payable monthly, bearing an interest rate of 1.82% at December 31, 2017 $ — $ 11.4 Ciner Wyoming Credit Facility, unsecured principal expiring on August 1, 2022, variable interest rate as a weighted average rate of 3.99% at December 31, 2018 and 3.08% at December 31, 2017 99.0 138.0 Total Debt 99.0 $ 149.4 Current portion of long-term debt — 11.4 Total long-term debt $ 99.0 $ 138.0
Aggregate Maturities on Long-term Debt	Aggregate maturities required on long-term debt at December 31, 2018 are due in future years as follows: Amount 2019 $ — 2020 — 2021 — 2022 99.0 2023 — Thereafter — Total $ 99.0

OTHER NON-CURRENT LIABILITIES (

OTHER NON-CURRENT LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Reclamation Reserve	Other non-current liabilities consisted of the following as of December 31: (In millions) 2018 2017 Reclamation reserve $ 5.4 $ 5.1 Derivative instruments and hedges, fair value liabilities 5.5 5.3 Total $ 10.9 $ 10.4 A reconciliation of the Partnership’s reclamation reserve liability is as follows: (In millions) 2018 2017 Reclamation reserve balance at beginning of year $ 5.1 $ 5.5 Accretion expense 0.3 0.3 Reclamation adjustments (1) $ — $ (0.7 ) Reclamation reserve balance at end of year $ 5.4 $ 5.1 (1) The reclamation adjustments are primarily a result of changes in the self-bond agreement with the Wyoming Department of Environmental Quality. See Note 14 “Commitments and Contingencies” for additional information on our reclamation reserve.

EQUITY - BASED COMPENSATION (Ta

EQUITY - BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Compensation, Restricted Unit Award Activity	The following table presents a summary of activity on the Time Restricted Unit Awards for the years ended December 31: 2018 2017 (Units in whole numbers) Number of Units Grant-Date Average Fair Value per Unit (1) Number of Units Grant-Date Average Fair Value per Unit (1) Unvested at the beginning of year 94,791 $ 27.22 39,170 $ 22.50 Granted (1) 37,914 26.13 80,370 28.41 Vested (42,989 ) 25.73 (13,055 ) 22.50 Forfeited (18,280 ) 27.12 (11,694 ) 24.90 Unvested at the end of the year 71,436 $ 27.56 94,791 $ 27.22 (1) Determined by dividing the aggregate grant date fair value of awards by the number of awards issued. No estimated forfeiture rate was applied to the awards as of December 31, 2018 as all awards granted are expected to vest.
Schedule of Nonvested Unit Activity	The following table presents a summary of activity on the TR Performance Unit Awards for the years ended December 31: 2018 2017 (Units in whole numbers) Number of Units Grant-Date Average Fair Value per Unit (1) Number of Units Grant-Date Average Fair Value per Unit (1) Unvested at the beginning of year 26,177 $ 42.93 5,787 $ 43.93 Granted 33,994 41.52 22,849 42.73 Forfeited (7,197 ) 41.53 (2,459 ) 43.47 Unvested at the end of the year 52,974 $ 42.22 26,177 $ 42.93 (1) Determined by dividing the aggregate grant date fair value of awards by the number of awards issued.
Schedule of Unrecognized Compensation Expense for Unvested Awards	A summary of the Partnership’s unrecognized compensation expense for its unvested restricted time and performance based units, and the weighted-average periods over which the compensation expense is expected to be recognized are as following: Year Ended Year Ended Unrecognized Compensation Expense (In millions) Weighted Average to be Recognized (In years) Unrecognized Compensation Expense (In millions) Weighted Average to be Recognized (In years) Time-based units $ 1.3 1.60 $ 1.7 2.03 Performance-based units 1.2 1.78 0.8 1.88 Total $ 2.5 $ 2.5

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	Amounts recorded in accumulated other comprehensive loss as of December 31, 2018 , 2017 and 2016 , and changes within the period, consisted of the following: Gains and Losses on Cash Flow Hedges (In millions) Balance at January 1, 2016 $ (2.1 ) Other comprehensive loss before reclassification (0.5 ) Amounts reclassified from accumulated other comprehensive loss $ 1.0 Net current-period other comprehensive income 0.5 Balance at December 31, 2016 $ (1.6 ) Other comprehensive loss before reclassification (2.8 ) Amounts reclassified from accumulated other comprehensive loss 0.7 Net current-period other comprehensive loss (2.1 ) Balance at December 31, 2017 $ (3.7 ) Other comprehensive loss before reclassification (0.6 ) Amounts reclassified from accumulated other comprehensive loss 0.5 Net current period other comprehensive loss (0.1 ) Balance at December 31, 2018 $ (3.8 )
Components of Other Comprehensive Income/(Loss)	The components of other comprehensive income/(loss) consisted of the following for the years ended December 31: (In millions) 2018 2017 2016 Unrealized gain/(loss) on derivatives: Mark to market adjustment on interest rate swap contracts $ (0.2 ) $ 0.4 $ 0.4 Mark to market adjustment on natural gas forward contracts — (4.4 ) 0.5 Income/(loss) on derivative financial instruments $ (0.2 ) $ (4.0 ) $ 0.9
Reclassification out of Accumulated Other Comprehensive Income	The components of other comprehensive income/(loss), attributable to Ciner Resources LP, that have been reclassified consisted of the following for the years ended December 31: (In millions) 2018 2017 2016 Affected Line Items on the Consolidated Statements of Operations and Comprehensive Income Details about other comprehensive income/(loss) components: Gains and losses on cash flow hedges: Interest rate swap contracts $ — $ 0.2 $ 0.4 Interest expense Natural gas forward contracts $ 0.5 $ 0.5 $ 0.6 Cost of products sold Total reclassifications for the period $ 0.5 $ 0.7 $ 1.0

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contractual Minimum Commitments Under Operating Leases	As of December 31, 2018 , the total minimum contractual rental commitments under the Partnership’s various operating leases, including renewal periods, are as follows: (In millions) Leased Land Track Leases Total Minimum Lease Payments 2019 0.10 0.10 0.20 2020 0.10 0.10 0.20 2021 0.10 0.03 0.13 2022 0.10 — 0.10 2023 0.10 — 0.10 Thereafter 1.30 — 1.30 Total $ 1.8 $ 0.2 $ 2.0

AGREEMENTS AND TRANSACTIONS W_2

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES (Tables)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Costs Charged by Affiliates
Related Party Transaction [Line Items]
Schedule of Transactions with Affiliates	The total selling, general and administrative costs charged to the Partnership by affiliates were as follows: Years Ended December 31, (In millions) 2018 2017 2016 Ciner Corp 14.6 14.5 14.9 ANSAC (1) 3.0 2.4 3.8 Total selling, general and administrative expenses - affiliates $ 17.6 $ 16.9 $ 18.7 (1) ANSAC allocates its expenses to its members using a pro rata calculation based on sales.
Net Sales to Affiliates
Related Party Transaction [Line Items]
Schedule of Transactions with Affiliates	Net sales to affiliates were as follows: Years Ended December 31, (In millions) 2018 2017 2016 ANSAC $ 253.3 $ 222.2 $ 262.2 CIDT — 82.3 9.0 Total $ 253.3 $ 304.5 $ 271.2
Receivables and Payables with Affiliates
Related Party Transaction [Line Items]
Schedule of Transactions with Affiliates		The Partnership had accounts receivable from affiliates and due to affiliates as follows: As of December 31, (In millions) 2018 2017 2018 2017 Accounts receivable from affiliates Due to affiliates ANSAC 48.7 57.7 $ 0.7 $ 1.3 CIDT 7.1 32.9 — — Ciner Resources Corporation 14.3 7.7 1.9 1.7 Total $ 70.1 $ 98.3 $ 2.6 $ 3.0

MAJOR CUSTOMERS AND SEGMENT R_2

MAJOR CUSTOMERS AND SEGMENT REPORTING (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Sales By Geographic Area	The net sales by geographic area consisted of the following: Years Ended December 31, (In millions) 2018 2017 2016 Domestic $ 233.4 $ 192.8 $ 192.6 International ANSAC 253.3 222.2 262.2 CIDT — 82.3 9.0 Other — — 11.4 Total international 253.3 304.5 282.6 Total net sales $ 486.7 $ 497.3 $ 475.2

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Derivative Assets and Liability Derivatives	The following table presents the fair value of derivative assets and liability derivatives and the respective locations on our consolidated balance sheets as of December 31, 2018 and December 31, 2017 : Assets Liabilities 2018 2017 2018 2017 (In millions) Balance Sheet Location Fair Value Balance Sheet Location Fair Value Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedges: Interest rate swap contracts - current $ — $ — Accrued Expenses $ 0.3 Accrued Expenses $ — Natural gas forward contracts - current Other Current Assets — — Accrued Expenses 1.6 Accrued Expenses 1.9 Natural gas forward contracts - non-current — — Other non-current liabilities 5.5 Other non-current liabilities 5.3 Total fair value of derivatives designated as hedging instruments $ — $ — $ 7.4 $ 7.2

GENERAL (Details)

GENERAL (Details)	Feb. 22, 2018	Dec. 31, 2018
Ciner Wyoming LLC | Ciner Resources LP
Variable Interest Entity [Line Items]
Membership interest		51.00%
Ciner Wyoming
Variable Interest Entity [Line Items]
Membership interest attributable to noncontrolling interest		49.00%
Ciner Wyoming | NRP Trona LLC
Variable Interest Entity [Line Items]
Membership interest attributable to noncontrolling interest		49.00%
Ciner Enterprises | KEW Soda
Variable Interest Entity [Line Items]
Percentage of general partner ownership interest held	100.00%
WE Soda | KEW Soda
Variable Interest Entity [Line Items]
Percentage of general partner ownership interest held	100.00%

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 1996
Land and land improvements
Corporate structure and ownership
Useful Life		10 years
Depletable land | Minimum
Corporate structure and ownership
Useful Life		15 years
Depletable land | Maximum
Corporate structure and ownership
Useful Life		60 years
Buildings and building improvements | Minimum
Corporate structure and ownership
Useful Life		10 years
Buildings and building improvements | Maximum
Corporate structure and ownership
Useful Life		30 years
Computer hardware | Minimum
Corporate structure and ownership
Useful Life		3 years
Computer hardware | Maximum
Corporate structure and ownership
Useful Life		5 years
Machinery and equipment | Minimum
Corporate structure and ownership
Useful Life		5 years
Machinery and equipment | Maximum
Corporate structure and ownership
Useful Life		20 years
Furniture and fixtures
Corporate structure and ownership
Useful Life		10 years
Mining reserves | Asset Retirement Obligation
Corporate structure and ownership
Useful Life		60 years	66 years	67 years	80 years
Mining reserves | Asset Retirement Obligation | Forecast
Corporate structure and ownership
Useful Life	59 years
Leased Land | Asset Retirement Obligation
Corporate structure and ownership
Useful Life		30 years
Measurement Input, Risk Free Interest Rate [Member] | Asset Retirement Obligation
Corporate structure and ownership
Credit-adjusted, risk-free interest rate		0.06
Measurement Input, Risk Free Interest Rate [Member] | Leased Land | Asset Retirement Obligation
Corporate structure and ownership
Credit-adjusted, risk-free interest rate		0.0425
Ciner Wyoming
Corporate structure and ownership
Membership interest attributable to noncontrolling interest		49.00%
Ciner Wyoming LLC | Natural Resource Partners LP
Corporate structure and ownership
Percentage of general partner ownership interest held		39.37%
Percentage of limited partner ownership interest held		9.63%

NET INCOME PER UNIT AND CASH _3

NET INCOME PER UNIT AND CASH DISTRIBUTION - Narrative (Details) - $ / shares	Feb. 28, 2019	Jan. 31, 2019	Nov. 14, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Partners' capital units converted (in shares)			9,775,500
End of subordination period converted units				1
Distributions declared per unit for the period (dollars per share)				$ 2.268	$ 2.2680	$ 2.2650
General Partner
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Percentage of general partner ownership interest held				2.00%
Second Target Distribution | General Partner
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Increasing percentage allocation of operating surplus				13.00%
Third Target Distribution | General Partner
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Increasing percentage allocation of operating surplus				23.00%
Thereafter | General Partner
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Increasing percentage allocation of operating surplus				48.00%
Subsequent Event
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Distributions declared per unit for the period (dollars per share)	$ 0.5670	$ 0.5670

NET INCOME PER UNIT AND CASH _4

NET INCOME PER UNIT AND CASH DISTRIBUTION - Calculation of net income per unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Ciner Resources LP	$ 49.9	$ 41.6	$ 41.4
Less: General partner’s interest in net income	1	0.8	0.8
Limited partners’ interest in net income	$ 48.9	$ 40.8	$ 40.6
Weighted average limited partner units outstanding:
Total weighted average limited partner units outstanding (basic) (in shares)	19.7	19.6	19.6
Total weighted average limited partner units outstanding (diluted) (in shares)	19.7	19.7	19.6
Net income per limited partner unit:
Net income per limited partner unit (basic) (in dollars per share)	$ 2.48	$ 2.08	$ 2.08
Net income per limited partner units (diluted) (in dollars per share)	$ 2.48	$ 2.07	$ 2.08
Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Limited partners’ interest in net income	$ 48.9	$ 40.8	$ 25.2
Weighted average limited partner units outstanding:
Total weighted average limited partner units outstanding (basic) (in shares)	19.7	19.6	12.3
Total weighted average limited partner units outstanding (diluted) (in shares)	19.7	19.7	12.3
Net income per limited partner unit:
Net income per limited partner unit (basic) (in dollars per share)	$ 2.48	$ 2.08	$ 2.06
Net income per limited partner units (diluted) (in dollars per share)	$ 2.48	$ 2.07	$ 2.06
Subordinated Unitholders
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Limited partners’ interest in net income	$ 0	$ 0	$ 15.4
Weighted average limited partner units outstanding:
Total weighted average limited partner units outstanding (basic) (in shares)	0	0	7.3
Total weighted average limited partner units outstanding (diluted) (in shares)	0	0	7.3
Net income per limited partner unit:
Net income per limited partner unit (basic) (in dollars per share)	$ 0	$ 0	$ 2.11
Net income per limited partner units (diluted) (in dollars per share)	$ 0	$ 0	$ 2.11

NET INCOME PER UNIT AND CASH _5

NET INCOME PER UNIT AND CASH DISTRIBUTION - Allocation of Net Income (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Common unitholders’ interest in net income	$ 48.9	$ 40.8	$ 40.6
Distributions declared per unit for the year (in dollars per share)	$ 2.268	$ 2.2680	$ 2.2650
Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distributions	$ 44.6	$ 44.5	$ 27.9
(Distributions in excess of net income)/undistributed earnings	4.3	(3.7)	(2.7)
Common unitholders’ interest in net income	48.9	40.8	25.2
Subordinated Unitholders
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distributions	0	0	16.6
(Distributions in excess of net income)/undistributed earnings	0	0	(1.2)
Common unitholders’ interest in net income	$ 0	$ 0	$ 15.4

NET INCOME PER UNIT AND CASH _6

NET INCOME PER UNIT AND CASH DISTRIBUTION - Target distributions and marginal percentage interests (Details)	12 Months Ended
	Dec. 31, 2018$ / shares
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum Quarterly Distribution	$ 0.5000
Minimum Quarterly Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Maximum Quarterly Distribution	0.5000
First Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum Quarterly Distribution	0.5000
Maximum Quarterly Distribution	0.5750
Second Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum Quarterly Distribution	0.5750
Maximum Quarterly Distribution	0.6250
Third Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum Quarterly Distribution	0.6250
Maximum Quarterly Distribution	0.7500
Thereafter
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum Quarterly Distribution	$ 0.7500
Unitholders | Minimum Quarterly Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	98.00%
Unitholders | First Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	98.00%
Unitholders | Second Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	85.00%
Unitholders | Third Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	75.00%
Unitholders | Thereafter
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	50.00%
General Partner | Minimum Quarterly Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	2.00%
General Partner | First Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	2.00%
General Partner | Second Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	15.00%
General Partner | Third Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	25.00%
General Partner | Thereafter
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Marginal Interest in Distributions	50.00%

ACCOUNTS RECEIVABLE, NET (Detai

ACCOUNTS RECEIVABLE, NET (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade receivables	$ 31	$ 27.5
Other receivables	5.9	6.7
Accounts receivable, net	$ 36.9	$ 34.2

INVENTORY (Details)

INVENTORY (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 10.9	$ 10.1
Finished goods	5.1	3.2
Stores inventory, current	6.3	6.5
Total	$ 22.3	$ 19.8

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 888.1	$ 861.5
Less accumulated depreciation, depletion and amortization	(667.7)	(644.7)
Total net book value	220.4	216.8
Total property, plant, and equipment, net	266.7	249.3
Depreciation, depletion and amortization expense	28.4	27.1	$ 26.1
Land and land improvements
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	0.3	0.3
Depletable land
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	3	3
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	137.1	135
Computer hardware
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	4.7	5.3
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	677.7	652.6
Mining reserves
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	65.3	65.3
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment, net	$ 46.3	$ 32.5

OTHER NON-CURRENT ASSETS (Detai

OTHER NON-CURRENT ASSETS (Details) - USD ($)	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Stores inventory, non-current		$ 19,400,000	$ 18,600,000
Internal-use software		6,200,000	0
Deferred financing costs and other		800,000	1,000,000
Total		26,400,000	$ 19,600,000
Property, Plant and Equipment [Line Items]
Amortization of software development costs		$ 0
Forecast
Property, Plant and Equipment [Line Items]
Amortization of software development costs	$ 600,000
Minimum | Software development costs
Property, Plant and Equipment [Line Items]
Useful Life	5 years
Maximum | Software development costs
Property, Plant and Equipment [Line Items]
Useful Life	10 years

ACCRUED EXPENSES (Details)

ACCRUED EXPENSES (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued capital expenditures	$ 13	$ 1
Accrued energy costs	6.6	5.2
Accrued royalty costs	6.5	4.5
Accrued employee compensation & benefits	7.5	6.8
Accrued other taxes	4.7	4.8
Accrued derivatives	1.9	1.9
Other accruals	4.2	3.5
Total	$ 44.4	$ 27.7

DEBT - Components of Long-term

DEBT - Components of Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt
Total Debt	$ 99	$ 149.4
Current portion of long-term debt	0	11.4
Total long-term debt	$ 99	$ 138
Variable Rate Demand Revenue Bonds
Debt
Interest rate (as a percent)	0.00%	1.82%
Total Debt	$ 0	$ 11.4
Line of Credit | Ciner Wyoming Credit Facility | Revolving credit facility
Debt
Interest rate (as a percent)	3.99%	3.08%
Total Debt	$ 99	$ 138

DEBT - Maturities of Long-term

DEBT - Maturities of Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2,019	$ 0
2,020	0
2,021	0
2,022	99
2,023	0
Thereafter	0
Total Debt	$ 99	$ 149.4

DEBT - Narrative (Details)

DEBT - Narrative (Details)	Oct. 01, 2018USD ($)	Aug. 01, 2017USD ($)
Variable Rate Demand Revenue Bonds
Line of Credit Facility [Line Items]
Extinguishment of debt	$ 11,400,000
Ciner Wyoming Credit Facility | Line of Credit | Ciner Wyoming LLC | Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 225,000,000
Line of credit facility, additional borrowing capacity		$ 75,000,000
Maximum leverage ratio		3
Interest coverage ratio		3
Ciner Wyoming Credit Facility | Line of Credit | Ciner Wyoming LLC | Same Day Swing Line Advances | Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit facility, sublimit		$ 20,000,000
Ciner Wyoming Credit Facility | Line of Credit | Ciner Wyoming LLC | Letters of Credit | Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit facility, sublimit		$ 40,000,000
Ciner Wyoming Credit Facility | Line of Credit | Ciner Wyoming LLC | Minimum | Revolving credit facility
Line of Credit Facility [Line Items]
Unused line fee		0.225%
Ciner Wyoming Credit Facility | Line of Credit | Ciner Wyoming LLC | Maximum | Revolving credit facility
Line of Credit Facility [Line Items]
Unused line fee		0.30%
Ciner Wyoming Credit Facility | Line of Credit | Ciner Resources LP | Revolving credit facility
Line of Credit Facility [Line Items]
Debt covenant, minimum economic interest		50.10%
Ciner Resources Credit Facility | Line of Credit | Ciner Resources LP | Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 10,000,000
Maximum leverage ratio		3
Debt covenant, minimum economic interest		50.10%
Ciner Resources Credit Facility | Line of Credit | Ciner Resources LP | Same Day Swing Line Advances | Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit facility, sublimit		$ 5,000,000
Ciner Resources Credit Facility | Line of Credit | Ciner Resources LP | Letters of Credit | Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit facility, sublimit		$ 5,000,000
Ciner Resources Credit Facility | Line of Credit | Ciner Resources LP | Minimum | Revolving credit facility
Line of Credit Facility [Line Items]
Unused line fee		0.225%
Ciner Resources Credit Facility | Line of Credit | Ciner Resources LP | Maximum | Revolving credit facility
Line of Credit Facility [Line Items]
Unused line fee		0.30%
Federal Funds rate | Ciner Wyoming Credit Facility | Line of Credit | Ciner Wyoming LLC | Revolving credit facility
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.50%
Federal Funds rate | Ciner Resources Credit Facility | Line of Credit | Ciner Resources LP | Revolving credit facility
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.50%
LIBOR | Ciner Wyoming Credit Facility | Line of Credit | Ciner Wyoming LLC | Revolving credit facility
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%
LIBOR | Ciner Resources Credit Facility | Line of Credit | Ciner Resources LP | Revolving credit facility
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%

OTHER NON-CURRENT LIABILITIES_2

OTHER NON-CURRENT LIABILITIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligation Disclosure [Abstract]
Reclamation reserve	$ 5.1	$ 5.5	$ 5.4	$ 5.1
Derivative instruments and hedges, fair value liabilities			5.5	5.3
Total			$ 10.9	$ 10.4
Reclamation reserve
Reclamation reserve balance at beginning of year	5.1	5.5
Accretion expense	0.3	0.3
Reclamation adjustments	0	(0.7)
Reclamation reserve balance at end of year	$ 5.4	$ 5.1

EMPLOYEE COMPENSATION (Details)

EMPLOYEE COMPENSATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Average compensation period	60 months
Period of last service	120 months
Pension
Defined Benefit Plan Disclosure [Line Items]
Net funded liability	$ 56.9	$ 57.4
Net periodic pension (benefit) cost	0.4	1.4	$ 2
Savings Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions by Ciner Corp	2.8	3.7	1.6
Postretirement benefit
Defined Benefit Plan Disclosure [Line Items]
Net funded liability	9.9	11.5
Net periodic pension (benefit) cost	$ (2.9)	$ (2.8)	$ 1.4

EQUITY - BASED COMPENSATION - N

EQUITY - BASED COMPENSATION - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	700,000
Units granted	6,807	7,887
Director - non employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested, grant date average fair value per unit (in dollars per share)	$ 27.55	$ 28.53
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested, grant date average fair value per unit (in dollars per share)	$ 25.73	$ 22.50
Restricted Stock Units (RSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Restricted Stock Units (RSUs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
TSR Unit Performance Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Payout range	0.00%
TSR Unit Performance Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Payout range	200.00%
Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation plan activity	$ 0.2	$ 0.2

EQUITY - BASED COMPENSATION - R

EQUITY - BASED COMPENSATION - Restricted Unit Award and Total Return Performance Unit Award Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restricted Stock Units (RSUs)
Number of Units
Unvested beginning of period (in shares)	94,791	39,170
Granted (in shares)	37,914	80,370
Vested (in shares)	(42,989)	(13,055)
Forfeited (in shares)	(18,280)	(11,694)
Unvested at end of period (in shares)	71,436	94,791
Grant-Date Average Fair Value per Unit
Nonvested at beginning of period, grant-date average fair value per unit (in dollars per share)	$ 27.22	$ 22.50
Granted, grant-date average fair value per unit (in dollars per share)	26.13	28.41
Vested, grant date average fair value per unit (in dollars per share)	25.73	22.50
Forfeited, grant date average fair value per unit (in dollars per share)	27.12	24.90
Nonvested at end of period, grant-date average fair value per unit (in dollars per share)	$ 27.56	$ 27.22
TSR Unit Performance Awards
Number of Units
Unvested beginning of period (in shares)	26,177	5,787
Granted (in shares)	33,994	22,849
Forfeited (in shares)	(7,197)	(2,459)
Unvested at end of period (in shares)	52,974	26,177
Grant-Date Average Fair Value per Unit
Nonvested at beginning of period, grant-date average fair value per unit (in dollars per share)	$ 42.93	$ 43.93
Granted, grant-date average fair value per unit (in dollars per share)	41.52	42.73
Forfeited, grant date average fair value per unit (in dollars per share)	41.53	43.47
Nonvested at end of period, grant-date average fair value per unit (in dollars per share)	$ 42.22	$ 42.93

EQUITY - BASED COMPENSATION - U

EQUITY - BASED COMPENSATION - Unrecognized Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized Compensation Expense	$ 2.5	$ 2.5
Time-based units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized Compensation Expense	$ 1.3	$ 1.7
Weighted Average to be Recognized	1 year 7 months 7 days	1 year 12 months 10 days
Performance-based units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized Compensation Expense	$ 1.2	$ 0.8
Weighted Average to be Recognized	1 year 9 months 11 days	1 year 10 months 16 days

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE LOSS - Amounts Recorded in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 248.2	$ 259.2	$ 263.2
Amounts reclassified from accumulated other comprehensive loss	(0.5)	(0.7)	(1)
Ending balance	260.1	248.2	259.2
Gains and Losses on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3.7)	(1.6)	(2.1)
Other comprehensive loss before reclassification	(0.6)	(2.8)	(0.5)
Amounts reclassified from accumulated other comprehensive loss	0.5	0.7	1
Net current-period other comprehensive income	(0.1)	(2.1)	0.5
Ending balance	$ (3.8)	$ (3.7)	$ (1.6)

ACCUMULATED OTHER COMPREHENSI_4

ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized gain (loss) on derivative financial instruments	$ (0.2)	$ (4)	$ 0.9
Interest rate swap contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized gain (loss) on derivative financial instruments	(0.2)	0.4	0.4
Commodity contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized gain (loss) on derivative financial instruments	$ 0	$ (4.4)	$ 0.5

ACCUMULATED OTHER COMPREHENSI_5

ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of Other Comprehensive Income/(Loss) Reclassified (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 5.1	$ 4.6	$ 3.6
Total reclassifications for the period	0.5	0.7	1
Gains and Losses on Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period	(0.5)	(0.7)	(1)
Interest rate swap contracts | Gains and Losses on Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	0	0.2	0.4
Commodity contracts | Gains and Losses on Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of products sold	$ 0.5	$ 0.5	$ 0.6

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details) $ in Thousands	Jun. 28, 2018USD ($)	Jan. 03, 2017USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)track_lease_agreement	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Other Commitments [Line Items]
2,019				$ 200
2,020				200
2,021				130
2,022				100
2,023				100
2024 and thereafter				1,300
Lease expense				13,900	$ 14,600	$ 14,500
Purchase Obligation, Fiscal Year Maturity [Abstract]
Average annual cost				3,800
Self-bond agreement for reclamation costs
Purchase Obligation, Fiscal Year Maturity [Abstract]
Off balance sheet commitment				$ 32,900	$ 32,900
Watco Companies, LLC
Other Commitments [Line Items]
Leases term				10 years
Rock Springs Grazing Association
Other Commitments [Line Items]
Renewal term				5 years
Total renewal term				30 years
Union Pacific Company
Other Commitments [Line Items]
Leases term				10 years
Number of track lease agreements | track_lease_agreement				2
Commodity
Other Commitments [Line Items]
Leases term				5 years
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation				$ 56,000
Purchase obligation, due in 2019				21,300
Purchase obligation, due in 2020				15,800
Purchase obligation, due in 2021				10,000
Purchase obligation, due in 2022				5,000
Purchase obligation, due in 2023				3,900
Rail Car Lease
Other Commitments [Line Items]
2,019				11,100
2,020				8,500
2,021				6,000
2,022				3,800
2,023				1,400
2024 and thereafter				$ 4,700
Minimum
Other Commitments [Line Items]
Leases term				1 year
Maximum
Other Commitments [Line Items]
Leases term				10 years
Ciner Wyoming vs. Rock Springs Royalty Company
Purchase Obligation, Fiscal Year Maturity [Abstract]
Royalty overpayments		$ 32,000
Litigation settlement receivable	$ 27,500
Royalty rate	8.00%
Settlement payment			$ 27,500

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Commitments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Other Commitments [Line Items]
2,019	$ 200
2,020	200
2,021	130
2,022	100
2,023	100
2024 and thereafter	1,300
Total	2,000
Leased Land
Other Commitments [Line Items]
2,019	100
2,020	100
2,021	100
2,022	100
2,023	100
2024 and thereafter	1,300
Total	1,800
Track Leases
Other Commitments [Line Items]
2,019	100
2,020	100
2,021	30
2,022	0
2,023	0
2024 and thereafter	0
Total	$ 200

AGREEMENTS AND TRANSACTIONS W_3

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES - Costs Charged by Affiliates (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Total selling, general and administrative expenses - affiliates	$ 17,600,000	$ 16,900,000	$ 18,700,000
Ciner Resources Corporation
Related Party Transaction [Line Items]
Total selling, general and administrative expenses - affiliates	14,600,000	14,500,000	14,900,000
ANSAC
Related Party Transaction [Line Items]
Total selling, general and administrative expenses - affiliates	3,000,000	2,400,000	3,800,000
CIDT
Related Party Transaction [Line Items]
Sales	0
Shipping and handling | ANSAC
Related Party Transaction [Line Items]
Cost of products sold	$ 0	$ 19,800,000	$ 3,300,000

AGREEMENTS AND TRANSACTIONS W_4

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES - Net Sales to Affiliates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Sales - affiliates	$ 253.3	$ 304.5	$ 271.2
ANSAC
Related Party Transaction [Line Items]
Sales - affiliates	253.3	222.2	262.2
CIDT
Related Party Transaction [Line Items]
Sales - affiliates	$ 0	$ 82.3	$ 9

AGREEMENTS AND TRANSACTIONS W_5

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES - Receivables From or Payables to Affiliates (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Accounts receivable from affiliates	$ 70.1	$ 98.3
Due to affiliates	2.6	3
ANSAC
Related Party Transaction [Line Items]
Accounts receivable from affiliates	48.7	57.7
Due to affiliates	0.7	1.3
CIDT
Related Party Transaction [Line Items]
Accounts receivable from affiliates	7.1	32.9
Due to affiliates	0	0
Ciner Resources Corporation
Related Party Transaction [Line Items]
Accounts receivable from affiliates	14.3	7.7
Due to affiliates	$ 1.9	$ 1.7

MAJOR CUSTOMERS AND SEGMENT R_3

MAJOR CUSTOMERS AND SEGMENT REPORTING - Sales by geographic area (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Sales by geographical area
Net sales	$ 486.7	$ 497.3	$ 475.2
Domestic
Sales by geographical area
Net sales	233.4	192.8	192.6
International
Sales by geographical area
Net sales	253.3	304.5	282.6
International | ANSAC
Sales by geographical area
Net sales	253.3	222.2	262.2
International | CIDT
Sales by geographical area
Net sales	0	82.3	9
Other | International
Sales by geographical area
Net sales	$ 0	$ 0	$ 11.4

MAJOR CUSTOMERS AND SEGMENT R_4

MAJOR CUSTOMERS AND SEGMENT REPORTING - Narrative (Details)	12 Months Ended
	Dec. 31, 2018segment
Segment Reporting [Abstract]
Number of operating segments	1

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details)	Dec. 31, 2018USD ($)swap	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of swap contracts | swap	4
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total derivatives designated as hedging instruments	$ 0	$ 0
Total derivatives designated as hedging instruments	7,400,000	7,200,000
Fair Value, Measurements, Recurring | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative aggregate notional value		70,000,000
Fair Value, Measurements, Recurring | Natural gas forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative aggregate notional value	41,200,000	37,000,000
Other Current Assets | Fair Value, Measurements, Recurring | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, current		0	$ 0
Other Current Assets | Fair Value, Measurements, Recurring | Natural gas forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, current	0	0
Accrued Expenses | Fair Value, Measurements, Recurring | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, current	300,000	0
Accrued Expenses | Fair Value, Measurements, Recurring | Natural gas forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, current	1,600,000	1,900,000
Other non-current liabilities | Fair Value, Measurements, Recurring | Natural gas forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, noncurrent	5,500,000	$ 5,300,000
Designated as Hedging Instrument | Cash Flow Hedging | Fair Value, Measurements, Recurring | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	12,500,000
Derivative aggregate notional value	$ 50,000,000

REVENUE (Details)

REVENUE (Details)	12 Months Ended
	Dec. 31, 2018USD ($)segment
Revenue from Contract with Customer [Abstract]
Number of reportable segments | segment	1
Contract assets	$ 0
Contract liabilities	$ 0

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 28, 2019	Feb. 14, 2019	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Distributions declared per unit for the period (dollars per share)				$ 2.268	$ 2.2680	$ 2.2650
Subsequent Event
Subsequent Event [Line Items]
Aggregate amount of cash distribution		$ 20
Distributions declared per unit for the period (dollars per share)	$ 0.5670		$ 0.5670