Sisecam Resources (SIRE) 10-K 16 Mar 21 2020 FY Annual report Financial data

Cover

Cover - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Mar. 10, 2021	Jun. 30, 2020
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-36062
Entity Registrant Name	CINER RESOURCES LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-2613366
Entity Address, Address Line One	Five Concourse Parkway
Entity Address, Address Line Two	Suite 2500
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30328
City Area Code	770
Local Phone Number	375-2300
Title of 12(b) Security	Common units representing limited partnership interests
Trading Symbol	CINR
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 65.8
Documents Incorporated by Reference	Documents Incorporated by Reference: None
Entity Central Index Key	0001575051
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Common Units
Document and Entity Information
Entity Common Stock, Shares Outstanding		19,765,781
General Partner
Document and Entity Information
Entity Common Stock, Shares Outstanding		399,000

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 0.5	$ 14.9
Accounts receivable-affiliates	86.5	95
Accounts receivable, net	40.6	36
Inventory	33.5	24.2
Other current assets	4.1	2.2
Total current assets	165.2	172.3
Property, plant and equipment, net	307.4	297.7
Other non-current assets	25.4	24.3
Total assets	498	494.3
Current liabilities:
Current portion of long-term debt	3	0
Accounts payable	16.4	14.2
Due to affiliates	2.9	3
Accrued expenses	33.6	39.1
Total current liabilities	55.9	56.3
Long-term debt	128.1	129.5
Other non-current liabilities	8.7	8.6
Total liabilities	192.7	194.4
Commitments and Contingencies (See Note 14)
Equity:
Common unitholders - Public and Ciner Holdings (19.8 and 19.8 units issued and outstanding at December 31, 2020 and 2019)	170	171.4
General partner unitholders - Ciner Resource Partners LLC (0.4 units issued and outstanding at December 31, 2020 and 2019)	4.2	4.3
Accumulated other comprehensive loss	0	(3)
Partners’ capital attributable to Ciner Resources LP	174.2	172.7
Noncontrolling interest	131.1	127.2
Total equity	305.3	299.9
Total liabilities and partners’ equity	$ 498	$ 494.3

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares shares in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common units issued (in shares)	19.8	19.8
Common units outstanding (in shares)	19.8	19.8
General partner units issued (in shares)	0.4	0.4
General partners units outstanding (in shares)	0.4	0.4

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net sales:
Sales - affiliates	$ 177.9	$ 315.8	$ 253.3
Sales - others	214.3	207	233.4
Total net sales	392.2	522.8	486.7
Cost of products sold:
Cost of goods and services sold	185.6	221.4	215.9
Depreciation, depletion and amortization expense	28.8
Total cost of products sold	338.1	391.9	383.4
Gross profit	54.1	130.9	103.3
Operating expenses:
Selling, general and administrative expenses—affiliates	17.5	18.4	17.6
Selling, general and administrative expenses—others	4.2	5.4	6.9
Litigation settlement	0	0	(27.5)
Total operating expenses	21.7	23.8	(3)
Operating income	32.4	107.1	106.3
Other income/(expenses):
Interest income	0.1	0.4	1.9
Interest expense	(5.3)	(5.9)	(5.1)
Other - net	(0.3)	0	(0.1)
Total other expense, net	(5.5)	(5.5)	(3.3)
Net income	26.9	101.6	103
Net income attributable to noncontrolling interest	15.2	52	53.1
Net income attributable to Ciner Resources LP	11.7	49.6	49.9
Other comprehensive income/(loss):
Income (loss) on derivative financial instruments	5.9	1.6
Income (loss) on derivative financial instruments			(0.2)
Comprehensive income	32.8	103.2	102.8
Comprehensive income attributable to noncontrolling interest	18.1	52.7	53
Comprehensive income attributable to Ciner Resources LP	$ 14.7	$ 50.5	$ 49.8
Net income per limited partner unit:
Net income per limited partner unit (basic) (in dollars per share)	$ 0.58	$ 2.46	$ 2.48
Net income per limited partner unit (diluted) (in dollars per share)	$ 0.58	$ 2.46	$ 2.48
Limited partner units outstanding:
Total weighted average limited partner units outstanding (basic) (in shares)	19.7	19.7	19.7
Weighted average limited partner units outstanding (diluted) (in shares)	19.8	19.7	19.7
Cargo and Freight
Cost of products sold:
Cost of goods and services sold	$ 123.7	$ 143.6	$ 139.1

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 26.9	$ 101.6	$ 103
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization expense	29.2	27.1	28.7
Impairment and loss on disposal of assets, net	0	0.6	0
Equity-based compensation expense	0.7	0.8	1.8
Other non-cash items	0.3	0.3	0.3
Changes in operating assets and liabilities:
Accounts receivable - net	(4.6)	0.9	(2.7)
Accounts receivable - affiliates	8.5	(24.9)	28.2
Inventory	(9.8)	(0.4)	(3)
Other current and other non-current assets	(0.5)	0.1	(0.2)
Increase/(decrease) in:
Accounts payable	2.2	(3.1)	2.4
Due to affiliates	(0.1)	0.4	(0.4)
Accrued expenses and other liabilities	1.9	0.4	4.1
Net cash provided by operating activities	54.7	103.8	162.2
Cash flows from investing activities:
Capital expenditures	(42.2)	(65.4)	(39.4)
Net cash used in investing activities	(42.2)	(65.4)	(39.4)
Cash flows from financing activities:
Borrowings on Ciner Wyoming and Ciner Resources credit facilities	212.5	102	104
Borrowings on Ciner Wyoming Equipment Financing Arrangement	30	0	0
Repayments on Ciner Wyoming credit facility	(238.5)	(71.5)	(143)
Repayments on Ciner Wyoming Equipment Financing Arrangement	(2.2)	0	0
Repayments on other long-term debt	0	0	(11.4)
Debt issuance costs	(0.6)	0	0
Common units surrendered for taxes	(0.2)	(0.5)	(0.3)
Distributions to noncontrolling interest	(14.2)	(31.9)	(46.6)
Net cash used in financing activities	(26.9)	(33.7)	(142.8)
Net increase/(decrease) in cash and cash equivalents	(14.4)	4.7	(20)
Cash and cash equivalents at beginning of year	14.9	10.2	30.2
Cash and cash equivalents at end of year	0.5	14.9	10.2
Supplemental disclosure of cash flow information:
Interest paid during the year	5.1	5.5	5.1
Supplemental disclosure of non-cash investing activities:
Capital expenditures on account	2	6.8	14
Common Units
Cash flows from financing activities:
Distributions	(13.4)	(31.2)	(44.6)
General Partner
Cash flows from financing activities:
Distributions	$ (0.3)	$ (0.6)	$ (0.9)

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Partnership unitsCommon Units	Partnership unitsGeneral Partner	Accumulated Other Comprehensive Loss	Partners’ Capital Attributable to Ciner Resources LP Equity	Noncontrolling Interests
Beginning balance at Dec. 31, 2017	$ 248.2	$ 148.3	$ 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 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	3.9	(3.8)	153.9	106.2
Increase (decrease) in shareholders' equity
Net income	101.6	48.6	1		49.6	52
Other comprehensive loss	1.6			0.8	0.8	0.8
Equity-based compensation plan activity	0.3	0.3			0.3
Distributions	(63.7)	(31.3)	(0.6)		(31.9)	(31.8)
Ending balance at Dec. 31, 2019	299.9	171.4	4.3	(3)	172.7	127.2
Increase (decrease) in shareholders' equity
Net income	26.9	11.5	0.2		11.7	15.2
Other comprehensive loss	5.9			3	3	2.9
Equity-based compensation plan activity	0.5	0.5			0.5
Distributions	(27.9)	(13.4)	(0.3)		(13.7)	(14.2)
Ending balance at Dec. 31, 2020	$ 305.3	$ 170	$ 4.2	$ 0	$ 174.2	$ 131.1

GENERAL

GENERAL	12 Months Ended
	Dec. 31, 2020
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., 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 (“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 of our soda ash processed is currently sold to various domestic and international customers, including American Natural Soda Ash Corporation (“ANSAC”), which is an affiliate for export sales. Ciner Corp, which is the exclusive sales agent for the Partnership, also serves as the exclusive sales agent of that material and receives a commission on those sales. Effective as of the end of day on December 31, 2020 Ciner Corp exited ANSAC. As of January 1, 2021, Ciner Corp began managing the sales and marketing efforts for exports with the ANSAC exit being complete. Ciner Corp is leveraging the distributor network established by Ciner Group while independently reviewing current and potential distribution partners to optimize our reach into each market. In connection with the settlement agreement with ANSAC, there are sales commitments to ANSAC in 2021 and 2022 where Ciner Corp will continue to sell, at substantially lower volumes, product to ANSAC for export sales purposes, with a fixed rate per ton selling, general and administrative expense, and will also purchase a limited amount of export logistics services in 2021. Through in part the Partnership’s affiliates, the Partnership has amongst other things: (i) obtained its own international customer sales arrangements for 2021, (ii) obtained third-party export port services, and (iii) chartered and executed its own international product delivery. NRP Trona LLC, a wholly owned subsidiary of Natural Resource Partners L.P. (“NRP”), currently owns a 49.0% membership interest in Ciner Wyoming. NRP’s membership interest in Ciner Wyoming is reflected as the noncontrolling interest in CINR’s financial results. 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 was 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, 2020
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 noncontrolling interest. 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. Furthermore, we considered the impact of the COVID-19 pandemic on the use of estimates and assumptions used for financial reporting. While our production is considered “essential”, the COVID-19 outbreak disrupted our customers and customer segments, which had a negative impact on the demand for our products which adversely affected our operations. At December 31, 2020, as we cannot predict the duration or the scope of the COVID-19 pandemic and its impact on our operations, the potential negative financial impact to our results cannot be reasonably estimated but could be material. As a result of these uncertainties, actual results could differ from those estimates and assumptions. If the economy or markets in which we operate remain weaker than pre-COVID-19 levels or deteriorate further, our business, financial condition and results of operations may be further materially and adversely impacted. Revenue Recognition The majority of the Partnership’s revenues are recognized upon satisfaction of our performance obligations, that is, 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 we ship the product from our production facility or third-party terminals, depending on the terms of the sales contract, rendering our performance obligation fulfilled. For certain international customers, it is the point when the product is loaded on the vessel at the port. Additionally, the Partnership has made an accounting policy election to account for shipping and handling activities as fulfillment costs. 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. Performance Obligations . A performance obligation is a promise in a contract to transfer a distinct good or service to the customer. 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 transferred 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. Revenue 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 generally 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 Sheets as of December 31, 2020 and December 31, 2019. There were no contract assets as of December 31, 2020 and December 31, 2019. • Contract Liabilities. There may be situations where customers are required to prepay for freight and insurance prior to shipment. The Partnership accounts for freight costs as fulfillment activities 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. Freight Costs The Partnership includes freight costs billed to customers for shipments administered by the Partnership in gross sales. The related freight costs incurred by the Partnership 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 On January 1, 2020, we adopted the current expected credit loss (CECL) model in accordance with ASU No. 2016-13, “Financial Instruments-Credit Losses (Topic 326)” as explained at Recently Issued and Adopted Accounting Standards below. We determined the expected credit losses on initial recognition and at December 31, 2020 based on information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. Inventory Inventory is carried at the lower of cost and net realizable value. 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. Net realizable value is defined as the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. • 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. If the inventory has been used within the preceding twelve months, it 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 5-10 years Mineral reserves are amortized over an estimated time period that is derived from total estimated proven and probable mineral reserves divided by our average annual tons mined which was approximately 58 years as of December 31, 2020. 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. When the Partnership has natural gas physical forward contracts, they 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. The liability was discounted using a weighted average credit-adjusted risk-free rate 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 18, “Subsequent Events” for additional information. Recent Accounting Guidance Recently Adopted Accounting Guidance In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments-Credit Losses (Topic 326)” ("ASU 2016-13"). This ASU introduces the current expected credit loss (CECL) model, which will require an entity to measure credit losses for certain financial instruments and financial assets, including trade receivables. Under this update, on initial recognition and at each reporting period, an entity will be required to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument. The Partnership adopted ASU 2016-13 effective January 1, 2020 and concluded there was no material impact to the Partnership’s consolidated financial statements. In August 2018, the FASB issued ASU 2018-15, “Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force)” (“ASU 2018-15”), which amends ASC 350-40 to address a customer’s accounting for implementation costs incurred in a cloud computing arrangement (“CCA”) that is a service contract. ASU 2018-15 amends ASC 350 and clarifies that a customer should apply ASC 350-40 to determine which implementation costs should be capitalized in a CCA. ASU 2018-15 does not expand on existing disclosure requirements except to require a description of the nature of hosting arrangements that are service contracts. Entities are permitted to apply either a retrospective or prospective transition approach to adopt the guidance. ASU 2018-15 is effective for periods beginning after December 15, 2019. The Partnership adopted ASU 2018-15 effective January 1, 2020 and concluded there was no material impact to the Partnership’s consolidated financial statements. Recent Accounting Guidance Not Yet Adopted In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”) providing temporary guidance to ease the potential burden in accounting for reference rate reform primarily resulting from the discontinuation of the London Inter-bank Offered Rate (“LIBOR”), which was expected to occur on December 31, 2021. The amendments in ASU 2020-04 are elective and apply to all entities that have contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued. The new guidance provides the following optional expedients: (i) simplifies accounting analyses under current GAAP for contract modifications; (ii) simplifies the assessment of hedge effectiveness and allows hedging relationships affected by reference rate reform to continue; and (iii) allows a one-time election to sell or transfer debt securities classified as held to maturity that reference a rate affected by reference rate reform. An entity may elect to apply the amendments prospectively from March 12, 2020 through December 31, 2022 by accounting topic. The Partnership continues to evaluate ASU 2020-04 but does not expect a 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, 2020
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 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) 2020 2019 2018 Net income attributable to Ciner Resources LP $ 11.7 $ 49.6 $ 49.9 Less: General partner’s interest in net income 0.2 1.0 1.0 Limited partners’ interest in net income $ 11.5 $ 48.6 $ 48.9 Weighted average limited partner units outstanding: Common - Public and Ciner Holdings (basic) 19.7 19.7 19.7 Total weighted average limited partner units outstanding (basic) 19.7 19.7 19.7 Common - Public and Ciner Holdings (diluted) 19.8 19.7 19.7 Total weighted average limited partner units outstanding (diluted) 19.8 19.7 19.7 Net income per limited partner unit: Common - Public and Ciner Holdings (basic) $ 0.58 $ 2.46 $ 2.48 Net income per limited partner units (basic) $ 0.58 $ 2.46 $ 2.48 Common - Public and Ciner Holdings (diluted) $ 0.58 $ 2.46 $ 2.48 Net income per limited partner units (diluted) $ 0.58 $ 2.46 $ 2.48 The calculation of limited partners’ interest in net income is as follows: Year Ended December 31, (In millions, except per unit data) 2020 2019 2018 Net income attributable to common unitholders: Distributions (1) $ 6.7 $ 26.8 $ 44.6 (Distributions in excess of net income)/undistributed earnings 4.8 21.8 4.3 Common unitholders’ interest in net income $ 11.5 $ 48.6 $ 48.9 (1) Distributions declared per unit for the year 0.340 1.360 2.268 Quarterly Distribution 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 or at any other rate, and we have no legal obligation to do so. In an effort to achieve greater financial and liquidity flexibility during the COVID-19 pandemic, on August 3, 2020, each of the members of the board of managers of Ciner Wyoming approved a suspension of quarterly distributions to its members. In addition, effective August 3, 2020, in connection with the quarterly distribution for the quarter ended June 30, 2020, each of the members of the board of directors of our general partner approved a suspension of quarterly distributions to our unitholders. Each of the board of managers of Ciner Wyoming and the board of directors of our general partner approved the continuation of the suspension of quarterly distributions to the members of Ciner Wyoming and our unitholders, as applicable, for each of the quarters ended September 30, 2020 and December 31, 2020 in a continued effort to achieve greater financial and liquidity flexibility during the COVID-19 pandemic. In March 2021, the board of managers of Ciner Wyoming approved a special $8.0 million distribution to, amongst other things, provide the Partnership with funds to retire the Ciner Resources Credit Facility. (See Note 9) Management and the board of directors of our general partner will continue to evaluate, on a quarterly basis, whether it is appropriate to reinstate a distribution to our unitholders, which will be dependent in part on our cash reserves, liquidity, total debt levels and anticipated capital expenditures. 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, including for the declared quarterly distributions of $0.340 per unit for the first quarter of 2020. Under the Partnership agreement, our general partner has considerable discretion to determine the amount of available cash (as defined therein) for distribution each quarter to the Partnership’s unitholders, including discretion to establish cash reserves that would limit the amount of available cash eligible for distribution to the Partnership’s unitholders for any quarter. The Partnership does not guarantee that it will pay the target amount of the minimum quarterly distribution listed below (or any distributions) on its units in any quarter. 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 that we do not issue additional classes of equity securities. Marginal Percentage Total Quarterly 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, 2020
Receivables [Abstract]
ACCOUNTS RECEIVABLE, NET	ACCOUNTS RECEIVABLE, NET Accounts receivable, net consisted of the following as of December 31: (In millions) 2020 2019 Trade receivables $ 32.6 $ 30.3 Other receivables 8.0 5.7 Total $ 40.6 $ 36.0

INVENTORY

INVENTORY	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
INVENTORY	INVENTORY Inventory consisted of the following as of December 31: (In millions) 2020 2019 Raw materials $ 9.9 $ 8.7 Finished goods 13.4 6.9 Stores inventory, current 10.2 8.6 Total $ 33.5 $ 24.2 The increase in finished goods inventory at December 31, 2020 compared to December 31, 2019 is primarily due to the Partnership building inventory to facilitate Ciner Corp’s exit from ANSAC and Ciner Corp providing the Partnership international sales, marketing and logistics services after December 31, 2020.

PROPERTY, PLANT, AND EQUIPMENT,

PROPERTY, PLANT, AND EQUIPMENT, NET	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT, AND EQUIPMENT, NET	PROPERTY, PLANT, AND EQUIPMENT, NET Property, plant, and equipment, net consisted of the following as of December 31: (In millions) 2020 2019 Land and land improvements $ 0.3 $ 0.3 Depletable land 3.0 3.0 Buildings and building improvements 163.4 137.8 Computer hardware 5.3 4.7 Machinery and equipment 709.8 672.4 Mining reserves 65.3 65.3 Total 947.1 883.5 Less accumulated depreciation, depletion and amortization (679.9) (676.6) Total net book value 267.2 206.9 Construction in progress 40.2 90.8 Total property, plant, and equipment, net $ 307.4 $ 297.7 Depreciation, depletion and amortization expense on property, plant, and equipment was $28.1 million, $26.9 million and $28.4 million for the years ended December 31, 2020, 2019 and 2018, respectively. The decrease in construction in progress from December 31, 2019 to December 31, 2020 is due to the new co-generation facility being constructed in 2019 and beginning operations in March 2020.

OTHER NON-CURRENT ASSETS

OTHER NON-CURRENT ASSETS	12 Months Ended
	Dec. 31, 2020
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) 2020 2019 Stores inventory, non-current $ 18.6 $ 17.6 Internal-use software, net of accumulated amortization 5.7 6.1 Deferred financing costs and other 1.1 0.6 Total $ 25.4 $ 24.3 During the years ended December 31, 2020, 2019 and 2018, in accordance with ASC 350-40, Internal-Use Software, we capitalized $0.5 million, $0.6 million and $6.2 million, respectively, of certain internal use software development costs. 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 five

ACCRUED EXPENSES

ACCRUED EXPENSES	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
ACCRUED EXPENSES	ACCRUED EXPENSES Accrued expenses consisted of the following as of December 31: (In millions) 2020 2019 Accrued capital expenditures $ 1.3 $ 6.2 Accrued energy costs 5.1 5.7 Accrued royalty costs 8.1 7.1 Accrued employee compensation & benefits 7.6 7.1 Accrued other taxes 5.0 4.8 Accrued derivatives 0.9 3.3 Other accruals 5.6 4.9 Total $ 33.6 $ 39.1

DEBT

DEBT	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
DEBT	DEBT Long-term debt consisted of the following as of December 31: (In millions) 2020 2019 Ciner Wyoming Equipment Financing Arrangement with maturity date of March 26, 2028, fixed interest rate of 2.479% $ 27.6 $ — Ciner Wyoming Credit Facility, unsecured principal expiring on August 1, 2022, variable interest rate as a weighted average rate of 2.25% and 3.27% at December 31, 2020 and December 31, 2019, respectively 102.5 129.5 Ciner Resources Credit Facility, unsecured principal expiring on August 1, 2022, variable interest rate as a weighted average rate of 2.25% at December 31, 2020 1.0 — Total Debt 131.1 129.5 Current portion of long-term debt 3.0 — Total long-term debt $ 128.1 $ 129.5 Aggregate maturities required on long-term debt at December 31, 2020 are due in future years as follows: (In millions) Amount 2021 $ 3.0 2022 106.6 2023 3.2 2024 3.3 2025 3.3 Thereafter 11.8 Total $ 131.2 Ciner Wyoming Equipment Financing Arrangement On March 26, 2020, Ciner Wyoming and Banc of America Leasing & Capital, LLC, as lender (the “Equipment Financing Lender”), entered into an equipment financing arrangement (the “Ciner Wyoming Equipment Financing Arrangement”) including a Master Loan and Security Agreement, dated as of March 25, 2020 (as amended, the “Master Agreement”) and an Equipment Security Note Number 001, dated as of March 25, 2020 (the “Initial Secured Note”), which provides the terms and conditions for the debt financing of certain equipment related to Ciner Wyoming’s new natural gas-fired turbine co-generation facility that became operational in March 2020. Each equipment financing under the Ciner Wyoming Equipment Financing Arrangement will be evidenced by the execution of one or more equipment notes (including the Initial Secured Note) that incorporate the terms and conditions of the Master Agreement (each, an “Equipment Note”). In order to secure the payment and performance of Ciner Wyoming’s obligations under the Ciner Wyoming Equipment Financing Arrangement and other debt obligations owed by Ciner Wyoming to the Equipment Financing Lender, Ciner Wyoming granted to the Equipment Financing Lender a continuing security interest in all of Ciner Wyoming’s right, title and interest in and to the Equipment (as defined in the Master Agreement) and certain related collateral. The Ciner Wyoming Equipment Financing Arrangement (1) incorporates all covenants in the Ciner Wyoming Credit Facility (as defined below), now or hereinafter existing, or in any applicable replacement credit facility accepted in writing by the Equipment Financing Lender, that are based upon a specified level or ratio relating to assets, liabilities, indebtedness, rentals, net worth, cash flow, earnings, profitability, or any other accounting-based measurement or test, and (2) includes customary events of default subject to applicable grace periods, including, among others, (i) payment defaults, (ii) certain mergers or changes in control of Ciner Wyoming, (iii) cross defaults with certain other indebtedness (a) to which the Equipment Financing Lender is a party or (b) to third parties in excess of $10 million, and (iv) the commencement of certain insolvency proceedings or related events identified in the Master Agreement. Upon the occurrence of an event of default, in its discretion, the Equipment Financing Lender may exercise certain remedies, including, among others, the ability to accelerate the maturity of any Equipment Note such that all amounts thereunder will become immediately due and payable, to take possession of the Equipment identified in any Equipment Note, and to charge Ciner Wyoming a default rate of interest on all then outstanding or thereafter incurred obligations under the Ciner Wyoming Equipment Financing Arrangement. Among other things, the Initial Secured Note: • has a principal amount of $30,000,000; • has a maturity date of March 26, 2028; • shall be payable by Ciner Wyoming to the Equipment Financing Lender in 96 consecutive monthly installments of principal and interest commencing on April 26, 2020 and continuing thereafter until the maturity date of the Initial Secured Note, which shall be in the amount of approximately $307,000 for the first 95 monthly installments and approximately $4,307,000 for the final monthly installment; and • entitles Ciner Wyoming to prepay all (but not less than all) of the outstanding principal balance of the Initial Secured Note (together with all accrued interest and other charges and amounts owed thereunder) at any time after one (1) year from the date of the Initial Secured Note, subject to Ciner Wyoming paying to the Equipment Financing Lender an additional prepayment amount determined by the amount of principal balance prepaid and the date such prepayment is made. In connection with the Second Ciner Wyoming Amendment (as defined below), the Master Agreement was amended to incorporate, among other things, the modified covenants set forth in the Second Ciner Wyoming Amendment related to consolidated leverage ratios of Ciner Wyoming. Ciner Wyoming’s balance under the Ciner Wyoming Equipment Financing Arrangement at December 31, 2020 was $27.8 million ($27.6 million net of financing costs). At December 31, 2020, Ciner Wyoming was in compliance with all financial covenants of the Ciner Wyoming Equipment Financing Arrangement. In connection with the event of default (the “Facilities Agreement Default”) under the Facilities Agreement that arose in February 2021 (as defined and described below in the WE Soda and Ciner Enterprises Facilities Agreement section), Ciner Wyoming entered into a second amendment to the Master Agreement (the “Second Amendment to the Master Agreement”) on March 5, 2021. Such amendment modified the definition of change of control under the Master Agreement in order to prevent an event of default thereunder that could have otherwise resulted from the Facilities Agreement lenders foreclosing on certain equity interests in Ciner Holdings (the “Equity Default Remedy”) as a remedy for the Facilities Agreement Default, or as a remedy for future events of default under the Facilities Agreement, as amended. Management is not aware of any current circumstances that would result in an event of default under the Ciner Wyoming Equipment Financing Arrangement in the next twelve months. Ciner Wyoming Credit Facility On August 1, 2017, Ciner Wyoming entered into a Credit Agreement (as amended, the “Ciner Wyoming Credit Facility” and together with the Ciner Wyoming Equipment Financing Arrangement, the “Ciner Wyoming Debt Agreements”) with each of the lenders listed on the respective signature pages thereof and PNC Bank, National Association (“PNC Bank”), as administrative agent, swing line lender and a Letter of Credit (“L/C”) issuer. The Ciner Wyoming Credit Facility is a $225.0 million senior 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, and 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. On February 28, 2020, the Ciner Wyoming Credit Facility was amended to, among other things, increase flexibility for debt financing to be incurred by Ciner Wyoming in connection with its new natural gas-fired turbine co-generation facility by, among other things (i) increasing the basket for purchase money indebtedness permitted from $5.0 million to $30.0 million; (ii) adding procedures for transition to a benchmark other than the Eurodollar Rate to determine the applicable interest rate (including reference to the Secured Overnight Financing Rate published by the Federal Reserve Bank of New York), with provisions applying to that alternate benchmark; and (iii) adding customary new provisions relating to qualified financial contracts, sanctions and anti-money laundering rules and laws. On July 27, 2020, the Ciner Wyoming Credit Facility was further amended (the “Second Ciner Wyoming Amendment”) to increase Ciner Wyoming’s financial and liquidity flexibility due to COVID-19. The Second Ciner Wyoming Amendment, among other things, (i) increased, for a limited period, certain restrictive debt covenants that require Ciner Wyoming and its subsidiaries to maintain certain leverage ratios and interest coverage ratios at the end of each period, (ii) provided a tiered interest rate structure based on applicable covenant ratios and established a 0.5% interest floor, (iii) effectuated changes to collateral restricted disbursements and covenanted to give security if covenant ratios are equal to or above certain levels. The Second Ciner Wyoming Amendment also provided for covenants to restrict certain payments and to give security in certain personal property of Ciner Wyoming following a fiscal quarter in which the leverage ratio is equal to or higher than 3.50:1.0, so long as the applicable leverage ratio limit is otherwise adhered to. Any such security would be released upon achievement of a leverage ratio less than 2.00:1.0 at the end of any quarter. In addition, 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 Second Ciner Wyoming Amendment also required quarterly maintenance of a leverage ratio below those shown in the table below and an interest coverage ratio of not less than 3.00:1.0. Fiscal Quarter ending Leverage Ratio December 31, 2020 4.50:1.0 March 31, 2021 4.50:1.0 June 30, 2021 (1) 4.00:1.0 September 30, 2021 (1) 3.50:1.0 December 31, 2021 and each fiscal quarter ending thereafter 3.00:1.0 (1) See discussion of Third Amendment below which changed this requirement to 3.00:1.00. The Second Ciner Wyoming Amendment added additional restrictions to (i) certain restricted payments (which includes cash dividends, distributions and other restricted payments) by requiring the leverage ratio, both before and after giving effect to such restricted payment, to be less than 2.50:1.0 (previously 3.00:1.0), (ii) permitted acquisitions by requiring that the leverage ratio, both before and after giving effect to a permitted acquisition, be less than 2.50:1.0, and (iii) liens by restricting the grant of any lien on any mineral right or mineral reserve, subject to certain exceptions. Once any restricted payment (other than a permitted tax distribution) or permitted acquisition is consummated by Ciner Wyoming, or one of its subsidiaries, the leverage ratio will reset to a maximum of 3.00:1.0. The Second Ciner Wyoming Amendment also added a covenant that states if the leverage ratio thereunder is: (i) below 3.50:1.0 as of the end of any fiscal quarter, any borrowings under the Ciner Wyoming Credit Agreement will be unsecured; or (ii) greater than or equal to 3.50:1.0 as of the end of any fiscal quarter, any borrowings under the Ciner Wyoming Credit Agreement will be secured by substantially all of Ciner Wyoming’s personal property, subject to certain customary exceptions, provided, that any such security shall be released upon achievement of a leverage ratio less than 2.00:1.0 at the end of any fiscal quarter. Prior to the Second Ciner Wyoming Amendment, a leverage ratio in excess of 3.00:1.0 for a quarterly period would have constituted an event of default, whereas following effectiveness of the Second Ciner Wyoming Amendment, for each quarterly period where the leverage ratio is permitted to be in excess of 3.50:1.0, a leverage ratio in excess of 3.50:1.0 for such quarterly period would not by itself constitute an event of default so long as the applicable leverage ratio limit is otherwise adhered to, but would permit the administrative agent and lenders under the Ciner Wyoming Credit Facility to obtain a lien on certain personal property of Ciner Wyoming. 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 ceases 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 • the Eurodollar Rate plus an applicable margin; provided , that with respect to an applicable loan, if the Eurodollar Rate has ceased or will cease to be provided, if the regulatory supervisor for the administrator of the Eurodollar Rate or a governmental authority having jurisdiction over the administrative agent determine that the Eurodollar Rate is no longer representative or if the administrative agent determines that similar U.S. dollar-denominated credit facilities are being executed or modified to incorporate or adopt a new benchmark interest rate to replace the Eurodollar Rate, the administrative agent and Ciner Wyoming may establish an alternative interest rate for the applicable loan. The Ciner Wyoming Credit Facility has an interest rate floor of 0.50%. The unused portion of the Ciner Wyoming Credit Facility is subject to a per annum commitment fee and the applicable margin of the interest rate under the Ciner Wyoming Credit Facility will be determined as follows: Pricing Leverage Ratio Eurodollar Rate Loans Base Rate Commitment 1 < 1.25:1.0 1.500% 0.500% 0.250% 2 ≥ 1.25:1.0 but < 1.75:1.0 1.750% 0.750% 0.275% 3 ≥ 1.75:1.0 but < 2.25:1.0 2.000% 1.000% 0.300% 4 ≥ 2.25:1.0 but < 3.00:1.0 2.250% 1.250% 0.375% 5 ≥ 3.00:1.0 but < 3.50:1.0 2.500% 1.500% 0.375% 6 ≥ 3.50:1.0 but < 4.00:1.0 2.750% 1.750% 0.425% 7 ≥ 4.00:1.0 3.000% 2.000% 0.475% At December 31, 2020, Ciner Wyoming was in compliance with all financial covenants of the Ciner Wyoming Credit Facility. In connection with the Facilities Agreement Default, Ciner Wyoming entered into a Third Amendment to the Ciner Wyoming Credit Facility (the “Third Amendment”) in order to prevent an event of default thereunder that could have otherwise resulted from the Facilities Agreement lenders exercising the Equity Default Remedy as a remedy for the Facilities Agreement Default, or a future event of default under the Facilities Agreement, as amended. Such amendment (i) modified the definition of change of control to exclude any change in control that could arise from lender actions under the Facilities Agreement relating to any events of default under the Facilities Agreement; (ii) reduced the leverage ratio to 3.00 to 1.00 for the quarter ended June 30, 2021 and each fiscal quarter thereafter; and (iii) added a covenant that any borrowings under the Wyoming Credit Facility are secured by substantially all of Ciner Wyoming’s personal property, subject to certain exclusions. Management is not aware of any current circumstances that would result in an event of default under the Ciner Wyoming Credit Facility in the next twelve months. Ciner Resources Credit Facility On August 1, 2017, the Partnership entered into a Credit Agreement (as amended, the “Ciner Resources Credit Facility”) with each of the lenders listed on the respective signature pages thereof and PNC Bank, as administrative agent, swing line lender and an L/C issuer. The Ciner Resources Credit Facility was a $10.0 million senior secured revolving credit facility with a syndicate of lenders, that would have matured on the fifth anniversary of the closing date of such credit facility. The Ciner Resources Credit Facility provided 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 included 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 were guaranteed by each of the Partnership’s material domestic subsidiaries other than Ciner Wyoming. In addition, the Partnership’s obligations under the Ciner Resources Credit Facility were 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. On February 28, 2020, the Ciner Resources Credit Facility was amended to, among other things, increase flexibility for debt financing to be incurred by Ciner Wyoming in connection with its new natural gas-fired turbine co-generation facility by, among other things (i) increasing the basket for purchase money indebtedness permitted under the Ciner Resources Credit Facility from $5.0 million to $30.0 million; (ii) adding procedures under the Ciner Resources Credit Facility for transition to a benchmark other than the Eurodollar Rate to determine the applicable interest rate (including reference to the Secured Overnight Financing Rate published by the Federal Reserve Bank of New York), with provisions applying to that alternate benchmark; and (iii) adding customary new provisions relating to qualified financial contracts, sanctions and anti-money laundering rules and laws. On July 27, 2020, the Ciner Resources Credit Facility was further amended (the “Second Ciner Resources Amendment”) to increase our financial and liquidity flexibility due to COVID-19. The Second Ciner Resources Amendment, among other things, increased the consolidated leverage ratios as set forth in the table below, provided increased interest pricing to allow for higher leverage ratios, and modified procedures for transition to a benchmark other than the Eurodollar Rate to determine the applicable interest rate. The Ciner Resources Credit Facility contained various covenants and restrictive provisions that limited (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 Second Ciner Resources Amendment also required quarterly maintenance of a consolidated leverage ratio below those shown in the table below and a consolidated interest coverage ratio (as defined in the Ciner Resources Credit Facility) of not less than 3.00:1.0. Fiscal Quarter ending Leverage Ratio December 31, 2020 4.50:1.0 March 31, 2021 4.50:1.0 June 30, 2021 4.00:1.0 September 30, 2021 3.50:1.0 December 31, 2021 and each fiscal quarter ending thereafter 3.00:1.0 The Second Ciner Resources Amendment added additional restrictions to (i) certain restricted payments (which included cash dividends, distributions and other restricted payments) by requiring the consolidated leverage ratio, both before and after giving effect to such restricted payment, to be less than 2.50:1.0 (previously 3.00:1.0), and (ii) permitted acquisitions by requiring that the consolidated leverage ratio, both before and after giving effect to a permitted acquisition, be less than 2.50:1.0. Once any restricted payment (other than a permitted tax distribution) or permitted acquisition is consummated by the Partnership or its subsidiaries, the consolidated leverage ratio would reset to a maximum of 3.00:1.0. In addition, the Ciner Resources Credit Facility contained events of default customary for transactions of that 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 have terminated all outstanding commitments under the Ciner Resources Credit Facility and may have declared 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 could have been triggered if Ciner Corp and its wholly-owned subsidiaries, directly or indirectly, ceased to own all of the equity interests, or ceased 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 could have been triggered if the Partnership ceased to own at least 50.1% of the economic interests in Ciner Wyoming or ceased 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 bore interest at our option at either: • a Base Rate, which equaled 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 • the Eurodollar Rate plus an applicable margin; provided, that with respect to an applicable loan, if the Eurodollar Rate ceased or would have ceased to be provided, if the regulatory supervisor for the administrator of the Eurodollar Rate or a governmental authority having jurisdiction over the administrative agent determined that the Eurodollar Rate was no longer representative or if the administrative agent determined that similar U.S. dollar-denominated credit facilities were being executed or modified to incorporate or adopt a new benchmark interest rate to replace the Eurodollar Rate, the administrative agent and the Partnership may have established an alternative interest rate for the applicable loan. The Ciner Resources Credit Facility had an interest rate floor of 0.50%. The unused portion of the Ciner Resources Credit Facility was subject to a per annum commitment fee and the applicable margin of the interest rate under the Ciner Resources Credit Facility was to be determined as follows: Pricing Leverage Ratio Eurodollar Rate Loans Base Rate Commitment 1 < 1.25:1.0 1.500% 0.500% 0.250% 2 ≥ 1.25:1.0 but < 1.75:1.0 1.750% 0.750% 0.275% 3 ≥ 1.75:1.0 but < 2.25:1.0 2.000% 1.000% 0.300% 4 ≥ 2.25:1.0 but < 3.00:1.0 2.250% 1.250% 0.375% 5 ≥ 3.00:1.0 but < 3.50:1.0 2.500% 1.500% 0.375% 6 ≥ 3.50:1.0 but < 4.00:1.0 2.750% 1.750% 0.425% 7 ≥ 4.00:1.0 3.000% 2.000% 0.475% At December 31, 2020, Ciner Resources was in compliance with all financial covenants of the Ciner Resources Credit Facility. In connection with the Facilities Agreement Default, on March 8, 2021, we terminated the Ciner Resources Credit Facility and repaid in full our obligations thereunder. WE Soda and Ciner Enterprises Facilities Agreement On August 1, 2018, Ciner Enterprises, the entity that indirectly owns and controls the Partnership, 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, WE Soda Kimya Yatırımları Anonim Şirketi, Ciner Kimya Yatırımları Sanayi ve Ticaret Anonim Şirketi, 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 we nor Ciner Wyoming are 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 certain transactions (including loans) with our affiliates, including such transactions 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, (iii) restrict the amount of our capital expenditures if certain ratios are not achieved by the Ciner Obligors thereunder and (iv) prevent actions that enable certain restrictions or prohibitions on our ability to upstream cash (including via distributions) to the borrowers under the Facilities Agreement. Based on the Ciner Obligors’ applicable ratios at December 31, 2020, the Partnership’s expansion capital expenditures are prohibited until the Ciner Obligors’ applicable ratios are at specified levels pursuant to the Facilities Agreement. In addition, Ciner Enterprises’ ownership in Ciner Holdings 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 Ciner Holdings, which controls the general partner of the Partnership, if any of the borrowers or guarantors under the Facilities Agreement are unable to satisfy its respective obligations under the Facilities Agreement. Ciner Wyoming was informed that the Ciner Obligors were in compliance with the Facilities Agreement, as amended, as of December 31, 2020. In February 2021, Ciner Wyoming was informed that an event of default under the Facilities Agreement arose and that the Ciner Obligors are currently working with the Facilities Agreement lenders to resolve this Facilities Agreement Default. Absent resolution, the Facilities Agreement lenders have the right to foreclose on the equity interest in Ciner Holdings. In order to prevent an event of default under each of the Ciner Wyoming Debt Agreements, which could have otherwise resulted from the Facilities Agreement lenders exercising their Equity Default Remedy, Ciner Wyoming entered into the Second Amendment to the Master Agreement and the Third Amendment to the Ciner Wyoming Credit Facility to modify the related definitions of change of control as described above. Furthermore, we terminated the Ciner Resources Credit Facility and repaid in full our obligations thereunder.

OTHER NON-CURRENT LIABILITIES

OTHER NON-CURRENT LIABILITIES	12 Months Ended
	Dec. 31, 2020
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) 2020 2019 Reclamation reserve $ 7.3 $ 5.7 Derivative instruments and hedges, fair value liabilities, and other 1.4 2.9 Total $ 8.7 $ 8.6 A reconciliation of the Partnership’s reclamation reserve liability is as follows: (In millions) 2020 2019 Reclamation reserve balance at beginning of year $ 5.7 $ 5.4 Accretion expense 0.3 0.3 Reclamation adjustments (1) 1.3 — Reclamation reserve balance at end of year $ 7.3 $ 5.7 (1) The reclamation costs are periodically evaluated for adjustments by the Wyoming Department of Environmental Quality. See Note 14 “Commitments and Contingencies,” “ Off-Balance Sheet Arrangements” for additional information on our reclamation reserve, including recent changes to the underlying reclamation obligation that has resulted in the asset retirement obligation reclamation adjustment.

EMPLOYEE COMPENSATION

EMPLOYEE COMPENSATION	12 Months Ended
	Dec. 31, 2020
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 Retirement Plan covers substantially all full-time employees hired before May 1, 2001. Ciner Corp’s Retirement Plans had a net liability balance of $55.1 million and $54.8 million at December 31, 2020 and December 31, 2019, respectively. Ciner Corp’s current 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 Retirement Plan’s net periodic pension (benefit) cost for the twelve months ended December 31, 2020, 2019 and 2018 were $(1.3) million, $1.0 million and $0.4 million, respectively. The decrease in pension costs during the twelve months ended December 31, 2020 was driven by a better-than-expected return on assets and lower interest expense assumptions. 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 401(k) 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, 2020, 2019 and 2018 were $3.4 million, $3.0 million and $2.8 million, respectively. 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, is not funded, and Ciner Corp has the right to modify or terminate the plan. The post-retirement plan had a net unfunded liability of $13.1 million and $13.8 million on December 31, 2020 and December 31, 2019, respectively. The Partnership’s allocated portion of postretirement cost (benefit) for the twelve months ended December 31, 2020, 2019 and 2018, were $1.2 million, $(2.2) million and $(2.9) million, respectively. The postretirement benefits for the Partnership in 2019 and 2018 are due to Ciner Corp amending its postretirement benefit plan in prior years.

EQUITY - BASED COMPENSATION

EQUITY - BASED COMPENSATION	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [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”). Historically, the Plan was 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, 2020, 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. The Partnership has made a policy election to recognize forfeitures as they occur in lieu of estimating future forfeiture activity under the Plan. Non-employee Director Awards During the twelve months ended December 31, 2020, a total of 21,720 common units were granted and fully vested to non-employee directors, and 8,832 were granted during the twelve months ended December 31, 2019. The grant date average fair value per unit of these awards was $9.88 and $25.48 for the twelve months ended December 31, 2020 and 2019, respectively. The total fair value of these awards were approximately $0.2 million during the twelve months ended December 31, 2020 and 2019, 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 The following table presents a summary of activity on the Time Restricted Unit Awards for the years ended December 31, 2020 and 2019: 2020 2019 (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 55,454 $ 20.33 71,436 $ 27.56 Granted (1) — $ — 38,402 $ 16.45 Vested (27,802) $ 22.99 (32,087) $ 27.85 Forfeited (5,715) $ 18.38 (22,297) $ 26.00 Unvested at the end of the year 21,937 $ 17.57 55,454 $ 20.33 (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, 2020 as all awards granted are expected to vest. Total Return Performance Unit Awards Historically, we have granted 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 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: 2020 2019 (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 20,173 $ 41.79 52,974 $ 42.22 Vested (7,654) 42.21 (4,766) $ 43.93 Forfeited (4,841) $ 41.53 (28,035) $ 42.24 Unvested at the end of the year 7,678 $ 41.53 20,173 $ 41.79 (1) Determined by dividing the aggregate grant date fair value of awards by the number of awards issued. 2019 Performance Unit Awards On September 23, 2019, the board of directors of our general partner approved a new form of performance unit award to be granted based upon the achievement of certain financial, operating and safety-related performance metrics (“2019 Performance Unit Awards”) pursuant to our LTIP, and the vesting of the 2019 Performance Unit Awards is linked to a weighted average consisting of internal performance metrics defined in the 2019 Performance Unit Award agreement (the “Performance Metrics”) during a three-year performance period (the “Measurement Period”). The vesting of the 2019 Performance Unit Awards, and number of common units of the Partnership distributable pursuant to such vesting, is dependent on our performance relative to a pre-established budget over the Measurement Period; provided, that the awardee remains continuously employed with our general partner or its affiliates or satisfies other service-related criteria through the end of the Measurement Period, except in certain cases of Changes in Control (as defined in our LTIP) or the awardee’s death or disability. Vested 2019 Performance Unit Awards will be settled in our common units, with the number of such common units payable under the award for a given year in the Measurement Period to be calculated by multiplying the target number provided in the corresponding 2019 Performance Unit Award agreement by a payout multiplier, which may range from 0%-200% in each case, as determined by aggregating the corresponding weighted average assigned to the Performance Metrics. The 2019 Performance Unit Awards also contain DERs and grant the recipient 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 of the 2019 Performance Unit Awards, the award recipient is entitled to receive a cash payment equal to the sum of the distribution equivalents accumulated with respect to vested 2019 Performance Unit Awards during the period beginning on January 1, 2019 and ending on the applicable vesting date. The 2019 Performance Unit Awards granted to award recipients during 2019 have a performance cycle that began on January 1, 2019 and will end on December 31, 2021. The following table presents a summary of activity on the 2019 Performance Unit Awards for the years ended December 31, 2020 and 2019: Year Ended Year Ended (Units in whole numbers) Number of Common Units Grant-Date Average Fair Value per Unit (1) Number of Common Units Grant-Date Average Fair Value per Unit (1) Unvested at the beginning of period 35,908 16.45 — — Granted — $ — 38,402 16.45 Forfeited (6,851) $ 16.45 (2,494) 16.45 Unvested at the end of the period 29,057 $ 16.45 35,908 16.45 (1) Determined by dividing the weighted average price per common unit on the date of grant. 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 follows: Year Ended Year Ended Unrecognized Compensation Expense Weighted Average to be Recognized Unrecognized Compensation Expense Weighted Average to be Recognized Time Restricted Unit Awards $ 0.2 1.14 $ 0.7 1.82 TR Performance Unit Awards — 0.08 0.2 1.03 2019 Performance Unit Awards 0.1 1.08 0.4 2.09 Total $ 0.3 $ 1.3

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE LOSS	12 Months Ended
	Dec. 31, 2020
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, 2020, 2019 and 2018, and changes within the period, consisted of the following: Gains and Losses on Cash Flow Hedges (In millions) Balance at January 1, 2018 $ (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 loss before reclassification 0.3 Amounts reclassified from accumulated other comprehensive loss 0.5 Net current-period other comprehensive loss 0.8 Balance at December 31, 2019 $ (3.0) Other comprehensive income before reclassification 1.3 Amounts reclassified from accumulated other comprehensive income 1.7 Net current period other comprehensive income 3.0 Balance at December 31, 2020 $ — Other Comprehensive Income/(Loss) Other comprehensive income/(loss), including portion attributable to noncontrolling 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) 2020 2019 2018 Unrealized gain/(loss) on derivatives: Mark to market adjustment on interest rate swap contracts $ (0.4) $ (0.5) $ (0.2) Mark to market adjustment on natural gas forward contracts 6.3 2.1 — Income/(loss) on derivative financial instruments $ 5.9 $ 1.6 $ (0.2) 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) 2020 2019 2018 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 $ 0.4 $ — $ — Interest expense Natural gas forward contracts 1.3 0.5 0.5 Cost of products sold Total reclassifications for the period $ 1.7 $ 0.5 $ 0.5

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2020
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 (“RSRC”) an affiliate of Occidental Petroleum Corporation (formerly an affiliate of Anadarko Petroleum Corporation), and other private parties which provide for royalties based upon production volume. The Partnership has a perpetual right of first refusal with respect to these leases and license and intends to continue renewing the leases and license 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 that Watco holds an easement from Sweetwater Surface LLC. The land lease is renewable every five years for a total period of thirty years, while the Sweetwater Surface LLC easement is perpetual. The Partnership has an option agreement with Watco to assign the lease and easement to the Partnership at any time during the land lease term. An immaterial annual rental is paid under the easement and lease. As of December 31, 2020, the total minimum contractual rental commitments under the Partnership’s various operating leases, including renewal periods is approximately $1.6 million with the amount due in any of the next five years being immaterial. Ciner Corp typically enters into operating lease contracts with various lessors for rail cars to transport product to customer locations and warehouses. Rail car leases under these contractual commitments range for periods from one Purchase Commitments We have financial natural gas supply contracts to mitigate volatility in the price of natural gas. As of December 31, 2020, these contracts totaled approximately $25.9 million for the purchase of a portion of our natural gas requirements over approximately the next four years. The supply purchase agreements have specific commitments of $14.5 million in 2021, $6.2 million in 2022, $4.3 million in 2023, and $0.9 million in 2024. 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 $4.0 million per year. In connection with the ANSAC exit we have an agreement for minimum logistics services in 2021. This arrangement includes bilateral take or pay terms. Legal and Environmental Matters 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 such legal proceedings we may be involved in from time to time 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 any such 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 Occidental Petroleum Corporation (formerly an affiliate of Anadarko Petroleum Corporation) and predecessor in interest to Sweetwater Royalties LLC, to mine sodium minerals from certain 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 an affiliate of Occidental Petroleum Corporation under a separate license. In the lawsuit, we claimed that RSRC had, 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. The $27.5 million litigation settlement was realized in the second quarter of 2018. Off-Balance Sheet Arrangements We have historically been subject to a self-bond agreement (the “Self-Bond Agreement”) with the Wyoming Department of Environmental Quality (“WDEQ”) under which we committed to pay directly for reclamation costs. The amount of the self-bond was $36.2 million as of December 31, 2019. In May 2019, the State of Wyoming enacted legislation that limits our and other mine operators’ ability to self-bond and required us to seek other acceptable financial instruments to provide alternate assurances for our reclamation obligations by November 2020. We provided such alternate assurances by timely securing a third-party surety bond effective October 15, 2020 (the “Surety Bond”) for the then-applicable full self-bond amount $36.2 million, which was also the amount of our obligation as of December 31, 2020. After we secured the Surety Bond, the previous Self-Bond Agreement was terminated. As of the date of this Report, the impact on our net income and liquidity due to securing the Surety Bond has been immaterial and we anticipate that to continue to be the case. The amount of such assurances that we are required to provide is subject to change upon periodic re-evaluation by the WDEQ’s Land Quality Division. As a result of the most recent such periodic re-evaluation, the Surety Bond amount was increased to $41.8 million effective March 1, 2021.
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 (“RSRC”) an affiliate of Occidental Petroleum Corporation (formerly an affiliate of Anadarko Petroleum Corporation), and other private parties which provide for royalties based upon production volume. The Partnership has a perpetual right of first refusal with respect to these leases and license and intends to continue renewing the leases and license 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 that Watco holds an easement from Sweetwater Surface LLC. The land lease is renewable every five years for a total period of thirty years, while the Sweetwater Surface LLC easement is perpetual. The Partnership has an option agreement with Watco to assign the lease and easement to the Partnership at any time during the land lease term. An immaterial annual rental is paid under the easement and lease. As of December 31, 2020, the total minimum contractual rental commitments under the Partnership’s various operating leases, including renewal periods is approximately $1.6 million with the amount due in any of the next five years being immaterial. Ciner Corp typically enters into operating lease contracts with various lessors for rail cars to transport product to customer locations and warehouses. Rail car leases under these contractual commitments range for periods from one Purchase Commitments We have financial natural gas supply contracts to mitigate volatility in the price of natural gas. As of December 31, 2020, these contracts totaled approximately $25.9 million for the purchase of a portion of our natural gas requirements over approximately the next four years. The supply purchase agreements have specific commitments of $14.5 million in 2021, $6.2 million in 2022, $4.3 million in 2023, and $0.9 million in 2024. 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 $4.0 million per year. In connection with the ANSAC exit we have an agreement for minimum logistics services in 2021. This arrangement includes bilateral take or pay terms. Legal and Environmental Matters 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 such legal proceedings we may be involved in from time to time 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 any such 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 Occidental Petroleum Corporation (formerly an affiliate of Anadarko Petroleum Corporation) and predecessor in interest to Sweetwater Royalties LLC, to mine sodium minerals from certain 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 an affiliate of Occidental Petroleum Corporation under a separate license. In the lawsuit, we claimed that RSRC had, 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. The $27.5 million litigation settlement was realized in the second quarter of 2018. Off-Balance Sheet Arrangements We have historically been subject to a self-bond agreement (the “Self-Bond Agreement”) with the Wyoming Department of Environmental Quality (“WDEQ”) under which we committed to pay directly for reclamation costs. The amount of the self-bond was $36.2 million as of December 31, 2019. In May 2019, the State of Wyoming enacted legislation that limits our and other mine operators’ ability to self-bond and required us to seek other acceptable financial instruments to provide alternate assurances for our reclamation obligations by November 2020. We provided such alternate assurances by timely securing a third-party surety bond effective October 15, 2020 (the “Surety Bond”) for the then-applicable full self-bond amount $36.2 million, which was also the amount of our obligation as of December 31, 2020. After we secured the Surety Bond, the previous Self-Bond Agreement was terminated. As of the date of this Report, the impact on our net income and liquidity due to securing the Surety Bond has been immaterial and we anticipate that to continue to be the case. The amount of such assurances that we are required to provide is subject to change upon periodic re-evaluation by the WDEQ’s Land Quality Division. As a result of the most recent such periodic re-evaluation, the Surety Bond amount was increased to $41.8 million effective March 1, 2021.

AGREEMENTS AND TRANSACTIONS WIT

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
AGREEMENTS AND TRANSACTIONS WITH AFFILIATES	AGREEMENTS AND TRANSACTIONS WITH AFFILIATES Agreements and transactions with affiliates have a significant impact on the Partnership’s financial statements because the Partnership is a subsidiary in a global group structure. Agreements directly between the Partnership and other affiliates, or indirectly between affiliates that the Partnership does not control, can have a significant impact on recorded amounts or disclosures in the Partnership's financial statements, including any commitments and contingencies between the Partnership and affiliates, or potentially, third parties. Ciner Corp is the exclusive sales agent for the Partnership and through its membership in ANSAC, through December 31, 2020, Ciner Corp has responsibility for promoting and increasing the use and sale of soda ash and other refined or processed sodium products produced. Through December 31, 2020, ANSAC served as the primary international distribution channel for the Partnership and two other U.S. manufacturers of trona-based soda ash. ANSAC operated on a cooperative service-at-cost basis to its members such that typically any annual profit or loss is passed through to the members. As previously disclosed, the Partnership was informed on November 9, 2018 that Ciner Corp, an affiliate of the Partnership, had as part of its strategic initiative to gain better direct access and control of international customers and logistics and the ability to leverage the expertise of Ciner Group, the world’s largest natural soda ash producer, delivered a notice to terminate its membership in ANSAC. Such termination was expected to be effective as of the end of day on December 31, 2021. On July 27, 2020, ANSAC and the members thereof entered into an agreement, effective as of July 24, 2020, that, among other things, terminated Ciner Corp’s membership in ANSAC effective as of December 31, 2020 (the “ANSAC termination date”), a year earlier than previously announced (the “ANSAC Early Exit Agreement”). Effective as of the end of day on December 31, 2020 Ciner Corp exited ANSAC. In connection with the settlement agreement with ANSAC, there are sales commitments to ANSAC in 2021 and 2022 where Ciner Corp will continue to sell, at substantially lower volumes, product to ANSAC for export sales purposes, with a fixed rate per ton selling, general and administrative expense, and will also purchase a limited amount of export logistics services in 2021. Through in part the Partnership’s affiliates, the Partnership has amongst other things: (i) obtained its own international customer sales arrangements for 2021, (ii) obtained third-party export port services, and (iii) chartered and executed its own international product delivery. Historically, by design and prior to Ciner Corp’s exit from ANSAC, ANSAC managed most of our international sales, marketing and logistics, and as a result, was our largest customer for the years ended December 31, 2020, 2019 and 2018, accounting for 45.4%, 60.4% and 52.0%, respectively, of our net sales. Although ANSAC was our largest customer for the aforementioned periods, we anticipate that the impact of Ciner Corp’s exit from ANSAC on our net sales, net income and liquidity will be limited. We made this determination primarily based upon the belief that we will continue to be one of the lowest cost producers of soda ash in the global market. With a low-cost position combined with better direct access and control of our customers and logistics and the ability to leverage Ciner Group’s expertise in these areas, we believe we will be able to adequately replace these net ANSAC sales. As of January 1, 2021, Ciner Corp began managing the Partnership’s sales and marketing efforts for exports with the ANSAC exit being complete. Ciner Corp is leveraging the distributor network established by Ciner Group while independently reviewing current and potential distribution partners to optimize our reach into each market. Post-ANSAC International Export Capabilities In accordance with the ANSAC Early Exit Agreement, Ciner Corp has begun marketing soda ash on our behalf directly into international markets and building its international sales, marketing and supply chain infrastructure. We now have access to utilize the distribution network that has already been established by the global Ciner Group. We believe that by having the option of combining our volumes with Ciner Group’s soda ash exports from Turkey, Ciner Corp’s strategic exit from ANSAC has allowed us to leverage global Ciner Group’s, the world’s largest natural soda ash producer, soda ash operations which we expect will improve our ability to optimize our market share both domestically and internationally. Being able to work with the global Ciner Group provides us with the opportunity to better attract and more efficiently serve larger global customers. In addition, the Partnership is working to enhance its international logistics infrastructure that includes, among other things, a domestic port for export capabilities. These export capabilities are being developed by an affiliated company and options being evaluated range from continued outsourcing in the near term to developing its own port capabilities in the longer term. 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”) with 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 Ciner Wyoming 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) 2020 2019 2018 Ciner Corp $ 16.1 $ 14.9 $ 14.6 ANSAC (1) 1.4 3.5 3.0 Total selling, general and administrative expenses - affiliates $ 17.5 $ 18.4 $ 17.6 (1) ANSAC allocates its expenses to its members using a pro-rata calculation based on sales. Net sales to affiliates were as follows: Years Ended December 31, (In millions) 2020 2019 2018 ANSAC $ 177.9 $ 315.8 $ 253.3 Total $ 177.9 $ 315.8 $ 253.3 The Partnership had accounts receivable from affiliates and due to affiliates as follows: As of December 31, (In millions) 2020 2019 2020 2019 Accounts receivable from affiliates Due to affiliates ANSAC $ 41.9 $ 53.8 $ 0.2 $ 1.6 Ciner Corp 44.6 35.7 2.6 1.4 Other — 5.5 0.1 — Total $ 86.5 $ 95.0 $ 2.9 $ 3.0 The increase in due from Ciner Corp from December 31, 2019 to December 31, 2020 is due to timing of funding of pension and postretirement plans offered and administered by Ciner Corp.

MAJOR CUSTOMERS AND SEGMENT REP

MAJOR CUSTOMERS AND SEGMENT REPORTING	12 Months Ended
	Dec. 31, 2020
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) 2020 2019 2018 Domestic $ 208.8 $ 207.0 $ 233.4 International 183.4 315.8 253.3 Total net sales $ 392.2 $ 522.8 $ 486.7

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2020
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: Level 1-inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market. 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. 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, accrued expenses, derivative financial instruments and long-term debt. The carrying amounts of cash and cash equivalents, accounts receivable and accounts payable and accrued expenses 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 three individual $12.5 million swaps with an aggregate notional value of $37.5 million at December 31, 2020 and four individual $12.5 million swaps with an aggregate notional value of $50.0 million at December 31, 2019 The swaps outstanding at December 31, 2020 have various maturities through 2023. 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 2024. These contracts had an aggregate notional value of $25.9 million and $31.2 million at December 31, 2020 and December 31, 2019, 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, 2020 and December 31, 2019: Assets Liabilities 2020 2019 2020 2019 (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 $ 0.2 Accrued Expenses $ 0.9 Natural gas forward contracts - current Other Current Assets 1.4 Other Current Assets 0.1 Accrued Expenses 0.7 Accrued Expenses 2.4 Interest rate swap contracts - non-current — — Other non-current liabilities 1.1 — Natural gas forward contracts - non-current Other non-current assets 0.9 0.2 Other non-current liabilities 0.2 Other non-current liabilities 2.9 Total fair value of derivatives designated as hedging instruments $ 2.3 $ 0.3 $ 2.2 $ 6.2 Financial Assets and Liabilities not Measured at Fair Value

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS In an effort to achieve greater financial and liquidity flexibility during the COVID-19 pandemic, (i) effective February 22, 2021, the board of directors of the general partner of the Partnership unanimously approved a continuation of the suspension of quarterly distributions to the unitholders of the Partnership for the quarter ended December 31, 2020, and (ii) effective February 22, 2021, the board of managers of Ciner Wyoming unanimously approved a continuation of the suspension of quarterly distributions to the members of Ciner Wyoming for the quarter ended December 31, 2020 in a continued effort to achieve greater financial and liquidity flexibility during the COVID-19 pandemic. In March 2021, the board of managers of Ciner Wyoming approved a special $8.0 million distribution to, amongst other things, provide the Partnership with funds to retire the Ciner Resources Credit Facility. In connection with the Facilities Agreement Default (as defined and described in Note 9 “Debt” in the Ciner Wyoming Equipment Financing Arrangement section), effective March 5, 2021 the Ciner Wyoming Equipment Financing Arrangement and the Ciner Wyoming Credit Facility were each amended in order to, amongst other things, carveout from the definition of Change of Control any change in control that could arise from lender actions under the Facilities Agreement relating to any events of default under the Facilities Agreement, and, effective March 8, 2021, the Ciner Resources Credit Facility was terminated. See Note 9 “Debt” for additional information.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2020
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 noncontrolling interest.
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. Furthermore, we considered the impact of the COVID-19 pandemic on the use of estimates and assumptions used for financial reporting. While our production is considered “essential”, the COVID-19 outbreak disrupted our customers and customer segments, which had a negative impact on the demand for our products which adversely affected our operations. At December 31, 2020, as we cannot predict the duration or the scope of the COVID-19 pandemic and its impact on our operations, the potential negative financial impact to our results cannot be reasonably estimated but could be material. As a result of these uncertainties, actual results could differ from those estimates and assumptions.
Revenue Recognition and Freight Costs	Revenue Recognition The majority of the Partnership’s revenues are recognized upon satisfaction of our performance obligations, that is, 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 we ship the product from our production facility or third-party terminals, depending on the terms of the sales contract, rendering our performance obligation fulfilled. For certain international customers, it is the point when the product is loaded on the vessel at the port. Additionally, the Partnership has made an accounting policy election to account for shipping and handling activities as fulfillment costs. 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. Performance Obligations . A performance obligation is a promise in a contract to transfer a distinct good or service to the customer. 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 transferred 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. Revenue 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 generally 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 Sheets as of December 31, 2020 and December 31, 2019. There were no contract assets as of December 31, 2020 and December 31, 2019. • Contract Liabilities. There may be situations where customers are required to prepay for freight and insurance prior to shipment. The Partnership accounts for freight costs as fulfillment activities 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. Freight Costs
Cash and Cash Equivalents	Cash and Cash EquivalentsThe 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 On January 1, 2020, we adopted the current expected credit loss (CECL) model in accordance with ASU No. 2016-13, “Financial Instruments-Credit Losses (Topic 326)” as explained at Recently Issued and Adopted Accounting Standards below. We determined the expected credit losses on initial recognition and at December 31, 2020 based on information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount.
Inventory	Inventory Inventory is carried at the lower of cost and net realizable value. 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. Net realizable value is defined as the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. • 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
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 5-10 years Mineral reserves are amortized over an estimated time period that is derived from total estimated proven and probable mineral reserves divided by our average annual tons mined which was approximately 58 years as of December 31, 2020. 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
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging ActivitiesThe 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. When the Partnership has natural gas physical forward contracts, they are accounted for under the normal purchases and normal sales scope exception.
Income Tax	Income TaxWe 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. The liability was discounted using a weighted average credit-adjusted risk-free rate 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.
Fair Value of Financial Instruments	Fair Value of Financial InstrumentsFair 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
Subsequent Events	Subsequent EventsWe have evaluated subsequent events through the filing of this Annual Report on Form 10-K.
Recent Accounting Guidance	Recent Accounting Guidance Recently Adopted Accounting Guidance In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments-Credit Losses (Topic 326)” ("ASU 2016-13"). This ASU introduces the current expected credit loss (CECL) model, which will require an entity to measure credit losses for certain financial instruments and financial assets, including trade receivables. Under this update, on initial recognition and at each reporting period, an entity will be required to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument. The Partnership adopted ASU 2016-13 effective January 1, 2020 and concluded there was no material impact to the Partnership’s consolidated financial statements. In August 2018, the FASB issued ASU 2018-15, “Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force)” (“ASU 2018-15”), which amends ASC 350-40 to address a customer’s accounting for implementation costs incurred in a cloud computing arrangement (“CCA”) that is a service contract. ASU 2018-15 amends ASC 350 and clarifies that a customer should apply ASC 350-40 to determine which implementation costs should be capitalized in a CCA. ASU 2018-15 does not expand on existing disclosure requirements except to require a description of the nature of hosting arrangements that are service contracts. Entities are permitted to apply either a retrospective or prospective transition approach to adopt the guidance. ASU 2018-15 is effective for periods beginning after December 15, 2019. The Partnership adopted ASU 2018-15 effective January 1, 2020 and concluded there was no material impact to the Partnership’s consolidated financial statements. Recent Accounting Guidance Not Yet Adopted In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”) providing temporary guidance to ease the potential burden in accounting for reference rate reform primarily resulting from the discontinuation of the London Inter-bank Offered Rate (“LIBOR”), which was expected to occur on December 31, 2021. The amendments in ASU 2020-04 are elective and apply to all entities that have contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued. The new guidance provides the following optional expedients: (i) simplifies accounting analyses under current GAAP for contract modifications; (ii) simplifies the assessment of hedge effectiveness and allows hedging relationships affected by reference rate reform to continue; and (iii) allows a one-time election to sell or transfer debt securities classified as held to maturity that reference a rate affected by reference rate reform. An entity may elect to apply the amendments prospectively from March 12, 2020 through December 31, 2022 by accounting topic. The Partnership continues to evaluate ASU 2020-04 but does not expect a material impact to the Partnership’s consolidated financial statements.

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Property, Plant and Equipment	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 5-10 years Property, plant, and equipment, net consisted of the following as of December 31: (In millions) 2020 2019 Land and land improvements $ 0.3 $ 0.3 Depletable land 3.0 3.0 Buildings and building improvements 163.4 137.8 Computer hardware 5.3 4.7 Machinery and equipment 709.8 672.4 Mining reserves 65.3 65.3 Total 947.1 883.5 Less accumulated depreciation, depletion and amortization (679.9) (676.6) Total net book value 267.2 206.9 Construction in progress 40.2 90.8 Total property, plant, and equipment, net $ 307.4 $ 297.7

NET INCOME PER UNIT AND CASH _2

NET INCOME PER UNIT AND CASH DISTRIBUTION (Tables)	12 Months Ended
	Dec. 31, 2020
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) 2020 2019 2018 Net income attributable to Ciner Resources LP $ 11.7 $ 49.6 $ 49.9 Less: General partner’s interest in net income 0.2 1.0 1.0 Limited partners’ interest in net income $ 11.5 $ 48.6 $ 48.9 Weighted average limited partner units outstanding: Common - Public and Ciner Holdings (basic) 19.7 19.7 19.7 Total weighted average limited partner units outstanding (basic) 19.7 19.7 19.7 Common - Public and Ciner Holdings (diluted) 19.8 19.7 19.7 Total weighted average limited partner units outstanding (diluted) 19.8 19.7 19.7 Net income per limited partner unit: Common - Public and Ciner Holdings (basic) $ 0.58 $ 2.46 $ 2.48 Net income per limited partner units (basic) $ 0.58 $ 2.46 $ 2.48 Common - Public and Ciner Holdings (diluted) $ 0.58 $ 2.46 $ 2.48 Net income per limited partner units (diluted) $ 0.58 $ 2.46 $ 2.48
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) 2020 2019 2018 Net income attributable to common unitholders: Distributions (1) $ 6.7 $ 26.8 $ 44.6 (Distributions in excess of net income)/undistributed earnings 4.8 21.8 4.3 Common unitholders’ interest in net income $ 11.5 $ 48.6 $ 48.9 (1) Distributions declared per unit for the year 0.340 1.360 2.268
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, including for the declared quarterly distributions of $0.340 per unit for the first quarter of 2020. Under the Partnership agreement, our general partner has considerable discretion to determine the amount of available cash (as defined therein) for distribution each quarter to the Partnership’s unitholders, including discretion to establish cash reserves that would limit the amount of available cash eligible for distribution to the Partnership’s unitholders for any quarter. The Partnership does not guarantee that it will pay the target amount of the minimum quarterly distribution listed below (or any distributions) on its units in any quarter. 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 that we do not issue additional classes of equity securities. Marginal Percentage Total Quarterly 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, 2020
Receivables [Abstract]
Schedule of Accounts Receivable	Accounts receivable, net consisted of the following as of December 31: (In millions) 2020 2019 Trade receivables $ 32.6 $ 30.3 Other receivables 8.0 5.7 Total $ 40.6 $ 36.0

INVENTORY (Tables)

INVENTORY (Tables)	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consisted of the following as of December 31: (In millions) 2020 2019 Raw materials $ 9.9 $ 8.7 Finished goods 13.4 6.9 Stores inventory, current 10.2 8.6 Total $ 33.5 $ 24.2

PROPERTY, PLANT, AND EQUIPMEN_2

PROPERTY, PLANT, AND EQUIPMENT, NET (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	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 5-10 years Property, plant, and equipment, net consisted of the following as of December 31: (In millions) 2020 2019 Land and land improvements $ 0.3 $ 0.3 Depletable land 3.0 3.0 Buildings and building improvements 163.4 137.8 Computer hardware 5.3 4.7 Machinery and equipment 709.8 672.4 Mining reserves 65.3 65.3 Total 947.1 883.5 Less accumulated depreciation, depletion and amortization (679.9) (676.6) Total net book value 267.2 206.9 Construction in progress 40.2 90.8 Total property, plant, and equipment, net $ 307.4 $ 297.7

OTHER NON-CURRENT ASSETS (Table

OTHER NON-CURRENT ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
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) 2020 2019 Stores inventory, non-current $ 18.6 $ 17.6 Internal-use software, net of accumulated amortization 5.7 6.1 Deferred financing costs and other 1.1 0.6 Total $ 25.4 $ 24.3

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following as of December 31: (In millions) 2020 2019 Accrued capital expenditures $ 1.3 $ 6.2 Accrued energy costs 5.1 5.7 Accrued royalty costs 8.1 7.1 Accrued employee compensation & benefits 7.6 7.1 Accrued other taxes 5.0 4.8 Accrued derivatives 0.9 3.3 Other accruals 5.6 4.9 Total $ 33.6 $ 39.1

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Components of Long-term Debt	Long-term debt consisted of the following as of December 31: (In millions) 2020 2019 Ciner Wyoming Equipment Financing Arrangement with maturity date of March 26, 2028, fixed interest rate of 2.479% $ 27.6 $ — Ciner Wyoming Credit Facility, unsecured principal expiring on August 1, 2022, variable interest rate as a weighted average rate of 2.25% and 3.27% at December 31, 2020 and December 31, 2019, respectively 102.5 129.5 Ciner Resources Credit Facility, unsecured principal expiring on August 1, 2022, variable interest rate as a weighted average rate of 2.25% at December 31, 2020 1.0 — Total Debt 131.1 129.5 Current portion of long-term debt 3.0 — Total long-term debt $ 128.1 $ 129.5
Aggregate Maturities on Long-term Debt	Aggregate maturities required on long-term debt at December 31, 2020 are due in future years as follows: (In millions) Amount 2021 $ 3.0 2022 106.6 2023 3.2 2024 3.3 2025 3.3 Thereafter 11.8 Total $ 131.2
Schedule Of Debt Covenants	The Second Ciner Wyoming Amendment also required quarterly maintenance of a leverage ratio below those shown in the table below and an interest coverage ratio of not less than 3.00:1.0. Fiscal Quarter ending Leverage Ratio December 31, 2020 4.50:1.0 March 31, 2021 4.50:1.0 June 30, 2021 (1) 4.00:1.0 September 30, 2021 (1) 3.50:1.0 December 31, 2021 and each fiscal quarter ending thereafter 3.00:1.0 The unused portion of the Ciner Wyoming Credit Facility is subject to a per annum commitment fee and the applicable margin of the interest rate under the Ciner Wyoming Credit Facility will be determined as follows: Pricing Leverage Ratio Eurodollar Rate Loans Base Rate Commitment 1 < 1.25:1.0 1.500% 0.500% 0.250% 2 ≥ 1.25:1.0 but < 1.75:1.0 1.750% 0.750% 0.275% 3 ≥ 1.75:1.0 but < 2.25:1.0 2.000% 1.000% 0.300% 4 ≥ 2.25:1.0 but < 3.00:1.0 2.250% 1.250% 0.375% 5 ≥ 3.00:1.0 but < 3.50:1.0 2.500% 1.500% 0.375% 6 ≥ 3.50:1.0 but < 4.00:1.0 2.750% 1.750% 0.425% 7 ≥ 4.00:1.0 3.000% 2.000% 0.475% The Second Ciner Resources Amendment also required quarterly maintenance of a consolidated leverage ratio below those shown in the table below and a consolidated interest coverage ratio (as defined in the Ciner Resources Credit Facility) of not less than 3.00:1.0. Fiscal Quarter ending Leverage Ratio December 31, 2020 4.50:1.0 March 31, 2021 4.50:1.0 June 30, 2021 4.00:1.0 September 30, 2021 3.50:1.0 December 31, 2021 and each fiscal quarter ending thereafter 3.00:1.0 Pricing Leverage Ratio Eurodollar Rate Loans Base Rate Commitment 1 < 1.25:1.0 1.500% 0.500% 0.250% 2 ≥ 1.25:1.0 but < 1.75:1.0 1.750% 0.750% 0.275% 3 ≥ 1.75:1.0 but < 2.25:1.0 2.000% 1.000% 0.300% 4 ≥ 2.25:1.0 but < 3.00:1.0 2.250% 1.250% 0.375% 5 ≥ 3.00:1.0 but < 3.50:1.0 2.500% 1.500% 0.375% 6 ≥ 3.50:1.0 but < 4.00:1.0 2.750% 1.750% 0.425% 7 ≥ 4.00:1.0 3.000% 2.000% 0.475%

OTHER NON-CURRENT LIABILITIES (

OTHER NON-CURRENT LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]
Other Noncurrent Liabilities	Other non-current liabilities consisted of the following as of December 31: (In millions) 2020 2019 Reclamation reserve $ 7.3 $ 5.7 Derivative instruments and hedges, fair value liabilities, and other 1.4 2.9 Total $ 8.7 $ 8.6
Schedule of Reclamation Reserve	A reconciliation of the Partnership’s reclamation reserve liability is as follows: (In millions) 2020 2019 Reclamation reserve balance at beginning of year $ 5.7 $ 5.4 Accretion expense 0.3 0.3 Reclamation adjustments (1) 1.3 — Reclamation reserve balance at end of year $ 7.3 $ 5.7 (1) The reclamation costs are periodically evaluated for adjustments by the Wyoming Department of Environmental Quality. See Note 14 “Commitments and Contingencies,” “ Off-Balance Sheet Arrangements” for additional information on our reclamation reserve, including recent changes to the underlying reclamation obligation that has resulted in the asset retirement obligation reclamation adjustment.

EQUITY - BASED COMPENSATION (Ta

EQUITY - BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [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, 2020 and 2019: 2020 2019 (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 55,454 $ 20.33 71,436 $ 27.56 Granted (1) — $ — 38,402 $ 16.45 Vested (27,802) $ 22.99 (32,087) $ 27.85 Forfeited (5,715) $ 18.38 (22,297) $ 26.00 Unvested at the end of the year 21,937 $ 17.57 55,454 $ 20.33
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: 2020 2019 (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 20,173 $ 41.79 52,974 $ 42.22 Vested (7,654) 42.21 (4,766) $ 43.93 Forfeited (4,841) $ 41.53 (28,035) $ 42.24 Unvested at the end of the year 7,678 $ 41.53 20,173 $ 41.79 (1) Determined by dividing the aggregate grant date fair value of awards by the number of awards issued. The following table presents a summary of activity on the 2019 Performance Unit Awards for the years ended December 31, 2020 and 2019: Year Ended Year Ended (Units in whole numbers) Number of Common Units Grant-Date Average Fair Value per Unit (1) Number of Common Units Grant-Date Average Fair Value per Unit (1) Unvested at the beginning of period 35,908 16.45 — — Granted — $ — 38,402 16.45 Forfeited (6,851) $ 16.45 (2,494) 16.45 Unvested at the end of the period 29,057 $ 16.45 35,908 16.45 (1) Determined by dividing the weighted average price per common unit on the date of grant.
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 follows: Year Ended Year Ended Unrecognized Compensation Expense Weighted Average to be Recognized Unrecognized Compensation Expense Weighted Average to be Recognized Time Restricted Unit Awards $ 0.2 1.14 $ 0.7 1.82 TR Performance Unit Awards — 0.08 0.2 1.03 2019 Performance Unit Awards 0.1 1.08 0.4 2.09 Total $ 0.3 $ 1.3

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	Amounts recorded in accumulated other comprehensive loss as of December 31, 2020, 2019 and 2018, and changes within the period, consisted of the following: Gains and Losses on Cash Flow Hedges (In millions) Balance at January 1, 2018 $ (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 loss before reclassification 0.3 Amounts reclassified from accumulated other comprehensive loss 0.5 Net current-period other comprehensive loss 0.8 Balance at December 31, 2019 $ (3.0) Other comprehensive income before reclassification 1.3 Amounts reclassified from accumulated other comprehensive income 1.7 Net current period other comprehensive income 3.0 Balance at December 31, 2020 $ —
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) 2020 2019 2018 Unrealized gain/(loss) on derivatives: Mark to market adjustment on interest rate swap contracts $ (0.4) $ (0.5) $ (0.2) Mark to market adjustment on natural gas forward contracts 6.3 2.1 — Income/(loss) on derivative financial instruments $ 5.9 $ 1.6 $ (0.2)
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) 2020 2019 2018 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 $ 0.4 $ — $ — Interest expense Natural gas forward contracts 1.3 0.5 0.5 Cost of products sold Total reclassifications for the period $ 1.7 $ 0.5 $ 0.5

AGREEMENTS AND TRANSACTIONS W_2

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES (Tables)	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
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) 2020 2019 2018 Ciner Corp $ 16.1 $ 14.9 $ 14.6 ANSAC (1) 1.4 3.5 3.0 Total selling, general and administrative expenses - affiliates $ 17.5 $ 18.4 $ 17.6 (1) ANSAC allocates its expenses to its members using a pro-rata calculation based on sales. Net sales to affiliates were as follows: Years Ended December 31, (In millions) 2020 2019 2018 ANSAC $ 177.9 $ 315.8 $ 253.3 Total $ 177.9 $ 315.8 $ 253.3 The Partnership had accounts receivable from affiliates and due to affiliates as follows: As of December 31, (In millions) 2020 2019 2020 2019 Accounts receivable from affiliates Due to affiliates ANSAC $ 41.9 $ 53.8 $ 0.2 $ 1.6 Ciner Corp 44.6 35.7 2.6 1.4 Other — 5.5 0.1 — Total $ 86.5 $ 95.0 $ 2.9 $ 3.0

MAJOR CUSTOMERS AND SEGMENT R_2

MAJOR CUSTOMERS AND SEGMENT REPORTING (Tables)	12 Months Ended
	Dec. 31, 2020
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) 2020 2019 2018 Domestic $ 208.8 $ 207.0 $ 233.4 International 183.4 315.8 253.3 Total net sales $ 392.2 $ 522.8 $ 486.7

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 and December 31, 2019: Assets Liabilities 2020 2019 2020 2019 (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 $ 0.2 Accrued Expenses $ 0.9 Natural gas forward contracts - current Other Current Assets 1.4 Other Current Assets 0.1 Accrued Expenses 0.7 Accrued Expenses 2.4 Interest rate swap contracts - non-current — — Other non-current liabilities 1.1 — Natural gas forward contracts - non-current Other non-current assets 0.9 0.2 Other non-current liabilities 0.2 Other non-current liabilities 2.9 Total fair value of derivatives designated as hedging instruments $ 2.3 $ 0.3 $ 2.2 $ 6.2

GENERAL (Details)

GENERAL (Details)	Feb. 22, 2018	Dec. 31, 2020
Ciner Wyoming LLC | Ciner Resources LP
Variable Interest Entity [Line Items]
Membership interest		51.00%
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) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)segment	Dec. 31, 1996	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Corporate structure and ownership
Number of reportable segments | segment	1
Contract assets | $	$ 0		$ 0	$ 0
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 | Minimum
Corporate structure and ownership
Useful Life	5 years
Furniture and fixtures | Maximum
Corporate structure and ownership
Useful Life	10 years
Land | Asset Retirement Obligation
Corporate structure and ownership
Useful Life	30 years
Mining reserves | Asset Retirement Obligation
Corporate structure and ownership
Useful Life	58 years	80 years
Measurement Input, Risk Free Interest Rate | Asset Retirement Obligation
Corporate structure and ownership
Credit-adjusted, risk-free interest rate	0.06
Measurement Input, Risk Free Interest Rate | Land | Asset Retirement Obligation
Corporate structure and ownership
Credit-adjusted, risk-free interest rate	0.0425

NET INCOME PER UNIT AND CASH _3

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Ciner Resources LP	$ 11.7	$ 49.6	$ 49.9
Less: General partner’s interest in net income	0.2	1	1
Limited partners’ interest in net income	$ 11.5	$ 48.6	$ 48.9
Weighted average limited partner units outstanding:
Total weighted average limited partner units outstanding (basic) (in shares)	19.7	19.7	19.7
Total weighted average limited partner units outstanding (diluted) (in shares)	19.8	19.7	19.7
Net income per limited partner unit:
Net income per limited partner unit (basic) (in dollars per share)	$ 0.58	$ 2.46	$ 2.48
Net income per limited partner units (diluted) (in dollars per share)	$ 0.58	$ 2.46	$ 2.48
Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Limited partners’ interest in net income	$ 11.5	$ 48.6	$ 48.9
Weighted average limited partner units outstanding:
Total weighted average limited partner units outstanding (basic) (in shares)	19.7	19.7	19.7
Total weighted average limited partner units outstanding (diluted) (in shares)	19.8	19.7	19.7
Net income per limited partner unit:
Net income per limited partner unit (basic) (in dollars per share)	$ 0.58	$ 2.46	$ 2.48
Net income per limited partner units (diluted) (in dollars per share)	$ 0.58	$ 2.46	$ 2.48

NET INCOME PER UNIT AND CASH _4

NET INCOME PER UNIT AND CASH DISTRIBUTION - Allocation of Net Income (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Common unitholders’ interest in net income		$ 11.5	$ 48.6	$ 48.9
Distributions declared per unit for the year (in dollars per share)	$ 0.340	$ 0.340	$ 1.360	$ 2.268
Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distributions		$ 6.7	$ 26.8	$ 44.6
(Distributions in excess of net income)/undistributed earnings		4.8	21.8	4.3
Common unitholders’ interest in net income		$ 11.5	$ 48.6	$ 48.9

NET INCOME PER UNIT AND CASH _5

NET INCOME PER UNIT AND CASH DISTRIBUTION - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 15, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Distributions declared per unit for the year (in dollars per share)		$ 0.340	$ 0.340	$ 1.360	$ 2.268
Revolving credit facility | Ciner Resources Credit Facility | Line of Credit | Subsequent Event
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Repayments of debt	$ 8
General Partner | Ciner Resource Partners LLC
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%

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, 2020$ / shares
Minimum Quarterly Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum quarterly distribution (in dollars per share)	$ 0.5000
First Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum quarterly distribution (in dollars per share)	0.5000
Maximum quarterly distribution (in dollars per share)	0.5750
Second Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum quarterly distribution (in dollars per share)	0.5750
Maximum quarterly distribution (in dollars per share)	0.6250
Third Target Distribution
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum quarterly distribution (in dollars per share)	0.6250
Maximum quarterly distribution (in dollars per share)	0.7500
Thereafter
Schedule of Percentage Allocation of Distributions From Operating Surplus [Line Items]
Minimum quarterly distribution (in dollars per share)	$ 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, 2020	Dec. 31, 2019
Receivables [Abstract]
Trade receivables	$ 32.6	$ 30.3
Other receivables	8	5.7
Total	$ 40.6	$ 36

INVENTORY (Details)

INVENTORY (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 9.9	$ 8.7
Finished goods	13.4	6.9
Stores inventory, current	10.2	8.6
Total	$ 33.5	$ 24.2

PROPERTY, PLANT, AND EQUIPMEN_3

PROPERTY, PLANT, AND EQUIPMENT, NET (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 947.1	$ 883.5
Less accumulated depreciation, depletion and amortization	(679.9)	(676.6)
Total net book value	267.2	206.9
Total property, plant, and equipment, net	307.4	297.7
Depreciation, depletion and amortization expense	28.8
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	163.4	137.8
Computer hardware
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	5.3	4.7
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	709.8	672.4
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	40.2	90.8
Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization expense	$ 28.1	$ 26.9	$ 28.4

OTHER NON-CURRENT ASSETS (Detai

OTHER NON-CURRENT ASSETS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Stores inventory, non-current	$ 18.6	$ 17.6
Internal-use software, net of accumulated amortization	5.7	6.1
Deferred financing costs and other	1.1	0.6
Total	25.4	24.3
Property, Plant and Equipment [Line Items]
Capitalized computer software, additions	0.5	0.6	$ 6.2
Amortization of software development costs	0.7	$ 0.7	$ 0
Amortization costs per year	$ 0.8
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, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued capital expenditures	$ 1.3	$ 6.2
Accrued energy costs	5.1	5.7
Accrued royalty costs	8.1	7.1
Accrued employee compensation & benefits	7.6	7.1
Accrued other taxes	5	4.8
Accrued derivatives	0.9	3.3
Other accruals	5.6	4.9
Total	$ 33.6	$ 39.1

DEBT - Components of long-term

DEBT - Components of long-term debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt
Total debt	$ 131.1	$ 129.5
Current portion of long-term debt	3	0
Total long-term debt	$ 128.1	129.5
Ciner Wyoming Equipment Financing Arrangement | Secured Debt
Debt
Stated interest rate	2.479%
Total debt	$ 27.6	0
Ciner Wyoming Credit Facility | Revolving credit facility | Line of Credit
Debt
Total debt	$ 102.5	$ 129.5
Interest rate	2.25%	3.27%
Ciner Resources Credit Facility | Revolving credit facility | Line of Credit
Debt
Total debt	$ 1	$ 0
Interest rate	2.25%

DEBT - Maturities of long-term

DEBT - Maturities of long-term debt (Details) $ in Millions	Dec. 31, 2020USD ($)
Debt Disclosure [Abstract]
2021	$ 3
2022	106.6
2023	3.2
2024	3.3
2025	3.3
Thereafter	11.8
Total	$ 131.2

DEBT - Ciner Wyoming Equipment

DEBT - Ciner Wyoming Equipment Financing Arrangement (Details)	3 Months Ended
	Dec. 31, 2020USD ($)installment	Dec. 31, 2019USD ($)
Debt
Long-term debt, gross	$ 131,200,000
Long-term debt	131,100,000	$ 129,500,000
Secured Debt | Ciner Wyoming Equipment Financing Arrangement
Debt
Face amount	$ 30,000,000
Number of installments | installment	96
Periodic payment	$ 307,000
Number of monthly installments | installment	95
Periodic payment terms, balloon payment to be paid	$ 4,307,000
Long-term debt, gross	27,800,000
Long-term debt	27,600,000	$ 0
Secured Debt | Ciner Wyoming Equipment Financing Arrangement | Minimum
Debt
Third party indebtedness	$ 10,000,000

DEBT - Ciner Wyoming Credit Fac

DEBT - Ciner Wyoming Credit Facility (Details) - Ciner Wyoming Credit Facility	Jul. 27, 2020	Aug. 01, 2017USD ($)	Dec. 31, 2020USD ($)	Jul. 26, 2020	Feb. 28, 2020USD ($)
Revolving credit facility
Debt
Line of credit facility, maximum borrowing capacity			$ 225,000,000
Accordion feature, increase limit			$ 75,000,000
Revolving credit facility | Base Rate
Debt
Covenant interest rate floor	0.50%
Revolving credit facility | Line of Credit
Debt
Capacity available for trade purchases		$ 5,000,000			$ 30,000,000
Consolidated leverage ratio, maximum threshold for release	2
Interest coverage ratio, minimum			3
Consolidated leverage ratio, maximum threshold for restrictions	2.50			3
Consolidated leverage ratio, maximum threshold for acquisitions	2.50
Consolidated leverage ratio	3
Consolidated leverage ratio, maximum threshold for unsecured debt				3.50
Consolidated leverage ratio, minimum threshold for secured debt				3.50
Consolidated leverage ratio, minimum threshold for default				3
Change of control percentage threshold			50.10%
Revolving credit facility | Line of Credit | Ciner Wyoming LLC
Debt
Debt instrument, term		5 years
Revolving credit facility | Line of Credit | Minimum
Debt
Consolidated leverage ratio, restriction threshold	3.50
Interest rate floor			0.50%
Revolving credit facility | Line of Credit | Base Rate
Debt
Basis spread on variable rate			0.50%
Revolving credit facility | Line of Credit | LIBOR
Debt
Basis spread on variable rate			1.00%
Swing Line Advances
Debt
Line of credit facility, maximum borrowing capacity			$ 20,000,000
Letters of Credit
Debt
Line of credit facility, maximum borrowing capacity			$ 40,000,000

DEBT - Ciner Resources Credit F

DEBT - Ciner Resources Credit Facility (Details) - Line of Credit - Ciner Resources Credit Facility	Aug. 01, 2017USD ($)	Dec. 31, 2020USD ($)	Jul. 27, 2020	Jul. 26, 2020	Feb. 28, 2020USD ($)
Revolving credit facility
Debt
Line of credit facility, maximum borrowing capacity		$ 10,000,000
Capacity available for trade purchases	$ 5,000,000				$ 30,000,000
Consolidated leverage ratio			3
Consolidated leverage ratio, maximum threshold for restrictions			2.50	3
Consolidated leverage ratio, maximum threshold for acquisitions			2.50
Interest coverage ratio, minimum		3
Change of control percentage threshold		50.10%
Covenant interest rate floor		0.50%
Revolving credit facility | Ciner Resources LP
Debt
Debt instrument, term	5 years
Revolving credit facility | Base Rate
Debt
Basis spread on variable rate		0.50%
Revolving credit facility | LIBOR
Debt
Basis spread on variable rate		1.00%
Swing Line Advances
Debt
Line of credit facility, maximum borrowing capacity		$ 5,000,000
Letters of Credit
Debt
Line of credit facility, maximum borrowing capacity		$ 5,000,000

DEBT - Schedule of Debt Covenan

DEBT - Schedule of Debt Covenants: Table 1 (Details) - Revolving credit facility - Line of Credit	Jul. 27, 2020
Ciner Wyoming Credit Facility
Consolidated Leverage Ratio
December 31, 2020	4.50
March 31, 2021	4.50
June 30, 2021	4
September 30, 2021	3.50
December 31, 2021 and each fiscal quarter ending thereafter	3
Ciner Resources Credit Facility
Consolidated Leverage Ratio
December 31, 2020	4.50
March 31, 2021	4.50
June 30, 2021	4
September 30, 2021	3.50
December 31, 2021 and each fiscal quarter ending thereafter	3

DEBT - Schedule of Debt Coven_2

DEBT - Schedule of Debt Covenants: Table 2 (Details) - Revolving credit facility - Line of Credit	12 Months Ended
	Dec. 31, 2020	Jul. 27, 2020
Ciner Wyoming Credit Facility
Debt
Consolidated leverage ratio		3
Ciner Wyoming Credit Facility | Base Rate
Debt
Basis spread on variable rate	0.50%
Ciner Resources Credit Facility
Debt
Consolidated leverage ratio		3
Ciner Resources Credit Facility | Base Rate
Debt
Basis spread on variable rate	0.50%
Pricing Tier 1 | Ciner Wyoming Credit Facility
Debt
Unused capacity, commitment fee percentage	0.25%
Pricing Tier 1 | Ciner Wyoming Credit Facility | Maximum
Debt
Consolidated leverage ratio	1.25
Pricing Tier 1 | Ciner Wyoming Credit Facility | Eurodollar
Debt
Basis spread on variable rate	1.50%
Pricing Tier 1 | Ciner Wyoming Credit Facility | Base Rate
Debt
Basis spread on variable rate	0.50%
Pricing Tier 1 | Ciner Resources Credit Facility
Debt
Unused capacity, commitment fee percentage	0.25%
Pricing Tier 1 | Ciner Resources Credit Facility | Maximum
Debt
Consolidated leverage ratio	1.25
Pricing Tier 1 | Ciner Resources Credit Facility | Eurodollar
Debt
Basis spread on variable rate	1.50%
Pricing Tier 1 | Ciner Resources Credit Facility | Base Rate
Debt
Basis spread on variable rate	0.50%
Pricing Tier 2 | Ciner Wyoming Credit Facility
Debt
Unused capacity, commitment fee percentage	0.275%
Pricing Tier 2 | Ciner Wyoming Credit Facility | Maximum
Debt
Consolidated leverage ratio	1.75
Pricing Tier 2 | Ciner Wyoming Credit Facility | Minimum
Debt
Consolidated leverage ratio	1.25
Pricing Tier 2 | Ciner Wyoming Credit Facility | Eurodollar
Debt
Basis spread on variable rate	1.75%
Pricing Tier 2 | Ciner Wyoming Credit Facility | Base Rate
Debt
Basis spread on variable rate	0.75%
Pricing Tier 2 | Ciner Resources Credit Facility
Debt
Unused capacity, commitment fee percentage	0.275%
Pricing Tier 2 | Ciner Resources Credit Facility | Maximum
Debt
Consolidated leverage ratio	1.75
Pricing Tier 2 | Ciner Resources Credit Facility | Minimum
Debt
Consolidated leverage ratio	1.25
Pricing Tier 2 | Ciner Resources Credit Facility | Eurodollar
Debt
Basis spread on variable rate	1.75%
Pricing Tier 2 | Ciner Resources Credit Facility | Base Rate
Debt
Basis spread on variable rate	0.75%
Pricing Tier 3 | Ciner Wyoming Credit Facility
Debt
Unused capacity, commitment fee percentage	0.30%
Pricing Tier 3 | Ciner Wyoming Credit Facility | Maximum
Debt
Consolidated leverage ratio	2.25
Pricing Tier 3 | Ciner Wyoming Credit Facility | Minimum
Debt
Consolidated leverage ratio	1.75
Pricing Tier 3 | Ciner Wyoming Credit Facility | Eurodollar
Debt
Basis spread on variable rate	2.00%
Pricing Tier 3 | Ciner Wyoming Credit Facility | Base Rate
Debt
Basis spread on variable rate	1.00%
Pricing Tier 3 | Ciner Resources Credit Facility
Debt
Unused capacity, commitment fee percentage	0.30%
Pricing Tier 3 | Ciner Resources Credit Facility | Maximum
Debt
Consolidated leverage ratio	2.25
Pricing Tier 3 | Ciner Resources Credit Facility | Minimum
Debt
Consolidated leverage ratio	1.75
Pricing Tier 3 | Ciner Resources Credit Facility | Eurodollar
Debt
Basis spread on variable rate	2.00%
Pricing Tier 3 | Ciner Resources Credit Facility | Base Rate
Debt
Basis spread on variable rate	1.00%
Pricing Tier 4 | Ciner Wyoming Credit Facility
Debt
Unused capacity, commitment fee percentage	0.375%
Pricing Tier 4 | Ciner Wyoming Credit Facility | Maximum
Debt
Consolidated leverage ratio	3
Pricing Tier 4 | Ciner Wyoming Credit Facility | Minimum
Debt
Consolidated leverage ratio	2.25
Pricing Tier 4 | Ciner Wyoming Credit Facility | Eurodollar
Debt
Basis spread on variable rate	2.25%
Pricing Tier 4 | Ciner Wyoming Credit Facility | Base Rate
Debt
Basis spread on variable rate	1.25%
Pricing Tier 4 | Ciner Resources Credit Facility
Debt
Unused capacity, commitment fee percentage	0.375%
Pricing Tier 4 | Ciner Resources Credit Facility | Maximum
Debt
Consolidated leverage ratio	3
Pricing Tier 4 | Ciner Resources Credit Facility | Minimum
Debt
Consolidated leverage ratio	2.25
Pricing Tier 4 | Ciner Resources Credit Facility | Eurodollar
Debt
Basis spread on variable rate	2.25%
Pricing Tier 4 | Ciner Resources Credit Facility | Base Rate
Debt
Basis spread on variable rate	1.25%
Pricing Tier 5 | Ciner Wyoming Credit Facility
Debt
Unused capacity, commitment fee percentage	0.375%
Pricing Tier 5 | Ciner Wyoming Credit Facility | Maximum
Debt
Consolidated leverage ratio	3.50
Pricing Tier 5 | Ciner Wyoming Credit Facility | Minimum
Debt
Consolidated leverage ratio	3
Pricing Tier 5 | Ciner Wyoming Credit Facility | Eurodollar
Debt
Basis spread on variable rate	2.50%
Pricing Tier 5 | Ciner Wyoming Credit Facility | Base Rate
Debt
Basis spread on variable rate	1.50%
Pricing Tier 5 | Ciner Resources Credit Facility
Debt
Unused capacity, commitment fee percentage	0.375%
Pricing Tier 5 | Ciner Resources Credit Facility | Maximum
Debt
Consolidated leverage ratio	3.50
Pricing Tier 5 | Ciner Resources Credit Facility | Minimum
Debt
Consolidated leverage ratio	3
Pricing Tier 5 | Ciner Resources Credit Facility | Eurodollar
Debt
Basis spread on variable rate	2.50%
Pricing Tier 5 | Ciner Resources Credit Facility | Base Rate
Debt
Basis spread on variable rate	1.50%
Pricing Tier 6 | Ciner Wyoming Credit Facility
Debt
Unused capacity, commitment fee percentage	0.425%
Pricing Tier 6 | Ciner Wyoming Credit Facility | Maximum
Debt
Consolidated leverage ratio	4
Pricing Tier 6 | Ciner Wyoming Credit Facility | Minimum
Debt
Consolidated leverage ratio	3.50
Pricing Tier 6 | Ciner Wyoming Credit Facility | Eurodollar
Debt
Basis spread on variable rate	2.75%
Pricing Tier 6 | Ciner Wyoming Credit Facility | Base Rate
Debt
Basis spread on variable rate	1.75%
Pricing Tier 6 | Ciner Resources Credit Facility
Debt
Unused capacity, commitment fee percentage	0.425%
Pricing Tier 6 | Ciner Resources Credit Facility | Maximum
Debt
Consolidated leverage ratio	4
Pricing Tier 6 | Ciner Resources Credit Facility | Minimum
Debt
Consolidated leverage ratio	3.50
Pricing Tier 6 | Ciner Resources Credit Facility | Eurodollar
Debt
Basis spread on variable rate	2.75%
Pricing Tier 6 | Ciner Resources Credit Facility | Base Rate
Debt
Basis spread on variable rate	1.75%
Pricing Tier 7 | Ciner Wyoming Credit Facility
Debt
Unused capacity, commitment fee percentage	0.475%
Pricing Tier 7 | Ciner Wyoming Credit Facility | Minimum
Debt
Consolidated leverage ratio	4
Pricing Tier 7 | Ciner Wyoming Credit Facility | Eurodollar
Debt
Basis spread on variable rate	3.00%
Pricing Tier 7 | Ciner Wyoming Credit Facility | Base Rate
Debt
Basis spread on variable rate	2.00%
Pricing Tier 7 | Ciner Resources Credit Facility
Debt
Unused capacity, commitment fee percentage	0.475%
Pricing Tier 7 | Ciner Resources Credit Facility | Minimum
Debt
Consolidated leverage ratio	4
Pricing Tier 7 | Ciner Resources Credit Facility | Eurodollar
Debt
Basis spread on variable rate	3.00%
Pricing Tier 7 | Ciner Resources Credit Facility | Base Rate
Debt
Basis spread on variable rate	2.00%

DEBT - WE Soda and Ciner Enterp

DEBT - WE Soda and Ciner Enterprises Facilities Agreement (Details)	Dec. 31, 2020
WE Soda and Ciner Enterprises Facilities Agreement
Debt
Commitment percentage threshold	66.66%

OTHER NON-CURRENT LIABILITIES_2

OTHER NON-CURRENT LIABILITIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Reclamation reserve	$ 7.3	$ 5.4	$ 7.3	$ 5.7
Derivative instruments and hedges, fair value liabilities, and other			1.4	2.9
Total			8.7	8.6
Reclamation reserve
Reclamation reserve balance at beginning of year	5.7	5.4
Accretion expense	0.3	0.3
Reclamation adjustments			$ 1.3	$ 0
Reclamation reserve balance at end of year	$ 7.3	$ 5.7

EMPLOYEE COMPENSATION (Details)

EMPLOYEE COMPENSATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
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	$ 55.1	$ 54.8
Net periodic pension (benefit) cost	(1.3)	1	$ 0.4
Savings Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions by Ciner Corp	3.4	3	2.8
Postretirement benefit
Defined Benefit Plan Disclosure [Line Items]
Net funded liability	13.1	13.8
Net periodic pension (benefit) cost	$ 1.2	$ (2.2)	$ (2.9)

EQUITY - BASED COMPENSATION - N

EQUITY - BASED COMPENSATION - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	700,000
2019 Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0	38,402
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0	38,402
Vested (in dollars per share)	$ 22.99	$ 27.85
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 | Minimum | 2019 Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
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%
TSR Unit Performance Awards | Maximum | 2019 Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range	200.00%
Director | Common Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Director awards, vested in period, fair value	$ 0.2	$ 0.2
Director - Non-Employee | Common Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	21,720	8,832
Vested (in dollars per share)	$ 9.88	$ 25.48

EQUITY - BASED COMPENSATION - R

EQUITY - BASED COMPENSATION - Restricted Unit Award and Total Return Performance Unit Award Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Restricted Stock Units (RSUs)
Number of Units
Unvested beginning of period (in shares)	55,454	71,436
Granted (in shares)	0	38,402
Vested (in shares)	(27,802)	(32,087)
Forfeited (in shares)	(5,715)	(22,297)
Unvested at end of period (in shares)	21,937	55,454
Grant-Date Average Fair Value per Unit
Unvested at the beginning of year (in dollars per share)	$ 20.33	$ 27.56
Granted (in dollars per share)	0	16.45
Vested (in dollars per share)	22.99	27.85
Forfeited (in dollars per share)	18.38	26
Unvested at the end of the year (in dollars per share)	$ 17.57	$ 20.33
Total Return Performance Unit Awards | TSR Unit Performance Awards
Number of Units
Unvested beginning of period (in shares)	20,173	52,974
Vested (in shares)	(7,654)	(4,766)
Forfeited (in shares)	(4,841)	(28,035)
Unvested at end of period (in shares)	7,678	20,173
Grant-Date Average Fair Value per Unit
Unvested at the beginning of year (in dollars per share)	$ 41.79	$ 42.22
Vested (in dollars per share)	42.21	43.93
Forfeited (in dollars per share)	41.53	42.24
Unvested at the end of the year (in dollars per share)	$ 41.53	$ 41.79
2019 Performance Unit Awards
Number of Units
Unvested beginning of period (in shares)	35,908	0
Granted (in shares)	0	38,402
Forfeited (in shares)	(6,851)	(2,494)
Unvested at end of period (in shares)	29,057	35,908
Grant-Date Average Fair Value per Unit
Unvested at the beginning of year (in dollars per share)	$ 16.45	$ 0
Granted (in dollars per share)	0	16.45
Forfeited (in dollars per share)	16.45	16.45
Unvested at the end of the year (in dollars per share)	$ 16.45	$ 16.45

EQUITY - BASED COMPENSATION - U

EQUITY - BASED COMPENSATION - Unrecognized Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized Compensation Expense	$ 0.3	$ 1.3
Time-based units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized Compensation Expense	$ 0.2	$ 0.7
Weighted Average to be Recognized	1 year 1 month 20 days	1 year 9 months 25 days
Total Return Performance Unit Awards | Performance-based units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized Compensation Expense	$ 0	$ 0.2
Weighted Average to be Recognized	29 days	1 year 10 days
2019 Performance Unit Awards | Performance-based units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized Compensation Expense	$ 0.1	$ 0.4
Weighted Average to be Recognized	1 year 29 days	2 years 1 month 2 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, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 299.9	$ 260.1	$ 248.2
Net current-period other comprehensive loss	5.9	1.6	(0.2)
Ending balance	305.3	299.9	260.1
Gains and Losses on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(3.8)	(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)
Ending balance			$ (3.8)
Gains and Losses on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3)
Other comprehensive loss before reclassification	1.3	0.3
Amounts reclassified from accumulated other comprehensive loss	1.7	0.5
Net current-period other comprehensive loss	3	0.8
Ending balance	$ 0	$ (3)

ACCUMULATED OTHER COMPREHENSI_4

ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, before tax	$ 5.9	$ 1.6
Other comprehensive income (loss), derivatives qualifying as hedges, before tax			$ (0.2)
Interest rate swap contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, before tax	(0.4)	(0.5)
Other comprehensive income (loss), derivatives qualifying as hedges, before tax			(0.2)
Commodity contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, before tax	$ 6.3	$ 2.1
Other comprehensive income (loss), derivatives qualifying as hedges, before tax			$ 0

ACCUMULATED OTHER COMPREHENSI_5

ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of Other Comprehensive Income/(Loss) Reclassified (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 5.3	$ 5.9	$ 5.1
Cost of products sold	185.6	221.4	215.9
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period	1.7	0.5	0.5
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
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	0.4	0
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
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	$ 1.3	$ 0.5

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions	Jun. 28, 2018	Jan. 03, 2017	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 01, 2021
Other Commitments [Line Items]
Lease liability payments due				$ 1.6
Lease expense				11.3	$ 11.8	$ 13.9
Purchase Obligation, Fiscal Year Maturity [Abstract]
Average annual cost				$ 4
Self-bond agreement for reclamation costs
Purchase Obligation, Fiscal Year Maturity [Abstract]
Off balance sheet commitment					$ 36.2
Self-bond agreement for reclamation costs | Subsequent Event
Purchase Obligation, Fiscal Year Maturity [Abstract]
Off balance sheet commitment							$ 41.8
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
Commodity
Other Commitments [Line Items]
Leases term				4 years
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation				$ 25.9
Purchase obligation, due in 2021				14.5
Purchase obligation, due in 2022				6.2
Purchase obligation, due in 2023				4.3
Purchase obligation, due in 2024				0.9
Purchase obligation, due in 2025				0
Rail Car Lease
Other Commitments [Line Items]
2021				9.7
2022				6.7
2023				3.4
2024				2.3
2025				2
Thereafter				$ 2.1
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
Litigation settlement receivable	$ 27.5
Royalty rate	8.00%
Settlement payment			$ 27.5	$ 27.5

AGREEMENTS AND TRANSACTIONS W_3

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES - Narrative (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
ANSAC | Revenue from Contract with Customer Benchmark | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	45.40%	60.40%	52.00%

AGREEMENTS AND TRANSACTIONS W_4

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES - Costs Charged by Affiliates (Details) - Costs Charged by Affiliates - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Total selling, general and administrative expenses - affiliates	$ 17.5	$ 18.4	$ 17.6
Ciner Corp
Related Party Transaction [Line Items]
Total selling, general and administrative expenses - affiliates	16.1	14.9	14.6
ANSAC
Related Party Transaction [Line Items]
Total selling, general and administrative expenses - affiliates	$ 1.4	$ 3.5	$ 3

AGREEMENTS AND TRANSACTIONS W_5

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES - Net Sales to Affiliates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Sales - affiliates	$ 177.9	$ 315.8	$ 253.3
Net Sales to Affiliates
Related Party Transaction [Line Items]
Sales - affiliates	177.9	315.8	253.3
Net Sales to Affiliates | ANSAC
Related Party Transaction [Line Items]
Sales - affiliates	$ 177.9	$ 315.8	$ 253.3

AGREEMENTS AND TRANSACTIONS W_6

AGREEMENTS AND TRANSACTIONS WITH AFFILIATES - Receivables From or Payables to Affiliates (Details) - Receivables and Payables with Affiliates - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Accounts receivable from affiliates	$ 86.5	$ 95
Due to affiliates	2.9	3
Ciner Corp
Related Party Transaction [Line Items]
Accounts receivable from affiliates	44.6	35.7
Due to affiliates	2.6	1.4
ANSAC
Related Party Transaction [Line Items]
Accounts receivable from affiliates	41.9	53.8
Due to affiliates	0.2	1.6
Other
Related Party Transaction [Line Items]
Accounts receivable from affiliates	0	5.5
Due to affiliates	$ 0.1	$ 0

MAJOR CUSTOMERS AND SEGMENT R_3

MAJOR CUSTOMERS AND SEGMENT REPORTING - Narrative (Details)	12 Months Ended
	Dec. 31, 2020segment
Segment Reporting [Abstract]
Number of operating segments	1

MAJOR CUSTOMERS AND SEGMENT R_4

MAJOR CUSTOMERS AND SEGMENT REPORTING - Sales by geographic area (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Sales by geographical area
Net sales	$ 392.2	$ 522.8	$ 486.7
Domestic
Sales by geographical area
Net sales	208.8	207	233.4
International
Sales by geographical area
Net sales	$ 183.4	$ 315.8	$ 253.3

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details)	Dec. 31, 2020USD ($)swap	Dec. 31, 2019USD ($)swap	Dec. 31, 2018USD ($)
Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of swap contracts | swap	3	4
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total derivatives designated as hedging instruments	$ 2,300,000	$ 300,000
Total derivatives designated as hedging instruments	2,200,000	6,200,000
Fair Value, Measurements, Recurring | Natural gas forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, notional amount	25,900,000	31,200,000
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	1,400,000	100,000
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	200,000	900,000
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	700,000	2,400,000
Other Noncurrent Assets | Fair Value, Measurements, Recurring | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, noncurrent	0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring | Natural gas forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, noncurrent	900,000		$ 200,000
Other non-current liabilities | Fair Value, Measurements, Recurring | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, noncurrent	1,100,000	0
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	200,000	2,900,000
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	12,500,000
Derivative, notional amount	$ 37,500,000	$ 50,000,000

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) $ in Millions	Mar. 15, 2021USD ($)
Revolving credit facility | Line of Credit | Ciner Resources Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Repayments of debt	$ 8