Compass Minerals International (CMP) 10-K 26 Feb 21 2020 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 23, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Current Fiscal Year End Date	--12-31
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	001-31921
Entity Registrant Name	Compass Minerals International, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-3972986
Entity Address, Address Line One	9900 West 109th Street, Suite 100
Entity Address, Postal Zip Code	66210
Entity Address, City or Town	Overland Park,
Entity Address, State or Province	KS
City Area Code	913
Local Phone Number	344-9200
Title of 12(b) Security	Common stock, $0.01 par value
Trading Symbol	CMP
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,653,658,110
Entity Common Stock, Shares Outstanding		33,974,215
Documents Incorporated by Reference	Document Parts into which Incorporated Portions of the Proxy Statement for the Annual Meeting of Stockholders to be held May 18, 2021 Part III, Items 10, 11, 12, 13 and 14
Entity Central Index Key	0001227654
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 21	$ 34.7
Receivables, less allowance for doubtful accounts of $11.1 in 2020 and $10.7 in 2019	296.7	342.4
Inventories	370.6	311.5
Other	68.9	96.4
Total current assets	757.2	785
Property, plant and equipment, net	964.9	1,030.8
Intangible assets, net	85	103
Goodwill	281.3	343
Investment in equity investee	20	24.9
Other	154	156.5
Total assets	2,262.4	2,443.2
Current liabilities:
Current portion of long-term debt	63.7	52.1
Accounts payable	116.8	126.2
Accrued salaries and wages	38.7	34.4
Income taxes payable	5.5	10.4
Accrued interest	10.4	11.3
Accrued expenses and other current liabilities	61.2	61.5
Total current liabilities	296.3	295.9
Long-term debt, net of current portion	1,337.7	1,363.9
Deferred income taxes, net	87.5	89.9
Other noncurrent liabilities	153.9	163.9
Commitments and contingencies (Note 12)
Stockholders' equity:
Common stock: $0.01 par value, 200,000,000 authorized shares; 35,367,264 issued shares	0.4	0.4
Additional paid-in capital	127	117.1
Treasury stock, at cost — 1,407,926 shares at December 31, 2020 and 1,481,611 shares at December 31, 2019	(4.4)	(3.2)
Retained earnings	567.3	607.4
Accumulated other comprehensive loss	(303.3)	(192.1)
Total stockholders' equity	387	529.6
Total liabilities and stockholders' equity	$ 2,262.4	$ 2,443.2

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Allowance for doubtful accounts	$ 11.1	$ 10.7
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	35,367,264	35,367,264
Treasury stock, shares (in shares)	1,407,926	1,481,611

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Sales	$ 1,373.5	$ 1,490.5	$ 1,493.6
Gross profit	312.3	336.8	293.9
Selling, general and administrative expenses	171.8	173.2	163.6
Operating earnings	140.5	163.6	130.3
Other expense (income):
Interest expense	71.2	68.4	62.5
Net earnings in equity investee	(1.4)	(0.7)	(1)
(Gain) loss on foreign exchange	(0.4)	13	(5.8)
Other, net	(0.1)	(1.7)	(3)
Earnings before income taxes	71.2	84.6	77.6
Income tax expense	11.7	22.1	8.8
Net earnings	$ 59.5	$ 62.5	$ 68.8
Basic net earnings per common share (in dollars per share)	$ 1.72	$ 1.82	$ 2.02
Diluted net earnings per common share (in dollars per share)	$ 1.72	$ 1.81	$ 2.02
Weighted-average common shares outstanding (in thousands):
Basic (in shares)	33,928	33,882	33,848
Diluted (in shares)	33,928	33,882	33,848
Shipping and handling cost
Cost of goods and services	$ 266.6	$ 312.5	$ 320
Product cost
Cost of goods and services	$ 794.6	$ 841.2	$ 879.7

Consolidated Statements of Comp

Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net earnings	$ 59.5	$ 62.5	$ 68.8
Other comprehensive (loss) income:
Unrealized loss from change in pension costs, net of tax of $0.8, $0.5 and $0.1 in 2020, 2019 and 2018, respectively	(2.5)	(2.4)	(0.6)
Unrealized gain on cash flow hedges, net of tax of $(0.3), $(0.1) and $(0.2) in 2020, 2019 and 2018, respectively	0.8	0.1	0.4
Cumulative translation adjustment	(109.5)	21.1	(132.6)
Comprehensive (loss) income	$ (51.7)	$ 81.3	$ (64)

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive (Loss) Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Unrealized loss from change in pension costs, tax	$ 0.8	$ 0.5	$ 0.1
Unrealized gain on cash flow hedges, tax	$ (0.3)	$ (0.1)	$ (0.2)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative effect of change in accounting principle	Common Stock	Additional Paid-In Capital	Treasury Stock	Retained Earnings	Retained EarningsCumulative effect of change in accounting principle	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2017	$ 694.6		$ 0.4	$ 102.5	$ (2.9)	$ 672.5		$ (77.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	$ (64)					68.8		(132.8)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Stranded tax effect from tax reform	$ 0					0.2		(0.2)
Dividends on common stock/equity awards	(97.7)			0.3		(98)
Stock-based compensation	7.3			7.3
Ending balance at Dec. 31, 2018	540.2	$ (0.1)	0.4	110.1	(2.9)	643.5	$ (0.1)	(210.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	81.3					62.5		18.8
Dividends on common stock/equity awards	(98.1)			0.4		(98.5)
Stock-based compensation	6.6			6.6
Shares issued for stock units, net of shares withheld for taxes	(0.3)				(0.3)
Ending balance at Dec. 31, 2019	529.6		0.4	117.1	(3.2)	607.4		(192.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	(51.7)					59.5		(111.2)
Dividends on common stock/equity awards	(99.1)			0.5		(99.6)
Stock-based compensation	9.4			9.4
Shares issued for stock units, net of shares withheld for taxes	(1.1)				(1.1)
Stock options exercised, net of shares withheld for taxes	(0.1)				(0.1)
Ending balance at Dec. 31, 2020	$ 387		$ 0.4	$ 127	$ (4.4)	$ 567.3		$ (303.3)

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends on common stock/equity awards (in dollars per share)	$ 2.88	$ 2.88	$ 2.88

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 earnings	$ 59.5	$ 62.5	$ 68.8
Adjustments to reconcile net earnings to net cash flows provided by operating activities:
Depreciation, depletion and amortization	137.9	137.9	136.9
Finance fee amortization	3.2	2.8	2.2
Refinancing of long-term debt	0.1	0.3	0
Stock-based compensation	9.4	6.3	7.8
Deferred income taxes	5.4	(11.8)	(16.7)
Net earnings in equity investee	(1.4)	(0.7)	(1)
Unrealized foreign exchange (gain) loss	(2.8)	15	0.1
Other, net	6.8	7.2	4.1
Changes in operating assets and liabilities:
Receivables	19.5	(31.3)	16.4
Inventories	(71.4)	(45.4)	(16.8)
Other assets	21.1	23.9	(18.4)
Accounts payable and accrued expenses and other current liabilities	(3.7)	(12.1)	21.1
Other liabilities	(8.4)	5	(22.2)
Net cash provided by operating activities	175.2	159.6	182.3
Cash flows from investing activities:
Capital expenditures	(84.9)	(98.1)	(96.8)
Other, net	(3.3)	(2.3)	(2.8)
Net cash used in investing activities	(88.2)	(100.4)	(99.6)
Cash flows from financing activities:
Proceeds from revolving credit facility borrowings	300	574.1	457.4
Principal payments on revolving credit facility borrowings	(329.7)	(611.1)	(429.1)
Proceeds from issuance of long-term debt	115.8	1,001.8	54.3
Principal payments on long-term debt	(79.2)	(902.8)	(68.1)
Dividends paid	(99.1)	(98.1)	(97.7)
Deferred financing costs	(1)	(12.8)	(1.7)
Shares withheld to satisfy employee tax obligations	(1.1)	(0.3)	0
Other, net	(1.9)	(1.3)	(1)
Net cash used in financing activities	(96.2)	(50.5)	(85.9)
Effect of exchange rate changes on cash and cash equivalents	(4.5)	(1)	(6.4)
Net change in cash and cash equivalents	(13.7)	7.7	(9.6)
Cash and cash equivalents, beginning of the year	34.7	27	36.6
Cash and cash equivalents, end of period	21	34.7	27
Supplemental cash flow information:
Interest paid, net of amounts capitalized	65	60.7	52.1
Income taxes paid, net of refunds	$ (10.3)	$ 33.9	$ 38.3

ORGANIZATION AND FORMATION

ORGANIZATION AND FORMATION	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION AND FORMATION	ORGANIZATION AND FORMATION Compass Minerals International, Inc. (“CMI”), through its subsidiaries (collectively, “CMP,” “Compass Minerals” or the “Company”), is a leading producer of essential minerals focused on safely delivering where and when it matters to help solve nature’s challenges for customers and communities. Its salt products help keep roadways safe during winter weather and are used in numerous other consumer, industrial and agricultural applications. Its plant nutrition business manufactures an innovative and diverse portfolio of products that improve the quality and yield of crops, while supporting sustainable agriculture. Additionally, its specialty chemical business serves the water treatment industry and other industrial processes. The Company’s principal products are salt, consisting of sodium chloride and magnesium chloride, sulfate of potash (“SOP”), secondary nutrients and micronutrients; and specialty chemicals. The Company’s production sites are located in the United States (“U.S.”), Canada, Brazil and the United Kingdom (“U.K.”). The Company also provides records management services in the U.K. CMI is a holding company with no operations other than those of its subsidiaries.

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 a. Management Estimates: The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (“GAAP”) as included in the Accounting Standards Codification requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. b. Basis of Consolidation: The Company’s consolidated financial statements include the accounts of CMI and its wholly-owned domestic and foreign subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. c. Reclassifications: The Company has made reclassifications of prior year amounts in Consolidated Statements of Operations to conform to current year presentation. d. Foreign Currency: Assets and liabilities are translated into U.S. dollars at end of period exchange rates. Revenues and expenses are translated using the monthly average rates of exchange during the year. Adjustments resulting from the translation of foreign-currency financial statements into the reporting currency, U.S. dollars, are included in accumulated other comprehensive loss. The Company recorded foreign exchange losses of $(72.6) million, $(1.2) million and $(56.5) million in 2020, 2019 and 2018, respectively, in accumulated other comprehensive loss related to intercompany notes which were deemed to be of long-term investment nature. Aggregate exchange (gains) losses from transactions denominated in a currency other than the functional currency, which are included in other expense (income), for the years ended December 31, 2020, 2019 and 2018, were $(0.4) million, $13.0 million and $(5.8) million, respectively. e. Revenue Recognition: The Financial Accounting Standards Board (the “FASB”) revenue recognition guidance provides a single, comprehensive model for recognizing revenue from contracts with customers. The revenue recognition model requires revenue to be recognized upon the transfer of promised goods or services to customers in an amount that reflects the consideration an entity expects to receive in exchange for those goods or services. The Company’s revenue arrangements generally consist of a single performance obligation to transfer promised goods or services. Accordingly, substantially all of the Company’s revenue is recognized at a point in time when control of the goods transfers to the customer. The Company typically recognizes revenue at the time of shipment to the customer, which coincides with the transfer of title and risk of ownership to the customer. Sales represent billings to customers net of sales taxes charged for the sale of the product. Sales include amounts charged to customers for shipping and handling costs, which are expensed when the related product is sold. f. Cash and Cash Equivalents: The Company considers all investments with original maturities of three months or less to be cash equivalents. The Company maintains the majority of its cash in bank deposit accounts with several commercial banks with high credit ratings in the U.S., Canada, Brazil and Europe. Typically, the Company has bank deposits in excess of federally insured limits. Currently, the Company does not believe it is exposed to significant credit risk on its cash and cash equivalents. g. Accounts Receivable and Allowance for Doubtful Accounts: Receivables consist almost entirely of trade accounts receivable. Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in its existing trade accounts receivable. The Company determines the allowance based on historical write-off experience by business line and a current assessment of its portfolio, including information regarding individual customers. The Company reviews its past due account balances for collectability and adjusts its allowance for doubtful accounts accordingly. Account balances are charged off against the allowance when the Company believes it is probable that the trade accounts receivable will not be recovered. During 2020, the Company sold approximately $22.1 million of Brazilian trade accounts receivable for $21.0 million. The proceeds of the transaction were used to maintain liquidity for working capital needs. The Company is contingently liable for up to 20% of the sale balance up to $4.1 million if the banks are unable to collect on these accounts. During 2019, the Company sold approximately $16.4 million of trade accounts receivable for $15.6 million. The proceeds of these transactions were used to refinance Brazilian loans (see Note 10 ). The Company is contingently liable for up to 20% of the sale balance up to $2.7 million if the banks are unable to collect on these accounts. During 2018, the Company sold approximately $32.7 million of trade accounts receivable for $30.4 million. The Company does not believe the amount which may ultimately be payable for any unpaid receivables to be material to its consolidated financial statements. The Company has no further involvement with these accounts. h. Inventories: Inventories are stated at the lower of cost or net realizable value. Finished goods and raw material and supply costs are valued using the average cost method on a first-in-first-out basis. Raw materials and supply costs primarily consist of raw materials purchased to aid in the production of mineral and chemical products, maintenance materials and packaging materials. Finished goods are primarily comprised of salt, magnesium chloride, and plant nutrition and chemical products readily available for sale. Substantially all costs associated with the production of finished goods at the Company’s production locations are captured as inventory costs. As required by U.S. GAAP, a portion of the fixed costs at a location are not included in inventory and are expensed as a product cost if production at that location is determined to be abnormally low in any period. Additionally, since the Company’s products are often stored at third-party warehousing locations, the Company includes in the cost of inventory the freight and handling costs necessary to move the product to storage until the product is sold to a customer. i. Other Current Assets: In the fourth quarter of 2015, the Company began marketing certain assets used in farming operations. Management remains committed to sell these assets, and the assets continue to be marketed at a reasonable price. The Company has performed an impairment analysis and concluded that the fair market value of these assets exceeds their carrying value. These assets have been recorded in other current assets in the Consolidated Balance Sheets as of December 31, 2020 and 2019. The amounts classified as held for sale as of December 31, 2020 and 2019, of $6.8 million and $7.2 million, respectively, include water rights of approximately $5.2 million with the remaining balance consisting of property, plant and equipment. In February 2021, the Company completed the sale of the remaining assets and any gain or loss recognized is expected to be immaterial. In addition, other current assets as of December 31, 2020 and 2019, include $2.8 million and $58.3 million, respectively, of tax refunds from U.S. taxing authorities pursuant to the tax settlement with Canadian and U.S. tax authorities described in Note 8 . The remaining other amounts included in other current assets as of December 31, 2020 and 2019, respectively, consist principally of prepaid expenses. j. Property, Plant and Equipment: Property, plant and equipment is stated at cost and includes capitalized interest. The costs of replacements or renewals, which improve or extend the life of existing property, are capitalized. Maintenance and repairs are expensed as incurred. Upon retirement or disposition of an asset, any resulting gain or loss is included in the Company’s operating results. Property, plant and equipment also includes mineral interests. The mineral interests for the Company’s Winsford U.K. mine are owned. The Company leases probable mineral reserves at its Cote Blanche and Goderich mines, its Ogden facility and several of its other North American facilities. These leases have varying terms, and many provide for a royalty payment to the lessor based on a specific amount per ton of mineral extracted or as a percentage of sales. The Company’s rights to extract minerals are contractually limited by time. The Cote Blanche mine is operated under land and mineral leases, and the mineral lease expires in 2060 with two additional 25-year renewal periods. The Goderich mine mineral reserve lease expires in 2022 with the Company’s option to renew until 2043 after demonstrating to the lessor that the mine’s useful life is greater than the lease’s term. The Ogden facility mineral reserve lease renews annually. The Company believes it will be able to continue to extend lease agreements as it has in the past, at commercially reasonable terms, without incurring substantial costs or material modifications to the existing lease terms and conditions, and therefore, management believes that assigned lives are appropriate. The Company’s mineral interests are depleted on a units-of-production basis based upon the latest available mineral study. The weighted average amortization period for the leased probable mineral reserves is 90 years as of December 31, 2020. The Company also owns other mineral properties. The weighted average life for the probable owned mineral reserves is 36 years as of December 31, 2020, based upon management’s current production estimates. Buildings and structures are depreciated on a straight-line basis over lives generally ranging from 10 to 30 years. Portable buildings generally have shorter lives than permanent structures. Leasehold and building improvements typically have shorter estimated lives of 5 to 20 years or lower based on the life of the lease to which the improvement relates. The Company’s fixed assets are amortized on a straight-line basis over their respective lives. The following table summarizes the estimated useful lives of the Company’s different classes of property, plant and equipment: Years Land improvements 10 to 25 Buildings and structures 10 to 30 Leasehold and building improvements 2 to 40 Machinery and equipment – vehicles 2 to 10 Machinery and equipment – other mining and production 2 to 50 Office furniture and equipment 2 to 10 Mineral interests 20 to 99 The Company has finance leases which are recorded in property, plant and equipment at the beginning of the lease at the lower of the fair value of the leased property or the present value of the minimum lease payments. Lease payments are recorded as interest expense and a reduction of the lease liability. A finance lease asset is depreciated over the lower of its useful life or the lease term. The Company has capitalized computer software costs of $13.4 million and $16.0 million as of December 31, 2020 and 2019, respectively, recorded in property, plant and equipment. The capitalized costs are being amortized over five years. The Company recorded $5.8 million, $6.6 million and $7.3 million of amortization expense related to capitalized computer software for 2020, 2019 and 2018, respectively. The Company recognizes and measures obligations related to the retirement of tangible long-lived assets in accordance with applicable U.S. GAAP. Asset retirement obligations are not material to the Company’s consolidated financial position, results of operations or cash flows. The Company reviews its long-lived assets and the related mineral reserves for impairment whenever events or changes in circumstances indicate the carrying amounts of such assets may not be recoverable. If an indication of a potential impairment exists, recoverability of the respective assets is determined by comparing the forecasted undiscounted net cash flows of the operation to which the assets relate, to the carrying amount, including associated intangible assets, of such operation. If the operation is determined to be unable to recover the carrying amount of its assets, then intangible assets are written down first, followed by the other long-lived assets of the operation, to fair value. Fair value is determined based on discounted cash flows or appraised values, depending upon the nature of the assets. k. Leases: In February 2016, the FASB issued guidance which requires lessees to recognize on their balance sheet a right-of-use asset which represents a lessee’s right to use the underlying asset, and a lease liability which represents a lessee’s obligation to make lease payments for the right to use the asset. In addition, the guidance requires expanded qualitative and quantitative disclosures. The Company adopted this guidance on January 1, 2019, using a modified retrospective transition method, which required the cumulative effect of this change in accounting of $0.1 million to be recorded as an adjustment to beginning retained earnings. The Company elected the transition provisions available for existing contracts, which allowed entities to carryforward the historical assessment of whether the contract contained a lease and the lease classification. Refer to Note 4 for additional details. l. Goodwill and Intangible Assets: The Company amortizes its intangible assets deemed to have finite lives on a straight-line basis over their estimated useful lives which, for the Company, range from 4 to 50 years. The Company reviews goodwill and other indefinite-lived intangible assets annually for impairment. In addition, goodwill and other intangible assets are reviewed when an event or change in circumstances indicates the carrying amounts of such assets may not be recoverable. m. Investments: The Company uses the equity method of accounting for equity securities when it has significant influence or when it has more than a minor ownership interest or more than minor influence over an investee’s operations but does not have a controlling financial interest. Initial investments are recorded at cost (including certain transaction costs) and are adjusted by the Company’s share of the investees’ undistributed earnings and losses. The Company may recognize its share of an investee’s earnings on a lag, if an investee’s financial results are not available in a timely manner. The Company’s Brazilian subsidiary holds a 50% interest in Fermavi Eletroquímica Ltda. (“Fermavi”). Fermavi, which was founded in 1987, is a Brazilian corporation with headquarters in Varginha, Minas Gerais, Brazil, and its operations focus on the production and sale of manganese-based products. The Company’s investment in Fermavi was recorded at its estimated fair value in conjunction with the purchase price allocation as of the date the Company completed the full acquisition of Compass Minerals América do Sul Indústria e Comércio Ltda. (“Compass Minerals South America”), which was in excess of the book value of net assets acquired. This basis difference was approximately $2 million and $4 million as of December 31, 2020 and 2019, respectively. The portion of the basis differences related to tangible and intangible assets is amortized over their remaining useful lives, as appropriate. The Company accounts for its investment in Fermavi under the equity method of accounting. n. Other Noncurrent Assets: Other noncurrent assets include certain inventories of spare parts and related inventory, net of reserve, of $27.9 million and $31.0 million at December 31, 2020 and 2019, respectively, which will be utilized with respect to long-lived assets. As of December 31, 2020 and 2019, other noncurrent assets also include net operating lease assets of $55.6 million and $53.7 million, respectively. The Company sponsors a non-qualified defined contribution plan for certain of its executive officers and key employees as described in Note 9 . As of December 31, 2020 and 2019, investments in marketable securities representing amounts deferred by employees, Company contributions and unrealized gains or losses totaling $1.9 million and $1.4 million, respectively, were included in other noncurrent assets in the Consolidated Balance Sheets. The marketable securities are classified as trading securities and accordingly, gains and losses are recorded as a component of other expense (income), net in the Consolidated Statements of Operations. o. Income Taxes: The Company accounts for income taxes using the liability method in accordance with the provisions of GAAP. Under the liability method, deferred taxes are determined based on the differences between the consolidated financial statements and the tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. The Company’s foreign subsidiaries file separate company returns in their respective jurisdictions. The Company recognizes potential liabilities in accordance with applicable GAAP for anticipated tax issues in the U.S. and other tax jurisdictions based on its estimate of whether, and the extent to which, additional taxes will be due. If payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities would result in tax benefits being recognized in the period when the Company determines the liabilities are no longer necessary. If the Company’s estimate of tax liabilities proves to be less than the ultimate assessment, a further charge to expense would result. Any penalties and interest that are accrued on the Company’s uncertain tax positions are included as a component of income tax expense. In evaluating the Company’s ability to realize deferred tax assets, the Company considers the sources and timing of taxable income, including the reversal of existing temporary differences, the ability to carryback tax attributes to prior periods, qualifying tax-planning strategies, and estimates of future taxable income exclusive of reversing temporary differences. In determining future taxable income, the Company’s assumptions include the amount of pre-tax operating income according to different state, federal and international taxing jurisdictions, the origination of future temporary differences, and the implementation of feasible and prudent tax-planning strategies. If the Company determines that a portion of its deferred tax assets will not be realized, a valuation allowance is recorded in the period that such determination is made. In the future, if the Company determines, based on the existence of sufficient evidence, that more or less of the deferred tax assets are more likely than not to be realized, an adjustment to the valuation allowance will be made in the period such a determination is made. As discussed in Note 8 , on December 22, 2017, the U.S. enacted the Tax Cuts and Jobs Act (the “Act”) which subjects U.S. shareholders, including the Company, to tax on Global Intangible Low-Taxed Income (“GILTI”) earned by certain foreign subsidiaries. The FASB issued guidance stating that an entity can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or to provide for the tax expense related to GILTI in the year the tax is incurred as a period expense only. The Company has elected to account for GILTI as a period expense only. p. Environmental Costs: Environmental costs, other than those of a capital nature, are accrued at the time the exposure becomes known and costs can be reasonably estimated. Costs are accrued based upon management’s estimates of all direct costs. Amounts reserved for environmental matters were not material at December 31, 2020 or 2019. q. Equity Compensation Plans: The Company has equity compensation plans under the oversight of the Company’s Board of Directors, whereby stock options, restricted stock units, performance stock units, deferred stock units and shares of common stock are granted to the Company’s employees and directors. See Note 13 for additional discussion. r. Earnings per Share: When calculating earnings per share, the Company’s participating securities are accounted for under the two-class method. The two-class method requires allocating the Company’s net earnings to both common shares and participating securities based upon their rights to receive dividends. Basic earnings per share is computed by dividing net earnings available to common stockholders by the weighted-average number of outstanding common shares during the period. Diluted earnings per share reflects the potential dilution that could occur under the more dilutive of either the treasury stock method or the two-class method for calculating the weighted-average number of outstanding common shares. The treasury stock method is calculated assuming unrecognized compensation expense, income tax benefits and proceeds from the potential exercise of employee stock options are used to repurchase common stock. s. Derivatives: The Company is exposed to the impact of fluctuations in foreign exchange and interest rates on its borrowings and fluctuations in the purchase price of natural gas consumed in operations. The Company hedges portions of these risks through the use of derivative agreements. The Company records derivative financial instruments as assets or liabilities measured at fair value. Accounting for the changes in the fair value of a derivative depends on its designation and effectiveness. Derivatives qualify for treatment as hedges when there is a high correlation between the change in fair value of the derivative instrument and the related change in value of the underlying hedged item. For qualifying hedges, the effective portion of the change in fair value is recognized through earnings when the underlying transaction being hedged affects earnings, allowing a derivative’s gains and losses to offset related results from the hedged item in the Consolidated Statements of Operations. Until the effective portion of a derivative’s change in fair value is recognized in the Consolidated Statements of Operations, the change in fair value is recognized in other comprehensive income. For derivative instruments that are not accounted for as hedges, or for the ineffective portions of qualifying hedges, the change in fair value is recorded through earnings in the period of change. The Company formally documents, designates and assesses the effectiveness of transactions that receive hedge accounting treatment initially and on an ongoing basis. t. Concentration of Credit Risk: The Company sells its salt and magnesium chloride products to various governmental agencies, manufacturers, distributors and retailers primarily in the Midwestern U.S. and throughout Canada and the U.K. The Company’s plant nutrition products are sold across the Western Hemisphere and globally. No single customer or group of affiliated customers accounted for more than 10% of the Company’s sales in any year during the three-year period ended December 31, 2020, or more than 10% of receivables at December 31, 2020 or 2019. u. Recent Accounting Pronouncements: In January 2017, the FASB issued guidance to simplify the accounting for goodwill impairment. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. All other goodwill impairment guidance remains largely unchanged. The adoption of this guidance on January 1, 2020, did not have an impact on the Company’s consolidated financial statements. On January 1, 2020, the Company adopted guidance issued by the FASB related to credit losses for financial instruments, which replaces the incurred loss methodology with a current expected credit loss methodology (“CECL”). The Company has determined that its receivables are the only financial instrument that is within scope of this CECL guidance. The CECL methodology requires financial assets to be recorded at the net amount expected to be collected over the lifetime of the asset such that the estimated losses are accrued on the day the asset is acquired. The CECL methodology also requires financial assets to be aggregated and evaluated within pools with similar risk characteristics. The Company has recorded an allowance on its receivables based on historical loss rates modified to consider supportable forecasts related to customer-specific and macroeconomic factors. For instance, the Company’s 2020 allowance for doubtful

REVENUES

REVENUES	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
REVENUES	REVENUES Nature of Products and Services The Company’s Salt segment products include salt and magnesium chloride for use in road deicing and dust control, food processing, water softeners, and agricultural and industrial applications. The Company’s plant nutrition products include SOP, secondary nutrients, micronutrients and magnesium chloride for agricultural purposes and chemicals for the industrial chemical industry. In the U.K., the Company operates a records management business utilizing excavated areas of the Winsford salt mine with one other location in London, England. Identifying the Contract The Company accounts for a customer contract when there is approval and commitment from both parties, the rights of the parties and payment terms are identified, the contract has commercial substance and collectability of consideration is probable. Identifying the Performance Obligations At contract inception, the Company assesses the goods and services it has promised to its customers and identifies a performance obligation for each promise to transfer to the customer a distinct good or service (or bundle of goods or services). Determining whether products and services are considered distinct performance obligations that should be accounted for separately or aggregated together may require significant judgment. Identifying and Allocating the Transaction Price The Company’s revenues are measured based on consideration specified in the customer contract, net of any sales incentives and amounts collected on behalf of third parties such as sales taxes. In certain cases, the Company’s customer contracts may include promises to transfer multiple products and services to a customer. For multiple-element arrangements, the Company generally allocates the transaction price to each performance obligation in proportion to its stand-alone selling price. When Performance Obligations Are Satisfied The vast majority of the Company’s revenues are recognized at a point in time when the performance obligations are satisfied based upon transfer of control of the product or service to a customer. To determine when the control of goods is transferred, the Company typically assesses, among other things, the shipping terms of the contract, as shipping is an indicator of transfer of control. Some of the Company’s products are sold when the control of the goods transfers to the customer at the time of shipment. There are also instances when the Company provides shipping services to deliver its products. Shipping and handling costs that occur before the customer obtains control of the goods are deemed to be fulfillment activities and are accounted for as fulfillment costs. The Company has made an accounting policy election to recognize any shipping and handling costs that are incurred after the customer obtains control of the goods as fulfillment costs which are accrued at the time of revenue recognition. Significant Payment Terms The customer contract states the final terms of the sale, including the description, quantity and price of each product or service purchased. Payment is typically due in full within 30 days of delivery. As a practical expedient, the Company does not adjust the consideration for the effects of a significant financing component if the Company expects, at contract inception, that the period between when the good or service is transferred to the customer and when the customer pays for that good or service will be one year or less. Refunds, Returns and Warranties The Company’s products are generally not sold with a right of return and the Company does not generally provide credits or incentives, which may be required to be accounted for as variable consideration when estimating the amount of revenue to be recognized. The Company uses historical experience to estimate accruals for refunds due to manufacturing or other defects. Practical Expedients and Accounting Policy Elections Upon adoption of the guidance, the Company elected (i) to exclude disclosures of transaction prices allocated to remaining performance obligations when the Company recognized such revenue for all periods prior to the date of initial application of the new guidance, (ii) not to adjust the amount of consideration for the effects of a significant financing component when the Company expects, at contract inception, that the period between the Company's transfer of a product or service to a customer and when the customer pays for that product or service will be one year or less, (iii) to expense costs to obtain a contract as incurred for costs when the Company expects that the amortization period would have been one year or less, (iv) not to recast revenue for customer contracts that begin and end in the same fiscal period, and (v) not to assess whether promised goods or services are performance obligations if they are immaterial in the context of the customer contract. See Note 15 for disaggregation of sales by segment, type and geographical region.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
LEASES	LEASES The Company enters into leases for warehouses and depots, rail cars, vehicles, mobile equipment, office space and certain other types of property and equipment. The Company determines whether an arrangement is or contains a lease at the inception of the contract. The right-of-use asset and lease liability are recognized based on the present value of the future minimum lease payments over the estimated lease term. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. The Company estimates its incremental borrowing rate for each lease based upon the estimated lease term, the type of asset and the location of the leased asset. The most significant judgments in the application of the FASB guidance include whether a contract contains a lease and the lease term. Leases with an initial term of 12 months or less are not recorded on the Company’s Consolidated Balance Sheets. The Company recognizes lease expense for these short-term leases on a straight-line basis over the lease term. Many of the Company’s leases include one or more options to renew and extend the initial lease term. The exercise of lease renewal options is generally at the Company’s discretion. The lease term includes renewal periods in only those instances in which the Company determines it is reasonably assured of renewal. The depreciable lives of assets and leasehold improvements are limited by the expected lease term, unless there is a transfer of title or purchase option reasonably certain of exercise. In these instances, the assets are depreciated over the useful life of the asset. The Company has elected the practical expedient available under the FASB guidance to not separate lease and non-lease components on all of its lease categories. As a result, many of the Company’s leases include variable payments for services (such as handling or storage) or payments based on the usage of the asset. In addition, certain of the Company’s lease agreements include rental payments that are adjusted periodically for inflation. The Company’s lease agreements do not contain any material residual value guarantees or any material restrictive covenants. The Company’s sublease income is immaterial. The Company’s Consolidated Balance Sheets includes the following (in millions): Consolidated Balance Sheets Location December 31, December 31, Assets Operating lease assets Other assets $ 55.6 $ 53.7 Finance lease assets Property, plant and equipment, net 7.2 5.8 Total lease assets $ 62.8 $ 59.5 Liabilities Current liabilities: Operating Accrued expenses and other current liabilities $ 14.8 $ 12.8 Finance Accrued expenses and other current liabilities 1.3 1.1 Noncurrent liabilities: Operating Other noncurrent liabilities 42.8 41.0 Finance Other noncurrent liabilities 7.0 6.2 Total lease liabilities $ 65.9 $ 61.1 The Company’s components of lease cost are as follows (in millions): Year Ended December 31, 2020 Year Ended December 31, 2019 Finance lease cost: Amortization of lease assets $ 1.8 $ 1.1 Interest on lease liabilities 0.6 0.6 Operating lease cost 17.4 19.2 Variable lease cost (a) 11.7 18.8 Total lease cost $ 31.5 $ 39.7 (a) Short-term leases are immaterial and included in variable lease cost. Maturities of lease liabilities are as follows (in millions): Operating Leases Finance Leases Total 2021 $ 16.4 $ 1.8 $ 18.2 2022 13.1 1.2 14.3 2023 8.4 1.1 9.5 2024 5.7 0.9 6.6 2025 4.9 0.9 5.8 After 2025 18.0 6.1 24.1 Total lease payments 66.5 12.0 78.5 Less: Interest (8.9) (3.7) (12.6) Present value of lease liabilities $ 57.6 $ 8.3 $ 65.9 Supplemental lease term and discount rate information related to leases is as follows: December 31, 2020 December 31, 2019 Weighted-average remaining lease term (years) Operating leases 7.0 7.7 Finance leases 9.3 7.2 Weighted-average discount rate Operating leases 3.7 % 4.3 % Finance leases 7.3 % 7.6 % Supplemental cash flow information related to leases is as follows (in millions): Year Ended December 31, 2020 Year Ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 15.3 $ 18.9 Operating cash flows from finance leases 0.6 0.6 Financing cash flows from finance leases 1.8 1.3 Leased assets obtained in exchange for new operating lease liabilities 16.5 20.3 Leased assets obtained in exchange for new finance lease liabilities 3.8 0.2
LEASES	LEASES The Company enters into leases for warehouses and depots, rail cars, vehicles, mobile equipment, office space and certain other types of property and equipment. The Company determines whether an arrangement is or contains a lease at the inception of the contract. The right-of-use asset and lease liability are recognized based on the present value of the future minimum lease payments over the estimated lease term. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. The Company estimates its incremental borrowing rate for each lease based upon the estimated lease term, the type of asset and the location of the leased asset. The most significant judgments in the application of the FASB guidance include whether a contract contains a lease and the lease term. Leases with an initial term of 12 months or less are not recorded on the Company’s Consolidated Balance Sheets. The Company recognizes lease expense for these short-term leases on a straight-line basis over the lease term. Many of the Company’s leases include one or more options to renew and extend the initial lease term. The exercise of lease renewal options is generally at the Company’s discretion. The lease term includes renewal periods in only those instances in which the Company determines it is reasonably assured of renewal. The depreciable lives of assets and leasehold improvements are limited by the expected lease term, unless there is a transfer of title or purchase option reasonably certain of exercise. In these instances, the assets are depreciated over the useful life of the asset. The Company has elected the practical expedient available under the FASB guidance to not separate lease and non-lease components on all of its lease categories. As a result, many of the Company’s leases include variable payments for services (such as handling or storage) or payments based on the usage of the asset. In addition, certain of the Company’s lease agreements include rental payments that are adjusted periodically for inflation. The Company’s lease agreements do not contain any material residual value guarantees or any material restrictive covenants. The Company’s sublease income is immaterial. The Company’s Consolidated Balance Sheets includes the following (in millions): Consolidated Balance Sheets Location December 31, December 31, Assets Operating lease assets Other assets $ 55.6 $ 53.7 Finance lease assets Property, plant and equipment, net 7.2 5.8 Total lease assets $ 62.8 $ 59.5 Liabilities Current liabilities: Operating Accrued expenses and other current liabilities $ 14.8 $ 12.8 Finance Accrued expenses and other current liabilities 1.3 1.1 Noncurrent liabilities: Operating Other noncurrent liabilities 42.8 41.0 Finance Other noncurrent liabilities 7.0 6.2 Total lease liabilities $ 65.9 $ 61.1 The Company’s components of lease cost are as follows (in millions): Year Ended December 31, 2020 Year Ended December 31, 2019 Finance lease cost: Amortization of lease assets $ 1.8 $ 1.1 Interest on lease liabilities 0.6 0.6 Operating lease cost 17.4 19.2 Variable lease cost (a) 11.7 18.8 Total lease cost $ 31.5 $ 39.7 (a) Short-term leases are immaterial and included in variable lease cost. Maturities of lease liabilities are as follows (in millions): Operating Leases Finance Leases Total 2021 $ 16.4 $ 1.8 $ 18.2 2022 13.1 1.2 14.3 2023 8.4 1.1 9.5 2024 5.7 0.9 6.6 2025 4.9 0.9 5.8 After 2025 18.0 6.1 24.1 Total lease payments 66.5 12.0 78.5 Less: Interest (8.9) (3.7) (12.6) Present value of lease liabilities $ 57.6 $ 8.3 $ 65.9 Supplemental lease term and discount rate information related to leases is as follows: December 31, 2020 December 31, 2019 Weighted-average remaining lease term (years) Operating leases 7.0 7.7 Finance leases 9.3 7.2 Weighted-average discount rate Operating leases 3.7 % 4.3 % Finance leases 7.3 % 7.6 % Supplemental cash flow information related to leases is as follows (in millions): Year Ended December 31, 2020 Year Ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 15.3 $ 18.9 Operating cash flows from finance leases 0.6 0.6 Financing cash flows from finance leases 1.8 1.3 Leased assets obtained in exchange for new operating lease liabilities 16.5 20.3 Leased assets obtained in exchange for new finance lease liabilities 3.8 0.2

INVENTORIES

INVENTORIES	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
INVENTORIES	INVENTORIES Inventories consist of the following at December 31 (in millions): 2020 2019 Finished goods $ 287.4 $ 235.3 Raw materials and supplies 83.2 76.2 Total inventories $ 370.6 $ 311.5 Based on the nature of the Company’s inventories, and specifically related to bulk SOP stockpiles, certain estimates are required to measure the amount of inventories at any point in time. During the third quarter of 2020, the Company identified an error in the valuation of its bulk SOP stockpile inventory at its Ogden facility when one of its stockpiles was largely depleted, which resulted in an estimated overstatement of inventories of approximately $7.4 million. The Company evaluated the error and believes it is not material to any previous period and has therefore recorded this additional expense to product cost within its Plant Nutrition North America segment during 2020.

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment consists of the following at December 31 (in millions): 2020 2019 Land, buildings and structures and leasehold improvements $ 626.8 $ 596.0 Machinery and equipment 1,085.1 1,001.9 Office furniture and equipment 53.3 60.7 Mineral interests 172.4 171.1 Construction in progress 58.7 141.3 1,996.3 1,971.0 Less accumulated depreciation and depletion (1,031.4) (940.2) Property, plant and equipment, net $ 964.9 $ 1,030.8

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS	GOODWILL AND OTHER INTANGIBLE ASSETS The asset value and accumulated amortization as of December 31, 2020 and 2019 for the finite-lived intangibles assets are as follows (in millions): Supply Agreement SOP Production Rights Customer/Distributor Relationships Lease Rights Trade Names Developed Technologies Patents Other Total December 31, 2020 Gross intangible asset $ 28.5 $ 24.3 $ 11.6 $ 1.8 $ 30.3 $ 26.2 $ 16.2 $ 1.3 $ 140.2 Accumulated amortization (5.7) (16.6) (6.8) (0.6) (11.8) (21.4) (9.6) (1.0) (73.5) Net intangible assets $ 22.8 $ 7.7 $ 4.8 $ 1.2 $ 18.5 $ 4.8 $ 6.6 $ 0.3 $ 66.7 Supply Agreement SOP Production Rights Customer/Distributor Relationships Lease Rights Trade Names Developed Technologies Patents Other Total December 31, 2019 Gross intangible asset $ 27.9 $ 24.3 $ 12.7 $ 1.7 $ 36.8 $ 32.8 $ 16.0 $ 1.3 $ 153.5 Accumulated amortization (5.0) (15.6) (6.1) (0.5) (10.9) (21.7) (8.1) (0.9) (68.8) Net intangible assets $ 22.9 $ 8.7 $ 6.6 $ 1.2 $ 25.9 $ 11.1 $ 7.9 $ 0.4 $ 84.7 The estimated lives of the Company’s finite-lived intangible assets are as follows: Intangible asset Estimated Lives Supply agreement 50 years SOP production rights 25 years Patents 10-20 years Developed technology 4-7 years Lease rights 25 years Customer and distributor relationships 10-14 years Trademarks 10 years Trade names 10-11 years None of the finite-lived intangible assets have a residual value. Aggregate amortization expense was $10.7 million in 2020, $13.6 million in 2019 and $15.0 million in 2018 and is projected to be between $5 million and $10 million per year over the next five years. The weighted average life for the Company’s finite-lived intangibles is 20 years. In addition, the Company had water rights of $17.7 million as of December 31, 2020 and 2019, and trade names of $0.6 million as of December 31, 2020 and 2019, which have indefinite lives.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company files tax returns in the U.S., Canada, Brazil and the U.K. at the federal and local taxing jurisdictional levels. The Company’s U.S. federal tax returns for tax years 2017 forward remain open and subject to examination. Generally, the Company’s state, local and foreign tax returns for years as early as 2002 forward remain open and subject to examination, depending on the jurisdiction. Tax Cuts and Jobs Act On December 22, 2017, the U.S. enacted the Act (which is commonly referred to as “U.S. tax reform”). The Act significantly changes U.S. corporate income tax laws by reducing the U.S. corporate income tax rate to 21% beginning in 2018 and creating a quasi-territorial tax system with a one-time mandatory tax on previously deferred foreign earnings. As of December 31, 2018, the Company has completed its accounting for the tax effects of enactment of the Act. In 2017, the Company recorded a reasonable estimated net charge of $46.8 million, consisting of $55.2 million related to the one-time mandatory tax on unremitted foreign earnings, offset by an $8.4 million benefit related to the remeasurement of the Company’s deferred tax liabilities at the new income tax rate. During 2018, the Company finalized the accounting for the enactment of the Act and recorded a tax benefit of $3.0 million, consisting of a $3.1 million tax benefit related to the one-time mandatory tax on unremitted foreign earnings offset by a $0.1 million charge related to the remeasurement of the Company’s deferred tax liabilities. The 2018 tax effects of the Act are included in income tax expense in the Company’s Consolidated Statements of Operations. Although the unremitted foreign earnings subjected to the one-time mandatory tax on unremitted foreign earnings would not be subject to additional U.S. federal income tax, the Company must still account for the tax consequences of outside basis differences and other tax impacts of its investments in non-U.S. subsidiaries. As such, the Company revised its permanently reinvested assertion and now expects to repatriate approximately $150 million of unremitted foreign earnings on which $4.3 million of income tax expense has been recorded for foreign withholding tax and state income taxes, consisting of $0.9 million recorded in 2019 and $3.4 million recorded in 2018. All remaining unremitted earnings of non-U.S. subsidiaries and outside basis differences are considered permanently reinvested. The following table summarizes the Company’s income tax provision for the years ended December 31 (in millions): 2020 2019 2018 Current: Federal $ (22.3) $ 5.3 $ 8.1 State 0.4 2.0 4.3 Foreign 28.2 26.6 13.1 Total current 6.3 33.9 25.5 Deferred: Federal 1.2 (7.2) (8.6) State (1.2) (1.9) (0.5) Foreign 5.4 (2.7) (7.6) Total deferred 5.4 (11.8) (16.7) Total provision for income taxes $ 11.7 $ 22.1 $ 8.8 The following table summarizes components of earnings before income taxes and shows the tax effects of significant adjustments from the expected income tax expense computed at the federal statutory rate for the years ended December 31 (in millions): 2020 2019 2018 U.S. (loss) income $ (4.1) $ 31.7 $ (80.6) Foreign income 75.3 52.9 158.2 Earnings before income taxes $ 71.2 $ 84.6 $ 77.6 Computed tax at the U.S. federal statutory rate of 21% 15.0 17.8 16.3 Foreign income rate differential, mining, and withholding taxes, net of U.S. federal deduction 9.3 10.2 0.9 Percentage depletion in excess of basis (4.4) (5.8) (4.7) Other domestic tax reserves, net of reversals (9.7) 0.2 1.5 State income taxes, net of federal income tax benefit (0.9) — 2.1 Change in valuation allowance on deferred tax asset 2.4 0.2 (5.7) Interest expense recognition differences (3.5) (3.5) (3.6) GILTI 3.8 1.0 1.0 Tax Cuts and Jobs Act of 2017 — 1.6 (3.0) Tax on repatriated amounts — 0.9 3.4 Transfer pricing settlement with taxing authorities — — 2.2 Other, net (0.3) (0.5) (1.6) Provision for income taxes $ 11.7 $ 22.1 $ 8.8 Effective tax rate 16 % 26 % 11 % Under U.S. GAAP, deferred tax assets and liabilities are recognized for the estimated future tax effects, based on enacted tax law, of temporary differences between the values of assets and liabilities recorded for financial reporting and tax purposes, and of net operating losses and other carryforwards. The significant components of the Company’s deferred tax assets and liabilities were as follows at December 31 (in millions): 2020 2019 Deferred tax assets: Reluz Nordeste Indústria e Comércio Ltda net operating loss carryforwards $ 0.4 $ 0.6 Compass Minerals South America net operating loss carryforwards — 3.3 Excess interest expense 9.9 14.9 Foreign tax credit 39.4 38.1 Right of use lease liability 11.3 11.1 Stock-based compensation 2.0 2.3 Other, net 20.5 16.5 Total deferred tax assets before valuation allowance 83.5 86.8 Valuation allowance (42.0) (39.8) Total deferred tax assets 41.5 47.0 Deferred tax liabilities to be netted with deferred tax assets: Property, plant and equipment 17.2 21.2 Right of use lease asset 11.3 11.1 Other, net 1.4 1.0 Total deferred tax liabilities to be netted with deferred tax assets 29.9 33.3 Net noncurrent deferred tax assets $ 11.6 $ 13.7 Deferred tax assets to be netted with deferred tax liabilities: Net operating loss carryforwards $ 1.7 $ 2.2 Right of use lease liability 1.9 0.9 Other, net 0.9 2.1 Total deferred tax assets before valuation allowance 4.5 5.2 Valuation allowance (1.4) (1.4) Total deferred tax assets to be netted with deferred tax liabilities 3.1 3.8 Deferred tax liabilities: Property, plant and equipment 66.5 63.7 Intangible asset 22.2 29.1 Right of use lease asset 1.9 0.9 Total deferred tax liabilities 90.6 93.7 Net deferred tax liabilities $ 87.5 $ 89.9 At December 31, 2020 and 2019, the Company had $7.7 million and $18.8 million, respectively, of gross foreign federal net operating loss (“NOL”) carryforwards that have no expiration date, $0.1 million and $1.7 million, respectively, of gross foreign federal NOL carryforwards which expire in 2033 and $0.2 million and $0.3 million, respectively, of net operating tax-effected state NOL carryforwards which will expire beginning in 2027. The Company has recorded a valuation allowance for a portion of its deferred tax asset relating to various tax attributes that it does not believe are, more likely than not to be realized. During 2018, the Company determined it is more likely than not that all of its Brazilian deferred tax assets acquired in connection with the acquisition of Compass Minerals South America will be used to reduce taxable income. As a result, the Company released the remaining $7.2 million of valuation allowances during the year ending December 31, 2018. As of December 31, 2020 and 2019, the Company’s valuation allowance was $43.4 million and $41.2 million, respectively. In the future, if the Company determines, based on existence of sufficient evidence, that it should realize more or less of its deferred tax assets, an adjustment to the valuation allowance will be made in the period such a determination is made. The calculation of the Company’s tax liabilities involves dealing with uncertainties in the application of complex tax regulations in multiple jurisdictions. The Company recognizes potential liabilities for unrecognized tax benefits in the U.S. and other tax jurisdictions in accordance with applicable U.S. GAAP, which requires uncertain tax positions to be recognized only if they are more likely than not to be upheld based on their technical merits. The measurement of the uncertain tax position is based on the largest benefit amount that is more likely than not (determined on a cumulative probability basis) to be realized upon settlement of the matter. If payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities would result in tax benefits being recognized in the period when the Company determines the liabilities are no longer necessary. If the Company’s estimate of tax liabilities proves to be less than the ultimate assessment, a further charge to expense may result. The Company’s uncertain tax positions primarily relate to transactions and deductions involving U.S., Canadian and Brazilian operations. If favorably resolved, $28.8 million of unrecognized tax benefits would decrease the Company’s effective tax rate. Management believes that it is reasonably possible that unrecognized tax benefits will decrease by approximately $1.1 million in the next twelve months largely as a result of tax returns being closed to future audits. In 2020, the Company’s income tax expense included a benefit of approximately $11.0 million related to the release of uncertain tax positions due to the expiration of statutes of limitations. The following table shows a reconciliation of the beginning and ending amount of unrecognized tax benefits (in millions): 2020 2019 2018 Unrecognized tax benefits: Balance at January 1 $ 47.4 $ 50.9 $ 67.4 Additions resulting from current year tax positions — 0.2 8.0 Additions relating to tax positions taken in prior years 1.4 4.5 2.6 Reductions due to settlements — — (25.0) Reductions due to cash payments — (7.5) — Reductions relating to tax positions taken in prior years (0.1) (0.4) (0.3) Reductions due to expiration of tax years (10.4) (0.3) (1.8) Balance at December 31 $ 38.3 $ 47.4 $ 50.9 The Company accrues interest and penalties related to its uncertain tax positions within its tax provision. During the years ended December 31, 2020, 2019 and 2018, the Company accrued interest and penalties, net of reversals, of $2.0 million, $4.6 million and $(2.1) million, respectively. As of December 31, 2020 and 2019, accrued interest and penalties included in the Consolidated Balance Sheets totaled $22.3 million and $20.3 million, respectively. The Company has historically considered the undistributed earnings of its foreign subsidiaries to be permanently reinvested. In December 2017, however, U.S. tax reform legislation was enacted, which included a one-time mandatory tax on previously deferred foreign earnings. As such, in 2018, the Company revised its permanently reinvested assertion and now expects to repatriate approximately $150 million of unremitted foreign earnings on which $4.3 million of income tax expense has been recorded for foreign withholding tax and state income taxes, consisting of $0.9 million recorded in 2019 and $3.4 million recorded in 2018. The Company intends to continue its permanently reinvested assertion on the remaining undistributed earnings of its foreign subsidiaries indefinitely. As of December 31, 2020, the Company has approximately $213.6 million of outside basis differences on which no deferred taxes have been recorded as the determination of the unrecognized deferred taxes is not practicable. Canadian provincial tax authorities have challenged tax positions claimed by one of the Company’s Canadian subsidiaries and have issued tax reassessments for years 2002-2015. The reassessments are a result of ongoing audits and total approximately $153.4 million, including interest, through December 31, 2020. The Company disputes these reassessments and plans to continue to work with the appropriate authorities in Canada to resolve the dispute. There is a reasonable possibility that the ultimate resolution of this dispute, and any related disputes for other open tax years, may be materially higher or lower than the amounts the Company has reserved for such disputes. In connection with this dispute, local regulations require the Company to post security with the tax authority until the dispute is resolved. The Company has posted collateral in the form of a $120.1 million performance bond and has paid $39.0 million (most of which is recorded in other assets in the Consolidated Balance Sheets at December 31, 2020), which is necessary to proceed with future appeals or litigation. The Company expects that it will be required by local regulations to provide security for additional interest on the above unresolved disputed amounts and for any future reassessments issued by these Canadian tax authorities in the form of cash, letters of credit, performance bonds, asset liens or other arrangements agreeable with the tax authorities until the disputes are resolved. The Company expects that the ultimate outcome of these matters will not have a material impact on its results of operations or financial condition. However, the Company can provide no assurance as to the ultimate outcome of these matters and the impact could be material if they are not resolved in the Company’s favor. As of December 31, 2020, the Company believes it has adequately reserved for these reassessments. Additionally, the Company has other uncertain tax positions as well as assessments and disputed positions with taxing authorities in its various jurisdictions. Settlements In 2017, the Company, the CRA and the IRS reached a settlement agreement on transfer pricing for its 2007-2012 tax years. As a result of this settlement, the Company recognized $13.8 million of income tax expense in the Consolidated Statement of Operations related to the Company’s Canadian tax positions for the years 2007-2016. The recording of this settlement resulted in increased sales for the Company’s Canadian subsidiary of $85.7 million and increased offsetting expenses for its U.S. subsidiary in 2017 causing a domestic loss and significant foreign income. During 2018, in accordance with the agreement, the Company’s U.S. subsidiary made intercompany cash payments of $85.7 million to its Canadian subsidiary and tax payments were made to Canadian taxing authorities of $17.5 million. Additional tax payments of $5.3 million were made during 2019 with the remaining liability of $1.4 million expected to be paid in 2021. Corresponding tax refunds of $22.2 million have been received as of December 31, 2020, from U.S. taxing authorities with the remaining refund of approximately $0.9 million expected in 2021 (recorded in other current assets in the Consolidated Balance Sheets). Additionally, the reassessed Canadian tax, penalties and interest for the Company for years 2007 and 2008 of approximately $34.2 million are effectively resolved. In 2018, the Company, the CRA and the IRS reached a settlement agreement on transfer pricing and management fees as part of an advanced pricing agreement that covers tax years 2013-2021. The income tax expense was previously recognized in 2017, however the recording of this settlement resulted in increased sales for the Company’s Canadian subsidiary of $106.1 million and offsetting expenses for its U.S. subsidiary in 2018 causing a domestic loss and significant foreign income. During 2019, in accordance with the settlement agreement, the Company’s U.S. subsidiary made intercompany cash payments of $106.1 million to its Canadian subsidiary and tax payments were made to Canadian taxing authorities of $29.9 million, with the remaining $1.4 million balance paid during 2020. Corresponding tax refunds of $59.7 million have been received as of December 31, 2020, from U.S. taxing authorities, with the remaining $1.9 million expected in 2021 (recorded in other current assets in the Consolidated Balance Sheets).

PENSION PLANS AND OTHER BENEFIT

PENSION PLANS AND OTHER BENEFITS	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
PENSION PLANS AND OTHER BENEFITS	PENSION PLANS AND OTHER BENEFITS The Company has a defined benefit pension plan for certain of its U.K. employees. Benefits of this pension plan are based on a combination of years of service and compensation levels. This plan was closed to new participants in 1992. Beginning December 1, 2008, future benefits ceased to accrue for the remaining active employee participants in the pension plan concurrent with the establishment of a defined contribution plan for these employees. In addition, the Company has a defined benefit plan with certain Compass Minerals South America employees. The pension assets, obligations and net pension expense related to this plan are immaterial. The Company’s U.K. pension plan investment strategy is to maximize return on investments while minimizing risk. This is accomplished by investing in high-grade equity and debt securities. The Company’s portfolio guidelines recommend that equity securities comprise approximately 75% of the total portfolio and that approximately 25% be invested in debt securities. The Company’s portfolio has shifted to a smaller proportion of equity funds due to the increased volatility of these funds over the last several years, and it is researching strategies that will reduce volatility, while also maximizing returns. Investment strategies and portfolio allocations are based on the U.K. pension plan’s benefit obligations and its funded or underfunded status, expected returns, and the Company’s portfolio guidelines and are monitored on a regular basis. The weighted-average asset allocations by asset category are as follows: Plan Assets at December 31, Asset Category 2020 2019 Cash and cash equivalents 2 % 3 % Blended funds 48 % 51 % Bond funds 50 % 46 % Total 100 % 100 % The fair value of the Company’s U.K. pension plan assets at December 31, 2020 and 2019, by asset category (see Note 14 for a discussion regarding fair value measurements) are as follows (in millions): December 31, 2020 Level One Level Two Level Three Asset category: Cash and cash equivalents (a) $ 1.3 $ 1.3 $ — $ — Blended funds (b) 34.9 — 34.9 — Bond funds (c) : Treasuries 35.9 — 35.9 — Total Pension Assets $ 72.1 $ 1.3 $ 70.8 $ — December 31, 2019 Level One Level Two Level Three Asset category: Cash and cash equivalents (a) $ 1.9 $ 1.9 $ — $ — Blended funds (b) 33.6 — 33.6 — Bond funds (c) : Treasuries 30.1 — 30.1 — Total Pension Assets $ 65.6 $ 1.9 $ 63.7 $ — (a) The fair value of cash and cash equivalents is its carrying value. (b) The Company is invested in a diversified growth fund. The diversified growth fund is valued at the last traded or official close for the underlying equities and bid or mid for the underlying fixed income securities depending on the portfolio benchmark. Where representative prices are unavailable, underlying fixed income investments are valued based on other observable market-based inputs. (c) This category includes investments in investment-grade fixed-income instruments and funds linked to U.K. treasury notes. The funds are valued using the bid amounts for each fund. All of the Company’s bond fund pension assets are invested in U.K.-linked treasuries as of December 31, 2020 and 2019. As of December 31, 2020 and 2019, amounts recognized in accumulated other comprehensive loss, net of tax, consisted of actuarial net losses of $9.4 million (including $10.4 million of accumulated loss less prior service cost of $1.0 million) and $6.8 million (including $7.9 million of accumulated loss less prior service cost of $1.1 million), respectively. During 2020, the amounts recognized in accumulated other comprehensive loss, net of tax, consisted of actuarial net losses of $(2.9) million, amortization of loss of $0.8 million, amortization of prior service cost of $(0.1) million and foreign exchange of $(0.3) million. During 2019, the amounts recognized in accumulated other comprehensive loss, net of tax, consisted of actuarial net losses of $(2.4) million, amortization of loss of $0.4 million, amortization of prior service cost of $(0.1) million and foreign exchange of $(0.3) million. During 2018, the amounts recognized in accumulated other comprehensive loss, net of tax, consisted of actuarial net losses of $(1.2) million, amortization of loss of $0.3 million, amortization of prior service cost of $(0.1) million and foreign exchange of $0.4 million. The Company expects to recognize approximately $1.4 million ($1.5 million of amortization of loss less $0.1 million of prior service cost) of losses from accumulated other comprehensive loss as a component of net periodic pension cost in 2021. Total net periodic pension cost in 2021 is expected to be $0.1 million. The assumptions used in determining pension information for the U.K. pension plan for the years ended December 31 were as follows: 2020 2019 2018 Discount rate 1.20 % 2.00 % 2.90 % Expected return on plan assets 3.10 % 3.10 % 3.70 % The overall expected long-term rate of return on plan assets is a weighted-average expectation based on the fair value of targeted and expected portfolio composition. The Company considers historical performance and current benchmarks to arrive at expected long-term rates of return in each asset category. The Company determines its discount rate based on a forward yield curve for a portfolio of high-credit-quality bonds with expected cash flows and an average duration closely matching the expected benefit payments under the plan. The Company’s funding policy is to make the minimum annual contributions required by applicable regulations or agreements with the plan administrator. Management expects there will be no contributions during 2021. In addition, the Company may periodically make contributions to the plan based upon the underfunded status of the plan or other transactions, which warrant incremental contributions in the judgment of management. The U.K. pension plan includes a provision whereby supplemental benefits may be available to participants under certain circumstances after case review and approval by the plan trustees. Because instances of this type of benefit have historically been infrequent, the development of the projected benefit obligation and net periodic pension cost (benefit) has not provided for any future supplemental benefits. If additional benefits are approved by the trustees, it is likely that an additional contribution would be required and the amount of incremental benefits would be expensed by the Company. The Company expects to pay the following benefit payments (in millions): Calendar Year Future Expected Benefit Payments 2021 $ 3.2 2022 3.2 2023 3.3 2024 3.4 2025 3.4 2026-2030 18.4 The following table sets forth pension obligations and plan assets for the Company’s U.K. pension plan, as of December 31 (in millions): 2020 2019 Change in benefit obligation: Benefit obligation as of January 1 $ 64.1 $ 58.6 Interest cost 1.2 1.7 Actuarial loss 8.3 4.8 Plan amendment 0.1 — Benefits paid (2.9) (3.5) Currency fluctuation adjustment 2.5 2.5 Benefit obligation as of December 31 73.3 64.1 Change in plan assets: Fair value as of January 1 65.6 60.7 Actual return 6.7 4.2 Company contributions 0.4 1.7 Currency fluctuation adjustment 2.3 2.5 Benefits paid (2.9) (3.5) Fair value of plan assets as of December 31 72.1 65.6 (Underfunded) Overfunded status of the plan $ (1.2) $ 1.5 The Company’s U.K. pension plan was underfunded as of December 31, 2020, and overfunded as of December 31, 2019, and accordingly, $1.2 million and $1.5 million has been recorded as a noncurrent liability and a noncurrent asset, respectively, in the Company’s Consolidated Balance Sheets. The accumulated benefit obligation for the U.K. pension plan was $73.3 million and $64.1 million as of December 31, 2020 and 2019, respectively. The plan assets were less than the accumulated benefit obligation as of December 31, 2020, but were in excess of the accumulated benefit obligation as of December 31, 2019. The vested benefit obligation is the actuarial present value of the vested benefits to which the employee is currently entitled but based on the employee’s expected date of retirement. Since all employees are vested, the accumulated benefit obligation and the vested benefit obligation are the same amount. The Company uses a straight-line methodology of amortization subject to a corridor based upon the higher of the fair value of assets and the pension benefit obligation over a five-year period. The components of net periodic pension cost (benefit) were as follows for the years ended December 31 (in millions): 2020 2019 2018 Interest cost on projected benefit obligation $ 1.2 $ 1.7 $ 1.6 Prior service cost (0.1) (0.1) (0.1) Expected return on plan assets (1.9) (2.2) (2.5) Plan amendment 0.1 — — Net amortization 1.0 0.5 0.3 Net periodic pension cost (benefit) $ 0.3 $ (0.1) $ (0.7) The Company has defined contribution and pre-tax savings plans (the “Savings Plans”) for certain of its employees. Under each of the Savings Plans, participants are permitted to defer a portion of their compensation. Company matching contributions to the Savings Plans are based on a percentage of employee contributions. Additionally, certain of the Savings Plans have a profit-sharing feature for salaried and non-union hourly employees. The Company contribution to the profit-sharing feature is discretionary and based on the Company’s financial performance and other factors. Expense attributable to the Savings Plans was $12.5 million, $11.6 million and $12.6 million for the years ended December 31, 2020, 2019 and 2018, respectively. The Savings Plans include a non-qualified plan for certain executive officers and other key employees who are limited in their ability to participate in qualified plans due to existing regulations. These employees are allowed to defer a portion of their compensation, upon which they will be entitled to receive Company contributions despite the limitations imposed by current U.S. regulations for qualified plans. The Company’s contributions to the Savings Plans include Company matching contributions based on a percentage of the employee’s deferred salary, discretionary profit sharing contributions and any investment income (loss) that would have been credited to their account had the contributions been made according to employee-designated investment specifications. Although not required to do so, the Company invests amounts equal to the salary deferrals, the corresponding Company matching contribution and discretionary profit sharing amounts according to the employee-designated investment specifications. As of December 31, 2020 and 2019, investments in marketable securities totaling $1.9 million and $1.4 million, respectively, were included in other noncurrent assets with a corresponding deferred compensation liability included in other noncurrent liabilities in the Consolidated Balance Sheets. Compensation expense recorded for the non-qualified plan was immaterial for each of the years ended December 31, 2020, 2019 and 2018, including amounts attributable to investment income, and was included in other, net in the Consolidated Statements of Operations.

LONG TERM DEBT

LONG TERM DEBT	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
LONG TERM DEBT	LONG TERM DEBT Long-term debt consists of the following at December 31 (in millions): 2020 2019 4.875% Senior Notes due July 2024 $ 250.0 $ 250.0 Term Loan due January 2025 390.0 400.0 Revolving Credit Facility due January 2025 130.3 160.0 6.75% Senior Notes due December 2027 500.0 500.0 AR Securitization Facility expires June 2023 51.2 — 3.7% Banco Itaú loan due March 2020 — 15.4 Banco Santander loan due October 2020 — 16.2 Banco Itaú loan due February 2021 10.4 — Banco Rabobank loan due July 2021 6.8 17.4 Banco BTG loan due July 2021 2.6 — Banco Santander loan due September 2021 — 19.9 Banco do Brasil loan due September 2021 9.6 12.4 Banco Rabobank loan due September 2021 6.8 — Banco BTG loan due October 2021 2.6 — Banco Rabobank loan due November 2021 13.5 17.4 Banco Santander loan due December 2021 — 14.9 Banco BTG loan due January 2022 1.0 — Banco Votorantim loan due February 2022 7.7 — Banco Bradesco loan due February 2022 4.8 — Banco Santander loan due March 2022 2.9 — Banco BTG loan due April 2022 1.0 — Banco BTG loan due July 2022 2.6 — Banco Safra loan due October 2022 3.9 — Banco Santander loan due October 2022 12.5 — Financiadora de Estudos e Projetos loan due November 2023 4.1 7.2 1,414.3 1,430.8 Less unamortized debt issuance costs (12.9) (14.8) Total debt 1,401.4 1,416.0 Less current portion (63.7) (52.1) Long-term debt $ 1,337.7 $ 1,363.9 Credit Agreement In November 2019, the Company entered into an agreement to amend and restate its credit agreement (the “2019 Credit Agreement”), which matures in January 2025. The 2019 Credit Agreement provides for senior secured financing consisting of a $400 million term loan facility and a $300 million revolving credit facility. The term loan is repayable in quarterly installments of interest and principal which began in March 2020 with principal payments equal to 2.5% per year during the first 2 years and 5% per year during the final 3 years. The Company may elect for the credit facility to bear interest at either an alternate base rate or an adjusted eurocurrency bank deposit rate plus, in each case, an interest rate margin, based upon a defined consolidated leverage ratio. The outstanding term loan can be prepaid at any time without penalty. Prior to the 2019 Credit Agreement, the Company’s credit agreement consisted of two senior secured term loans and a senior secured revolving credit facility which matured in July 2021. Interest on the Company’s borrowings under the previous outstanding credit agreement was variable based on either the LIBOR or a base rate (defined as the greater of a specified U.S. or Canadian prime lending rate or the federal funds effective rate, increased by 0.5%) plus a margin which was dependent upon the Company’s leverage ratio and the type of term loan borrowing. As of December 31, 2020, the weighted average interest rate was 2.2% on all borrowings outstanding under the 2019 Credit Agreement. Both credit agreements require the Company to maintain certain financial ratios, including a minimum interest coverage ratio and a maximum total leverage ratio. Under the current revolving credit facility, up to $40 million may be drawn in Canadian dollars and $10 million may be drawn in British pounds sterling. Additionally, the revolving credit facility includes a sub-limit for short-term letters of credit in an amount not to exceed $50 million. As of December 31, 2020, there was $130.3 million outstanding under the revolving credit facility, and, after deducting outstanding letters of credit totaling $12.5 million, the Company’s borrowing availability was $157.2 million. The Company incurs participation fees related to its outstanding letters of credit and commitment fees on its available borrowing capacity. The rates vary depending on the Company’s leverage ratio. Bank fees are not material. In connection with the 2019 Credit Agreement, the Company paid $4.1 million of fees ($3.8 million was capitalized as deferred financing costs with $0.3 million recorded as an expense). The Company also wrote-off $0.3 million of previously capitalized deferred financing costs as part of this refinancing in 2019. In December 2018, the Company entered into an amendment to its credit agreement, which eased restrictions in certain covenants contained in the agreement. In connection with this amendment, the Company paid fees totaling $1.4 million ($1.4 million was capitalized as deferred financing costs with less than $0.1 million recorded as an expense). The Company’s 2019 Credit Agreement borrowings are secured by substantially all existing and future U.S. assets of the Company, the Goderich mine in Ontario, Canada, and capital stock of certain subsidiaries. As of December 31, 2020, the Company was in compliance with each of its covenants under the 2019 Credit Agreement. Senior Notes In November 2019, the Company also issued $500 million 6.75% Senior Notes due December 2027 (the “6.75% Notes”), which are subordinate to the 2019 Credit Agreement borrowings. The 6.75% Notes are unsecured obligations and are guaranteed by certain of the Company’s domestic subsidiaries. Interest on the 6.75% Notes is due semi-annually in June and December beginning in 2020. The 6.75% Notes are subordinated to all existing and future indebtedness. In connection with the 6.75% Notes, the Company paid $8.2 million of fees, all of which were capitalized as deferred financing costs. The 4.875% Senior Notes due July 2024 (the “4.875% Notes”) are subordinate to the 2019 Credit Agreement borrowings. Interest on the 4.875% Notes is due annually in January and July. The 2019 Credit Agreement and the agreements governing the 4.875% Notes and the 6.75% Notes and other indebtedness contain covenants that limit the Company’s ability, among other things, to incur additional indebtedness or contingent obligations or grant liens; pay dividends or make distributions to stockholders; repurchase or redeem the Company’s stock; make investments or dispose of assets; prepay, or amend the terms of certain junior indebtedness; engage in sale and leaseback transactions; make changes to the Company’s organizational documents or fiscal periods; grant liens on the Company’s assets or make certain intercompany dividends, investments or asset transfers; enter into new lines of business; enter into transactions with the Company’s stockholders and affiliates; and acquire the assets of or merge or consolidate with other companies. Other Debt As of December 31, 2020, the Company had $92.8 million of loans related to Compass Minerals South America, which have maturity dates ranging from February 2021 through November 2023 and bear interest at rates of either a percentage of CDI, an overnight inter-bank lending rate in Brazil, or LIBOR plus a margin. A portion of the loans are denominated in U.S. dollars and a portion of the loans are denominated in Brazilian real, Compass Minerals South America’s functional currency. The Company has entered into foreign currency swap agreements in relation to some of these loans whereby the Company agreed to swap interest and principal payments on loans denominated in U.S. dollars for principal and interest payments denominated in Brazilian real (see N ote 11 for further discussion). In the first quarter of 2020, the Company entered into three loans totaling $20.0 million which mature between February 2021 and March 2022, respectively. Two of the loans were denominated in Brazilian real and one loan was denominated in euros. In connection with the loan denominated in euros, the Company entered into a swap to exchange principal a nd interest payments denominated in euros to Brazilian real (see Note 11 ). These loans bear interest ranging from 143% - 150% of CDI. During the third quarter of 2020, the Company entered into six new loans totaling $15.1 million which mature between July 2021 and July 2022. These loans are denominated in Brazilian real and bear interest rates ranging from 200% - 204% of CDI. The liquidity created from these loans allowed the Company to prepay $15.4 million worth of existing loans with maturity date of September 2021. During the fourth quarter of 2020, the Company entered into three new loans totaling $21.2 million which mature between F ebruary 2022 and October 2022. These loans are denominated in Brazilian real and bear interest rates ranging from 171% - 186% of CDI. The proceeds of the new loans were used to pay a loan that matured in October 2020 and a loan scheduled to mature in December 2021. In the first quarter of 2019, the Company entered into two Brazilian real-denominated loans totaling $18.0 million which matured in July and September of 2019, respectively. These loans bore interest at 123% and 128% of CDI, respectively. In the third quarter of 2019, the Company entered into Brazilian real-denominated loans totaling $36.0 million which mature in July and September of 2021. These loans bear interest at 120% and 141% of CDI, respectively. During the fourth quarter of 2019, the Company entered into two Brazilian real-denominated loans totaling $27.3 million which mature in September and December 2021. These loans bear interest at 126% and 129% of CDI, respectively. The Company also refinanced a loan with Rabobank that expired during the fourth quarter of 2019 in the amount of $17.4 million with a new loan with the same principal that bears interest at 122% of CDI and matures in November 2021. Securitization On June 30, 2020, certain of the Company’s U.S. subsidiaries entered into a three-year committed revolving accounts receivable financing facility (the “AR Facility”) of up to $100.0 million with PNC Bank, National Association (“PNC”), as administrative agent and lender, and PNC Capital Markets, LLC, as structuring agent. In connection with the AR Facility, two of the Company’s U.S. subsidiaries, from time to time, sell and contribute receivables and certain related assets to a special purposes entity and wholly-owned U.S. subsidiary of the Company (the “SPE”). The SPE finances its acquisition of the receivables by obtaining secured loans from PNC and the other lenders party to a receivables financing agreement. A U.S. subsidiary of the Company services the receivables on behalf of t he SPE for a fee. In addition, the Company has agreed to guarantee the performance by its subsidiaries. The Company and its subsidiaries do not guarantee the loan principal or interest under the receivables financing agreement or the collectability of the receivables under the AR Facility. As of December 31, 2020 , the Company received proceeds from the AR Facility in the amount of $51.2 million. The purchase price for the sale of receivables consists of cash available to the SPE from loans under the AR Facility and from collections on previously sold receivables and, to the extent the SPE does not have funds available to pay the purchase price due on any day in cash, through an increase in the principal amount of a subordinated intercompany loan. The SPE pays monthly interest and fees with respect to amounts advanced by the lenders under the AR Facility. The SPE’s sole business consists of the purchase or acceptance through capital contributions of the receivables and the subsequent granting of a security interest in these receivables and related rights to PNC on behalf of the lenders under the AR Facility. The SPE is a separate legal entity with its own separate creditors who will be entitled, upon its liquidation, to be satisfied out of the SPE’s assets prior to any assets or value in the SPE becoming available to the Company and the assets of the SPE are not available to pay creditors of the Company or any of its affiliates other than the SPE. Future maturities of long-term debt for the years ending December 31, are as follows (in millions): Debt Maturity 2021 $ 63.7 2022 57.8 2023 72.5 2024 270.0 2025 450.3 Thereafter 500.0 Total $ 1,414.3

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	DERIVATIVE FINANCIAL INSTRUMENTS The Company is subject to various types of market risks, including interest rate risk, foreign currency exchange rate transaction and translation risk and commodity pricing risk. Management may take actions to mitigate the exposure to these types of risks, including entering into forward purchase contracts and other financial instruments. Currently, the Company manages a portion of its commodity pricing and foreign currency exchange rate risks by using derivative instruments. From time to time, the Company may enter into immaterial foreign exchange contracts to mitigate foreign exchange risk on its sales and accounts receivable. The Company does not seek to engage in trading activities or take speculative positions with any financial instrument arrangement. The Company has entered into natural gas derivative instruments and foreign currency derivative instruments with counterparties it views as creditworthy. However, the Company does attempt to mitigate its counterparty credit risk exposures by, among other things, entering into master netting agreements with some of these counterparties. The Company records derivative financial instruments as either assets or liabilities at fair value in the consolidated balance sheets. Derivatives qualify for treatment as hedges when there is a high correlation between the change in fair value of the derivative instrument and the related change in value of the underlying hedged item. Depending on the exposure being hedged, the Company must designate the hedging instrument as a fair value hedge, a cash flow hedge or a net investment in foreign operations hedge. For the qualifying derivative instruments that have been designated as hedges, the effective portion of the change in fair value is recognized through earnings when the underlying transaction being hedged affects earnings, allowing a derivative’s gains and losses to offset related results from the hedged item in the statements of operations. Any ineffectiveness related to these hedges was not material for any of the periods presented. For derivative instruments that have not been designated as hedges, the entire change in fair value is recorded through earnings in the period of change. Natural Gas Derivative Instruments Natural gas is consumed at several of the Company’s production facilities, and a change in natural gas prices impacts the Company’s operating margin. The Company’s objective is to reduce the earnings and cash flow impacts of changes in market prices of natural gas by fixing the purchase price of up to 90% of its forecasted natural gas usage. It is the Company’s policy to consider hedging portions of its natural gas usage up to 36 months in advance of the forecasted purchase. As of December 31, 2020, the Company had entered into natural gas derivative instruments to hedge a portion of its natural gas purchase requirements through December 2022. As of December 31, 2020 and 2019, the Company had agreements in place to hedge forecasted natural gas purchases of 2.5 million and 2.8 million MMBtus, respectively. All natural gas derivative instruments held by the Company as of December 31, 2020 and 2019, qualified and were designated as cash flow hedges. As of December 31, 2020, the Company expects to reclassify from accumulated other comprehensive loss to earnings during the next twelve months $0.3 million of net gains on derivative instruments related to its natural gas hedges. Foreign Currency Swaps not Designated as Hedges In March 2020, the Company entered into forward instruments to swap currency denominated in U.S. dollars to Canadian dollars for a future intercompany payment from a U.S. subsidiary to a Canadian subsidiary. These instruments matured in April 2020 with combined notional amounts of $89.9 million. The objective of the instruments was to mitigate the foreign currency fluctuation risk related to intercompany payments denominated in a currency other than U.S. dollars, the Company’s functional currency. The instrument was not desi gnated as a hedge. When these agreements settled in April 2020, the Company recognized a foreign exchange loss of $3.1 million in its Consolidated Statements of Operations. In February 2018, the Company entered into a forward instrument to swap currency denominated in Brazilian real to Canadian dollars for the amounts borrowed under an intercompany note. The instrument matured in November 2018 and was for a notional amount of approximately $19.9 million U.S. dollars. The objective of the instrument was to mitigate the foreign currency fluctuation risk related to holding debt denominated in a currency other than Compass Minerals South America’s functional currency. The instrument was not designated as a hedge. During 2018, the Company recognized a net gain of $1.5 million in other expense in its Consolidated Statements of Operations for this agreement. In the latter half of 2018, the Company entered into non-deliverable forward contracts to fix $11.9 million of its net position in receivables and accounts payable in Brazil that were U.S. dollar denominated. The objective of these instruments was to mitigate the foreign currency fluctuation risk related to the Company’s receivables and accounts payable denominated in a currency other than Compass Minerals South America’s functional currency. These forward contracts were not designated as hedges and matured in December 2018. During 2018, the Company recognized a net loss of $1.0 million in other expense in its Consolidated Statements of Operations for these forward contracts. From time to time, the Company’s Brazilian subsidiary may enter into forward instruments to swap currency for sales invoices that are denominated in Brazilian real. These instruments are not material to the Company’s consolidated financial statements. Foreign Currency Swaps Designated as Hedges The Company has entered into euro-denominated debt instruments to provide funds for its operations in Brazil (see Note 10 for more information). The Company may also concurrently enter into foreign currency agreements whereby the Company agrees to swap interest and principal payments on loans denominated in euros for principal and interest payments denominated in Brazilian real, its South American subsidiary’s functional currency. The objective of the swap agreements is to mitigate the foreign currency fluctuation risk related to holding debt denominated in a currency other than the Company’s South American subsidiary’s functional currency. As of both December 31, 2020 and 2019, the Company had one swap agreement in place to hedge $10.5 million and $15.7 million, respectively, of loans denominated in a currency other than its South American subsidiary’s functional currency. Payments on the December 31, 2020, loan are due on various dates extending through February 2021, while payments on the December 31, 2019, loan were due on various dates extending through March 2020. As of both December 31, 2020 and 2019, the foreign currency derivative instrument qualified and was designated as a cash flow hedge. As of December 31, 2020, the Company expects to reclassify from accumulated other comprehensive loss to earnings during the next twelve months $2.6 million of net gains on derivative instruments related to this foreign currency swap agreement. The following tables present the fair value of the Company’s derivatives as of December 31, 2020 and 2019 (in millions): Asset Derivatives Liability Derivatives Derivatives designated as hedging instruments: Consolidated Balance Sheet Location December 31, 2020 Consolidated Balance Sheet Location December 31, 2020 Commodity contracts Other current assets $ 0.4 Accrued expenses and other current liabilities $ 0.1 Commodity contracts Other assets 0.1 Other noncurrent liabilities 0.2 Swap contracts Other current assets 2.6 Accrued expenses and other current liabilities — Total derivatives designated as hedging instruments (a)(b) $ 3.1 $ 0.3 (a) The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $0.3 million of its commodity contracts that are in payable positions against its contracts in receivable positions. (b) The Company has commodity hedge agreements with two counterparties and a foreign currency swap agreement with one counterparty. Amounts recorded for the Company’s commodity contracts are receivable from both counterparties. Asset Derivatives Liability Derivatives Derivatives designated as hedging instruments: Consolidated Balance Sheet Location December 31, 2019 Consolidated Balance Sheet Location December 31, 2019 Commodity contracts Other current assets $ 0.3 Accrued expenses and other current liabilities $ 0.8 Commodity contracts Other assets 0.1 Other noncurrent liabilities 0.2 Swap contracts Other current assets 2.8 Accrued expenses and other current liabilities — Total derivatives designated as hedging instruments (a)(b) $ 3.2 $ 1.0 (a) The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $0.4 million of its commodity contracts that are in a receivable position against its contracts in payable positions. (b) The Company has both commodity hedge and foreign currency swap agreements with two counterparties each. Amounts recorded as liabilities for the Company’s commodity contracts are payable to both counterparties, and amounts recorded as assets for the Company’s swap contracts are receivable from both counterparties. The following tables present activity related to other comprehensive (loss) income before taxes for the years ended December 31, 2020 and 2019 (in millions): Year Ended December 31, 2020 Derivatives in Cash Flow Hedging Relationships Location of Gain Reclassified from Accumulated OCI Into Income (Effective Portion) Amount of Gain Recognized in OCI on Derivative (Effective Portion) Amount of Gain Reclassified from Accumulated OCI Into Income (Effective Portion) Commodity contracts Product cost $ (1.8) $ 1.0 Swap contracts Interest expense (3.9) 3.6 Total $ (5.7) $ 4.6 Year Ended December 31, 2019 Derivatives in Cash Flow Hedging Relationships Location of Gain Reclassified from Accumulated OCI Into Income Effective Portion) Amount of Gain Recognized in OCI on Derivative (Effective Portion) Amount of Gain Reclassified from Accumulated OCI Into Income (Effective Portion) Commodity contracts Product cost $ (0.8) $ 0.9 Swap contracts Interest expense (2.5) 2.2 Total $ (3.3) $ 3.1

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Contingent Obligations: The Wisconsin Department of Agriculture, Trade and Consumer Protection (“DATCP”) has information indicating that agricultural chemicals are present within the subsurface area of the Company’s Kenosha, Wisconsin property. The agricultural chemicals were used by previous owners and operators of the site. None of the identified chemicals have been used in association with the Company’s operations since it acquired the property in 2002. DATCP directed the Company to conduct further investigations into the possible presence of agricultural chemicals in soil and ground water at the Kenosha property. The Company has completed initial on-property investigations and has provided the findings to DATCP. All investigations and mitigation activities to date, and any potential future remediation work, are being conducted under the Wisconsin Agricultural Chemical Cleanup Program (the “ACCP”), which provides for reimbursement of some of the costs. The Company may seek participation by, or cost reimbursement from, other parties responsible for the presence of any agricultural chemicals found in soil and ground water at this site if the Company does not receive an acknowledgment of no further action and is required to conduct further investigation or remedial work that may not be eligible for reimbursement under the ACCP. The Company conducts business operations in several countries and is subject to various federal and local labor, social security, environmental and tax laws. While the Company believes it complies with such laws, they are complex and subject to interpretation. In addition to the tax assessments discussed in Note 8 , the Company’s Brazilian subsidiaries are party to administrative tax proceedings and claims which totaled $7.9 million and $15.8 million as of December 31, 2020 and 2019, respectively, and relate primarily to value added tax, state tax (ICMS) and social security tax (PIS and COFINS) assessments. The Company has assessed the likelihood of a loss at less than probable and therefore, has not established a reserve for these matters. The Company also has assumed liabilities for labor-related matters in connection with the acquisition of Compass Minerals South America, which are primarily related to compensation, labor benefits and consequential tax claims and totaled $3.5 million and $5.6 million as of December 31, 2020 and 2019, respectively. The Company believes the maximum exposure for these other labor matters totaled approximately $16 million and $25 million as of December 31, 2020 and 2019, respectively. The Division of Enforcement of the U.S. Securities and Exchange Commission (“SEC”) is investigating the Company’s disclosures concerning the operation of the Goderich mine. The Company has cooperated with this investigation and will continue to do so. While it is not possible to predict the timing or the outcome of the SEC inquiry, the Company believes that this matter will not have a material impact on its results of operation, cash flows or financial position. The Company is also involved in legal and administrative proceedings and claims of various types from the ordinary course of the Company’s business. Management cannot predict the outcome of legal claims and proceedings with certainty. Nevertheless, management believes that the outcome of legal proceeding and claims, which are pending or known to be threatened, even if determined adversely, will not, individually or in the aggregate, have a material adverse effect on the Company’s results of operations, cash flows or financial position. Approximately 50% of workforce in the U.S., Canada and the U.K. and approximately 30% of the Company’s global workforce is represented by collective bargaining agreements. Of the Company’s 12 collective bargaining agreements in effect on January 1, 2021, two will expire in 2021 (including one for the Goderich mine, which expires on March 31, 2021), five will expire in 2022, three will expire in 2023 and one will expire in 2027. In addition, trade union membership is mandatory in Brazil, where approximately 40% of the Company’s global workforce is located. Commitments: Royalties: The Company has various private, state and Canadian provincial leases associated with the salt and specialty potash businesses, most of which are renewable by the Company. Many of these leases provide for a royalty payment to the lessor based on a specific amount per ton of mineral extracted or as a percentage of revenue. Royalty expense related to these leases was $18.3 million, $16.3 million and $14.8 million for the years ended December 31, 2020, 2019 and 2018, respectively. Performance Bonds: The Company has various salt and other deicing product sales contracts that include performance provisions governing delivery and product quality. These sales contracts either require the Company to maintain performance bonds for stipulated amounts or contain contractual penalty provisions in the event of non-performance. For the three years ended December 31, 2020, the Company has had no material penalties related to these sales contracts. At December 31, 2020, the Company had $51.4 million of outstanding performance bonds, which includes bonds related to Ontario mining tax reassessments. Purchase Commitments: In connection with the operations of the Company’s facilities, the Company purchases utilities, other raw materials and services from third parties under contracts extending, in some cases, for multiple years. Purchases under these contracts are generally based on prevailing market prices. The Company has minimum throughput contracts with some of its depots and warehouses. The purchase commitments for these contracts are estimated to be $43.6 million for 2021, $13.3 million in 2022, $10.0 million in 2023, $7.8 million in 2024, $2.1 million in 2025 and $7.5 million thereafter.

STOCKHOLDERS' EQUITY AND EQUITY

STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS	STOCKHOLDERS’ EQUITY AND EQUITY INSTRUMENTS The Company paid dividends of $2.88 per share in 2020 and currently intends to continue paying quarterly cash dividends. The declaration and payment of future dividends to holders of the Company’s common stock will be at the discretion of the Company’s Board of Directors and will depend upon many factors, including the Company’s financial condition, earnings, legal requirements, restrictions in its debt agreements (see Note 10 ) and other factors the Company’s Board of Directors deems relevant. Non-Employee Director Compensation Non-employee directors may defer all or a portion of the fees payable for their service into deferred stock units, equivalent to the value of the Company’s common stock. Beginning in May 2020, the annual fees related to the director’s equity compensation were granted in deferred stock units or restricted stock units and vest at the next annual meeting. Additionally, as dividends are declared on the Company’s common stock, these deferred stock units are entitled to accrete dividends in the form of additional units based on the stock price on the dividend payment date. Accumulated deferred stock units are distributed in the form of Company common stock at a future specified date or following resignation from the Board of Directors, based upon the director’s annual election. During the years ended December 31, 2020, 2019 and 2018, members of the Board of Directors were credited with 42,313, 33,883 and 26,291 deferred stock units, respectively. During the year ended December 31, 2020, the directors were granted 3,750 restricted stock units. During the years ended December 31, 2020, 2019 and 2018, 8,525, 9,041 and 6,728 shares of common stock, respectively, were issued from treasury shares for director compensation. Preferred stock The Company is authorized to issue up to 10,000,000 shares of preferred stock, of which no shares are currently issued or outstanding. Of those, 200,000 shares of preferred stock were designated as series A junior participating preferred stock in connection with the Company’s now expired rights agreement. Equity Compensation Awards In 2005, the Company adopted the 2005 Incentive Award Plan (as amended, the “2005 Plan”), which authorized the issuance of 3,240,000 shares of Company common stock. In May 2015, the Company’s stockholders approved the 2015 Incentive Award Plan (as amended, the “2015 Plan”), which authorizes the issuance of 3,000,000 shares of Company common stock. Upon the approval of the 2015 Plan , the Company ceased issuing equity awards under the 2005 Plan. In May 2020, the Company’s stockholders approved the 2020 Incentive Award Plan (the “2020 Plan”), which authorizes the issuance of 2,977,933 shares of Company common stock. Since the date the 2020 Plan was approved, the Company ceased issuing equity awards under the 2015 Plan. The 2005 Plan, 2015 Plan and 2020 Plan allow for grants of equity awards to executive officers, other employees and directors, including shares of common stock, restricted stock units (“RSUs”), performance stock units (“PSUs”), stock options and deferred stock units. Options Substantially all of the stock options granted under each of the plans vest ratably, in tranches, over a four-year service period. Unexercised options expire after seven years. Options do not have dividend or voting rights. Upon vesting, each option can be exercised to purchase one share of the Company’s common stock. The exercise price of options is equal to the closing stock price on the day of grant. To estimate the fair value of options on the grant date, the Company uses the Black-Scholes option valuation model. Award recipients are grouped according to expected exercise behavior. Unless better information is available to estimate the expected term of the options, the estimate is based on historical exercise experience. The risk-free rate, using U.S. Treasury yield curves in effect at the time of grant, is selected based on the expected term of each group. The Company’s historical stock price is used to estimate expected volatility. The weighted average assumptions and fair values for options granted for each of the years ended December 31 is included in the following table. 2020 2019 2018 Fair value of options granted $ 10.91 $ 9.15 $ 8.77 Expected term (years) 4.8 4.5 4.5 Expected volatility 29.3 % 28.0 % 22.9 % Dividend yield 3.5 % 4.1 % 3.6 % Risk-free interest rates 1.6 % 2.3 % 2.5 % RSUs Most of the RSUs granted under the 2015 Plan and 2020 Plan vest after one PSUs Substantially all of the PSUs granted under the 2015 Plan and 2020 Plan are either total stockholder return PSUs (the “TSR PSUs”), return on invested capital PSUs (the “ROIC PSUs”) or earnings before interest, taxes, depreciation and amortization growth PSUs (“EBITDA PSUs”). The actual number of shares of the Company’s common stock that may be earned with respect to TSR PSUs is calculated by comparing the Company’s total stockholder return to the total stockholder return for each company comprising the Company’s peer group over the three-year performance period and may range from 0% to 150% or 0% to 200% of the target number of shares based upon the attainment of these performance conditions. The actual number of shares of common stock that may be earned with respect to ROIC PSUs is calculated based on the average of the Company’s annual return on invested capital for each year in the three-year performance period and may range from 0% to 200% of the target number of shares based upon the attainment of these performance conditions. The actual number of shares of common stock that may be earned with respect to EBITDA PSUs is calculated based on the attainment of EBITDA growth during the performance period. EBITDA PSUs granted in 2020 have a two-year performance period that begins in 2021 and ends in 2022. Generally, TSR PSUs granted in 2020 have a three-year performance period that begins in 2020 and ends in 2022. Both types of PSUs granted in 2020 vest in the first quarter of 2023. PSUs represent a target number of shares of Company common stock that may be earned before adjustment based upon the attainment of certain performance conditions. Holders of PSUs are entitled to receive non-forfeitable dividends or other distributions equal to those declared on the Company’s common stock for PSUs that are earned, which are paid when the shares underlying the PSUs are issued. To estimate the fair value of the TSR PSUs on the grant date, the Company uses a Monte-Carlo simulation model, which simulates future stock prices of the Company as well as the companies peer group. This model uses historical stock prices to estimate expected volatility and the Company’s correlation to the peer group. The risk-free rate was determined using the same methodology as the option valuations as discussed above. The Company’s closing stock price on the grant date was used to estimate the fair value of the ROIC PSUs and EBITDA PSUs. The Company will adjust the expense of the ROIC PSUs and EBITDA PSUs based upon its estimate of the number of shares that will ultimately vest at each interim date during the vesting period. The following is a summary of the Company’s stock option, RSU and PSU activity and related information for the following periods: Stock Options RSUs PSUs Number Weighted-average exercise price Number Weighted-average fair value Number Weighted-average fair value Outstanding at December 31, 2017 562,877 $ 75.89 70,856 $ 74.63 112,036 $ 79.48 Granted 250,514 59.61 42,013 60.28 67,235 64.30 Exercised (a) — — — — — — Released from restriction (a) — — (16,905) 88.78 (2,753) 78.92 Cancelled/Expired (104,645) 71.65 (12,656) 66.53 (49,880) 85.51 Outstanding at December 31, 2018 708,746 $ 70.76 83,308 $ 65.75 126,638 $ 69.06 Granted 369,716 54.15 218,071 49.73 123,003 56.88 Exercised (a) — — — — — — Released from restriction (a) — — (32,630) 66.95 — — Cancelled/Expired (190,595) 69.06 (51,336) 54.87 (70,244) 67.20 Outstanding at December 31, 2019 887,867 $ 64.21 217,413 $ 52.07 179,397 $ 61.43 Granted 94,945 58.91 95,276 58.24 107,072 74.73 Exercised (a) (4,454) 57.02 — — — — Released from restriction (a) — — (76,570) 50.03 (11,575) 78.87 Cancelled/Expired (109,586) 69.00 (28,137) 51.85 (33,100) 68.18 Outstanding at December 31, 2020 868,772 $ 63.06 207,982 $ 55.68 241,794 $ 65.57 (a) Common stock issued for exercised options, vested RSUs and vested and earned PSUs were issued from treasury shares. As of December 31, 2019, there were 887,867 options outstanding of which 416,860 were exercisable. The following table summarizes information about options outstanding and exercisable at December 31, 2020. Options Outstanding Options Exercisable Range of exercise prices Options outstanding Weighted-average remaining contractual life (years) Weighted-average exercise price of options outstanding Options exercisable Weighted-average remaining contractual life (years) Weighted-average exercise price of exercisable options $53.75 - $54.38 252,245 5.3 $ 53.75 84,082 5.3 $ 53.75 $54.39 - $59.21 159,424 5.7 57.01 18,836 5.2 55.01 $59.22 - $63.75 159,445 4.3 59.50 110,700 4.3 59.50 $63.76 - $69.77 119,357 3.1 68.03 104,796 3.0 68.01 $69.78 - $91.75 178,301 1.3 81.51 178,301 1.3 81.51 Totals 868,772 4.1 $ 63.06 496,715 3.1 $ 68.05 During the years ended December 31, 2020, 2019 and 2018, the Company recorded compensation expense of $9.9 million (includes $0.5 million paid in cash), $7.4 million (includes $1.1 million paid in cash) and $7.8 million, respectively, related to its stock-based compensation awards that are expected to vest. No amounts have been capitalized. The fair value of options vested was $1.4 million, $0.8 million and $2.7 million in 2020, 2019 and 2018, respectively. As of December 31, 2020, unrecorded compensation cost related to non-vested awards of $14.7 million is expected to be recognized from 2021 through 2023, with a weighted average period of 1.8 years. The intrinsic value of stock options exercised during the years ended December 31, 2020, 2019 and 2018 each totaled less than $0.1 million. As of December 31, 2020, the intrinsic value of options outstanding totaled $3.1 million, of which 496,715 options with an intrinsic value of $1.0 million were exercisable. The number of shares held in treasury is sufficient to cover all outstanding equity awards as of December 31, 2020. Accumulated Other Comprehensive Loss The Company’s comprehensive (loss) income is comprised of net earnings, net amortization of the unrealized loss of the pension obligation, the change in the unrealized gain (loss) on natural gas and foreign currency cash flow hedges, and foreign currency translation adjustments. The components of and changes in accumulated other comprehensive loss (“AOCL”) for the years ended December 31, 2020 and 2019 are as follows (in millions): Year Ended December 31, 2020 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (0.6) $ (6.9) $ (184.6) $ (192.1) Other comprehensive income (loss) before reclassifications 3.9 (3.2) (109.5) (108.8) Amounts reclassified from accumulated other comprehensive loss (3.1) 0.7 — (2.4) Net current period other comprehensive income (loss) 0.8 (2.5) (109.5) (111.2) Ending balance $ 0.2 $ (9.4) $ (294.1) $ (303.3) Year Ended December 31, 2019 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (0.7) $ (4.5) $ (205.7) $ (210.9) Other comprehensive income (loss) before reclassifications 2.2 (2.7) 21.1 20.6 Amounts reclassified from accumulated other comprehensive loss (2.1) 0.3 — (1.8) Net current period other comprehensive income (loss) 0.1 (2.4) 21.1 18.8 Ending balance $ (0.6) $ (6.9) $ (184.6) $ (192.1) (a) With the exception of the cumulative foreign currency translation adjustment, for which no tax effect is recorded, the changes in the components of AOCL presented in the table are reflected net of applicable income taxes. Year Ended December 31, 2020 Amount Reclassified from AOCL Line Item Impacted in the Consolidated Statement of Operations Losses on cash flow hedges: Natural gas instruments $ (1.0) Product cost Foreign currency contracts (3.6) Interest expense Income tax expense 1.5 Reclassifications, net of income taxes (3.1) Amortization of defined benefit pension: Amortization of loss $ 0.9 Product cost Income tax benefit (0.2) Reclassifications, net of income taxes 0.7 Total reclassifications, net of income taxes $ (2.4) Year Ended December 31, 2019 Amount Reclassified from AOCL Line Item Impacted in the Consolidated Statement of Operations Gains (losses) on cash flow hedges: Natural gas instruments $ (0.9) Product cost Foreign currency contracts (2.2) Interest Expense Income tax expense 1.0 Reclassifications, net of income taxes (2.1) Amortization of defined benefit pension: Amortization of loss $ 0.4 Product cost Income tax benefit (0.1) Reclassifications, net of income taxes 0.3 Total reclassifications, net of income taxes $ (1.8)

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Company’s financial instruments are measured and reported at their estimated fair value. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction. When available, the Company uses quoted prices in active markets to determine the fair values for its financial instruments (Level 1 inputs), or absent quoted market prices, observable market-corroborated inputs over the term of the financial instruments (Level 2 inputs). The Company does not have any unobservable inputs that are not corroborated by market inputs (Level 3 inputs). The Company holds marketable securities associated with its Savings Plans, which are valued based on readily available quoted market prices. The Company also holds short-term investments which are classified as trading securities with any gains or losses recognized through earnings. The Company utilizes derivative instruments to manage its risk of changes in natural gas prices and its risk of changes in foreign currency exchange rates (see Note 11 ). The fair value of the natural gas derivative instruments and the foreign currency swaps are determined using market data of forward prices for all of the Company’s contracts. The estimated fair values for each type of instrument are presented below (in millions). December 31, 2020 Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified savings plan (a) $ 1.9 $ 1.9 $ — $ — Derivatives – natural gas instruments, net 0.2 — 0.2 — Derivatives - foreign currency contracts, net 2.6 — 2.6 — Total Assets $ 4.7 $ 1.9 $ 2.8 $ — Liability Class: Liabilities related to non-qualified savings plan $ (1.9) $ (1.9) $ — $ — Total Liabilities $ (1.9) $ (1.9) $ — $ — (a) Includes mutual fund investments of approximately 30% in the common stock of large-cap U.S. companies, 10% in the common stock of small to mid-cap U.S. companies, 5% in the common stock of international companies, 15% in bond funds, 15% in short-term investments and 25% in blended funds. December 31, 2019 Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified savings plan (a) $ 1.4 $ 1.4 $ — $ — Derivatives - foreign currency contracts, net 2.8 — 2.8 — Total Assets $ 4.2 $ 1.4 $ 2.8 $ — Liability Class: Liabilities related to non-qualified savings plan $ (1.4) $ (1.4) $ — $ — Derivatives - natural gas instruments, net (0.6) — (0.6) — Total Liabilities $ (2.0) $ (1.4) $ (0.6) $ — (a) Includes mutual fund investments of approximately 30% in the common stock of large-cap U.S. companies, 15% in the common stock of small to mid-cap U.S. companies, 5% in the common stock of international companies, 10% in bond funds, 20% in short-term investments and 20% in blended funds. Cash and cash equivalents, receivables (net of reserve for doubtful accounts) and accounts payable are carried at cost, which approximates fair value due to their liquid and short-term nature. The Company’s investments related to its nonqualified retirement plan of $1.9 million and $1.4 million as of December 31, 2020 and 2019, respectively, are stated at fair value based on quoted market prices. As of December 31, 2020 and 2019, the estimated fair value of the Company’s fixed-rate 4.875% Notes, based on available trading information (Level 2), totaled $260.3 million and $249.1 million, respectively, compared with the aggregate principal amount at maturity of $250.0 million. As of December 31, 2020 and 2019, the estimated fair value of the Company’s fixed-rate 6.75% Notes, based on available trading information (Level 2), totaled $543.1 million and $530.6 million, respectively, compared with the aggregate principal amount at maturity of $500.0 million. The fair value at December 31, 2020 and 2019 of amounts outstanding under the Company’s term loans and revolving credit facility, based upon available bid information received from the Company’s lender (Level 2), totaled approximately $513.8 million and $552.8 million, respectively, compared with the aggregate principal amount at maturity of $520.3 million and $560.0 million, respectively. The Brazilian loans have floating rates and their fair value approximates their carrying value (see Note 10 ).

OPERATING SEGMENTS

OPERATING SEGMENTS	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
OPERATING SEGMENTS	OPERATING SEGMENTS The Company’s reportable segments are strategic business units that offer different products and services, and each business requires different technology and marketing strategies. The Company has three reportable segments: Salt, Plant Nutrition North America and Plant Nutrition South America. The Salt segment produces and markets salt and magnesium chloride for use in road deicing and dust control, food processing, water softeners and agricultural and industrial applications. SOP crop nutrients, industrial-grade SOP and micronutrients are produced and marketed through the Plant Nutrition North America segment. The Company’s Plant Nutrition South America segment operates two primary businesses in Brazil – agricultural productivity and chemical solutions. The agricultural productivity division manufactures and distributes a broad offering of specialty plant nutrition solution-based products that are used in direct soil and foliar applications, as well as through irrigation systems and for seed treatment. It also manufactures and markets specialty chemicals for the industrial chemical industry. The accounting policies of the segments are the same as those described in the summary of significant accounting policies. All intersegment sales prices are market-based. The Company evaluates performance based on the operating earnings of the respective segments. Segment information as of and for the years ended December 31, is as follows (in millions): 2020 Salt Plant Nutrition North America Plant Nutrition South America Corporate& Other (a) Total Sales to external customers $ 779.4 $ 239.6 $ 344.4 $ 10.1 $ 1,373.5 Intersegment sales — 5.4 0.3 (5.7) — Shipping and handling cost 217.8 34.0 14.8 — 266.6 Operating earnings (loss) 161.8 12.1 40.3 (73.7) 140.5 Depreciation, depletion and amortization 66.6 40.4 17.4 13.5 137.9 Total assets 1,020.8 520.8 579.2 141.6 2,262.4 Capital expenditures 56.8 12.5 9.6 6.0 84.9 2019 Salt Plant Nutrition North America Plant Nutrition South America Corporate& Other (a) Total Sales to external customers $ 889.5 $ 206.2 $ 385.1 $ 9.7 $ 1,490.5 Intersegment sales — 6.4 2.7 (9.1) — Shipping and handling cost 267.4 28.5 16.6 — 312.5 Operating earnings (loss) (b) 168.0 22.5 40.0 (66.9) 163.6 Depreciation, depletion and amortization 60.4 44.6 22.4 10.5 137.9 Total assets 1,056.3 575.5 715.3 96.1 2,443.2 Capital expenditures 65.9 15.2 10.5 6.5 98.1 2018 Salt Plant Nutrition North America Plant Nutrition South America Corporate& Other (a) Total Sales to external customers $ 858.1 $ 233.2 $ 391.8 $ 10.5 $ 1,493.6 Intersegment sales — 5.6 3.4 (9.0) — Shipping and handling cost 272.4 29.0 18.6 — 320.0 Operating earnings (loss) (b) 115.7 25.3 48.7 (59.4) 130.3 Depreciation, depletion and amortization 56.2 48.6 22.2 9.9 136.9 Total assets 948.9 589.3 709.9 119.8 2,367.9 Capital expenditures 58.7 20.7 10.1 7.3 96.8 Disaggregated revenue by product type is as follows (in millions): Year Ended December 31, 2020 Salt Plant Nutrition North America Plant Nutrition South America Corporate & Other (a) Total Highway Deicing Salt $ 473.8 $ — $ — $ — $ 473.8 Consumer & Industrial Salt 305.6 — — — 305.6 SOP and Specialty Plant Nutrients — 245.0 272.8 — 517.8 Industrial Chemicals — — 71.9 — 71.9 Eliminations & Other — (5.4) (0.3) 10.1 4.4 Sales to external customers $ 779.4 $ 239.6 $ 344.4 $ 10.1 $ 1,373.5 Year Ended December 31, 2019 Salt Plant Nutrition North America Plant Nutrition South America Corporate & Other (a) Total Highway Deicing Salt $ 545.5 $ — $ — $ — $ 545.5 Consumer & Industrial Salt 344.0 — — — 344.0 SOP and Specialty Plant Nutrients — 212.6 298.6 — 511.2 Industrial Chemicals — — 89.2 — 89.2 Eliminations & Other — (6.4) (2.7) 9.7 0.6 Sales to external customers $ 889.5 $ 206.2 $ 385.1 $ 9.7 $ 1,490.5 Year Ended December 31, 2018 Salt Plant Nutrition North America Plant Nutrition South America Corporate & Other (a) Total Highway Deicing Salt $ 532.0 $ — $ — $ — $ 532.0 Consumer & Industrial Salt 326.1 — — — 326.1 SOP and Specialty Plant Nutrients — 238.8 300.2 — 539.0 Industrial Chemicals — — 95.0 — 95.0 Eliminations & Other — (5.6) (3.4) 10.5 1.5 Sales to external customers $ 858.1 $ 233.2 $ 391.8 $ 10.5 $ 1,493.6 (a) Corporate and Other includes corporate entities, records management operations and other incidental operations and eliminations. Operating earnings (loss) for corporate and other includes indirect corporate overhead including costs for general corporate governance and oversight, as well as costs for the human resources, information technology and finance functions. (b) In 2019, operating results included $2.8 million of additional logistics costs related to Mississippi River flooding and $2.3 million of severance and other costs related to executive transition. In 2018, corporate and other operating results included $5.1 million for executive transition costs. Financial information relating to the Company’s operations by geographic area for the years ended December 31 is as follows (in millions): Sales 2020 2019 2018 United States (a) $ 766.6 $ 821.9 $ 769.9 Canada 207.6 228.8 238.6 Brazil 336.6 375.2 381.8 United Kingdom 41.6 45.2 83.1 Other 21.1 19.4 20.2 Total sales $ 1,373.5 $ 1,490.5 $ 1,493.6 (a) United States sales exclude product sold to foreign customers at U.S. ports. Financial information relating to the Company’s long-lived assets, excluding the investments related to the nonqualified retirement plan and pension plan assets, by geographic area as of December 31 (in millions): Long-Lived Assets 2020 2019 2018 United States $ 532.9 $ 561.5 $ 551.6 Canada 514.0 522.8 497.4 United Kingdom 73.9 71.4 62.5 Brazil 376.0 493.1 524.8 Other 6.5 6.5 6.5 Total long-lived assets $ 1,503.3 $ 1,655.3 $ 1,642.8

EARNINGS PER SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE The two-class method requires allocating the Company’s net earnings to both common shares and participating securities. The following table sets forth the computation of basic and diluted earnings per common share (in millions, except for share and per share data): Year ended December 31, 2020 2019 2018 Numerator: Net earnings $ 59.5 $ 62.5 $ 68.8 Less: Net earnings allocated to participating securities (a) (1.3) (1.1) (0.5) Net earnings available to common stockholders $ 58.2 $ 61.4 $ 68.3 Denominator (in thousands): Weighted average common shares outstanding, shares for basic earnings per share (b) 33,928 33,882 33,848 Weighted average equity awards outstanding — — — Shares for diluted earnings per share 33,928 33,882 33,848 Net earnings per common share, basic $ 1.72 $ 1.82 $ 2.02 Net earnings per common share, diluted $ 1.72 $ 1.81 $ 2.02 (a) Participating securities include PSUs and RSUs that receive non-forfeitable dividends. Net earnings were allocated to participating securities of 397,000, 307,000 and 186,000 for 2020, 2019 and 2018, respectively. (b) For the calculation of diluted earnings per share, the Company uses the more dilutive of either the treasury stock method or the two-class method to determine the weighted average number of outstanding common shares. In addition, the Company had 1,188,000, 1,067,000 and 788,000 weighted options outstanding for 2020, 2019 and 2018, respectively, which were anti-dilutive and therefore not included in the diluted earnings per share calculation.

QUARTERLY RESULTS (Unaudited)

QUARTERLY RESULTS (Unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY RESULTS (Unaudited)	QUARTERLY RESULTS (Unaudited) (in millions, except share and per share data) Quarter First Second Third Fourth 2020 Sales $ 413.9 $ 256.1 $ 282.4 $ 421.1 Gross profit 87.3 66.3 58.7 100.0 Net earnings (loss) (a) 27.6 1.7 (2.1) 32.3 Net earnings (loss) per share, basic (a) 0.80 0.04 (0.07) 0.94 Net earnings (loss) per share, diluted (a) 0.80 0.04 (0.07) 0.94 Basic weighted-average shares outstanding (in thousands) 33,892 33,915 33,947 33,958 Diluted weighted-average shares outstanding (in thousands) 33,892 33,915 33,947 33,977 2019 Sales $ 403.7 $ 245.2 $ 341.3 $ 500.3 Gross profit 72.6 45.8 76.4 142.0 Net earnings (loss) (a) 7.6 (11.8) 10.6 56.1 Net earnings (loss) per share, basic (a) 0.22 (0.36) 0.31 1.64 Net earnings (loss) per share, diluted (a) 0.22 (0.36) 0.31 1.63 Basic weighted-average shares outstanding (in thousands) 33,874 33,883 33,884 33,886 Diluted weighted-average shares outstanding (in thousands) 33,874 33,883 33,884 33,886 (a) In the fourth quarter of 2020, the Company released a domestic tax reserve of $11.0 million. In the second quarter of 2019, the Company incurred $2.8 million ($2.1 million, net of tax) of additional logistics costs related to Mississippi River flooding. In the third quarter of 2019, the Company incurred $2.3 million ($1.7 million, net of tax) of severance and other costs related to executive transition.

SUBSEQUENT EVENT

SUBSEQUENT EVENT	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENT	SUBSEQUENT EVENT Dividend Declared: On February 25, 2021, the Board of Directors declared a quarterly cash dividend of $0.72 per share on the Company’s outstanding common stock, unchanged from the quarterly cash dividends paid in 2020. The dividend will be paid on March 19, 2021, to stockholders of record as of the close of business on March 10, 2021.

Schedule II - Valuation Reserve

Schedule II - Valuation Reserves	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation Reserves	Schedule II — Valuation Reserves Compass Minerals International, Inc. December 31, 2020, 2019 and 2018 Description (in millions) Balance at the Beginning of the Year Additions (Deductions) Charged to Expense Deductions (1) Balance at the End of the Year Deducted from Receivables — Allowance for Doubtful Accounts 2020 $ 10.7 $ 9.3 $ (8.9) $ 11.1 2019 9.9 4.7 (3.9) 10.7 2018 10.9 1.0 (2.0) 9.9 Deducted from Deferred Income Taxes — Valuation Allowance 2020 $ 41.2 $ 2.5 $ (0.3) $ 43.4 2019 40.9 0.3 — 41.2 2018 (2) 10.2 39.2 (8.5) 40.9 (1) Deduction for purposes for which reserve was created. (2) The 2018 additions primarily relate to foreign tax credits which offset a deferred tax asset. This amount was not charged to expense.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Management Estimates	Management Estimates:The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (“GAAP”) as included in the Accounting Standards Codification requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates.
Basis of Consolidation	Basis of Consolidation:The Company’s consolidated financial statements include the accounts of CMI and its wholly-owned domestic and foreign subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Reclassifications	Reclassifications:The Company has made reclassifications of prior year amounts in Consolidated Statements of Operations to conform to current year presentation.
Foreign Currency	Foreign Currency:Assets and liabilities are translated into U.S. dollars at end of period exchange rates. Revenues and expenses are translated using the monthly average rates of exchange during the year. Adjustments resulting from the translation of foreign-currency financial statements into the reporting currency, U.S. dollars, are included in accumulated other comprehensive loss.
Revenue Recognition	Revenue Recognition: The Financial Accounting Standards Board (the “FASB”) revenue recognition guidance provides a single, comprehensive model for recognizing revenue from contracts with customers. The revenue recognition model requires revenue to be recognized upon the transfer of promised goods or services to customers in an amount that reflects the consideration an entity expects to receive in exchange for those goods or services. The Company’s revenue arrangements generally consist of a single performance obligation to transfer promised goods or services. Accordingly, substantially all of the Company’s revenue is recognized at a point in time when control of the goods transfers to the customer. The Company typically recognizes revenue at the time of shipment to the customer, which coincides with the transfer of title and risk of ownership to the customer. Sales represent billings to customers net of sales taxes charged for the sale of the product. Sales include amounts charged to customers for shipping and handling costs, which are expensed when the related product is sold.
Cash and Cash Equivalents	Cash and Cash Equivalents: The Company considers all investments with original maturities of three months or less to be cash equivalents. The Company maintains the majority of its cash in bank deposit accounts with several commercial banks with high credit ratings in the U.S., Canada, Brazil and Europe. Typically, the Company has bank deposits in excess of federally insured limits. Currently, the Company does not believe it is exposed to significant credit risk on its cash and cash equivalents.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts: Receivables consist almost entirely of trade accounts receivable. Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in its existing trade accounts receivable. The Company determines the allowance based on historical write-off experience by business line and a current assessment of its portfolio, including information regarding individual customers. The Company reviews its past due account balances for collectability and adjusts its allowance for doubtful accounts accordingly. Account balances are charged off against the allowance when the Company believes it is probable that the trade accounts receivable will not be recovered.
Inventories	Inventories:Inventories are stated at the lower of cost or net realizable value. Finished goods and raw material and supply costs are valued using the average cost method on a first-in-first-out basis. Raw materials and supply costs primarily consist of raw materials purchased to aid in the production of mineral and chemical products, maintenance materials and packaging materials. Finished goods are primarily comprised of salt, magnesium chloride, and plant nutrition and chemical products readily available for sale. Substantially all costs associated with the production of finished goods at the Company’s production locations are captured as inventory costs. As required by U.S. GAAP, a portion of the fixed costs at a location are not included in inventory and are expensed as a product cost if production at that location is determined to be abnormally low in any period. Additionally, since the Company’s products are often stored at third-party warehousing locations, the Company includes in the cost of inventory the freight and handling costs necessary to move the product to storage until the product is sold to a customer.
Other Current Assets	Other Current Assets:In the fourth quarter of 2015, the Company began marketing certain assets used in farming operations. Management remains committed to sell these assets, and the assets continue to be marketed at a reasonable price. The Company has performed an impairment analysis and concluded that the fair market value of these assets exceeds their carrying value. These assets have been recorded in other current assets in the Consolidated Balance Sheets as of December 31, 2020 and 2019.
Property, Plant and Equipment	Property, Plant and Equipment: Property, plant and equipment is stated at cost and includes capitalized interest. The costs of replacements or renewals, which improve or extend the life of existing property, are capitalized. Maintenance and repairs are expensed as incurred. Upon retirement or disposition of an asset, any resulting gain or loss is included in the Company’s operating results. Property, plant and equipment also includes mineral interests. The mineral interests for the Company’s Winsford U.K. mine are owned. The Company leases probable mineral reserves at its Cote Blanche and Goderich mines, its Ogden facility and several of its other North American facilities. These leases have varying terms, and many provide for a royalty payment to the lessor based on a specific amount per ton of mineral extracted or as a percentage of sales. The Company’s rights to extract minerals are contractually limited by time. The Cote Blanche mine is operated under land and mineral leases, and the mineral lease expires in 2060 with two additional 25-year renewal periods. The Goderich mine mineral reserve lease expires in 2022 with the Company’s option to renew until 2043 after demonstrating to the lessor that the mine’s useful life is greater than the lease’s term. The Ogden facility mineral reserve lease renews annually. The Company believes it will be able to continue to extend lease agreements as it has in the past, at commercially reasonable terms, without incurring substantial costs or material modifications to the existing lease terms and conditions, and therefore, management believes that assigned lives are appropriate. The Company’s mineral interests are depleted on a units-of-production basis based upon the latest available mineral study. The weighted average amortization period for the leased probable mineral reserves is 90 years as of December 31, 2020. The Company also owns other mineral properties. The weighted average life for the probable owned mineral reserves is 36 years as of December 31, 2020, based upon management’s current production estimates. Buildings and structures are depreciated on a straight-line basis over lives generally ranging from 10 to 30 years. Portable buildings generally have shorter lives than permanent structures. Leasehold and building improvements typically have shorter estimated lives of 5 to 20 years or lower based on the life of the lease to which the improvement relates. The Company’s fixed assets are amortized on a straight-line basis over their respective lives. The following table summarizes the estimated useful lives of the Company’s different classes of property, plant and equipment: Years Land improvements 10 to 25 Buildings and structures 10 to 30 Leasehold and building improvements 2 to 40 Machinery and equipment – vehicles 2 to 10 Machinery and equipment – other mining and production 2 to 50 Office furniture and equipment 2 to 10 Mineral interests 20 to 99 The Company has finance leases which are recorded in property, plant and equipment at the beginning of the lease at the lower of the fair value of the leased property or the present value of the minimum lease payments. Lease payments are recorded as interest expense and a reduction of the lease liability. A finance lease asset is depreciated over the lower of its useful life or the lease term. The Company has capitalized computer software costs of $13.4 million and $16.0 million as of December 31, 2020 and 2019, respectively, recorded in property, plant and equipment. The capitalized costs are being amortized over five years. The Company recorded $5.8 million, $6.6 million and $7.3 million of amortization expense related to capitalized computer software for 2020, 2019 and 2018, respectively. The Company recognizes and measures obligations related to the retirement of tangible long-lived assets in accordance with applicable U.S. GAAP. Asset retirement obligations are not material to the Company’s consolidated financial position, results of operations or cash flows. The Company reviews its long-lived assets and the related mineral reserves for impairment whenever events or changes in circumstances indicate the carrying amounts of such assets may not be recoverable. If an indication of a potential impairment exists, recoverability of the respective assets is determined by comparing the forecasted undiscounted net cash flows of the operation to which the assets relate, to the carrying amount, including associated intangible assets, of such operation. If the operation is determined to be unable to recover the carrying amount of its assets, then intangible assets are written down first, followed by the other long-lived assets of the operation, to fair value. Fair value is determined based on discounted cash flows or appraised values, depending upon the nature of the assets.
Leases	Leases:In February 2016, the FASB issued guidance which requires lessees to recognize on their balance sheet a right-of-use asset which represents a lessee’s right to use the underlying asset, and a lease liability which represents a lessee’s obligation to make lease payments for the right to use the asset. In addition, the guidance requires expanded qualitative and quantitative disclosures. The Company adopted this guidance on January 1, 2019, using a modified retrospective transition method, which required the cumulative effect of this change in accounting of $0.1 million to be recorded as an adjustment to beginning retained earnings. The Company elected the transition provisions available for existing contracts, which allowed entities to carryforward the historical assessment of whether the contract contained a lease and the lease classification.
Goodwill and Intangible Assets	Goodwill and Intangible Assets:The Company amortizes its intangible assets deemed to have finite lives on a straight-line basis over their estimated useful lives which, for the Company, range from 4 to 50 years. The Company reviews goodwill and other indefinite-lived intangible assets annually for impairment. In addition, goodwill and other intangible assets are reviewed when an event or change in circumstances indicates the carrying amounts of such assets may not be recoverable.
Investments	Investments: The Company uses the equity method of accounting for equity securities when it has significant influence or when it has more than a minor ownership interest or more than minor influence over an investee’s operations but does not have a controlling financial interest. Initial investments are recorded at cost (including certain transaction costs) and are adjusted by the Company’s share of the investees’ undistributed earnings and losses. The Company may recognize its share of an investee’s earnings on a lag, if an investee’s financial results are not available in a timely manner. The Company’s Brazilian subsidiary holds a 50% interest in Fermavi Eletroquímica Ltda. (“Fermavi”). Fermavi, which was founded in 1987, is a Brazilian corporation with headquarters in Varginha, Minas Gerais, Brazil, and its operations focus on the production and sale of manganese-based products. The Company’s investment in Fermavi was recorded at its estimated fair value in conjunction with the purchase price allocation as of the date the Company completed the full acquisition of Compass Minerals América do Sul Indústria e Comércio Ltda. (“Compass Minerals South America”), which was in excess of the book value of net assets acquired. This basis difference was approximately $2 million and $4 million as of December 31, 2020 and 2019, respectively. The portion of the basis differences related to tangible and intangible assets is amortized over their remaining useful lives, as appropriate. The Company accounts for its investment in Fermavi under the equity method of accounting.
Marketable Securities	The marketable securities are classified as trading securities and accordingly, gains and losses are recorded as a component of other expense (income), net in the Consolidated Statements of Operations.
Income Taxes	Income Taxes: The Company accounts for income taxes using the liability method in accordance with the provisions of GAAP. Under the liability method, deferred taxes are determined based on the differences between the consolidated financial statements and the tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. The Company’s foreign subsidiaries file separate company returns in their respective jurisdictions. The Company recognizes potential liabilities in accordance with applicable GAAP for anticipated tax issues in the U.S. and other tax jurisdictions based on its estimate of whether, and the extent to which, additional taxes will be due. If payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities would result in tax benefits being recognized in the period when the Company determines the liabilities are no longer necessary. If the Company’s estimate of tax liabilities proves to be less than the ultimate assessment, a further charge to expense would result. Any penalties and interest that are accrued on the Company’s uncertain tax positions are included as a component of income tax expense. In evaluating the Company’s ability to realize deferred tax assets, the Company considers the sources and timing of taxable income, including the reversal of existing temporary differences, the ability to carryback tax attributes to prior periods, qualifying tax-planning strategies, and estimates of future taxable income exclusive of reversing temporary differences. In determining future taxable income, the Company’s assumptions include the amount of pre-tax operating income according to different state, federal and international taxing jurisdictions, the origination of future temporary differences, and the implementation of feasible and prudent tax-planning strategies. If the Company determines that a portion of its deferred tax assets will not be realized, a valuation allowance is recorded in the period that such determination is made. In the future, if the Company determines, based on the existence of sufficient evidence, that more or less of the deferred tax assets are more likely than not to be realized, an adjustment to the valuation allowance will be made in the period such a determination is made. As discussed in Note 8 , on December 22, 2017, the U.S. enacted the Tax Cuts and Jobs Act (the “Act”) which subjects U.S. shareholders, including the Company, to tax on Global Intangible Low-Taxed Income (“GILTI”) earned by certain foreign subsidiaries. The FASB issued guidance stating that an entity can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or to provide for the tax expense related to GILTI in the year the tax is incurred as a period expense only. The Company has elected to account for GILTI as a period expense only.
Environmental Costs	Environmental Costs:Environmental costs, other than those of a capital nature, are accrued at the time the exposure becomes known and costs can be reasonably estimated. Costs are accrued based upon management’s estimates of all direct costs.
Equity Compensation Plans	Equity Compensation Plans:The Company has equity compensation plans under the oversight of the Company’s Board of Directors, whereby stock options, restricted stock units, performance stock units, deferred stock units and shares of common stock are granted to the Company’s employees and directors.
Earnings per Share	Earnings per Share:When calculating earnings per share, the Company’s participating securities are accounted for under the two-class method. The two-class method requires allocating the Company’s net earnings to both common shares and participating securities based upon their rights to receive dividends. Basic earnings per share is computed by dividing net earnings available to common stockholders by the weighted-average number of outstanding common shares during the period. Diluted earnings per share reflects the potential dilution that could occur under the more dilutive of either the treasury stock method or the two-class method for calculating the weighted-average number of outstanding common shares. The treasury stock method is calculated assuming unrecognized compensation expense, income tax benefits and proceeds from the potential exercise of employee stock options are used to repurchase common stock.
Derivatives	Derivatives:The Company is exposed to the impact of fluctuations in foreign exchange and interest rates on its borrowings and fluctuations in the purchase price of natural gas consumed in operations. The Company hedges portions of these risks through the use of derivative agreements. The Company records derivative financial instruments as assets or liabilities measured at fair value. Accounting for the changes in the fair value of a derivative depends on its designation and effectiveness. Derivatives qualify for treatment as hedges when there is a high correlation between the change in fair value of the derivative instrument and the related change in value of the underlying hedged item. For qualifying hedges, the effective portion of the change in fair value is recognized through earnings when the underlying transaction being hedged affects earnings, allowing a derivative’s gains and losses to offset related results from the hedged item in the Consolidated Statements of Operations. Until the effective portion of a derivative’s change in fair value is recognized in the Consolidated Statements of Operations, the change in fair value is recognized in other comprehensive income. For derivative instruments that are not accounted for as hedges, or for the ineffective portions of qualifying hedges, the change in fair value is recorded through earnings in the period of change. The Company formally documents, designates and assesses the effectiveness of transactions that receive hedge accounting treatment initially and on an ongoing basis.
Concentration of Credit Risk	Concentration of Credit Risk:The Company sells its salt and magnesium chloride products to various governmental agencies, manufacturers, distributors and retailers primarily in the Midwestern U.S. and throughout Canada and the U.K. The Company’s plant nutrition products are sold across the Western Hemisphere and globally. No single customer or group of affiliated customers accounted for more than 10% of the Company’s sales in any year during the three-year period ended December 31, 2020, or more than 10% of receivables at December 31, 2020 or 2019.
Recent Accounting Pronouncements	Recent Accounting Pronouncements: In January 2017, the FASB issued guidance to simplify the accounting for goodwill impairment. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. All other goodwill impairment guidance remains largely unchanged. The adoption of this guidance on January 1, 2020, did not have an impact on the Company’s consolidated financial statements. On January 1, 2020, the Company adopted guidance issued by the FASB related to credit losses for financial instruments, which replaces the incurred loss methodology with a current expected credit loss methodology (“CECL”). The Company has determined that its receivables are the only financial instrument that is within scope of this CECL guidance. The CECL methodology requires financial assets to be recorded at the net amount expected to be collected over the lifetime of the asset such that the estimated losses are accrued on the day the asset is acquired. The CECL methodology also requires financial assets to be aggregated and evaluated within pools with similar risk characteristics. The Company has recorded an allowance on its receivables based on historical loss rates modified to consider supportable forecasts related to customer-specific and macroeconomic factors. For instance, the Company’s 2020 allowance for doubtful

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of estimated useful lives of property, plant and equipment	The following table summarizes the estimated useful lives of the Company’s different classes of property, plant and equipment: Years Land improvements 10 to 25 Buildings and structures 10 to 30 Leasehold and building improvements 2 to 40 Machinery and equipment – vehicles 2 to 10 Machinery and equipment – other mining and production 2 to 50 Office furniture and equipment 2 to 10 Mineral interests 20 to 99

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of Operating and Finance Leases by Balance Sheets Location	The Company’s Consolidated Balance Sheets includes the following (in millions): Consolidated Balance Sheets Location December 31, December 31, Assets Operating lease assets Other assets $ 55.6 $ 53.7 Finance lease assets Property, plant and equipment, net 7.2 5.8 Total lease assets $ 62.8 $ 59.5 Liabilities Current liabilities: Operating Accrued expenses and other current liabilities $ 14.8 $ 12.8 Finance Accrued expenses and other current liabilities 1.3 1.1 Noncurrent liabilities: Operating Other noncurrent liabilities 42.8 41.0 Finance Other noncurrent liabilities 7.0 6.2 Total lease liabilities $ 65.9 $ 61.1
Schedule of Lease Cost, Lease Terms and Supplemental Cash Flow Information	The Company’s components of lease cost are as follows (in millions): Year Ended December 31, 2020 Year Ended December 31, 2019 Finance lease cost: Amortization of lease assets $ 1.8 $ 1.1 Interest on lease liabilities 0.6 0.6 Operating lease cost 17.4 19.2 Variable lease cost (a) 11.7 18.8 Total lease cost $ 31.5 $ 39.7 (a) Short-term leases are immaterial and included in variable lease cost. Supplemental lease term and discount rate information related to leases is as follows: December 31, 2020 December 31, 2019 Weighted-average remaining lease term (years) Operating leases 7.0 7.7 Finance leases 9.3 7.2 Weighted-average discount rate Operating leases 3.7 % 4.3 % Finance leases 7.3 % 7.6 % Supplemental cash flow information related to leases is as follows (in millions): Year Ended December 31, 2020 Year Ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 15.3 $ 18.9 Operating cash flows from finance leases 0.6 0.6 Financing cash flows from finance leases 1.8 1.3 Leased assets obtained in exchange for new operating lease liabilities 16.5 20.3 Leased assets obtained in exchange for new finance lease liabilities 3.8 0.2
Schedule of Operating Lease Maturities	Maturities of lease liabilities are as follows (in millions): Operating Leases Finance Leases Total 2021 $ 16.4 $ 1.8 $ 18.2 2022 13.1 1.2 14.3 2023 8.4 1.1 9.5 2024 5.7 0.9 6.6 2025 4.9 0.9 5.8 After 2025 18.0 6.1 24.1 Total lease payments 66.5 12.0 78.5 Less: Interest (8.9) (3.7) (12.6) Present value of lease liabilities $ 57.6 $ 8.3 $ 65.9
Schedule of Financing Lease Maturities	Maturities of lease liabilities are as follows (in millions): Operating Leases Finance Leases Total 2021 $ 16.4 $ 1.8 $ 18.2 2022 13.1 1.2 14.3 2023 8.4 1.1 9.5 2024 5.7 0.9 6.6 2025 4.9 0.9 5.8 After 2025 18.0 6.1 24.1 Total lease payments 66.5 12.0 78.5 Less: Interest (8.9) (3.7) (12.6) Present value of lease liabilities $ 57.6 $ 8.3 $ 65.9

INVENTORIES (Tables)

INVENTORIES (Tables)	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Schedule of inventories	Inventories consist of the following at December 31 (in millions): 2020 2019 Finished goods $ 287.4 $ 235.3 Raw materials and supplies 83.2 76.2 Total inventories $ 370.6 $ 311.5

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of property, plant and equipment	Property, plant and equipment consists of the following at December 31 (in millions): 2020 2019 Land, buildings and structures and leasehold improvements $ 626.8 $ 596.0 Machinery and equipment 1,085.1 1,001.9 Office furniture and equipment 53.3 60.7 Mineral interests 172.4 171.1 Construction in progress 58.7 141.3 1,996.3 1,971.0 Less accumulated depreciation and depletion (1,031.4) (940.2) Property, plant and equipment, net $ 964.9 $ 1,030.8

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of finite-lived intangible assets	The asset value and accumulated amortization as of December 31, 2020 and 2019 for the finite-lived intangibles assets are as follows (in millions): Supply Agreement SOP Production Rights Customer/Distributor Relationships Lease Rights Trade Names Developed Technologies Patents Other Total December 31, 2020 Gross intangible asset $ 28.5 $ 24.3 $ 11.6 $ 1.8 $ 30.3 $ 26.2 $ 16.2 $ 1.3 $ 140.2 Accumulated amortization (5.7) (16.6) (6.8) (0.6) (11.8) (21.4) (9.6) (1.0) (73.5) Net intangible assets $ 22.8 $ 7.7 $ 4.8 $ 1.2 $ 18.5 $ 4.8 $ 6.6 $ 0.3 $ 66.7 Supply Agreement SOP Production Rights Customer/Distributor Relationships Lease Rights Trade Names Developed Technologies Patents Other Total December 31, 2019 Gross intangible asset $ 27.9 $ 24.3 $ 12.7 $ 1.7 $ 36.8 $ 32.8 $ 16.0 $ 1.3 $ 153.5 Accumulated amortization (5.0) (15.6) (6.1) (0.5) (10.9) (21.7) (8.1) (0.9) (68.8) Net intangible assets $ 22.9 $ 8.7 $ 6.6 $ 1.2 $ 25.9 $ 11.1 $ 7.9 $ 0.4 $ 84.7
Schedule of estimated lives of intangible assets	The estimated lives of the Company’s finite-lived intangible assets are as follows: Intangible asset Estimated Lives Supply agreement 50 years SOP production rights 25 years Patents 10-20 years Developed technology 4-7 years Lease rights 25 years Customer and distributor relationships 10-14 years Trademarks 10 years Trade names 10-11 years

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of income tax provision (benefit) related to earnings	The following table summarizes the Company’s income tax provision for the years ended December 31 (in millions): 2020 2019 2018 Current: Federal $ (22.3) $ 5.3 $ 8.1 State 0.4 2.0 4.3 Foreign 28.2 26.6 13.1 Total current 6.3 33.9 25.5 Deferred: Federal 1.2 (7.2) (8.6) State (1.2) (1.9) (0.5) Foreign 5.4 (2.7) (7.6) Total deferred 5.4 (11.8) (16.7) Total provision for income taxes $ 11.7 $ 22.1 $ 8.8
Schedule of income tax expense reconciliation	The following table summarizes components of earnings before income taxes and shows the tax effects of significant adjustments from the expected income tax expense computed at the federal statutory rate for the years ended December 31 (in millions): 2020 2019 2018 U.S. (loss) income $ (4.1) $ 31.7 $ (80.6) Foreign income 75.3 52.9 158.2 Earnings before income taxes $ 71.2 $ 84.6 $ 77.6 Computed tax at the U.S. federal statutory rate of 21% 15.0 17.8 16.3 Foreign income rate differential, mining, and withholding taxes, net of U.S. federal deduction 9.3 10.2 0.9 Percentage depletion in excess of basis (4.4) (5.8) (4.7) Other domestic tax reserves, net of reversals (9.7) 0.2 1.5 State income taxes, net of federal income tax benefit (0.9) — 2.1 Change in valuation allowance on deferred tax asset 2.4 0.2 (5.7) Interest expense recognition differences (3.5) (3.5) (3.6) GILTI 3.8 1.0 1.0 Tax Cuts and Jobs Act of 2017 — 1.6 (3.0) Tax on repatriated amounts — 0.9 3.4 Transfer pricing settlement with taxing authorities — — 2.2 Other, net (0.3) (0.5) (1.6) Provision for income taxes $ 11.7 $ 22.1 $ 8.8 Effective tax rate 16 % 26 % 11 %
Schedule of significant components of deferred tax assets and liabilities	The significant components of the Company’s deferred tax assets and liabilities were as follows at December 31 (in millions): 2020 2019 Deferred tax assets: Reluz Nordeste Indústria e Comércio Ltda net operating loss carryforwards $ 0.4 $ 0.6 Compass Minerals South America net operating loss carryforwards — 3.3 Excess interest expense 9.9 14.9 Foreign tax credit 39.4 38.1 Right of use lease liability 11.3 11.1 Stock-based compensation 2.0 2.3 Other, net 20.5 16.5 Total deferred tax assets before valuation allowance 83.5 86.8 Valuation allowance (42.0) (39.8) Total deferred tax assets 41.5 47.0 Deferred tax liabilities to be netted with deferred tax assets: Property, plant and equipment 17.2 21.2 Right of use lease asset 11.3 11.1 Other, net 1.4 1.0 Total deferred tax liabilities to be netted with deferred tax assets 29.9 33.3 Net noncurrent deferred tax assets $ 11.6 $ 13.7 Deferred tax assets to be netted with deferred tax liabilities: Net operating loss carryforwards $ 1.7 $ 2.2 Right of use lease liability 1.9 0.9 Other, net 0.9 2.1 Total deferred tax assets before valuation allowance 4.5 5.2 Valuation allowance (1.4) (1.4) Total deferred tax assets to be netted with deferred tax liabilities 3.1 3.8 Deferred tax liabilities: Property, plant and equipment 66.5 63.7 Intangible asset 22.2 29.1 Right of use lease asset 1.9 0.9 Total deferred tax liabilities 90.6 93.7 Net deferred tax liabilities $ 87.5 $ 89.9
Schedule of reconciliation of unrecognized tax benefits	The following table shows a reconciliation of the beginning and ending amount of unrecognized tax benefits (in millions): 2020 2019 2018 Unrecognized tax benefits: Balance at January 1 $ 47.4 $ 50.9 $ 67.4 Additions resulting from current year tax positions — 0.2 8.0 Additions relating to tax positions taken in prior years 1.4 4.5 2.6 Reductions due to settlements — — (25.0) Reductions due to cash payments — (7.5) — Reductions relating to tax positions taken in prior years (0.1) (0.4) (0.3) Reductions due to expiration of tax years (10.4) (0.3) (1.8) Balance at December 31 $ 38.3 $ 47.4 $ 50.9

PENSION PLANS AND OTHER BENEF_2

PENSION PLANS AND OTHER BENEFITS (Tables)	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Schedule of weighted-average asset allocations	The weighted-average asset allocations by asset category are as follows: Plan Assets at December 31, Asset Category 2020 2019 Cash and cash equivalents 2 % 3 % Blended funds 48 % 51 % Bond funds 50 % 46 % Total 100 % 100 %
Schedule of fair value of pension plan assets	The fair value of the Company’s U.K. pension plan assets at December 31, 2020 and 2019, by asset category (see Note 14 for a discussion regarding fair value measurements) are as follows (in millions): December 31, 2020 Level One Level Two Level Three Asset category: Cash and cash equivalents (a) $ 1.3 $ 1.3 $ — $ — Blended funds (b) 34.9 — 34.9 — Bond funds (c) : Treasuries 35.9 — 35.9 — Total Pension Assets $ 72.1 $ 1.3 $ 70.8 $ — December 31, 2019 Level One Level Two Level Three Asset category: Cash and cash equivalents (a) $ 1.9 $ 1.9 $ — $ — Blended funds (b) 33.6 — 33.6 — Bond funds (c) : Treasuries 30.1 — 30.1 — Total Pension Assets $ 65.6 $ 1.9 $ 63.7 $ — (a) The fair value of cash and cash equivalents is its carrying value. (b) The Company is invested in a diversified growth fund. The diversified growth fund is valued at the last traded or official close for the underlying equities and bid or mid for the underlying fixed income securities depending on the portfolio benchmark. Where representative prices are unavailable, underlying fixed income investments are valued based on other observable market-based inputs. (c) This category includes investments in investment-grade fixed-income instruments and funds linked to U.K. treasury notes. The funds are valued using the bid amounts for each fund. All of the Company’s bond fund pension assets are invested in U.K.-linked treasuries as of December 31, 2020 and 2019.
Schedule of assumptions used in determining pension information	The assumptions used in determining pension information for the U.K. pension plan for the years ended December 31 were as follows: 2020 2019 2018 Discount rate 1.20 % 2.00 % 2.90 % Expected return on plan assets 3.10 % 3.10 % 3.70 %
Schedule of future expected benefit payments	The Company expects to pay the following benefit payments (in millions): Calendar Year Future Expected Benefit Payments 2021 $ 3.2 2022 3.2 2023 3.3 2024 3.4 2025 3.4 2026-2030 18.4
Schedule of pension obligations, plan assets and net funded status	The following table sets forth pension obligations and plan assets for the Company’s U.K. pension plan, as of December 31 (in millions): 2020 2019 Change in benefit obligation: Benefit obligation as of January 1 $ 64.1 $ 58.6 Interest cost 1.2 1.7 Actuarial loss 8.3 4.8 Plan amendment 0.1 — Benefits paid (2.9) (3.5) Currency fluctuation adjustment 2.5 2.5 Benefit obligation as of December 31 73.3 64.1 Change in plan assets: Fair value as of January 1 65.6 60.7 Actual return 6.7 4.2 Company contributions 0.4 1.7 Currency fluctuation adjustment 2.3 2.5 Benefits paid (2.9) (3.5) Fair value of plan assets as of December 31 72.1 65.6 (Underfunded) Overfunded status of the plan $ (1.2) $ 1.5
Schedule of components of net pension expense	The components of net periodic pension cost (benefit) were as follows for the years ended December 31 (in millions): 2020 2019 2018 Interest cost on projected benefit obligation $ 1.2 $ 1.7 $ 1.6 Prior service cost (0.1) (0.1) (0.1) Expected return on plan assets (1.9) (2.2) (2.5) Plan amendment 0.1 — — Net amortization 1.0 0.5 0.3 Net periodic pension cost (benefit) $ 0.3 $ (0.1) $ (0.7)

LONG TERM DEBT (Tables)

LONG TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of long-term debt	Long-term debt consists of the following at December 31 (in millions): 2020 2019 4.875% Senior Notes due July 2024 $ 250.0 $ 250.0 Term Loan due January 2025 390.0 400.0 Revolving Credit Facility due January 2025 130.3 160.0 6.75% Senior Notes due December 2027 500.0 500.0 AR Securitization Facility expires June 2023 51.2 — 3.7% Banco Itaú loan due March 2020 — 15.4 Banco Santander loan due October 2020 — 16.2 Banco Itaú loan due February 2021 10.4 — Banco Rabobank loan due July 2021 6.8 17.4 Banco BTG loan due July 2021 2.6 — Banco Santander loan due September 2021 — 19.9 Banco do Brasil loan due September 2021 9.6 12.4 Banco Rabobank loan due September 2021 6.8 — Banco BTG loan due October 2021 2.6 — Banco Rabobank loan due November 2021 13.5 17.4 Banco Santander loan due December 2021 — 14.9 Banco BTG loan due January 2022 1.0 — Banco Votorantim loan due February 2022 7.7 — Banco Bradesco loan due February 2022 4.8 — Banco Santander loan due March 2022 2.9 — Banco BTG loan due April 2022 1.0 — Banco BTG loan due July 2022 2.6 — Banco Safra loan due October 2022 3.9 — Banco Santander loan due October 2022 12.5 — Financiadora de Estudos e Projetos loan due November 2023 4.1 7.2 1,414.3 1,430.8 Less unamortized debt issuance costs (12.9) (14.8) Total debt 1,401.4 1,416.0 Less current portion (63.7) (52.1) Long-term debt $ 1,337.7 $ 1,363.9
Schedule of future maturities of long-term debt	Future maturities of long-term debt for the years ending December 31, are as follows (in millions): Debt Maturity 2021 $ 63.7 2022 57.8 2023 72.5 2024 270.0 2025 450.3 Thereafter 500.0 Total $ 1,414.3

DERIVATIVE FINANCIAL INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of fair value of hedged items	The following tables present the fair value of the Company’s derivatives as of December 31, 2020 and 2019 (in millions): Asset Derivatives Liability Derivatives Derivatives designated as hedging instruments: Consolidated Balance Sheet Location December 31, 2020 Consolidated Balance Sheet Location December 31, 2020 Commodity contracts Other current assets $ 0.4 Accrued expenses and other current liabilities $ 0.1 Commodity contracts Other assets 0.1 Other noncurrent liabilities 0.2 Swap contracts Other current assets 2.6 Accrued expenses and other current liabilities — Total derivatives designated as hedging instruments (a)(b) $ 3.1 $ 0.3 (a) The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $0.3 million of its commodity contracts that are in payable positions against its contracts in receivable positions. (b) The Company has commodity hedge agreements with two counterparties and a foreign currency swap agreement with one counterparty. Amounts recorded for the Company’s commodity contracts are receivable from both counterparties. Asset Derivatives Liability Derivatives Derivatives designated as hedging instruments: Consolidated Balance Sheet Location December 31, 2019 Consolidated Balance Sheet Location December 31, 2019 Commodity contracts Other current assets $ 0.3 Accrued expenses and other current liabilities $ 0.8 Commodity contracts Other assets 0.1 Other noncurrent liabilities 0.2 Swap contracts Other current assets 2.8 Accrued expenses and other current liabilities — Total derivatives designated as hedging instruments (a)(b) $ 3.2 $ 1.0 (a) The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $0.4 million of its commodity contracts that are in a receivable position against its contracts in payable positions. (b) The Company has both commodity hedge and foreign currency swap agreements with two counterparties each. Amounts recorded as liabilities for the Company’s commodity contracts are payable to both counterparties, and amounts recorded as assets for the Company’s swap contracts are receivable from both counterparties.
Schedule of other comprehensive income attributable to derivatives	The following tables present activity related to other comprehensive (loss) income before taxes for the years ended December 31, 2020 and 2019 (in millions): Year Ended December 31, 2020 Derivatives in Cash Flow Hedging Relationships Location of Gain Reclassified from Accumulated OCI Into Income (Effective Portion) Amount of Gain Recognized in OCI on Derivative (Effective Portion) Amount of Gain Reclassified from Accumulated OCI Into Income (Effective Portion) Commodity contracts Product cost $ (1.8) $ 1.0 Swap contracts Interest expense (3.9) 3.6 Total $ (5.7) $ 4.6 Year Ended December 31, 2019 Derivatives in Cash Flow Hedging Relationships Location of Gain Reclassified from Accumulated OCI Into Income Effective Portion) Amount of Gain Recognized in OCI on Derivative (Effective Portion) Amount of Gain Reclassified from Accumulated OCI Into Income (Effective Portion) Commodity contracts Product cost $ (0.8) $ 0.9 Swap contracts Interest expense (2.5) 2.2 Total $ (3.3) $ 3.1

STOCKHOLDERS' EQUITY AND EQUI_2

STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of weighted average assumptions and fair value for options granted	The weighted average assumptions and fair values for options granted for each of the years ended December 31 is included in the following table. 2020 2019 2018 Fair value of options granted $ 10.91 $ 9.15 $ 8.77 Expected term (years) 4.8 4.5 4.5 Expected volatility 29.3 % 28.0 % 22.9 % Dividend yield 3.5 % 4.1 % 3.6 % Risk-free interest rates 1.6 % 2.3 % 2.5 %
Schedule of stock-based compensation activity	The following is a summary of the Company’s stock option, RSU and PSU activity and related information for the following periods: Stock Options RSUs PSUs Number Weighted-average exercise price Number Weighted-average fair value Number Weighted-average fair value Outstanding at December 31, 2017 562,877 $ 75.89 70,856 $ 74.63 112,036 $ 79.48 Granted 250,514 59.61 42,013 60.28 67,235 64.30 Exercised (a) — — — — — — Released from restriction (a) — — (16,905) 88.78 (2,753) 78.92 Cancelled/Expired (104,645) 71.65 (12,656) 66.53 (49,880) 85.51 Outstanding at December 31, 2018 708,746 $ 70.76 83,308 $ 65.75 126,638 $ 69.06 Granted 369,716 54.15 218,071 49.73 123,003 56.88 Exercised (a) — — — — — — Released from restriction (a) — — (32,630) 66.95 — — Cancelled/Expired (190,595) 69.06 (51,336) 54.87 (70,244) 67.20 Outstanding at December 31, 2019 887,867 $ 64.21 217,413 $ 52.07 179,397 $ 61.43 Granted 94,945 58.91 95,276 58.24 107,072 74.73 Exercised (a) (4,454) 57.02 — — — — Released from restriction (a) — — (76,570) 50.03 (11,575) 78.87 Cancelled/Expired (109,586) 69.00 (28,137) 51.85 (33,100) 68.18 Outstanding at December 31, 2020 868,772 $ 63.06 207,982 $ 55.68 241,794 $ 65.57 (a) Common stock issued for exercised options, vested RSUs and vested and earned PSUs were issued from treasury shares.
Schedule of information about options outstanding and exercisable	The following table summarizes information about options outstanding and exercisable at December 31, 2020. Options Outstanding Options Exercisable Range of exercise prices Options outstanding Weighted-average remaining contractual life (years) Weighted-average exercise price of options outstanding Options exercisable Weighted-average remaining contractual life (years) Weighted-average exercise price of exercisable options $53.75 - $54.38 252,245 5.3 $ 53.75 84,082 5.3 $ 53.75 $54.39 - $59.21 159,424 5.7 57.01 18,836 5.2 55.01 $59.22 - $63.75 159,445 4.3 59.50 110,700 4.3 59.50 $63.76 - $69.77 119,357 3.1 68.03 104,796 3.0 68.01 $69.78 - $91.75 178,301 1.3 81.51 178,301 1.3 81.51 Totals 868,772 4.1 $ 63.06 496,715 3.1 $ 68.05
Schedule of components of and changes in accumulated other comprehensive income (loss)	The components of and changes in accumulated other comprehensive loss (“AOCL”) for the years ended December 31, 2020 and 2019 are as follows (in millions): Year Ended December 31, 2020 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (0.6) $ (6.9) $ (184.6) $ (192.1) Other comprehensive income (loss) before reclassifications 3.9 (3.2) (109.5) (108.8) Amounts reclassified from accumulated other comprehensive loss (3.1) 0.7 — (2.4) Net current period other comprehensive income (loss) 0.8 (2.5) (109.5) (111.2) Ending balance $ 0.2 $ (9.4) $ (294.1) $ (303.3) Year Ended December 31, 2019 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (0.7) $ (4.5) $ (205.7) $ (210.9) Other comprehensive income (loss) before reclassifications 2.2 (2.7) 21.1 20.6 Amounts reclassified from accumulated other comprehensive loss (2.1) 0.3 — (1.8) Net current period other comprehensive income (loss) 0.1 (2.4) 21.1 18.8 Ending balance $ (0.6) $ (6.9) $ (184.6) $ (192.1) (a) With the exception of the cumulative foreign currency translation adjustment, for which no tax effect is recorded, the changes in the components of AOCL presented in the table are reflected net of applicable income taxes.
Schedule of changes in the components of accumulated other comprehensive gain (loss)	Year Ended December 31, 2020 Amount Reclassified from AOCL Line Item Impacted in the Consolidated Statement of Operations Losses on cash flow hedges: Natural gas instruments $ (1.0) Product cost Foreign currency contracts (3.6) Interest expense Income tax expense 1.5 Reclassifications, net of income taxes (3.1) Amortization of defined benefit pension: Amortization of loss $ 0.9 Product cost Income tax benefit (0.2) Reclassifications, net of income taxes 0.7 Total reclassifications, net of income taxes $ (2.4) Year Ended December 31, 2019 Amount Reclassified from AOCL Line Item Impacted in the Consolidated Statement of Operations Gains (losses) on cash flow hedges: Natural gas instruments $ (0.9) Product cost Foreign currency contracts (2.2) Interest Expense Income tax expense 1.0 Reclassifications, net of income taxes (2.1) Amortization of defined benefit pension: Amortization of loss $ 0.4 Product cost Income tax benefit (0.1) Reclassifications, net of income taxes 0.3 Total reclassifications, net of income taxes $ (1.8)

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of estimated fair values for each type of instrument	The estimated fair values for each type of instrument are presented below (in millions). December 31, 2020 Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified savings plan (a) $ 1.9 $ 1.9 $ — $ — Derivatives – natural gas instruments, net 0.2 — 0.2 — Derivatives - foreign currency contracts, net 2.6 — 2.6 — Total Assets $ 4.7 $ 1.9 $ 2.8 $ — Liability Class: Liabilities related to non-qualified savings plan $ (1.9) $ (1.9) $ — $ — Total Liabilities $ (1.9) $ (1.9) $ — $ — (a) Includes mutual fund investments of approximately 30% in the common stock of large-cap U.S. companies, 10% in the common stock of small to mid-cap U.S. companies, 5% in the common stock of international companies, 15% in bond funds, 15% in short-term investments and 25% in blended funds. December 31, 2019 Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified savings plan (a) $ 1.4 $ 1.4 $ — $ — Derivatives - foreign currency contracts, net 2.8 — 2.8 — Total Assets $ 4.2 $ 1.4 $ 2.8 $ — Liability Class: Liabilities related to non-qualified savings plan $ (1.4) $ (1.4) $ — $ — Derivatives - natural gas instruments, net (0.6) — (0.6) — Total Liabilities $ (2.0) $ (1.4) $ (0.6) $ — (a) Includes mutual fund investments of approximately 30% in the common stock of large-cap U.S. companies, 15% in the common stock of small to mid-cap U.S. companies, 5% in the common stock of international companies, 10% in bond funds, 20% in short-term investments and 20% in blended funds.

OPERATING SEGMENTS (Tables)

OPERATING SEGMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of segment information	Segment information as of and for the years ended December 31, is as follows (in millions): 2020 Salt Plant Nutrition North America Plant Nutrition South America Corporate& Other (a) Total Sales to external customers $ 779.4 $ 239.6 $ 344.4 $ 10.1 $ 1,373.5 Intersegment sales — 5.4 0.3 (5.7) — Shipping and handling cost 217.8 34.0 14.8 — 266.6 Operating earnings (loss) 161.8 12.1 40.3 (73.7) 140.5 Depreciation, depletion and amortization 66.6 40.4 17.4 13.5 137.9 Total assets 1,020.8 520.8 579.2 141.6 2,262.4 Capital expenditures 56.8 12.5 9.6 6.0 84.9 2019 Salt Plant Nutrition North America Plant Nutrition South America Corporate& Other (a) Total Sales to external customers $ 889.5 $ 206.2 $ 385.1 $ 9.7 $ 1,490.5 Intersegment sales — 6.4 2.7 (9.1) — Shipping and handling cost 267.4 28.5 16.6 — 312.5 Operating earnings (loss) (b) 168.0 22.5 40.0 (66.9) 163.6 Depreciation, depletion and amortization 60.4 44.6 22.4 10.5 137.9 Total assets 1,056.3 575.5 715.3 96.1 2,443.2 Capital expenditures 65.9 15.2 10.5 6.5 98.1 2018 Salt Plant Nutrition North America Plant Nutrition South America Corporate& Other (a) Total Sales to external customers $ 858.1 $ 233.2 $ 391.8 $ 10.5 $ 1,493.6 Intersegment sales — 5.6 3.4 (9.0) — Shipping and handling cost 272.4 29.0 18.6 — 320.0 Operating earnings (loss) (b) 115.7 25.3 48.7 (59.4) 130.3 Depreciation, depletion and amortization 56.2 48.6 22.2 9.9 136.9 Total assets 948.9 589.3 709.9 119.8 2,367.9 Capital expenditures 58.7 20.7 10.1 7.3 96.8 Disaggregated revenue by product type is as follows (in millions): Year Ended December 31, 2020 Salt Plant Nutrition North America Plant Nutrition South America Corporate & Other (a) Total Highway Deicing Salt $ 473.8 $ — $ — $ — $ 473.8 Consumer & Industrial Salt 305.6 — — — 305.6 SOP and Specialty Plant Nutrients — 245.0 272.8 — 517.8 Industrial Chemicals — — 71.9 — 71.9 Eliminations & Other — (5.4) (0.3) 10.1 4.4 Sales to external customers $ 779.4 $ 239.6 $ 344.4 $ 10.1 $ 1,373.5 Year Ended December 31, 2019 Salt Plant Nutrition North America Plant Nutrition South America Corporate & Other (a) Total Highway Deicing Salt $ 545.5 $ — $ — $ — $ 545.5 Consumer & Industrial Salt 344.0 — — — 344.0 SOP and Specialty Plant Nutrients — 212.6 298.6 — 511.2 Industrial Chemicals — — 89.2 — 89.2 Eliminations & Other — (6.4) (2.7) 9.7 0.6 Sales to external customers $ 889.5 $ 206.2 $ 385.1 $ 9.7 $ 1,490.5 Year Ended December 31, 2018 Salt Plant Nutrition North America Plant Nutrition South America Corporate & Other (a) Total Highway Deicing Salt $ 532.0 $ — $ — $ — $ 532.0 Consumer & Industrial Salt 326.1 — — — 326.1 SOP and Specialty Plant Nutrients — 238.8 300.2 — 539.0 Industrial Chemicals — — 95.0 — 95.0 Eliminations & Other — (5.6) (3.4) 10.5 1.5 Sales to external customers $ 858.1 $ 233.2 $ 391.8 $ 10.5 $ 1,493.6 (a) Corporate and Other includes corporate entities, records management operations and other incidental operations and eliminations. Operating earnings (loss) for corporate and other includes indirect corporate overhead including costs for general corporate governance and oversight, as well as costs for the human resources, information technology and finance functions.
Schedule of revenue from external customers and long-lived assets	Financial information relating to the Company’s operations by geographic area for the years ended December 31 is as follows (in millions): Sales 2020 2019 2018 United States (a) $ 766.6 $ 821.9 $ 769.9 Canada 207.6 228.8 238.6 Brazil 336.6 375.2 381.8 United Kingdom 41.6 45.2 83.1 Other 21.1 19.4 20.2 Total sales $ 1,373.5 $ 1,490.5 $ 1,493.6 (a) United States sales exclude product sold to foreign customers at U.S. ports. Financial information relating to the Company’s long-lived assets, excluding the investments related to the nonqualified retirement plan and pension plan assets, by geographic area as of December 31 (in millions): Long-Lived Assets 2020 2019 2018 United States $ 532.9 $ 561.5 $ 551.6 Canada 514.0 522.8 497.4 United Kingdom 73.9 71.4 62.5 Brazil 376.0 493.1 524.8 Other 6.5 6.5 6.5 Total long-lived assets $ 1,503.3 $ 1,655.3 $ 1,642.8

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of earnings per share	The following table sets forth the computation of basic and diluted earnings per common share (in millions, except for share and per share data): Year ended December 31, 2020 2019 2018 Numerator: Net earnings $ 59.5 $ 62.5 $ 68.8 Less: Net earnings allocated to participating securities (a) (1.3) (1.1) (0.5) Net earnings available to common stockholders $ 58.2 $ 61.4 $ 68.3 Denominator (in thousands): Weighted average common shares outstanding, shares for basic earnings per share (b) 33,928 33,882 33,848 Weighted average equity awards outstanding — — — Shares for diluted earnings per share 33,928 33,882 33,848 Net earnings per common share, basic $ 1.72 $ 1.82 $ 2.02 Net earnings per common share, diluted $ 1.72 $ 1.81 $ 2.02 (a) Participating securities include PSUs and RSUs that receive non-forfeitable dividends. Net earnings were allocated to participating securities of 397,000, 307,000 and 186,000 for 2020, 2019 and 2018, respectively. (b) For the calculation of diluted earnings per share, the Company uses the more dilutive of either the treasury stock method or the two-class method to determine the weighted average number of outstanding common shares. In addition, the Company had 1,188,000, 1,067,000 and 788,000 weighted options outstanding for 2020, 2019 and 2018, respectively, which were anti-dilutive and therefore not included in the diluted earnings per share calculation.

QUARTERLY RESULTS (Unaudited) (

QUARTERLY RESULTS (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly information	Quarter First Second Third Fourth 2020 Sales $ 413.9 $ 256.1 $ 282.4 $ 421.1 Gross profit 87.3 66.3 58.7 100.0 Net earnings (loss) (a) 27.6 1.7 (2.1) 32.3 Net earnings (loss) per share, basic (a) 0.80 0.04 (0.07) 0.94 Net earnings (loss) per share, diluted (a) 0.80 0.04 (0.07) 0.94 Basic weighted-average shares outstanding (in thousands) 33,892 33,915 33,947 33,958 Diluted weighted-average shares outstanding (in thousands) 33,892 33,915 33,947 33,977 2019 Sales $ 403.7 $ 245.2 $ 341.3 $ 500.3 Gross profit 72.6 45.8 76.4 142.0 Net earnings (loss) (a) 7.6 (11.8) 10.6 56.1 Net earnings (loss) per share, basic (a) 0.22 (0.36) 0.31 1.64 Net earnings (loss) per share, diluted (a) 0.22 (0.36) 0.31 1.63 Basic weighted-average shares outstanding (in thousands) 33,874 33,883 33,884 33,886 Diluted weighted-average shares outstanding (in thousands) 33,874 33,883 33,884 33,886 (a) In the fourth quarter of 2020, the Company released a domestic tax reserve of $11.0 million. In the second quarter of 2019, the Company incurred $2.8 million ($2.1 million, net of tax) of additional logistics costs related to Mississippi River flooding. In the third quarter of 2019, the Company incurred $2.3 million ($1.7 million, net of tax) of severance and other costs related to executive transition.

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2020USD ($)extension_period	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jan. 01, 2020USD ($)	Jan. 01, 2019USD ($)	Dec. 31, 2017USD ($)
Finite-Lived Intangible Assets [Line Items]
Gain (loss) on foreign exchange of intercompany notes of long-term nature			$ (72.6)	$ (1.2)	$ (56.5)
Foreign currency exchange expense (income)			(0.4)	13	(5.8)
Value of receivables sold	$ 16.4	$ 32.7	22.1
Cash proceeds from sale of receivables	$ 15.6	30.4	$ 21
Sale of receivable, contingent liability (percent)	20.00%		20.00%
Receivables due of contingent consideration	$ 2.7		$ 4.1	2.7
Assets held-for-sale	7.2		6.8	7.2
Tax refund from settlement		(17.5)	(1.4)		(17.5)
Capitalized computer software costs	16		$ 13.4	16
Period of amortization of capitalized computer software costs			5 years
Amortization of capitalized computer software costs			$ 5.8	6.6	7.3
Impact of new accounting pronouncement	(529.6)	(540.2)	(387)	(529.6)	(540.2)			$ (694.6)
Inventories of spare parts related to long term assets	31		27.9	31
Operating lease assets	53.7		55.6	53.7
Investments in marketable securities relating to deferred compensation arrangement	1.4		1.9	1.4
Accounting Standards Update 2016-13
Finite-Lived Intangible Assets [Line Items]
Allowance for doubtful accounts			11.1			$ 9.4
Retained Earnings
Finite-Lived Intangible Assets [Line Items]
Impact of new accounting pronouncement	(607.4)	(643.5)	(567.3)	(607.4)	(643.5)			$ (672.5)
Cumulative effect of change in accounting principle
Finite-Lived Intangible Assets [Line Items]
Impact of new accounting pronouncement		0.1			0.1
Cumulative effect of change in accounting principle | Retained Earnings
Finite-Lived Intangible Assets [Line Items]
Impact of new accounting pronouncement		$ 0.1			$ 0.1	$ 0.1	$ (0.1)
U.S. taxing authorities
Finite-Lived Intangible Assets [Line Items]
Tax refund from settlement			0.9
Other current assets | Water rights
Finite-Lived Intangible Assets [Line Items]
Assets held-for-sale	5.2		5.2	5.2
Other current assets | U.S. taxing authorities
Finite-Lived Intangible Assets [Line Items]
Tax refund from settlement	58.3		$ 2.8	58.3
Cote Blanche
Finite-Lived Intangible Assets [Line Items]
Number of renewal periods (in extension periods) | extension_period			2
Lease renewal period			25 years
Leased Mineral Interests
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			90 years
Owned Mineral Properties
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			36 years
Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets			4 years
Minimum | Buildings and structures
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			10 years
Minimum | Typical maximum life leasehold and building improvements
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			5 years
Minimum | Land improvements
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			10 years
Minimum | Leasehold and building improvements
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			2 years
Minimum | Vehicles
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			2 years
Minimum | Machinery and Equipment - Other Mining and Production
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			2 years
Minimum | Office furniture and equipment
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			2 years
Minimum | Mineral interests
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			20 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets			50 years
Maximum | Buildings and structures
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			30 years
Maximum | Typical maximum life leasehold and building improvements
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			20 years
Maximum | Land improvements
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			25 years
Maximum | Leasehold and building improvements
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			40 years
Maximum | Vehicles
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			10 years
Maximum | Machinery and Equipment - Other Mining and Production
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			50 years
Maximum | Office furniture and equipment
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			10 years
Maximum | Mineral interests
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			99 years
Fermavi
Finite-Lived Intangible Assets [Line Items]
Ownership interest in investment			50.00%
Basis difference	$ 4		$ 2	$ 4

REVENUES (Details)

REVENUES (Details)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Payment terms	30 days

LEASES - Operating and Finance

LEASES - Operating and Finance Leases by Balance Sheets Location (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating lease assets	$ 55.6	$ 53.7
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Finance lease assets	$ 7.2	5.8
Total lease assets	$ 62.8	$ 59.5
Current liabilities:
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Operating	$ 14.8	$ 12.8
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Finance	$ 1.3	$ 1.1
Noncurrent liabilities:
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Operating	$ 42.8	$ 41
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Finance	$ 7	$ 6.2
Total lease liabilities	$ 65.9	$ 61.1

LEASES - Operating and Financ_2

LEASES - Operating and Finance Leases by Income Statement Location (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Amortization of lease assets	$ 1.8	$ 1.1
Interest on lease liabilities	0.6	0.6
Operating lease cost	17.4	19.2
Variable lease cost	11.7	18.8
Total lease cost	$ 31.5	$ 39.7

LEASES - Schedule of Operating

LEASES - Schedule of Operating and Finance Lease Maturities (Details) $ in Millions	Dec. 31, 2020USD ($)
Operating Leases
2021	$ 16.4
2022	13.1
2023	8.4
2024	5.7
2025	4.9
After 2025	18
Total lease payments	66.5
Less: Interest	(8.9)
Present value of lease liabilities	57.6
Finance Leases
2021	1.8
2022	1.2
2023	1.1
2024	0.9
2025	0.9
After 2025	6.1
Total lease payments	12
Less: Interest	(3.7)
Present value of lease liabilities	8.3
Total
2021	18.2
2022	14.3
2023	9.5
2024	6.6
2025	5.8
After 2025	24.1
Total lease payments	78.5
Less: Interest	(12.6)
Present value of lease liabilities	$ 65.9

LEASES - Schedule of Lease Term

LEASES - Schedule of Lease Terms and Discount Rates (Details)	Dec. 31, 2020	Dec. 31, 2019
Weighted-average remaining lease term (years)
Operating leases	7 years	7 years 8 months 12 days
Finance leases	9 years 3 months 18 days	7 years 2 months 12 days
Weighted-average discount rate
Operating leases	3.70%	4.30%
Finance leases	7.30%	7.60%

LEASES - Supplemental Cash Flow

LEASES - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 15.3	$ 18.9
Operating cash flows from finance leases	0.6	0.6
Financing cash flows from finance leases	1.8	1.3
Leased assets obtained in exchange for new operating lease liabilities	16.5	20.3
Leased assets obtained in exchange for new finance lease liabilities	$ 3.8	$ 0.2

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Finished goods		$ 287.4	$ 235.3
Raw materials and supplies		83.2	76.2
Total inventories		$ 370.6	$ 311.5
Inventory Write-down	$ 7.4

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property plant and equipment, before accumulated depreciation	$ 1,996.3	$ 1,971
Less accumulated depreciation and depletion	(1,031.4)	(940.2)
Property, plant and equipment, net	964.9	1,030.8
Property plant and equipment under finance leases	11.2	9.2
Property plant and equipment under finance leases, accumulated depreciation	4	3.4
Land, buildings and structures and leasehold improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, before accumulated depreciation	626.8	596
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment, before accumulated depreciation	1,085.1	1,001.9
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment, before accumulated depreciation	53.3	60.7
Mineral interests
Property, Plant and Equipment [Line Items]
Property plant and equipment, before accumulated depreciation	172.4	171.1
Construction in progress
Property, Plant and Equipment [Line Items]
Property plant and equipment, before accumulated depreciation	$ 58.7	$ 141.3

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS (Schedule of Finite-Lived Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross intangible asset	$ 140.2	$ 153.5
Accumulated amortization	(73.5)	(68.8)
Net intangible assets	66.7	84.7
Supply Agreement
Finite-Lived Intangible Assets [Line Items]
Gross intangible asset	28.5	27.9
Accumulated amortization	(5.7)	(5)
Net intangible assets	22.8	22.9
SOP Production Rights
Finite-Lived Intangible Assets [Line Items]
Gross intangible asset	24.3	24.3
Accumulated amortization	(16.6)	(15.6)
Net intangible assets	7.7	8.7
Customer/Distributor Relationships
Finite-Lived Intangible Assets [Line Items]
Gross intangible asset	11.6	12.7
Accumulated amortization	(6.8)	(6.1)
Net intangible assets	4.8	6.6
Lease Rights
Finite-Lived Intangible Assets [Line Items]
Gross intangible asset	1.8	1.7
Accumulated amortization	(0.6)	(0.5)
Net intangible assets	1.2	1.2
Trade Names
Finite-Lived Intangible Assets [Line Items]
Gross intangible asset	30.3	36.8
Accumulated amortization	(11.8)	(10.9)
Net intangible assets	18.5	25.9
Developed Technologies
Finite-Lived Intangible Assets [Line Items]
Gross intangible asset	26.2	32.8
Accumulated amortization	(21.4)	(21.7)
Net intangible assets	4.8	11.1
Patents
Finite-Lived Intangible Assets [Line Items]
Gross intangible asset	16.2	16
Accumulated amortization	(9.6)	(8.1)
Net intangible assets	6.6	7.9
Other
Finite-Lived Intangible Assets [Line Items]
Gross intangible asset	1.3	1.3
Accumulated amortization	(1)	(0.9)
Net intangible assets	$ 0.3	$ 0.4

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS (Schedule of Estimated Useful Life) (Details)	12 Months Ended
	Dec. 31, 2020
Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	4 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	50 years
Supply Agreement
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	50 years
SOP Production Rights
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	25 years
Patents | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	10 years
Patents | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	20 years
Developed Technologies | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	4 years
Developed Technologies | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	7 years
Lease Rights
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	25 years
Customer/Distributor Relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	10 years
Customer/Distributor Relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	14 years
Trademarks
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	10 years
Trade Names | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	10 years
Trade Names | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	11 years

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS (Additional Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization expense	$ 10.7	$ 13.6	$ 15
Projected amortization expense over the next 5 years [Abstract]
Projected amortization expense, minimum	5
Projected amortization expense, maximum	$ 10
Remaining amortization period	5 years
Weighted-Average Amortization Period (in years)	20 years
Goodwill	$ 281.3	343
Plant Nutrition North America
Projected amortization expense over the next 5 years [Abstract]
Goodwill	56.4	55.4
Plant Nutrition South America
Projected amortization expense over the next 5 years [Abstract]
Goodwill	218.8	281.6
Water rights
Projected amortization expense over the next 5 years [Abstract]
Indefinite-lived intangible assets	17.7	17.7
Trade Names
Projected amortization expense over the next 5 years [Abstract]
Indefinite-lived intangible assets	$ 0.6	$ 0.6

INCOME TAXES (Tax Cuts and Jobs

INCOME TAXES (Tax Cuts and Jobs Act) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Tax cuts and jobs act of 2017, provisional income tax expense (benefit)				$ 46.8
Tax cuts and jobs act of 2017, one-time tax on unremitted foreign earnings				55.2
Tax cuts and jobs act of 2017, deferred tax liabilities			$ 0.1	$ 8.4
Tax cuts and jobs acts of 2017, tax benefit			3
Tax cuts and jobs act of 2017, tax benefit related to unremitted foreign earnings			(3.1)
Repatriation of foreign earnings			150
Tax on repatriated amounts	$ 0	$ 0.9	3.4
State and local jurisdiction
Operating Loss Carryforwards [Line Items]
Tax on repatriated amounts			$ 4.3

INCOME TAXES (Income Tax Provis

INCOME TAXES (Income Tax Provision (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ (22.3)	$ 5.3	$ 8.1
State	0.4	2	4.3
Foreign	28.2	26.6	13.1
Total current	6.3	33.9	25.5
Deferred:
Federal	1.2	(7.2)	(8.6)
State	(1.2)	(1.9)	(0.5)
Foreign	5.4	(2.7)	(7.6)
Total deferred	5.4	(11.8)	(16.7)
Total provision for income taxes	$ 11.7	$ 22.1	$ 8.8

INCOME TAXES (Components of Ear

INCOME TAXES (Components of Earnings Before Taxes and Tax Effect) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S. (loss) income	$ (4.1)	$ 31.7	$ (80.6)
Foreign income	75.3	52.9	158.2
Earnings before income taxes	$ 71.2	$ 84.6	$ 77.6
U.S. federal statutory rate	21.00%	21.00%	21.00%
Computed tax at the U.S. federal statutory rate of 21%	$ 15	$ 17.8	$ 16.3
Foreign income rate differential, mining, and withholding taxes, net of U.S. federal deduction	9.3	10.2	0.9
Percentage depletion in excess of basis	(4.4)	(5.8)	(4.7)
Other domestic tax reserves, net of reversals	(9.7)	0.2	1.5
State income taxes, net of federal income tax benefit	(0.9)	0	2.1
Change in valuation allowance on deferred tax asset	2.4	0.2	(5.7)
Interest expense recognition differences	(3.5)	(3.5)	(3.6)
GILTI	3.8	1	1
Tax Cuts and Jobs Act of 2017	0	1.6	(3)
Tax on repatriated amounts	0	0.9	3.4
Transfer pricing settlement with taxing authorities	0	0	2.2
Other, net	(0.3)	(0.5)	(1.6)
Total provision for income taxes	$ 11.7	$ 22.1	$ 8.8
Effective tax rate	16.00%	26.00%	11.00%

INCOME TAXES (Components of Def

INCOME TAXES (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Valuation allowance	$ (43.4)	$ (41.2)
Net noncurrent deferred tax assets	11.6	13.7
Deferred tax liabilities:
Property, plant and equipment	66.5	63.7
Intangible asset	22.2	29.1
Right of use lease asset	1.9	0.9
Total deferred tax liabilities	90.6	93.7
Net deferred tax liabilities	87.5	89.9
Deferred tax asset, not to be netted
Deferred tax assets:
Excess interest expense	9.9	14.9
Foreign tax credit	39.4	38.1
Right of use lease liability	11.3	11.1
Stock-based compensation	2	2.3
Other, net	20.5	16.5
Total deferred tax assets before valuation allowance	83.5	86.8
Valuation allowance	(42)	(39.8)
Total deferred tax assets	41.5	47
Deferred tax asset, not to be netted | Subsidiaries | Reluz Nordeste Industria E Comercio Ltda
Deferred tax assets:
Net operating loss carryforwards, foreign	0.4	0.6
Deferred tax asset, not to be netted | Subsidiaries | Compass Minerals South America
Deferred tax assets:
Net operating loss carryforwards, foreign	0	3.3
Deferred tax liabilities, to be netted
Deferred tax assets:
Total deferred tax liabilities to be netted with deferred tax assets	29.9	33.3
Deferred tax liabilities:
Property, plant and equipment	17.2	21.2
Right of use lease asset	11.3	11.1
Other, net	1.4	1
Deferred tax assets, to be netted
Deferred tax assets:
Right of use lease liability	1.9	0.9
Other, net	0.9	2.1
Net operating loss carryforwards	1.7	2.2
Total deferred tax assets before valuation allowance	4.5	5.2
Valuation allowance	(1.4)	(1.4)
Total deferred tax assets	$ 3.1	$ 3.8

INCOME TAXES (Additional Inform

INCOME TAXES (Additional Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Decrease in valuation allowance		$ 7.2
Valuation allowance	$ 43.4		$ 41.2
Unrecognized tax benefits that would impact effective tax rate	28.8
Reductions related to release of uncertain tax positions due to expiration of statutes of limitations	11
Foreign tax authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	7.7		18.8
Foreign country with expiration of 2033
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0.1		1.7
State and local jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0.2		$ 0.3
Resolution with various taxing authorities
Operating Loss Carryforwards [Line Items]
Amount of tax benefit decrease management believes is reasonably possible	$ 1.1

INCOME TAXES (Unrecognized Tax

INCOME TAXES (Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrecognized tax benefits [Roll forward]
Balance at January 1	$ 47.4	$ 50.9	$ 67.4
Additions resulting from current year tax positions	0	0.2	8
Additions relating to tax positions taken in prior years	1.4	4.5	2.6
Reductions due to settlements	0	0	(25)
Reductions due to cash payments	0	(7.5)	0
Reductions relating to tax positions taken in prior years	(0.1)	(0.4)	(0.3)
Reductions due to expiration of tax years	(10.4)	(0.3)	(1.8)
Balance at December 31	$ 38.3	$ 47.4	$ 50.9

INCOME TAXES (Foreign Subsidiar

INCOME TAXES (Foreign Subsidiaries) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Accrued interest and penalties, net of reversals	$ 2	$ 4.6	$ (2.1)
Interest and penalties	22.3	20.3
Repatriation of foreign earnings			150
Tax on repatriated amounts	0	$ 0.9	3.4
Outside basis difference	213.6
Canadian Provincial
Income Tax Contingency [Line Items]
Total reassessment amount including interest	153.4
Amount of security posted in the form of a performance bond	120.1
Amount of security posted in the form of cash	$ 39
State and local jurisdiction
Income Tax Contingency [Line Items]
Tax on repatriated amounts			$ 4.3

INCOME TAXES (Settlements) (Det

INCOME TAXES (Settlements) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Tax settlement			$ 5.3
Increase In sales					$ 85.7
Intercompany payments related to income tax settlement			106.1	$ 85.7
Liability (refund) adjustment for settlement		$ 1.4		17.5
Tax Year 2007 Through 2008
Income Tax Contingency [Line Items]
Tax, penalties, and interest		34.2
Canadian and Provincial
Income Tax Contingency [Line Items]
Increase In sales				$ 106.1
Canadian and Provincial | Tax Year 2007 Through 2016
Income Tax Contingency [Line Items]
Tax settlement					$ 13.8
U.S. taxing authorities
Income Tax Contingency [Line Items]
Liability (refund) adjustment for settlement		(0.9)
Tax refund received			22.2
U.S. taxing authorities | Tax Year 2013 Through 2021
Income Tax Contingency [Line Items]
Tax refund received		$ 59.7
Foreign tax authority
Income Tax Contingency [Line Items]
Liability (refund) adjustment for settlement			$ 29.9
Forecast
Income Tax Contingency [Line Items]
Tax settlement	$ 1.4
Forecast | U.S. taxing authorities | Tax Year 2013 Through 2021
Income Tax Contingency [Line Items]
Liability (refund) adjustment for settlement	$ 1.9

PENSION PLANS AND OTHER BENEF_3

PENSION PLANS AND OTHER BENEFITS (Additional Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts recognized in accumulated other comprehensive income, net of tax [Abstract]
Actuarial net losses recognized in accumulated other comprehensive income, net of tax	$ 9.4	$ 6.8
Accumulated other comprehensive income (loss) before adjustment of prior service costs	10.4	7.9
Accumulated other comprehensive (income) loss related to prior service cost net of tax	1	1.1
Other comprehensive income (loss) related to actuarial gains (losses), net of tax	(2.9)	(2.4)	$ (1.2)
Other comprehensive income (loss) related to amortization of loss, net of tax	0.8	0.4	0.3
Other comprehensive (income) loss related to prior service cost, net of tax	(0.1)	(0.1)	(0.1)
Other comprehensive income (loss) related to foreign exchange	(0.3)	(0.3)	0.4
Expected losses to be recognized in net periodic benefit costs in next fiscal year	1.4
Expected amortization of losses in next fiscal year	1.5
Expected amortization of prior service cost in next fiscal year	0.1
Net periodic (benefit) cost expected in next fiscal year	0.1
Amounts recognized in balance sheet [Abstract]
Underfunded plan status recorded in noncurrent assets	1.2
Noncurrent asset (liability)	(1.2)	1.5
Defined benefit pension plan	$ 73.3	64.1	58.6
Period of amortization of pension benefit obligations	5 years
Expense attributable to all Savings Plans	$ 12.5	11.6	$ 12.6
Investments in marketable securities relating to deferred compensation arrangement	$ 1.9	$ 1.4
Equity funds
Defined Benefit Plan Disclosure [Line Items]
Target allocation	75.00%
Bond funds
Defined Benefit Plan Disclosure [Line Items]
Target allocation	25.00%

PENSION PLANS AND OTHER BENEF_4

PENSION PLANS AND OTHER BENEFITS (Weighted-Average Asset Allocations and Fair Value of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	100.00%	100.00%
Fair value of pension plan assets [Abstract]
Total pension assets	$ 72.1	$ 65.6	$ 60.7
Level One
Fair value of pension plan assets [Abstract]
Total pension assets	1.3	1.9
Level Two
Fair value of pension plan assets [Abstract]
Total pension assets	70.8	63.7
Level Three
Fair value of pension plan assets [Abstract]
Total pension assets	$ 0	$ 0
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	2.00%	3.00%
Fair value of pension plan assets [Abstract]
Total pension assets	$ 1.3	$ 1.9
Cash and cash equivalents | Level One
Fair value of pension plan assets [Abstract]
Total pension assets	1.3	1.9
Cash and cash equivalents | Level Two
Fair value of pension plan assets [Abstract]
Total pension assets	0	0
Cash and cash equivalents | Level Three
Fair value of pension plan assets [Abstract]
Total pension assets	$ 0	$ 0
Blended funds
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	48.00%	51.00%
Fair value of pension plan assets [Abstract]
Total pension assets	$ 34.9	$ 33.6
Blended funds | Level One
Fair value of pension plan assets [Abstract]
Total pension assets	0	0
Blended funds | Level Two
Fair value of pension plan assets [Abstract]
Total pension assets	34.9	33.6
Blended funds | Level Three
Fair value of pension plan assets [Abstract]
Total pension assets	$ 0	$ 0
Bond funds
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	50.00%	46.00%
Treasuries
Fair value of pension plan assets [Abstract]
Total pension assets	$ 35.9	$ 30.1
Treasuries | Level One
Fair value of pension plan assets [Abstract]
Total pension assets	0	0
Treasuries | Level Two
Fair value of pension plan assets [Abstract]
Total pension assets	35.9	30.1
Treasuries | Level Three
Fair value of pension plan assets [Abstract]
Total pension assets	$ 0	$ 0

PENSION PLANS AND OTHER BENEF_5

PENSION PLANS AND OTHER BENEFITS (Summary of Assumptions Used in Calculating Net Periodic Benefit Costs) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assumptions used in calculating net periodic benefit cost [Abstract]
Discount rate	1.20%	2.00%	2.90%
Expected return on plan assets	3.10%	3.10%	3.70%

PENSION PLANS AND OTHER BENEF_6

PENSION PLANS AND OTHER BENEFITS (Summary of Future Expected Benefit Payments) (Details) $ in Millions	Dec. 31, 2020USD ($)
Future expected benefit payments [Abstract]
2021	$ 3.2
2022	3.2
2023	3.3
2024	3.4
2025	3.4
2026-2030	$ 18.4

PENSION PLANS AND OTHER BENEF_7

PENSION PLANS AND OTHER BENEFITS (Summary of Changes in Benefit Obligation and Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in benefit obligation:
Benefit obligation as of January 1	$ 64.1	$ 58.6
Interest cost	1.2	1.7	$ 1.6
Actuarial loss	8.3	4.8
Plan amendment	0.1	0	0
Benefits paid	(2.9)	(3.5)
Currency fluctuation adjustment	2.5	2.5
Benefit obligation as of December 31	73.3	64.1	58.6
Change in plan assets:
Beginning balance	65.6	60.7
Actual return	6.7	4.2
Company contributions	0.4	1.7
Currency fluctuation adjustment	2.3	2.5
Benefits paid	(2.9)	(3.5)
Ending balance	72.1	65.6	$ 60.7
(Underfunded) Overfunded status of the plan	$ (1.2)	$ 1.5

PENSION PLANS AND OTHER BENEF_8

PENSION PLANS AND OTHER BENEFITS (Summary of Components of Net Pension Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components of net pension expense [Abstract]
Interest cost on projected benefit obligation	$ 1.2	$ 1.7	$ 1.6
Prior service cost	(0.1)	(0.1)	(0.1)
Expected return on plan assets	(1.9)	(2.2)	(2.5)
Plan amendment	0.1	0	0
Net amortization	1	0.5	0.3
Net periodic pension cost (benefit)	$ 0.3	$ (0.1)	$ (0.7)

LONG TERM DEBT (Summary of Long

LONG TERM DEBT (Summary of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total debt, gross	$ 1,414.3	$ 1,430.8
Less unamortized debt issuance costs	(12.9)	(14.8)
Total debt	1,401.4	1,416
Less current portion	(63.7)	(52.1)
Long-term debt	$ 1,337.7	1,363.9
4.875% Senior Notes due July 2024
Debt Instrument [Line Items]
Stated interest rate (as a percent)	4.875%
Total debt, gross	$ 250	250
Term Loan due January 2025
Debt Instrument [Line Items]
Total debt, gross	390	400
Revolving Credit Facility due January 2025 | Revolving Credit Facility due January 2025
Debt Instrument [Line Items]
Total debt, gross	$ 130.3	160
6.75% Senior Notes due December 2027
Debt Instrument [Line Items]
Stated interest rate (as a percent)	6.75%
Total debt, gross	$ 500	500
3.7% Banco Itaú loan due March 2020
Debt Instrument [Line Items]
Stated interest rate (as a percent)	3.70%
Total debt, gross	$ 0	15.4
AR Securitization Facility expires June 2023
Debt Instrument [Line Items]
Total debt, gross	51.2	0
Banco Santander loan due October 2020
Debt Instrument [Line Items]
Total debt, gross	0	16.2
Banco Itaú loan due February 2021
Debt Instrument [Line Items]
Total debt, gross	10.4	0
Banco Rabobank loan due July 2021
Debt Instrument [Line Items]
Total debt, gross	6.8	17.4
Banco BTG loan due July 2021
Debt Instrument [Line Items]
Total debt, gross	2.6	0
Banco Santander loan due September 2021
Debt Instrument [Line Items]
Total debt, gross	0	19.9
Banco do Brasil loan due September 2021
Debt Instrument [Line Items]
Total debt, gross	9.6	12.4
Banco Rabobank loan due September 2021
Debt Instrument [Line Items]
Total debt, gross	6.8	0
Banco BTG loan due October 2021
Debt Instrument [Line Items]
Total debt, gross	2.6	0
Banco Rabobank loan due November 2021
Debt Instrument [Line Items]
Total debt, gross	13.5	17.4
Banco Santander loan due December 2021
Debt Instrument [Line Items]
Total debt, gross	0	14.9
Banco BTG loan due January 2022
Debt Instrument [Line Items]
Total debt, gross	1	0
Banco Votorantim loan due February 2022
Debt Instrument [Line Items]
Total debt, gross	7.7	0
Banco Bradesco loan due February 2022
Debt Instrument [Line Items]
Total debt, gross	4.8	0
Banco Santander loan due March 2022
Debt Instrument [Line Items]
Total debt, gross	2.9	0
Banco BTG loan due April 2022
Debt Instrument [Line Items]
Total debt, gross	1	0
Banco BTG loan due July 2022
Debt Instrument [Line Items]
Total debt, gross	2.6	0
Banco Safra loan due October 2022
Debt Instrument [Line Items]
Total debt, gross	3.9	0
Banco Santander loan due October 2022
Debt Instrument [Line Items]
Total debt, gross	12.5	0
Financiadora de Estudos e Projetos loan due November 2023
Debt Instrument [Line Items]
Total debt, gross	$ 4.1	$ 7.2

LONG TERM DEBT (Additional Info

LONG TERM DEBT (Additional Information) (Details)	Jun. 30, 2020USD ($)	Oct. 31, 2019	Nov. 30, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2020USD ($)loan	Sep. 30, 2020USD ($)loan	Mar. 31, 2020USD ($)loan	Dec. 31, 2019USD ($)loan	Mar. 31, 2019USD ($)loan	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2019USD ($)
Debt Instrument [Line Items]
Debt outstanding					$ 1,414,300,000			$ 1,430,800,000		$ 1,414,300,000	$ 1,430,800,000
Expense as result of amendment										3,200,000	2,800,000	$ 2,200,000
Repayments of debt						$ 15,400,000				$ 79,200,000	902,800,000	68,100,000
Short-term debt refinanced								17,400,000
Unallocated Financing Receivables | Account Receivable Financing Receivable
Debt Instrument [Line Items]
Financing receivable, term	3 years
Revolving accounts receivable financing facility	$ 100,000,000
2019 Credit Agreement
Debt Instrument [Line Items]
Weighted average interest rate on all borrowings outstanding					2.20%					2.20%
Fees paid as a result of amendment			$ 4,100,000
Capitalized deferred financing costs as result of amendment			3,800,000
Expense as result of amendment			300,000
Write off of previously capitalized deferred financing costs			300,000
Term Loan due January 2025
Debt Instrument [Line Items]
Debt outstanding					$ 390,000,000			400,000,000		$ 390,000,000	400,000,000
Compass Minerals South America Loan Mature from March 2020 through November 2023
Debt Instrument [Line Items]
Face amount					92,800,000					92,800,000
Brazilian Reais-denominated Loans
Debt Instrument [Line Items]
Face amount					$ 21,200,000	$ 15,100,000	$ 20,000,000	$ 27,300,000	$ 18,000,000	$ 21,200,000	$ 27,300,000		$ 36,000,000
Number of loans | loan					3	6	3	2	2
Number of loans denominated in foreign currency | loan							2
Brazilian Reais-denominated Loans | Certificado De Deposito Interbancario (CDI) | Minimum
Debt Instrument [Line Items]
Variable rate, percentage of reference rate					171.00%	200.00%	143.00%			171.00%
Brazilian Reais-denominated Loans | Certificado De Deposito Interbancario (CDI) | Maximum
Debt Instrument [Line Items]
Variable rate, percentage of reference rate					186.00%	204.00%	150.00%			186.00%
Euro-Denominated Loans
Debt Instrument [Line Items]
Number of loans denominated in foreign currency | loan							1
Brazilian Reais-denominated Loan Matured In July 2019 | Certificado De Deposito Interbancario (CDI)
Debt Instrument [Line Items]
Variable rate, percentage of reference rate									123.00%
Brazilian Reais-denominated Loan Matured In September 2019 | Certificado De Deposito Interbancario (CDI)
Debt Instrument [Line Items]
Variable rate, percentage of reference rate									128.00%
Brazilian Reais-denominated Loans Mature In July 2021 | Certificado De Deposito Interbancario (CDI)
Debt Instrument [Line Items]
Variable rate, percentage of reference rate													120.00%
Brazilian Reais-denominated Loans Mature September 2021, one | Certificado De Deposito Interbancario (CDI)
Debt Instrument [Line Items]
Variable rate, percentage of reference rate													141.00%
Brazilian Reais-denominated Loans Mature September 2021, two | Certificado De Deposito Interbancario (CDI)
Debt Instrument [Line Items]
Variable rate, percentage of reference rate								126.00%			126.00%
Brazilian Reais-denominated Loans Mature December 2021 | Certificado De Deposito Interbancario (CDI)
Debt Instrument [Line Items]
Variable rate, percentage of reference rate								129.00%			129.00%
Brazilian Reais-Denominated Loans Mature November 2021 | Certificado De Deposito Interbancario (CDI)
Debt Instrument [Line Items]
Variable rate, percentage of reference rate								122.00%			122.00%
Revolving Credit Facility due January 2025 | Revolving Credit Facility due January 2025
Debt Instrument [Line Items]
Debt outstanding					$ 130,300,000			$ 160,000,000		$ 130,300,000	$ 160,000,000
Revolving Credit Facility due January 2025 | Revolving Credit Facility Due July 2021
Debt Instrument [Line Items]
Fees paid as a result of amendment				$ 1,400,000
Capitalized deferred financing costs as result of amendment				1,400,000								$ 1,400,000
Expense as result of amendment				$ 100,000
Secured debt | Base Rate
Debt Instrument [Line Items]
Interest spread over base rate		0.50%
Secured debt | Term Loan due January 2025
Debt Instrument [Line Items]
Face amount			$ 400,000,000
Principal payments as a percentage, years one and two			2.50%
Principal payments as a percentage, years three through five			5.00%
Line of credit | Revolving Credit Facility due January 2025 | Revolving Credit Facility due January 2025
Debt Instrument [Line Items]
Long-term debt, revolving credit facility			$ 300,000,000
Amount of facility that may be drawn in Canadian dollars					40,000,000					40,000,000
Amount of facility that may be drawn in British pounds sterling					10,000,000					10,000,000
Remaining borrowing capacity					157,200,000					157,200,000
Line of credit | Letter of credit | Revolving Credit Facility due January 2025
Debt Instrument [Line Items]
Long-term debt, revolving credit facility					50,000,000					50,000,000
Outstanding letters of credit					$ 12,500,000					$ 12,500,000
Senior notes | Senior Notes due 2027
Debt Instrument [Line Items]
Face amount			500,000,000
Capitalized deferred financing costs as result of amendment			$ 8,200,000
Stated interest rate (as a percent)			6.75%		6.75%					6.75%
Senior notes | Senior Notes July 2024
Debt Instrument [Line Items]
Stated interest rate (as a percent)					4.875%					4.875%

LONG TERM DEBT (Future Maturiti

LONG TERM DEBT (Future Maturities of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Future maturities of long-term debt [Abstract]
2021	$ 63.7
2022	57.8
2023	72.5
2024	270
2025	450.3
Thereafter	500
Total	$ 1,414.3	$ 1,430.8

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS (Additional Information) (Details) MMBTU in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Apr. 30, 2020USD ($)	Dec. 31, 2020USD ($)MMBTU	Dec. 31, 2019USD ($)MMBTU	Dec. 31, 2018USD ($)	Mar. 31, 2020USD ($)	Feb. 28, 2018USD ($)
Derivatives, Fair Value [Line Items]
Period hedging portion of natural gas usage considered in advance of purchase		36 months
Forward Contracts
Derivatives, Fair Value [Line Items]
Notional amount			$ 11.9
Derivatives designated as hedging instruments | Commodity contracts
Derivatives, Fair Value [Line Items]
Percent of forecasted usage to be hedged		90.00%
Notional amount (in MMBtus) | MMBTU		2.5	2.8
Net gain (loss) to be reclassified from accumulated other comprehensive income to earnings during the next 12 months		$ 0.3
Derivatives designated as hedging instruments | Swap contracts
Derivatives, Fair Value [Line Items]
Notional amount		10.5	$ 15.7
Gain (loss) expected to be reclassified during the next twelve months		$ 2.6
Derivatives not designated as hedging instruments | Derivatives - foreign currency contracts, net
Derivatives, Fair Value [Line Items]
Net gain (loss) to be reclassified from accumulated other comprehensive income to earnings during the next 12 months			$ 1.5
Notional amount					$ 89.9	$ 19.9
Gain (loss) on foreign exchange, not designated as hedges	$ 3.1
Derivatives not designated as hedging instruments | Forward Contracts
Derivatives, Fair Value [Line Items]
Net gain (loss) to be reclassified from accumulated other comprehensive income to earnings during the next 12 months				$ (1)

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS (Fair Value of Hedged Items) (Details) $ in Millions	Dec. 31, 2020USD ($)counterparty	Dec. 31, 2019USD ($)counterparty
Derivatives, Fair Value [Line Items]
Number of counterparties (in counterparties) | counterparty		2
Commodity contracts
Derivatives, Fair Value [Line Items]
Netting of contracts in a receivable position against contracts in payable position	$ 0.3	$ 0.4
Number of counterparties (in counterparties) | counterparty	2
Swap contracts
Derivatives, Fair Value [Line Items]
Number of counterparties (in counterparties) | counterparty	1
Derivatives designated as hedging instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 3.1	3.2
Liability Derivatives	0.3	1
Derivatives designated as hedging instruments | Commodity contracts | Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	0.4	0.3
Derivatives designated as hedging instruments | Commodity contracts | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	0.1	0.8
Derivatives designated as hedging instruments | Commodity contracts | Other assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	0.1	0.1
Derivatives designated as hedging instruments | Commodity contracts | Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	0.2	0.2
Derivatives designated as hedging instruments | Swap contracts | Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	2.6	2.8
Derivatives designated as hedging instruments | Swap contracts | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 0	$ 0

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS (Activity Related to Other Comprehensive Income) (Details) - Derivatives in Cash Flow Hedging Relationships - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain Recognized in OCI on Derivative (Effective Portion)	$ (5.7)	$ (3.3)
Amount of Gain Reclassified from Accumulated OCI Into Income (Effective Portion)	4.6	3.1
Commodity contracts | Product cost
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain Recognized in OCI on Derivative (Effective Portion)	(1.8)	(0.8)
Amount of Gain Reclassified from Accumulated OCI Into Income (Effective Portion)	1	0.9
Swap contracts | Interest expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain Recognized in OCI on Derivative (Effective Portion)	(3.9)	(2.5)
Amount of Gain Reclassified from Accumulated OCI Into Income (Effective Portion)	$ 3.6	$ 2.2

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)agreement	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Loss Contingencies [Line Items]
Maximum exposure for other labor matters	$ 16	$ 25
Unions [Abstract]
Percentage of company's global workforce represented by labor unions	30.00%
Number of collective bargaining agreements (in agreements) | agreement	12
Number of collective bargaining agreements expiring in 2021 (in agreements) | agreement	2
Number of collective bargaining agreements expiring March 31, 2021 (in agreements) | agreement	1
Number of collective bargaining agreements expiring in 2022 (in agreements) | agreement	5
Number of collective bargaining agreements expiring in 2023 (in agreements) | agreement	3
Number of collective bargaining agreements expiring in 2027 (in agreements) | agreement	1
Royalties [Abstract]
Royalty expense	$ 18.3	16.3	$ 14.8
Sales contracts [Abstract]
Guarantor obligations, performance bonds outstanding	51.4
Purchase commitments [Abstract]
Purchase commitments for 2021	43.6
Purchase commitments for 2022	13.3
Purchase commitments for 2023	10
Purchase commitments for 2024	7.8
Purchase commitments for 2025	2.1
Purchase commitments, after 2025	$ 7.5
U.S., Canada, and U.K.
Unions [Abstract]
Percentage of company's global workforce represented by labor unions	50.00%
Workforce subject to collective bargaining arrangements | Labor force concentration risk | Brazil
Unions [Abstract]
Percentage of concentration risk	40.00%
Compass Minerals South America
Loss Contingencies [Line Items]
Contingent liabilities assumed	$ 3.5	5.6
Brazilian Tax Litigation And Assessments
Loss Contingencies [Line Items]
Possible tax proceedings and claims	$ 7.9	$ 15.8

STOCKHOLDERS' EQUITY AND EQUI_3

STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS (Summary of Plan Information) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 31, 2020	May 31, 2015	Dec. 31, 2005
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends paid (in dollars per share)	$ 2.88	$ 2.88	$ 2.88
Preferred stock, shares authorized (in shares)	10,000,000
Preferred stock, shares issued (in shares)	0
Preferred stock, shares Outstanding (in shares)	0
Series A preferred stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares designated as series A junior participating preferred stock (in shares)	200,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	4 years
Award expiration period	7 years
Number of shares available from conversion (in shares)	1
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available from conversion (in shares)	1
TSR PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period of PSUs	3 years	3 years
EBITDA Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period of PSUs		2 years
2005 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares (in shares)						3,240,000
2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares (in shares)					3,000,000
2020 Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares (in shares)				2,977,933
Deferred compensation agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred stock units credited in period (in shares)	42,313	33,883	26,291
Deferred compensation agreement | Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reissued from treasury stock (in shares)	8,525	9,041	6,728
Deferred compensation agreement | Director | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted to directors (in shares)	3,750
Minimum | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	1 year
Minimum | TSR PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned	0.00%
Minimum | Target Number Of Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned	0.00%
Minimum | EBITDA Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned	0.00%
Maximum | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	3 years
Maximum | TSR PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned	150.00%
Maximum | Target Number Of Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned	200.00%
Maximum | EBITDA Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned	200.00%

STOCKHOLDERS' EQUITY AND EQUI_4

STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS (Summary of Fair Value Assumptions and Methodology) (Details) - Stock options - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of options granted (in dollars per share)	$ 10.91	$ 9.15	$ 8.77
Expected term (years)	4 years 9 months 18 days	4 years 6 months	4 years 6 months
Expected volatility	29.30%	28.00%	22.90%
Dividend yield	3.50%	4.10%	3.60%
Risk-free interest rates	1.60%	2.30%	2.50%

STOCKHOLDERS' EQUITY AND EQUI_5

STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS (Summary of Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Options
Stock option activity
Outstanding at beginning of period (in shares)	887,867	708,746	562,877
Granted (in shares)	94,945	369,716	250,514
Exercised (in shares)	(4,454)	0	0
Cancelled/Expired (in shares)	(109,586)	(190,595)	(104,645)
Outstanding at end of period (in shares)	868,772	887,867	708,746
Stock option weighted-average exercise price
Outstanding at beginning of period (in dollars per share)	$ 64.21	$ 70.76	$ 75.89
Granted (in dollars per share)	58.91	54.15	59.61
Exercised (in dollars per share)	57.02	0	0
Cancelled/Expired (in dollars per share)	69	69.06	71.65
Outstanding at end of period (in dollars per share)	$ 63.06	$ 64.21	$ 70.76
RSUs
RSU and PSU activity
Outstanding at beginning of period (in shares)	217,413	83,308	70,856
Granted (in shares)	95,276	218,071	42,013
Released from restriction (in shares)	(76,570)	(32,630)	(16,905)
Cancelled/Expired (in shares)	(28,137)	(51,336)	(12,656)
Outstanding at end of period (in shares)	207,982	217,413	83,308
RSU and PSU weighted-average fair value
Outstanding at beginning of period (in dollars per share)	$ 52.07	$ 65.75	$ 74.63
Granted (in dollars per share)	58.24	49.73	60.28
Released from restriction (in dollars per share)	50.03	66.95	88.78
Cancelled/Expired (in dollars per share)	51.85	54.87	66.53
Outstanding at end of period (in dollars per share)	$ 55.68	$ 52.07	$ 65.75
PSUs
RSU and PSU activity
Outstanding at beginning of period (in shares)	179,397	126,638	112,036
Granted (in shares)	107,072	123,003	67,235
Released from restriction (in shares)	(11,575)	0	(2,753)
Cancelled/Expired (in shares)	(33,100)	(70,244)	(49,880)
Outstanding at end of period (in shares)	241,794	179,397	126,638
RSU and PSU weighted-average fair value
Outstanding at beginning of period (in dollars per share)	$ 61.43	$ 69.06	$ 79.48
Granted (in dollars per share)	74.73	56.88	64.30
Released from restriction (in dollars per share)	78.87	0	78.92
Cancelled/Expired (in dollars per share)	68.18	67.20	85.51
Outstanding at end of period (in dollars per share)	$ 65.57	$ 61.43	$ 69.06

STOCKHOLDERS' EQUITY AND EQUI_6

STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS (Additional Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	868,772	887,867
Number of options outstanding that are exercisable (in shares)	496,715	416,860
Compensation expense related to stock-based compensation awards	$ 9.9	$ 7.4	$ 7.8
Compensation expense paid in cash	0.5	1.1
Unrecorded compensation cost related to non-vested awards	$ 14.7
Unrecorded compensation cost, weighted average period of recognition	1 year 9 months 18 days
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of options vested	$ 1.4	0.8	2.7
Intrinsic value of stock options exercised during the period	0.1	$ 0.1	$ 0.1
Intrinsic value of options outstanding	3.1
Intrinsic value of options exercisable	$ 1

STOCKHOLDERS' EQUITY AND EQUI_7

STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS (Summary of Exercise Price Range) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding (in shares)	868,772	887,867
Weighted-average remaining contractual life (years)	4 years 1 month 6 days
Weighted-average exercise price of options outstanding (in dollars per share)	$ 63.06
Options exercisable (in shares)	496,715
Weighted-average remaining contractual life options exercisable	3 years 1 month 6 days
Weighted-average exercise price of exercisable options (in dollars per share)	$ 68.05
$53.75 - $54.38
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	53.75
Exercise price range, upper range limit (in dollars per share)	$ 54.38
Options outstanding (in shares)	252,245
Weighted-average remaining contractual life (years)	5 years 3 months 18 days
Weighted-average exercise price of options outstanding (in dollars per share)	$ 53.75
Options exercisable (in shares)	84,082
Weighted-average remaining contractual life options exercisable	5 years 3 months 18 days
Weighted-average exercise price of exercisable options (in dollars per share)	$ 53.75
$54.39 - $59.21
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	54.39
Exercise price range, upper range limit (in dollars per share)	$ 59.21
Options outstanding (in shares)	159,424
Weighted-average remaining contractual life (years)	5 years 8 months 12 days
Weighted-average exercise price of options outstanding (in dollars per share)	$ 57.01
Options exercisable (in shares)	18,836
Weighted-average remaining contractual life options exercisable	5 years 2 months 12 days
Weighted-average exercise price of exercisable options (in dollars per share)	$ 55.01
$59.22 - $63.75
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	59.22
Exercise price range, upper range limit (in dollars per share)	$ 63.75
Options outstanding (in shares)	159,445
Weighted-average remaining contractual life (years)	4 years 3 months 18 days
Weighted-average exercise price of options outstanding (in dollars per share)	$ 59.50
Options exercisable (in shares)	110,700
Weighted-average remaining contractual life options exercisable	4 years 3 months 18 days
Weighted-average exercise price of exercisable options (in dollars per share)	$ 59.50
$63.76 - $69.77
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	63.76
Exercise price range, upper range limit (in dollars per share)	$ 69.77
Options outstanding (in shares)	119,357
Weighted-average remaining contractual life (years)	3 years 1 month 6 days
Weighted-average exercise price of options outstanding (in dollars per share)	$ 68.03
Options exercisable (in shares)	104,796
Weighted-average remaining contractual life options exercisable	3 years
Weighted-average exercise price of exercisable options (in dollars per share)	$ 68.01
$69.78 - $91.75
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	69.78
Exercise price range, upper range limit (in dollars per share)	$ 91.75
Options outstanding (in shares)	178,301
Weighted-average remaining contractual life (years)	1 year 3 months 18 days
Weighted-average exercise price of options outstanding (in dollars per share)	$ 81.51
Options exercisable (in shares)	178,301
Weighted-average remaining contractual life options exercisable	1 year 3 months 18 days
Weighted-average exercise price of exercisable options (in dollars per share)	$ 81.51

STOCKHOLDERS' EQUITY AND EQUI_8

STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 529.6	$ 540.2	$ 694.6
Other comprehensive income (loss) before reclassifications	(108.8)	20.6
Amounts reclassified from accumulated other comprehensive loss	(2.4)	(1.8)
Net current period other comprehensive income (loss)	(111.2)	18.8
Reclassification of stranded tax out of AOCI to retained earnings			0
Ending balance	387	529.6	540.2
Gains and (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(0.6)	(0.7)
Other comprehensive income (loss) before reclassifications	3.9	2.2
Amounts reclassified from accumulated other comprehensive loss	(3.1)	(2.1)
Net current period other comprehensive income (loss)	0.8	0.1
Ending balance	0.2	(0.6)	(0.7)
Defined Benefit Pension
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(6.9)	(4.5)
Other comprehensive income (loss) before reclassifications	(3.2)	(2.7)
Amounts reclassified from accumulated other comprehensive loss	0.7	0.3
Net current period other comprehensive income (loss)	(2.5)	(2.4)
Ending balance	(9.4)	(6.9)	(4.5)
Foreign Currency
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(184.6)	(205.7)
Other comprehensive income (loss) before reclassifications	(109.5)	21.1
Amounts reclassified from accumulated other comprehensive loss	0	0
Net current period other comprehensive income (loss)	(109.5)	21.1
Ending balance	(294.1)	(184.6)	(205.7)
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(192.1)	(210.9)	(77.9)
Reclassification of stranded tax out of AOCI to retained earnings			(0.2)
Ending balance	$ (303.3)	$ (192.1)	$ (210.9)

STOCKHOLDERS' EQUITY AND EQUI_9

STOCKHOLDERS' EQUITY AND EQUITY INSTRUMENTS (Amount Reclassified from AOCI) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									$ (71.2)	$ (68.4)	$ (62.5)
Income tax expense									11.7	22.1	8.8
Net earnings	$ 32.3	$ (2.1)	$ 1.7	$ 27.6	$ 56.1	$ 10.6	$ (11.8)	$ 7.6	59.5	62.5	$ 68.8
Amount Reclassified from AOCL
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net earnings									(2.4)	(1.8)
Amount Reclassified from AOCL | Gains and (Losses) on Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense									1.5	1
Net earnings									(3.1)	(2.1)
Amount Reclassified from AOCL | Gains and (Losses) on Cash Flow Hedges | Natural gas instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product cost									(1)	(0.9)
Amount Reclassified from AOCL | Gains and (Losses) on Cash Flow Hedges | Foreign currency contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									(3.6)	(2.2)
Amount Reclassified from AOCL | Defined Benefit Pension
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product cost									0.9	0.4
Income tax expense									(0.2)	(0.1)
Net earnings									$ 0.7	$ 0.3

FAIR VALUE MEASUREMENTS (Summar

FAIR VALUE MEASUREMENTS (Summary of Estimated Fair Values) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Asset Class:
Mutual fund investments in a non-qualified savings plan	$ 1.9	$ 1.4
Derivative Asset		2.8
Total Assets	4.7	4.2
Liability Class:
Liabilities related to non-qualified savings plan	(1.9)	(1.4)
Derivatives - natural gas instruments, net		(0.6)
Total Liabilities	(1.9)	$ (2)
Derivatives – natural gas instruments, net
Asset Class:
Derivative Asset	0.2
Derivatives - foreign currency contracts, net
Asset Class:
Derivative Asset	$ 2.6
Mutual Fund Investments | Common Stock of Large-cap U.S. Companies
Liability Class:
Percentage of concentration risk	30.00%	30.00%
Mutual Fund Investments | Common Stock of Small To Mid-cap U.S. Companies
Liability Class:
Percentage of concentration risk	10.00%	15.00%
Mutual Fund Investments | Common Stock of International Companies
Liability Class:
Percentage of concentration risk	5.00%	5.00%
Mutual Fund Investments | Bond Funds
Liability Class:
Percentage of concentration risk	15.00%	10.00%
Mutual Fund Investments | Short-term Investments
Liability Class:
Percentage of concentration risk	15.00%	20.00%
Mutual Fund Investments | Blended funds
Liability Class:
Percentage of concentration risk	25.00%	20.00%
Level One
Asset Class:
Mutual fund investments in a non-qualified savings plan	$ 1.9	$ 1.4
Derivative Asset		0
Total Assets	1.9	1.4
Liability Class:
Liabilities related to non-qualified savings plan	(1.9)	(1.4)
Derivatives - natural gas instruments, net		0
Total Liabilities	(1.9)	(1.4)
Level One | Derivatives – natural gas instruments, net
Asset Class:
Derivative Asset	0
Level One | Derivatives - foreign currency contracts, net
Asset Class:
Derivative Asset	0
Level Two
Asset Class:
Mutual fund investments in a non-qualified savings plan	0	0
Derivative Asset		2.8
Total Assets	2.8	2.8
Liability Class:
Liabilities related to non-qualified savings plan	0	0
Derivatives - natural gas instruments, net		(0.6)
Total Liabilities	0	(0.6)
Level Two | Derivatives – natural gas instruments, net
Asset Class:
Derivative Asset	0.2
Level Two | Derivatives - foreign currency contracts, net
Asset Class:
Derivative Asset	2.6
Level Three
Asset Class:
Mutual fund investments in a non-qualified savings plan	0	0
Derivative Asset		0
Total Assets	0	0
Liability Class:
Liabilities related to non-qualified savings plan	0	0
Derivatives - natural gas instruments, net		0
Total Liabilities	0	$ 0
Level Three | Derivatives – natural gas instruments, net
Asset Class:
Derivative Asset	0
Level Three | Derivatives - foreign currency contracts, net
Asset Class:
Derivative Asset	$ 0

FAIR VALUE MEASUREMENTS (Additi

FAIR VALUE MEASUREMENTS (Additional Information) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Nov. 30, 2019
Debt Instrument [Line Items]
Mutual fund investments in a non-qualified savings plan	$ 1.9	$ 1.4
6.75% Senior Notes due December 2027
Debt Instrument [Line Items]
Stated interest rate (as a percent)	6.75%
Senior Notes July 2024
Debt Instrument [Line Items]
Stated interest rate (as a percent)	4.875%	4.875%
Senior notes | 6.75% Senior Notes due December 2027
Debt Instrument [Line Items]
Stated interest rate (as a percent)	6.75%
Senior notes	$ 543.1	$ 530.6
Senior notes | Senior Notes due 2027
Debt Instrument [Line Items]
Stated interest rate (as a percent)	6.75%		6.75%
Senior Notes due 2027
Debt Instrument [Line Items]
Debt instrument	$ 500	500
Fair Value | Senior Notes July 2024
Debt Instrument [Line Items]
Debt instrument	260.3	249.1
Fair Value | Credit agreement
Debt Instrument [Line Items]
Debt instrument	513.8	552.8
Carrying Value | Senior Notes July 2024
Debt Instrument [Line Items]
Debt instrument	250	250
Carrying Value | Credit agreement
Debt Instrument [Line Items]
Debt instrument	$ 520.3	$ 560

OPERATING SEGMENTS (Segment Inf

OPERATING SEGMENTS (Segment Information) (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)segmentBusiness	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments (in segments) | segment									3
Sales	$ 421.1	$ 282.4	$ 256.1	$ 413.9	$ 500.3	$ 341.3	$ 245.2	$ 403.7	$ 1,373.5	$ 1,490.5	$ 1,493.6
Operating earnings (loss)									140.5	163.6	130.3
Depreciation, depletion and amortization									137.9	137.9	136.9
Total assets	2,262.4				2,443.2				2,262.4	2,443.2	2,367.9
Capital expenditures									$ 84.9	98.1	96.8
Plant Nutrition South America
Segment Reporting Information [Line Items]
Number of primary businesses (in businesses) | Business									2
Reportable segments | Salt
Segment Reporting Information [Line Items]
Sales									$ 779.4	889.5	858.1
Operating earnings (loss)									161.8	168	115.7
Depreciation, depletion and amortization									66.6	60.4	56.2
Total assets	1,020.8				1,056.3				1,020.8	1,056.3	948.9
Capital expenditures									56.8	65.9	58.7
Reportable segments | Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									239.6	206.2	233.2
Operating earnings (loss)									12.1	22.5	25.3
Depreciation, depletion and amortization									40.4	44.6	48.6
Total assets	520.8				575.5				520.8	575.5	589.3
Capital expenditures									12.5	15.2	20.7
Reportable segments | Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									344.4	385.1	391.8
Operating earnings (loss)									40.3	40	48.7
Depreciation, depletion and amortization									17.4	22.4	22.2
Total assets	579.2				715.3				579.2	715.3	709.9
Capital expenditures									9.6	10.5	10.1
Corporate & other
Segment Reporting Information [Line Items]
Sales									10.1	9.7	10.5
Operating earnings (loss)									(73.7)	(66.9)	(59.4)
Depreciation, depletion and amortization									13.5	10.5	9.9
Total assets	$ 141.6				$ 96.1				141.6	96.1	119.8
Capital expenditures									6	6.5	7.3
Intersegment sales
Segment Reporting Information [Line Items]
Sales									(5.7)	(9.1)	(9)
Intersegment sales | Salt
Segment Reporting Information [Line Items]
Sales									0	0	0
Intersegment sales | Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									5.4	6.4	5.6
Intersegment sales | Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									0.3	2.7	3.4
Shipping and handling cost
Segment Reporting Information [Line Items]
Shipping and handling cost									266.6	312.5	320
Shipping and handling cost | Reportable segments | Salt
Segment Reporting Information [Line Items]
Shipping and handling cost									217.8	267.4	272.4
Shipping and handling cost | Reportable segments | Plant Nutrition North America
Segment Reporting Information [Line Items]
Shipping and handling cost									34	28.5	29
Shipping and handling cost | Reportable segments | Plant Nutrition South America
Segment Reporting Information [Line Items]
Shipping and handling cost									14.8	16.6	18.6
Shipping and handling cost | Corporate & other
Segment Reporting Information [Line Items]
Shipping and handling cost									$ 0	$ 0	$ 0

OPERATING SEGMENTS (Information

OPERATING SEGMENTS (Information by Product) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Sales	$ 421.1	$ 282.4	$ 256.1	$ 413.9	$ 500.3	$ 341.3	$ 245.2	$ 403.7	$ 1,373.5	$ 1,490.5	$ 1,493.6
Logistics costs							$ 2.8			2.8
Severance and other costs, gross										2.3	5.1
Reportable segments | Salt
Segment Reporting Information [Line Items]
Sales									779.4	889.5	858.1
Reportable segments | Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									239.6	206.2	233.2
Reportable segments | Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									344.4	385.1	391.8
Corporate & other
Segment Reporting Information [Line Items]
Sales									10.1	9.7	10.5
Highway Deicing Salt
Segment Reporting Information [Line Items]
Sales									473.8	545.5	532
Highway Deicing Salt | Reportable segments | Salt
Segment Reporting Information [Line Items]
Sales									473.8	545.5	532
Highway Deicing Salt | Reportable segments | Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									0	0	0
Highway Deicing Salt | Reportable segments | Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									0	0	0
Highway Deicing Salt | Corporate & other
Segment Reporting Information [Line Items]
Sales									0	0	0
Consumer & Industrial Salt
Segment Reporting Information [Line Items]
Sales									305.6	344	326.1
Consumer & Industrial Salt | Reportable segments | Salt
Segment Reporting Information [Line Items]
Sales									305.6	344	326.1
Consumer & Industrial Salt | Reportable segments | Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									0	0	0
Consumer & Industrial Salt | Reportable segments | Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									0	0	0
Consumer & Industrial Salt | Corporate & other
Segment Reporting Information [Line Items]
Sales									0	0	0
SOP and Specialty Plant Nutrients
Segment Reporting Information [Line Items]
Sales									517.8	511.2	539
SOP and Specialty Plant Nutrients | Reportable segments | Salt
Segment Reporting Information [Line Items]
Sales									0	0	0
SOP and Specialty Plant Nutrients | Reportable segments | Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									245	212.6	238.8
SOP and Specialty Plant Nutrients | Reportable segments | Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									272.8	298.6	300.2
SOP and Specialty Plant Nutrients | Corporate & other
Segment Reporting Information [Line Items]
Sales									0	0	0
Industrial Chemicals
Segment Reporting Information [Line Items]
Sales									71.9	89.2	95
Industrial Chemicals | Reportable segments | Salt
Segment Reporting Information [Line Items]
Sales									0	0	0
Industrial Chemicals | Reportable segments | Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									0	0	0
Industrial Chemicals | Reportable segments | Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									71.9	89.2	95
Industrial Chemicals | Corporate & other
Segment Reporting Information [Line Items]
Sales									0	0	0
Eliminations & Other
Segment Reporting Information [Line Items]
Sales									4.4	0.6	1.5
Eliminations & Other | Reportable segments | Salt
Segment Reporting Information [Line Items]
Sales									0	0	0
Eliminations & Other | Reportable segments | Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									(5.4)	(6.4)	(5.6)
Eliminations & Other | Reportable segments | Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									(0.3)	(2.7)	(3.4)
Eliminations & Other | Corporate & other
Segment Reporting Information [Line Items]
Sales									$ 10.1	$ 9.7	$ 10.5

OPERATING SEGMENTS (Informati_2

OPERATING SEGMENTS (Information by Geographic Area) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales	$ 421.1	$ 282.4	$ 256.1	$ 413.9	$ 500.3	$ 341.3	$ 245.2	$ 403.7	$ 1,373.5	$ 1,490.5	$ 1,493.6
Total long-lived assets	1,503.3				1,655.3				1,503.3	1,655.3	1,642.8
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									766.6	821.9	769.9
Total long-lived assets	532.9				561.5				532.9	561.5	551.6
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									207.6	228.8	238.6
Total long-lived assets	514				522.8				514	522.8	497.4
Brazil
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									336.6	375.2	381.8
Total long-lived assets	376				493.1				376	493.1	524.8
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									41.6	45.2	83.1
Total long-lived assets	73.9				71.4				73.9	71.4	62.5
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									21.1	19.4	20.2
Total long-lived assets	$ 6.5				$ 6.5				$ 6.5	$ 6.5	$ 6.5

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net earnings	$ 32.3	$ (2.1)	$ 1.7	$ 27.6	$ 56.1	$ 10.6	$ (11.8)	$ 7.6	$ 59.5	$ 62.5	$ 68.8
Less: net earnings allocated to participating securities									(1.3)	(1.1)	(0.5)
Net earnings available to common stockholders									$ 58.2	$ 61.4	$ 68.3
Denominator:
Weighted average common shares outstanding, shares for basic earnings per share (in shares)	33,958	33,947	33,915	33,892	33,886	33,884	33,883	33,874	33,928	33,882	33,848
Weighted average equity awards outstanding (in shares)									0	0	0
Shares for diluted earnings per share (in shares)	33,977	33,947	33,915	33,892	33,886	33,884	33,883	33,874	33,928	33,882	33,848
Net earnings per common share, basic (in dollars per share)	$ 0.94	$ (0.07)	$ 0.04	$ 0.80	$ 1.64	$ 0.31	$ (0.36)	$ 0.22	$ 1.72	$ 1.82	$ 2.02
Net earnings per common share, diluted (in dollars per share)	$ 0.94	$ (0.07)	$ 0.04	$ 0.80	$ 1.63	$ 0.31	$ (0.36)	$ 0.22	$ 1.72	$ 1.81	$ 2.02
Net earnings allocated to participating securities (in shares)									397	307	186
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive weighted options outstanding (in shares)									1,188	1,067	788

QUARTERLY RESULTS (Unaudited)_2

QUARTERLY RESULTS (Unaudited) (Schedule of Quarterly Results) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 421.1	$ 282.4	$ 256.1	$ 413.9	$ 500.3	$ 341.3	$ 245.2	$ 403.7	$ 1,373.5	$ 1,490.5	$ 1,493.6
Gross profit	100	58.7	66.3	87.3	142	76.4	45.8	72.6	312.3	336.8	293.9
Net earnings (loss)	$ 32.3	$ (2.1)	$ 1.7	$ 27.6	$ 56.1	$ 10.6	$ (11.8)	$ 7.6	$ 59.5	$ 62.5	$ 68.8
Net earnings (loss) per share, basic (in dollars per share)	$ 0.94	$ (0.07)	$ 0.04	$ 0.80	$ 1.64	$ 0.31	$ (0.36)	$ 0.22	$ 1.72	$ 1.82	$ 2.02
Net earnings (loss) per share, diluted (in dollars per share)	$ 0.94	$ (0.07)	$ 0.04	$ 0.80	$ 1.63	$ 0.31	$ (0.36)	$ 0.22	$ 1.72	$ 1.81	$ 2.02
Basic weighted-average shares outstanding (in shares)	33,958	33,947	33,915	33,892	33,886	33,884	33,883	33,874	33,928	33,882	33,848
Diluted weighted-average shares outstanding (in shares)	33,977	33,947	33,915	33,892	33,886	33,884	33,883	33,874	33,928	33,882	33,848

QUARTERLY RESULTS (Unaudited)_3

QUARTERLY RESULTS (Unaudited) (Schedule of Quarterly Results Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Release of domestic tax reserve	$ (11)
Logistics costs			$ 2.8	$ 2.8
Logistics costs, net			$ 2.1
Executive transition costs		$ 2.3
Executive transition costs, net of tax		$ 1.7

SUBSEQUENT EVENT (Details)

SUBSEQUENT EVENT (Details)	Feb. 25, 2021$ / shares
Subsequent Event
Subsequent Event [Line Items]
Cash dividend declared (in dollars per share)	$ 0.72

Schedule II - Valuation Reser_2

Schedule II - Valuation Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deducted from Receivables — Allowance for Doubtful Accounts
Valuation Reserves [Roll Forward]
Balance at the Beginning of the Year	$ 10.7	$ 9.9	$ 10.9
Additions (Deductions) Charged to Expense	9.3	4.7	1
Deductions	(8.9)	(3.9)	(2)
Balance at the End of the Year	11.1	10.7	9.9
Deducted from Deferred Income Taxes — Valuation Allowance
Valuation Reserves [Roll Forward]
Balance at the Beginning of the Year	41.2	40.9	10.2
Additions (Deductions) Charged to Expense	2.5	0.3	39.2
Deductions	(0.3)	0	(8.5)
Balance at the End of the Year	$ 43.4	$ 41.2	$ 40.9