Compass Minerals International (CMP) 10-Q 8 Aug 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Jun. 30, 2023	Aug. 04, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
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
Entity Address, Address Line Two	Suite 100
Entity Address, City or Town	Overland Park
Entity Address, State or Province	KS
Entity Address, Postal Zip Code	66210
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		41,150,609
Entity Central Index Key	0001227654
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Current assets:
Cash and cash equivalents	$ 58	$ 46.1
Receivables, less allowance for doubtful accounts of $2.9 at June 30, 2023 and $3.4 at September 30, 2022	95.8	167.2
Inventories	340.1	304.4
Other	38.2	44.3
Total current assets	532.1	562
Property, plant and equipment, net	817.1	776.6
Intangible assets, net	119.9	45.4
Goodwill	103.3	56.4
Equity method investments	0	46.6
Other	160.2	156.5
Total assets	1,732.6	1,643.5
Current liabilities:
Current portion of long-term debt	5	0
Accounts payable	96.9	114.7
Accrued salaries and wages	24.9	22.2
Income taxes payable	21	1
Accrued interest	4.1	14.1
Accrued expenses and other current liabilities	94.1	81.1
Total current liabilities	246	233.1
Long-term debt, net of current portion	716	947.6
Deferred income taxes, net	61.5	63.4
Other noncurrent liabilities	172.4	143
Commitments and contingencies
Stockholders’ equity:
Common stock: $0.01 par value, 200,000,000 authorized shares; 42,197,964 issued shares at June 30, 2023 and 35,367,264 issued shares at September 30, 2022	0.4	0.4
Additional paid-in capital	409.7	152.1
Treasury stock, at cost — 1,049,686 shares at June 30, 2023 and 1,196,300 shares at September 30, 2022	(8.6)	(7.3)
Retained earnings	225.8	226.5
Accumulated other comprehensive loss	(90.6)	(115.3)
Total stockholders’ equity	536.7	256.4
Total liabilities and stockholders’ equity	$ 1,732.6	$ 1,643.5

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
ASSETS
Allowance for doubtful accounts	$ 2.9	$ 3.4
Stockholders’ equity:
Common stock, par or stated value per share (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)	42,197,964	35,367,264
Treasury stock, shares (in shares)	1,049,686	1,196,300

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Sales	$ 207.6	$ 214.7	$ 971.1	$ 994.7
Gross profit	34.6	33.9	189.8	158.4
Selling, general and administrative expenses	35.2	37.4	114.6	121.5
Operating (loss) earnings	(0.6)	(3.5)	75.2	36.9
Other (income) expense:
Interest income	(1.7)	(0.2)	(4.7)	(0.5)
Interest expense	14.3	13.4	42.4	41.2
Loss (gain) on foreign exchange	2.3	(6.1)	4.6	(3.5)
Net loss in equity investee	0.8	1.3	3.1	3.4
Gain from remeasurement of equity method investment	(16.2)	0	(16.2)	0
Other expense (income), net	2.7	(0.1)	3.7	0
(Loss) earnings from continuing operations before income taxes	(2.8)	(11.8)	42.3	(3.7)
Income tax (benefit) expense from continuing operations	(42.7)	(1.1)	24.3	28.1
Net earnings (loss) from continuing operations	39.9	(10.7)	18	(31.8)
Net earnings from discontinued operations	0	2.8	0	14.2
Net earnings (loss)	$ 39.9	$ (7.9)	$ 18	$ (17.6)
Basic net earnings (loss) from continuing operations per common share (in dollars per share)	$ 0.96	$ (0.32)	$ 0.44	$ (0.94)
Basic net earnings from discontinued operations per common share (in dollars per share)	0	0.08	0	0.42
Basic net earnings (loss) per common share (in dollars per share)	0.96	(0.23)	0.44	(0.52)
Diluted net earnings (loss) from continuing operations per common share (in dollars per share)	0.96	(0.32)	0.44	(0.94)
Diluted net earnings from discontinued operations per common share (in dollars per share)	0	0.08	0	0.42
Diluted net earnings (loss) per common share (in dollars per share)	$ 0.96	$ (0.23)	$ 0.44	$ (0.52)
Weighted-average common shares outstanding (in thousands):
Basic (in shares)	41,142	34,154	40,663	34,105
Diluted (in shares)	41,142	34,154	40,663	34,110
Shipping and handling cost
Cost	$ 53.8	$ 58.7	$ 291.3	$ 314.5
Product cost
Cost	$ 119.2	$ 122.1	$ 490	$ 521.8

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ 39.9	$ (7.9)	$ 18	$ (17.6)
Other comprehensive income (loss):
Unrealized gain from change in pension obligations, net of tax of $0.0 for the three and nine months ended June 30, 2023 and 2022	0	0.1	0.1	0.3
Unrealized gain (loss) on cash flow hedges, net of tax of $0.0 and $0.3 for the three and nine months ended June 30, 2023, respectively, and $(0.4) and $0.0 for the three and nine months ended June 30, 2022, respectively	2.2	(4.4)	(1.7)	(5.4)
Cumulative translation adjustment	11.8	29.2	26.3	36.1
Comprehensive income	$ 53.9	$ 17	$ 42.7	$ 13.4

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Unrealized gain from change in pension obligations, tax	$ 0	$ 0	$ 0	$ 0
Unrealized gain (loss) on cash flow hedges, tax	$ 0	$ 0.3	$ (0.4)	$ 0

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive (Loss) Income
Beginning balance at Sep. 30, 2021	$ 293.1	$ 0.4	$ 136.3		$ 272.4	$ (110.5)
Beginning balance, treasury stock at Sep. 30, 2021				$ (5.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	(3.3)				2.4	(5.7)
Dividends on common stock	(5.3)		(0.1)		(5.2)
Stock options exercised, net of shares withheld for taxes	0.2		0.2
Stock-based compensation	3.3		3.3
Ending balance at Dec. 31, 2021	288	0.4	139.7		269.6	(116.2)
Ending balance , treasury stock at Dec. 31, 2021				(5.5)
Beginning balance at Sep. 30, 2021	293.1	0.4	136.3		272.4	(110.5)
Beginning balance, treasury stock at Sep. 30, 2021				(5.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	13.4
Ending balance at Jun. 30, 2022	300.9	0.4	148		239.2	(79.5)
Ending balance , treasury stock at Jun. 30, 2022				(7.2)
Beginning balance at Dec. 31, 2021	288	0.4	139.7		269.6	(116.2)
Beginning balance, treasury stock at Dec. 31, 2021				(5.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	(0.3)				(12.1)	11.8
Dividends on common stock	(5.2)				(5.2)
Shares issued for stock units, net of shares withheld for taxes	(0.5)		(0.1)	(0.4)
Stock-based compensation	4.5		4.5
Ending balance at Mar. 31, 2022	286.5	0.4	144.1		252.3	(104.4)
Ending balance , treasury stock at Mar. 31, 2022				(5.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	17				(7.9)	24.9
Dividends on common stock	(5.2)				(5.2)
Shares issued for stock units, net of shares withheld for taxes	(1.4)		(0.1)	(1.3)
Stock options exercised, net of shares withheld for taxes	0.1		0.1
Stock-based compensation	3.9		3.9
Ending balance at Jun. 30, 2022	300.9	0.4	148		239.2	(79.5)
Ending balance , treasury stock at Jun. 30, 2022				(7.2)
Beginning balance at Sep. 30, 2022	256.4	0.4	152.1		226.5	(115.3)
Beginning balance, treasury stock at Sep. 30, 2022				(7.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	8.7				(0.3)	9
Dividends on common stock	(6.3)				(6.3)
Private placement of common stock	240.7		240.7
Shares issued for stock units, net of shares withheld for taxes	(0.3)			(0.3)
Stock-based compensation	10.6		10.6
Ending balance at Dec. 31, 2022	509.8	0.4	403.4		219.9	(106.3)
Ending balance , treasury stock at Dec. 31, 2022				(7.6)
Beginning balance at Sep. 30, 2022	256.4	0.4	152.1		226.5	(115.3)
Beginning balance, treasury stock at Sep. 30, 2022				(7.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	42.7
Ending balance at Jun. 30, 2023	536.7	0.4	409.7		225.8	(90.6)
Ending balance , treasury stock at Jun. 30, 2023				(8.6)
Beginning balance at Dec. 31, 2022	509.8	0.4	403.4		219.9	(106.3)
Beginning balance, treasury stock at Dec. 31, 2022				(7.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	(19.9)				(21.6)	1.7
Dividends on common stock	(6.3)				(6.3)
Shares issued for stock units, net of shares withheld for taxes	(1.3)		(0.3)	(1)
Stock-based compensation	3.1		3.1
Ending balance at Mar. 31, 2023	485.4	0.4	406.2		192	(104.6)
Ending balance , treasury stock at Mar. 31, 2023				(8.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	53.9				39.9	14
Dividends on common stock	(6.1)				(6.1)
Stock-based compensation	3.5		3.5
Ending balance at Jun. 30, 2023	$ 536.7	$ 0.4	$ 409.7		$ 225.8	$ (90.6)
Ending balance , treasury stock at Jun. 30, 2023				$ (8.6)

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Statement of Stockholders' Equity [Abstract]
Cash dividends per share (in dollars per share)	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.15

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows from operating activities:
Net earnings (loss)	$ 18	$ (17.6)
Adjustments to reconcile net loss to net cash flows provided by operating activities:
Depreciation, depletion and amortization	72.7	83.2
Amortization of deferred financing costs	2.5	2.2
Early extinguishment of debt	1.1
Stock-based compensation	17.2	11.7
Deferred income taxes	(4.7)	15.9
Unrealized foreign exchange loss (gain)	4.5	(19.8)
Loss on impairment of long-lived assets	0	23.1
Net loss in equity investees	3.1	3.4
Gain from remeasurement of equity method investment	(16.2)	0
Other, net	3.3	2
Changes in operating assets and liabilities, net of acquisition:
Receivables	73.7	5.6
Inventories	(28.1)	48
Other assets	9.7	(6.6)
Accounts payable and accrued expenses and other current liabilities	(19.3)	7.5
Other liabilities	(16.2)	(9.7)
Net cash provided by operating activities	121.3	148.9
Cash flows from investing activities:
Capital expenditures	(78.9)	(68.9)
Proceeds from sale of business	0	61.2
Acquisition of business, net of cash acquired	(18.9)	0
Investments in equity method investees	0	(46.3)
Other, net	(2.5)	0.9
Net cash used in investing activities	(100.3)	(53.1)
Cash flows from financing activities:
Proceeds from revolving credit facility borrowings	66.7	346.3
Principal payments on revolving credit facility borrowings	(218.2)	(341.7)
Proceeds from issuance of long-term debt	237.5	50.8
Principal payments on long-term debt	(311.7)	(106.6)
Net proceeds from private placement of common stock	240.7	0
Dividends paid	(18.7)	(15.7)
Deferred financing costs	(3.9)	(0.4)
Proceeds from stock options exercised	0	0.3
Shares withheld to satisfy employee tax obligations	(1.6)	(1.9)
Other, net	(0.9)	(0.9)
Net cash used in financing activities	(10.1)	(69.8)
Effect of exchange rate changes on cash and cash equivalents	1	0.2
Net change in cash and cash equivalents	11.9	26.2
Cash and cash equivalents, beginning of the year	46.1	21
Cash and cash equivalents, end of period	58	47.2
Less: cash and cash equivalents included in current assets held for sale	0	0
Cash and cash equivalents of continuing operations, end of period	58	47.2
Supplemental cash flow information:
Interest paid, net of amounts capitalized	50.2	44.6
Income taxes paid, net of refunds	$ 11.9	$ 17

Accounting Policies and Basis o

Accounting Policies and Basis of Presentation	9 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Accounting Policies and Basis of Presentation	Accounting Policies and Basis of Presentation: Compass Minerals International, Inc. (“CMI”), through its subsidiaries (collectively, the “Company”), is a leading global provider of essential minerals focused on safely delivering where and when it matters to help solve nature’s challenges for customers and communities. The Company’s salt products help keep roadways safe during winter weather and are used in numerous other consumer, industrial, chemical and agricultural applications. Its plant nutrition business is the leading North American producer of sulfate of potash (“SOP”), which is used in the production of specialty fertilizers for high-value crops and turf and helps improve the quality and yield of crops, while supporting sustainable agriculture. The Company’s principal products are salt, consisting of sodium chloride and magnesium chloride, and SOP. Additionally, the Company is pursuing development of a sustainable lithium brine resource to support the North American battery market and is the owner of Fortress North America, LLC (“Fortress”), a next-generation fire retardant company (See Note 2 for a discussion of the acquisition of the remaining Fortress ownership interests). The Company’s production sites are located in the United States (“U.S.”), Canada and the United Kingdom (“U.K.”). The Company also provides records management services to businesses located in the U.K. Except where otherwise noted, references to North America include only the continental U.S. and Canada, and references to the U.K. include only England, Scotland and Wales. References to “Compass Minerals,” “our,” “us” and “we” refer to CMI and its consolidated subsidiaries. CMI is a holding company with no significant operations other than those of its wholly-owned subsidiaries. The 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. The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete consolidated financial statements. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements of the Company for the annual period ended September 30, 2022, as filed with the Securities and Exchange Commission (the “SEC”) in its Annual Report on Form 10-K on December 14, 2022. In the opinion of management, all adjustments, consisting of normal recurring adjustments considered necessary for a fair presentation, have been included. The Company experiences a substantial amount of seasonality in its sales, including its deicing salt product sales. As a result, Salt segment sales and operating income are generally higher in the first and second fiscal quarters (ending December 31 and March 31) and lower during the third and fourth fiscal quarters (ending June 30 and September 30) of each year. In particular, sales of highway and consumer deicing salt and magnesium chloride products vary based on the severity of the winter conditions in areas where the products are used. Following industry practice in North America and the U.K., the Company seeks to stockpile sufficient quantities of deicing salt throughout the first, third and fourth fiscal quarters (ending December 31, June 30 and September 30) to meet the estimated requirements for the winter season. Production of deicing salt can also vary based on the severity or mildness of the preceding winter season. Due to the seasonal nature of the deicing product lines, operating results for the interim periods are not necessarily indicative of the results that may be expected for the full fiscal year. The Company’s plant nutrition business is also seasonal. As a result, the Company and its customers generally build inventories during the plant nutrition business’ low demand periods of the year (which are typically winter and summer, but can vary due to weather and other factors) to ensure timely product availability during the peak sales seasons (which are typically spring and autumn, but can also vary due to weather and other factors). Lastly, the results of Fortress, the Company’s newly acquired fire retardant business, are also seasonal with peak demand for its fire retardant products and services occurring from June through September. Significant Accounting Policies The Company’s significant accounting policies are detailed in “Note 2 – Summary of Significant Accounting Policies” within Part II, Item 8 of its Annual Report on Form 10-K for the annual period ended September 30, 2022. The Company reports its financial results from discontinued operations and continuing operations separately to recognize the financial impact of disposal transactions apart from ongoing operations. Discontinued operations reporting occurs when a component or a group of components of an entity has been disposed or classified as held for sale and represents a strategic shift that has a major effect on the entity’s operations and financial results. In the Company’s Consolidated Statements of Cash Flows, the cash flows from discontinued operations are not separately classified. Unless otherwise indicated, amounts provided in these Notes pertain to continuing operations. See Note 2 for information on the Company’s business acquisition, Note 3 for information on discontinued operations and Note 12 for information on the Company’s reportable segments. Recent Accounting Pronouncements In October 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2021-08, “Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers.” ASU 2021-08 requires the company acquiring contract assets and contract liabilities obtained in a business combination to recognize and measure them in accordance with Accounting Standards Codification (“ASC”) 606, “Revenue from Contracts with Customers”. Following the acquisition date, the company acquiring the business should record related revenue as if it had originated the contracts. Before the update, contract assets and contract liabilities from acquired contracts were recognized by the acquiring company at fair value on the acquisition date. The amendments are effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted, including in interim periods, for any financial statements that have not yet been issued. The Company early adopted these requirements, effective on January 1, 2023, with no material impact to its consolidated financial statements. Strategic Evaluation and Plan to Sell Businesses Following an evaluation of the strategic fit of certain of the Company’s businesses and subsequent restructuring of its former South American Plant Nutrition segment to enable separate sales processes for its chemicals and specialty plant nutrition businesses and equity investment in Fermavi Eletroquímica Ltda. (“Fermavi”), in fiscal 2021 the Company’s Board of Directors approved the plan to sell each of these businesses and the North America micronutrient business (the “Specialty Businesses”) with a goal of reducing the Company’s leverage and enabling increased focus on optimizing the Company’s core businesses. The Company concluded that the sale of the Specialty Businesses represented a strategic shift for the Company that would have a material effect on its operations and financial results. Consequently, the Specialty businesses were reclassified as discontinued operations on the Consolidated Statements of Operations. See Note 3 for further discussion of the sales of these businesses.

Business Acquisition

Business Acquisition	9 Months Ended
	Jun. 30, 2023
Business Combination and Asset Acquisition [Abstract]
Business Acquisition	Business Acquisition: The Company accounts for its business combinations using the acquisition accounting method, which requires it to determine the fair value of identifiable assets acquired and liabilities assumed, including any contingent consideration, to properly allocate the purchase price to the individual assets acquired and liabilities assumed and record any residual purchase price as goodwill in accordance with the FASB ASC Topic 805, Business Combinations. The Company records assets acquired and liabilities assumed at their respective fair value at the date of acquisition. Management uses its best estimates and assumptions to assign fair value to the tangible and intangible assets acquired and liabilities assumed at the acquisition date. Such estimates are inherently uncertain and may be subject to refinement. If the initial accounting for the business combination has not been completed by the end of the reporting period in which the business combination occurs, provisional amounts are reported to present information about facts and circumstances that existed as of the acquisition date. During the measurement period, which may be up to one year from the acquisition date, the Company may record adjustments to the fair value of the tangible and intangible assets acquired and liabilities assumed with the corresponding offset to goodwill, to the extent such information was not available to the Company at the acquisition date to determine such amounts. Upon the conclusion of the measurement period or final determination of the fair value of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the Company’s Consolidated Statements of Operations. Accounting for business combinations requires the Company to make significant estimates and assumptions at the acquisition date. Significant assumptions relevant to the determination of the fair value of the tangible and intangible assets acquired and liabilities assumed include, but are not limited to, expected future cash flows, discount rates, royalty rates, in-process and developed technology lifecycle and obsolescence rates and other assumptions. The approach to valuing the initial contingent consideration, including milestone achievement and the earn-out, associated with the purchase price also uses similar unobservable factors such as projected revenues and expenses over the term of the contingent milestone achievement and earn-out periods, discounted for the period over which the initial contingent consideration is measured, and relevant volatility rates. Based upon these assumptions, the initial earn-out contingent consideration is then valued using a Monte Carlo simulation. All acquisition-related costs, other than the costs to issue debt or equity securities, are accounted for as expenses in the period in which they are incurred. Changes in the fair value of contingent consideration arrangements that are not measurement period adjustments are recognized in earnings. In the event the Company acquires an entity with which the Company has a preexisting relationship, the Company will generally recognize a gain or loss to remeasure its previously held equity interest at acquisition date fair value on its Consolidated Statements of Operations. Background On November 2, 2021, the Company announced an investment in Fortress, a next-generation fire retardant business dedicated to developing and producing a portfolio of magnesium chloride-based fire retardant products to help combat wildfires. On May 5, 2023, the Company acquired the remaining 55% interest in Fortress not previously owned in exchange for an initial cash payment of $18.9 million (net of cash held by Fortress of $6.5 million), and additional contingent consideration of up to $28 million to be paid in cash and/or Compass Minerals common stock upon the achievement of certain performance measures over the next five years, and a cash earn-out based on volumes of certain Fortress fire retardant products sold over a 10-year period. Building upon the previous 45% minority ownership stake in Fortress, the transaction provided the Company full ownership of all Fortress assets, contracts, and intellectual property. The Company is currently performing the analysis needed to finalize the fair values of intangible assets, intangible asset useful lives and the final purchase price including the value of contingent consideration. Purchase Price Allocation The fair value of the milestone contingent consideration is estimated using a probability-weighted discounted cash flow model with significant inputs not observable in the market and is therefore considered a Level 3 measurement (see Note 15 for a discussion of the levels in the fair value hierarchy) while the earn-out is valued using a Monte Carlo simulation, also a Level 3 measurement. A summary of the acquisition-date fair value of the consideration transferred is presented in the table below (in millions): May 5, 2023 Cash paid at closing (a) $ 25.4 Fair value of contingent consideration (b) 47.4 Fair value of 45% equity investment 59.6 Total $ 132.4 (a) Gross amount of cash held at Fortress at the time of the acquisition. (b) Contingent consideration includes the fair value of payments to be made upon the achievement of certain performance measures ($22.9 million) and the 10-year cash earn-out ($24.5 million), both described in the Background section above. Prior to the acquisition date, the Company accounted for its 45% interest in Fortress as an equity method investment. The acquisition-date fair value of the previously held equity investment was $59.6 million and is included in the consideration transferred. To measure the acquisition-date fair value of the previously held equity interest, the Company utilized a market-based approach which relied on Level 3 inputs (see Note 1 5 for a discussion of the levels in the fair value hierarchy). The Company recognized a $16.2 million non-cash gain as a result of remeasuring the value of its prior equity interest in Fortress, which is generally attributable to Fortress’ advancement from a pre-revenue, development-stage company to commercialization. The gain is reported in the “Gain from remeasurement of equity method investment” line in the Consolidated Statement of Operations. Acquisition-related expenses were not material. Under the acquisition method of accounting, the total purchase price is allocated on a preliminary basis to Fortress’ assets and liabilities based upon their estimated fair values as of the date of completion of the acquisition. Based upon the estimated purchase price and the preliminary valuation, the purchase price allocation, which is subject to change based on the Company’s final analysis, is presented in the table below (in millions): Purchase Price Allocation Cash and cash equivalents $ 6.5 Inventories 3.7 Other current assets 0.5 Property, plant and equipment 2.5 Identified intangible assets 75.3 Other noncurrent assets 0.8 Accounts payable (0.3) Accrued expenses and other current liabilities (1.4) Other noncurrent liabilities (1.3) Total identified intangible assets $ 86.3 Goodwill 46.1 Total fair value of business combination $ 132.4 The total purchase price in excess of the net identifiable assets was recognized as goodwill in the amount of $46.1 million at the acquisition date and has been included in the Company’s Corporate & Other segment. The goodwill recognized reflects expected earning potential of the business, synergies associated with the use of the Company’s existing systems and resources and logistics and production synergies including the magnesium chloride products used in the fire retardant products. Currently, the Company expects the full amount of goodwill to be deductible for tax purposes. In connection with the acquisition, the Company acquired identifiable intangible assets which consisted of customer relationships, developed technology, in-process research and development and trade name. The fair values were determined using Level 3 inputs (see Note 15 for a discussion of the levels in the fair value hierarchy). The fair value of the customer relationships was estimated using an income approach method while the fair values of developed technology and in-process R&D were estimated using the relief from royalty method. The in-process research and development includes potential future-generation retardant products. The estimated fair values and weighted average amortization period of the identifiable intangible assets are presented in the table below: Estimated Fair Value (in millions) Weighted-Average Amortization Period (in years) Customer relationships $ 56.8 25 years Developed technology 2.4 10 years In-process research and development 15.9 Indefinite Trade name 0.2 5 years Total identified intangible assets $ 75.3

Discontinued Operations

Discontinued Operations	9 Months Ended
	Jun. 30, 2023
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations: During fiscal 2021 the Company sold its South America specialty plant nutrition business and equity investment in Fermavi and its North America micronutrient business. In connection with the sale of its South America specialty plant nutrition business the Company received net cash of approximately $318.4 million with an additional earnout payment of up to R$88 million Brazilian reais. On April 7, 2022, the Company received the maximum earnout possible under the terms of the sale, or $18.5 million based on exchange rates at the time of receipt. Also in fiscal 2021, the Company completed the sale of its North America micronutrient business for approximately $56.7 million and its investment in Fermavi for R$45 million Brazilian reais (including R$30 million Brazilian reais of deferred purchase price). The Company received gross proceeds of approximately $2.9 million and recorded a discounted deferred proceeds receivable of approximately $4.8 million (based on exchange rates at the time of closing). As of June 30, 2023 approximately R$22.5 million Brazilian reais of deferred proceeds remains outstanding. On April 20, 2022, the Company completed the sale of its South America chemicals business to a subsidiary of Cape Acquisitions LLC. Upon closing of the all-cash sale, the Company received gross proceeds of approximately $51.5 million based on exchange rates at the time of receipt, including a post-closing adjustment and compensation of $6.4 million for cash on hand that transferred to the buyer. The Company also paid fees of $2.4 million related to this sale. The Company recognized a loss recovery of $1.6 million during the three months ended June 30, 2022, an incremental loss from the sale of $23.1 million during the nine months ended June 30, 2022 and released $49.5 million from accumulated currency translation adjustment (“CTA”). The sale included all of the Company’s remaining operations in Brazil, concluding its previously announced plan to exit the South American market. In measuring the assets and liabilities held for sale at fair value less estimated costs to sell, the Company completed an impairment analysis when its Board of Directors committed to a plan to sell the Specialty Businesses and the Company updated the analysis each quarter until each of the Specialty Businesses were sold. The information below sets forth selected financial information related to the operating results of the Specialty Businesses classified as discontinued operations. The Specialty Businesses’ revenue and expenses have been reclassified to net earnings from discontinued operations in prior periods. The Consolidated Statements of Operations present the revenue and expenses that were reclassified from the specified line items to discontinued operations. The following table represents summarized Consolidated Statements of Operations information of discontinued operations (in millions): Three Months Ended Nine Months Ended 2022 2022 Sales $ 6.9 $ 53.6 Shipping and handling cost 0.3 2.8 Product cost 3.1 28.4 Gross profit 3.5 22.4 Selling, general and administrative expenses 0.5 3.5 Operating earnings 3.0 18.9 Interest expense — 0.1 Gain on foreign exchange (0.2) (17.5) Net (gain) loss on adjustment to fair value less estimated costs to sell (1.6) 23.1 Other income, net (0.1) (0.6) Earnings from discontinued operations before income taxes 4.9 13.8 Income tax expense (benefit) 2.1 (0.4) Net earnings from discontinued operations $ 2.8 $ 14.2 The significant components included in the Company’s Consolidated Statements of Cash Flows for discontinued operations are as follows (in millions): Nine Months Ended 2022 Loss on impairment of long-lived assets $ 23.1 Capital expenditures (1.6) Proceeds from sale of businesses 61.2

Revenues

Revenues	9 Months Ended
	Jun. 30, 2023
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 softening, and agricultural and industrial applications. The Company’s Plant Nutrition segment produces and markets SOP in various grades worldwide to distributors and retailers of crop inputs, as well as growers and for industrial uses. The Company operates a records management business utilizing excavated areas of its Winsford salt mine with one other location in London, England and is the owner of Fortress North America, a next-generation fire retardant company. The Company has also entered into a full-service contract with the U.S. Forest Service (“USFS”). This contract is between Fortress and the USFS for the supply and service of long-term fire retardant to USFS designated air tanker bases. 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. The Company also derives revenue from full-service air base fire retardant contracts with customers. Full-service air bases include sales from the supply of fire retardant product and related equipment and service for inspection and loading the fire retardant onto aircraft at designated air tanker bases. The revenue derived from the contract with the USFS is comprised of three performance obligations, namely product sales, providing operations and maintenance personnel services and leasing of specified equipment. For full-service fire-retardant contracts, the Company identifies the fire-retardant product, equipment leases and services as separate units of account. The performance obligation for product sales is satisfied at a point in time when product is shipped and control is transferred to the customer, typically when the product is consumed by the customer. The services and leases represent “stand-ready obligations” and the revenue is recognized straight-line over the service period, which could be intermittent. 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. 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. Payment terms vary by contract and sales to customers are deemed collectible at the time of sale based on customer history, prior credit checks, and controls around customer credit limits. Sales and other taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction, which are collected by the Company from a customer, are excluded from revenue. 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. Therefore, there is no estimated obligation for returns. Standard terms of delivery are generally included in the Company's contracts of sale, order confirmation documents and invoices. Shipping and Handling The Company uses the policy election to account for the shipping and handling activities as activities to fulfill the Company’s promise to transfer goods to the customer, rather than as a performance obligation. Accordingly, the costs of the shipping and handling activities are accrued for at the time of shipment. Deferred Revenue Deferred revenue represents billings under non-cancellable contracts before the related product or service is transferred to the customer. The portion of deferred revenue that is anticipated to be recognized as revenue during the succeeding twelve-month period is recorded in accrued expenses and other current liabilities and the remaining portion is recorded in other non-current liabilities on the Consolidated Balance Sheets. Deferred revenue as of June 30, 2023 was approximately $1.2 million. See Note 12 for disaggregation of sales by segment, type and geographical region.

Inventories

Inventories	9 Months Ended
	Jun. 30, 2023
Inventory Disclosure [Abstract]
Inventories	Inventories: Inventories consist of the following (in millions): June 30, September 30, Finished goods $ 272.4 $ 251.6 Raw materials and supplies 67.7 52.8 Total inventories $ 340.1 $ 304.4

Property, Plant and Equipment,

Property, Plant and Equipment, Net	9 Months Ended
	Jun. 30, 2023
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, Net	Property, Plant and Equipment, Net: Property, plant and equipment, net, consists of the following (in millions): June 30, September 30, Land, buildings and structures, and leasehold improvements $ 549.1 $ 534.8 Machinery and equipment 1,103.2 1,026.3 Office furniture and equipment 21.8 56.8 Mineral interests 170.6 167.1 Construction in progress 81.0 64.3 1,925.7 1,849.3 Less: accumulated depreciation and depletion (1,108.6) (1,072.7) Property, plant and equipment, net $ 817.1 $ 776.6

Goodwill and Intangible Assets,

Goodwill and Intangible Assets, Net	9 Months Ended
	Jun. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets, Net	Goodwill and Intangible Assets, Net: Amounts related to the Company’s amortization of intangible assets are as follows (in millions): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Aggregate amortization expense $ 0.8 $ 0.4 $ 1.6 $ 1.2 Amounts related to the Company’s goodwill are as follows (in millions): June 30, September 30, Plant Nutrition $ 51.3 $ 50.9 Corporate & Other (a) 52.0 5.5 Total $ 103.3 $ 56.4 (a) Includes approximately $46.1 million of goodwill related to the Company’s acquisition of Fortress, as discussed further in Note 2 . The change in goodwill between September 30, 2022, and June 30, 2023 was due to $46.1 million of goodwill recorded in Corporate and Other related to the acquisition of the Fortress business in May 2023 (see Note 2

Equity Method Investments

Equity Method Investments	9 Months Ended
	Jun. 30, 2023
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Equity Method 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. For certain of the Company's equity method investments, such as investments where the capital structure of the equity investment results in different liquidation rights and priorities than what is reflected by the underlying percentage ownership interests, the Company's proportionate share of net earnings is accounted for using the Hypothetical Liquidation at Book Value ("HLBV") methodology available under the equity method of accounting. When applying HLBV, the Company determines the amount that would be received if the investee were to liquidate all of its assets and distribute the resulting cash to the investors based on contractually defined liquidation priorities, assuming the net assets were liquidated at their net book value. The Company evaluates its equity method investments for impairment whenever events or changes in circumstances indicate that the carrying amounts of such investments may not be recoverable. On November 2, 2021, the Company announced its investment in Fortress. On May 5, 2023, the Company acquired the remaining 55% interest in Fortress not previously owned. Refer to Note 2 for additional details. As of March 31, 2023, the Company had invested $50 million in Fortress in exchange for an ownership interest of approximately 45%. Under the HLBV methodology available under the equity method of accounting, the Company had reflected its share of the income or loss of Fortress in its results each period on a one quarter reporting lag. The Company recorded $0.3 million and $1.8 million for its share of Fortress’ net losses in the three and nine months ended June 30, 2023, respectively, and $1.1 million and $2.4 million for its share of Fortress’ net losses in the three and nine months ended June 30, 2022, respectively. The carrying value of the Company’s equity investment in Fortress was in excess of its share of Fortress’s net book value by approximately $27 million as of March 31, 2023. The basis difference primarily represented incremental value attributable to intangible assets and goodwill that had not been recognized in the financial statements of Fortress. The Company had liquidation preference under the terms of Fortress’ LLC agreement. Additionally, the Company had the right to purchase units from other Fortress unit holders and the right of first refusal to purchase all or any portion of any available Fortress units, both subject to certain conditions.

Income Taxes

Income Taxes	9 Months Ended
	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes: The Company’s effective income tax rate differs from the U.S. statutory federal income tax rate primarily due to U.S. statutory depletion, state income taxes (net of federal tax benefit), nondeductible executive compensation over $1 million, foreign income, mining and withholding taxes, base erosion and anti-abuse tax, and valuation allowances recorded on deferred tax assets. For the nine months ended June 30, 2022, there were also interest expense recognition differences for book and tax purposes. Management assesses the available positive and negative evidence to estimate whether sufficient future taxable income will be generated to permit use of the existing deferred tax assets. A significant piece of objective negative evidence evaluated was the cumulative loss incurred in the U.S. over the three-year period ended June 30, 2023. Such objective evidence limits the ability to consider other subjective evidence, such as the Company’s projections for future income. On the basis of this evaluation, during the nine months ended June 30, 2023 , an additional valuation allowance of $10.8 million has been recorded to recognize only the portion of the U.S. deferred tax assets that is more likely than not to be realized. The amount of the deferred tax assets considered realizable, however, could be adjusted if estimates of future taxable income during the carryforward period are increased or reduced or if objective negative evidence in the form of cumulative losses is no longer present and additional weight is given to subjective evidence such as the Company’s projections for income. As of June 30, 2023, and September 30, 2022, the Company had $73.4 million and $94.1 million, respectively of gross foreign federal NOL carryforwards that have no expiration date and $3.3 million and $3.2 million, respectively of net operating tax-effected state NOL carryforwards which expire beginning in 2035. Canadian provincial tax authorities have challenged tax positions claimed by one of the Company’s Canadian subsidiaries and have issued tax reassessments for fiscal years 2002-2017. The reassessments are a result of ongoing audits and to tal $180.2 million, including interest, through June 30, 2023. The Company disputes these reassessments and will continue to work with th e 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 di sputes. 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 $146.9 million performance bond and has paid $37.6 million to the Canadian tax authorities (most of which is recorded in other assets i n the Consolidated Balance Sheets at June 30, 2023, and September 30, 2022), 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 June 30, 2023, 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, which are consistent with those matters disclosed in the Company’s Annual Report on Form 10-K for the annual period ended September 30, 2022.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt: Long-term debt consists of the following (in millions): June 30, September 30, 4.875% Senior Notes due July 2024 $ — $ 250.0 Term Loan due January 2025 — 16.9 Revolving Credit Facility due January 2025 — 151.5 6.75% Senior Notes due December 2027 500.0 500.0 Term Loan due May 2028 200.0 — Revolving Credit Facility due May 2028 — — AR Securitization Facility expires June 2025 30.2 37.5 730.2 955.9 Less unamortized debt issuance costs (9.2) (8.3) Total debt 721.0 947.6 Less current portion 5.0 — Long-term debt $ 716.0 $ 947.6 On May 5, 2023, the Company entered into an agreement to amend and restate the Company’s credit agreement entered into on November 26, 2019 (as amended, the “2019 Credit Agreement”, as in effect prior to such restatement, the “Existing Credit Agreement”) with a new $575 million senior secured credit agreement due May 5, 2028 (as amended, the “2023 Credit Agreement”), comprised of a $375 million revolving credit facility and a $200 million term loan. The term loan is payable in quarterly installments of interest and principal beginning September 30, 2023. The 2023 Credit Agreement increases the Applicable Margins by 25 basis points over those defined in the Existing Credit Agreement and added an additional level to the pricing grid at a consolidated total leverage ratio of greater than 4:00 to 1.00. Proceeds from the 2023 Credit Agreement were used by the Company to redeem its $250 million 4.875% Senior Notes on May 10, 2023 and pay off the Existing Credit Agreement term loan balance of $16.9 million. The 2023 Credit Agreement, among other things, amended and restated the Existing Credit Agreement to (i) increase the Revolving Commitments (as defined in the Existing Credit Agreement) from $300 million to $375 million and extend the maturity date of the Revolving Commitments to May 5, 2028, (ii) refinance the Term Loans (as defined in the Existing Credit Agreement) with a new tranche of term loans in an aggregate principal amount equal to $200 million having a maturity date of May 5, 2028, and (iii) amend certain other terms of the Existing Credit Agreement, including, but not limited to, (a) expressly permit “run rate” cost savings in “Consolidated Adjusted EBITDA” (as defined in the Existing Credit Agreement) and (b) revise select covenants in the Existing Credit Agreement to, among other things, allow for Lithium Transactions (as defined below). The 2023 Credit Agreement will permit, on the terms and conditions set forth therein, the entry into, and consummation of, lithium development joint ventures, projects or similar arrangements by any Lithium Subsidiary (as defined below), and any related funding transactions in connection therewith (collectively, the “Lithium Transactions”). A “Lithium Subsidiary” shall mean (a) Compass Minerals Lithium Corp of America Inc., a Delaware corporation, or any successor thereto and (b) (x) any newly-formed domestic subsidiary that is a wholly-owned Subsidiary of the Company (each of which will become a Subsidiary Guarantor (as defined in the Existing Credit Agreement)) and/or (y) any newly-formed domestic subsidiary that is not a wholly-owned subsidiary of the Company (each of which may, but shall not be required to become, at the option of the Company, a Subsidiary Guarantor), in each case formed in order to effectuate the Lithium Transactions. The Term Loan requires the Company to maintain certain financial ratios, including a minimum interest coverage ratio and a maximum total net leverage ratio. In connection with the 2023 Credit Agreement, the Company paid $4.3 million in fees ($3.9 million was capitalized as deferred financing costs with $0.4 million recorded as an expense). These capitalized costs are amortized over the term of the debt and are included as a component of interest expense in the Consolidated Statements of Operations. The Company incurred a loss on the extinguishment of debt of $1.1 million to write off previously capitalized deferred financing costs, which is included as a component of interest expense in the Consolidated Statements of Operations. As of June 30, 2023, the term loan and revolving credit facility under the 2023 Credit Agreement were 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 June 30, 2023, t he weighted average interest rate on all borrowings outstanding under the term loan under the Credit Agreement was approximately 7.5%. The Company is in compliance as of June 30, 2023 with its debt covenants under the 2023 Credit Agreement and its AR Securitization Facility. Pursuant to the terms of the 2023 Credit Agreement, the maximum allowed consolidated total net leverage ratio (as defined and calculated under the terms of the Credit Agreement and discussed further below) was 5.0x for the quarter ended June 30, 2023, which steps down to 4.75x in the quarter ending March 31, 2024, and to 4.5x for the fiscal quarter ended June 30, 2024 and thereafter. The consolidated total net leverage ratio represents the ratio of (a) consolidated total net debt to (b) consolidated adjusted earnings before interest, taxes, depreciation and amortization (“EBITDA”). Consolidated total net debt includes the aggregate principal amount of total debt, net of unrestricted cash not to exceed $75.0 million. In November 2022, the Company entered into the third amendment to the 2019 Credit Agreement, principally to affect a transition from the London Inter-Bank Offered Rate to the Secured Overnight Financing Rate pricing benchmark provisions. During the quarter ended December 31, 2022, the Company paid off the outstanding revolving credit facility balance utilizing proceeds from a private placement of common stock. Refer to Note 13 for additional details of the private placement transaction. In January 2023, certain of the Company’s U.S. subsidiaries entered into the second amendment to the AR Securitization Facility with PNC Bank, which temporarily eased the restrictions of certain covenants contained in the agreement through March 2023. The amendment made certain adjustments to the financial tests including: (i) the default ratio and (ii) the delinquency ratio to make compliance with such tests more likely.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies: As previously disclosed, the Company was the subject of an investigation by the Division of Enforcement of the SEC regarding the Company’s disclosures primarily concerning the operation of the Goderich mine, the former South American businesses, and related accounting and internal control matters including Salt interim inventory valuation methodology issues that were disclosed in the Company’s Form 10-K/A for the year ended December 31, 2020, and Form 10-Q/A for the quarter ended March 31, 2021, each filed with the SEC on September 3, 2021. On September 23, 2022, the Company reached a settlement with the SEC, concluding and resolving the SEC investigation in its entirety. Under the terms of the settlement, the Company, without admitting or denying the findings in the administrative order issued by the SEC, agreed to pay a civil penalty of $12 million and to cease and desist from violations of specified provisions of the federal securities laws and rules promulgated thereunder, and to retain an independent compliance consultant for a period of approximately one year to review certain accounting practices and procedures. As set forth in the administrative order, the $12 million civil penalty is to be paid in installments: $2 million, which was paid on September 29, 2022, and $10 million to be paid no later than September 30, 2023. The Company previously recorded an accrual for the full amount of the penalty in the third quarter of fiscal 2022, which is reflected in accrued expenses and other current liabilities on the Company’s Consolidated Balance Sheets. 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 proceedings 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, except as otherwise described in Note 9 and this Note 11.

Operating Segments

Operating Segments	9 Months Ended
	Jun. 30, 2023
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. In connection with the executed business disposals discussed in Note 1 and Note 3 , the Company has identified two reportable segments. The Specialty Businesses that comprised the Company’s former Plant Nutrition South America reportable segment and the North America micronutrient product business previously reported within the former Plant Nutrition North America reportable segment were classified as discontinued operations for all periods presented in its consolidated financial statements in this Quarterly Report on Form 10-Q. For the three and nine months ended June 30, 2023 and 2022, the Company has presented two reportable segments in its Consolidated Financial Statements: Salt and Plant Nutrition. The Salt segment produces and markets salt, consisting of sodium chloride and magnesium chloride, for use in road deicing for winter roadway safety and for dust control, food processing, water softening and other consumer, agricultural and industrial applications. The Plant Nutrition segment produces and markets various grades of SOP. The results of operations for Fortress, the Company’s newly-acquired fire retardant business, are not material and are included in Corporate and Other in the tables below. Refer to Note 2 for a discussion of the acquisition. Segment information is as follows (in millions): Three Months Ended June 30, 2023 Salt Plant Corporate & Other (a) Total Sales to external customers $ 155.5 $ 47.5 $ 4.6 $ 207.6 Intersegment sales — 2.8 (2.8) — Shipping and handling cost 48.2 5.6 — 53.8 Operating earnings (loss) (b)(c) 21.7 2.5 (24.8) (0.6) Depreciation, depletion and amortization 14.2 8.2 1.9 24.3 Total assets (as of end of period) 995.7 468.2 268.7 1,732.6 Three Months Ended June 30, 2022 Salt Plant Corporate & Other (a) Total Sales to external customers $ 156.2 $ 55.6 $ 2.9 $ 214.7 Intersegment sales — 1.9 (1.9) — Shipping and handling cost 52.2 6.5 — 58.7 Operating earnings (loss) (b) 12.4 10.6 (26.5) (3.5) Depreciation, depletion and amortization 15.3 8.8 2.9 27.0 Total assets (as of end of period) 980.6 441.2 155.2 1,577.0 Nine Months Ended June 30, 2023 Salt Plant Corporate & Other (a) Total Sales to external customers $ 824.1 $ 136.8 $ 10.2 $ 971.1 Intersegment sales — 7.1 (7.1) — Shipping and handling cost 274.9 16.4 — 291.3 Operating earnings (loss) (b)(c) 141.9 12.8 (79.5) 75.2 Depreciation, depletion and amortization 42.9 24.6 5.2 72.7 Nine Months Ended June 30, 2022 Salt Plant Corporate & Other (a) Total Sales to external customers $ 821.4 $ 164.5 $ 8.8 $ 994.7 Intersegment sales — 5.0 (5.0) — Shipping and handling cost 294.0 20.5 — 314.5 Operating earnings (loss) (b) 101.1 24.5 (88.7) 36.9 Depreciation, depletion and amortization 47.7 26.4 9.1 83.2 Disaggregated revenue by product type is as follows (in millions): Three Months Ended June 30, 2023 Salt Plant Corporate & Other (a) Total Highway Deicing Salt $ 79.0 $ — $ — $ 79.0 Consumer & Industrial Salt 76.5 — — 76.5 SOP — 50.3 — 50.3 Fire Retardant — — 1.9 1.9 Eliminations & Other — (2.8) 2.7 (0.1) Sales to external customers $ 155.5 $ 47.5 $ 4.6 $ 207.6 Three Months Ended June 30, 2022 Salt Plant Corporate & Other (a) Total Highway Deicing Salt $ 78.5 $ — $ — $ 78.5 Consumer & Industrial Salt 77.7 — — 77.7 SOP — 57.5 — 57.5 Eliminations & Other — (1.9) 2.9 1.0 Sales to external customers $ 156.2 $ 55.6 $ 2.9 $ 214.7 Nine Months Ended June 30, 2023 Salt Plant Corporate & Other (a) Total Highway Deicing Salt $ 543.0 $ — $ — $ 543.0 Consumer & Industrial Salt 281.1 — — 281.1 SOP — 143.9 — 143.9 Fire Retardant — — 1.9 1.9 Eliminations & Other — (7.1) 8.3 1.2 Sales to external customers $ 824.1 $ 136.8 $ 10.2 $ 971.1 Nine Months Ended June 30, 2022 Salt Plant Corporate & Other (a) Total Highway Deicing Salt $ 542.3 $ — $ — $ 542.3 Consumer & Industrial Salt 279.1 — — 279.1 SOP — 169.5 — 169.5 Eliminations & Other — (5.0) 8.8 3.8 Sales to external customers $ 821.4 $ 164.5 $ 8.8 $ 994.7 (a) Corporate and Other includes corporate entities, records management operations, the Fortress fire retardant business, equity method investments, lithium development costs 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, lithium-related expenses, as well as costs for the human resources, information technology, legal and finance functions. (b) Corporate operating results include net reimbursements related to the settled SEC investigation of $0.1 million for the nine months ended June 30, 2023 and executive transition costs of $3.8 million for the nine months ended June 30, 2022. Corporate operating results for the three and nine months ended June 30, 2022 include a contingent loss accrual and costs related to the SEC investigation of $2.8 million and $19.5 million, respectively. Refer to Note 11 for more information regarding the SEC investigation. (c) Beginning in April 2023, the Company has taken steps to align its cost structure to its current business needs. These initiatives resulted in restructuring charges of $2.2 million and $5.5 million, which impacted Corporate operating results for the three and nine months ended June 30, 2023, respectively. The Company’s revenue by geographic area is as follows (in millions): Three Months Ended Nine Months Ended Revenue 2023 2022 2023 2022 United States (a) $ 164.4 $ 167.8 $ 695.7 $ 716.9 Canada 35.9 36.7 224.5 230.6 United Kingdom 6.6 5.5 43.9 40.9 Other 0.7 4.7 7.0 6.3 Total revenue $ 207.6 $ 214.7 $ 971.1 $ 994.7 (a) United States sales exclude product sold to foreign customers at U.S. ports.

Stockholders' Equity and Equity

Stockholders' Equity and Equity Instruments	9 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Stockholders' Equity and Equity Instruments	Stockholders’ Equity and Equity Instruments: In May 2020, the Company’s stockholders approved the 2020 Incentive Award Plan (as amended, the “2020 Plan”), which authorized the issuance of 2,977,933 shares of Company common stock. In February 2022, the Company’s stockholders approved an amendment to the 2020 Plan authorizing an additional 750,000 shares of Company stock. Since the date the 2020 Plan was approved, the Company ceased issuing equity awards under the 2015 Incentive Award Plan (as amended, the “2015 Plan”). Since the approval of the 2015 Plan in May 2015, the Company ceased issuing equity awards under the 2005 Incentive Award Plan (as amended, the “2005 Plan”). The 2005 Plan, the 2015 Plan and the 2020 Plan allow for grants of equity awards to executive officers, other employees and directors, including restricted stock units (“RSUs”), performance stock units (“PSUs”), stock options and deferred stock units. Koch Equity Investment On September 14, 2022, the Company entered into a Stock Purchase Agreement with Koch Minerals & Trading, LLC (“KM&T”), a subsidiary of Koch Industries, Inc. (“KII”), pursuant to which the Company agreed to issue and sell 6,830,700 shares of its common stock at a purchase price of $36.87 for aggregate net proceeds of approximately $240.7 million, net of transaction costs. On October 18, 2022, the Company closed the direct private placement with KM&T, through its affiliate KM&T Investment Holdings, LLC, resulting in their ownership of approximately 17% of the Company’s outstanding common stock. The Company expects to use approximately $200 million of the proceeds from the private placement to advance the first development phase of its sustainable lithium development project at its Ogden site. The Company used the remaining approximately $40.7 million of proceeds to reduce debt. Options Substantially all of the stock options granted 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 grant date. 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. RSUs Typically, the RSUs granted under the 2015 Plan and the 2020 Plan vest after one PSUs Substantially all of the PSUs outstanding under the 2015 Plan and the 2020 Plan are either total stockholder return PSUs (“TSR PSUs”) or adjusted EBITDA growth PSUs (“EBITDA Growth 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 or a total return percentage target over a two PSUs represent a target number of shares of the Company’s common stock that may be earned before adjustment based upon the attainment of certain performance conditions. Holders of PSUs do not have voting rights but 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 for accounting purposes, the Company uses a Monte-Carlo simulation model, which simulates future stock prices of the Company as well as the Company’s 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 EBITDA Growth PSUs. The Company will adjust the expense of the EBITDA Growth PSUs based upon its estimate of the number of shares that will ultimately vest at each interim date during the vesting period. During the nine months ended June 30, 2023, the Company reissued the following number of shares from treasury stock: 118,971 shares related to the release of RSUs which vested and 65,168 shares related to stock pay ments. In fiscal 2022, the Company issued 117,390 net shares from treasury stock. The Company withheld a total of 37,525 shares with a fair value of $1.7 million related to the vesting of RSUs and stock payments during the nine months ended June 30, 2023. The fair value of the shares was valued at the closing price at the vesting date and represent the employee tax withholding for the employee’s compensation. The Company recognized tax expense of $0.8 million from its equity compensation awards during the nine months ended June 30, 2023. During the nine months ended June 30, 2023 and 2022, the Company recorded $17.7 million and $13.2 million (includes $0.5 million and $1.5 million paid in cash), respectively, of compensation expense pursuant to its stock-based compensation plans. No amounts have been capitalized. The following table summarizes stock-based compensation activity during the nine months ended June 30, 2023: Stock Options RSUs PSUs (a) Number Weighted-average Number Weighted-average Number Weighted-average Outstanding at September 30, 2022 774,580 $ 60.68 208,735 $ 63.02 331,359 $ 71.51 Granted — — 318,380 37.19 183,974 68.33 Exercised (b) — — — — — — Released from restriction (b) — — (128,573) 61.15 — — Cancelled/expired (102,566) 67.75 (23,536) 45.05 (114,238) 66.61 Outstanding at June 30, 2023 672,014 $ 59.60 375,006 $ 42.88 401,095 $ 71.45 (a) Until the performance period is completed, PSUs are included in the table at the target level at their grant date and at that level represent one share of common stock per PSU. (b) Common stock issued for exercised options and for vested and earned RSUs and PSUs was issued from treasury stock. Accumulated Other Comprehensive Loss (“AOCL”) The Company’s comprehensive income (loss) is comprised of net earnings (loss), net amortization of the unrealized loss of the pension obligation, the change in the unrealized gain in other postretirement benefits, the change in the unrealized gain (loss) on natural gas and foreign currency cash flow hedges and CTA. The components of and changes in AOCL are as follows (in millions): Three Months Ended June 30, 2023 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Other Post-Employment Benefits Foreign Currency Total Beginning balance $ (5.5) $ (2.6) $ 1.3 $ (97.8) $ (104.6) Other comprehensive income before reclassifications (b) 0.4 — — 11.8 12.2 Amounts reclassified from AOCL 1.8 — — — 1.8 Net current period other comprehensive income 2.2 — — 11.8 14.0 Ending balance $ (3.3) $ (2.6) $ 1.3 $ (86.0) $ (90.6) Three Months Ended June 30, 2022 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ 2.1 $ (5.2) $ (101.3) $ (104.4) Other comprehensive loss before reclassifications (b) (3.3) — (20.3) (23.6) Amounts reclassified from AOCL (1.1) 0.1 49.5 48.5 Net current period other comprehensive (loss) income (4.4) 0.1 29.2 24.9 Ending balance $ (2.3) $ (5.1) $ (72.1) $ (79.5) Nine Months Ended June 30, 2023 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Other Post-Employment Benefits Foreign Currency Total Beginning balance $ (1.6) $ (2.7) $ 1.3 $ (112.3) $ (115.3) Other comprehensive (loss) income before reclassifications (b) (3.8) — — 26.3 22.5 Amounts reclassified from AOCL 2.1 0.1 — — 2.2 Net current period other comprehensive (loss) income (1.7) 0.1 — 26.3 24.7 Ending balance $ (3.3) $ (2.6) $ 1.3 $ (86.0) $ (90.6) Nine Months Ended June 30, 2022 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ 3.1 $ (5.4) $ (108.2) $ (110.5) Other comprehensive loss before reclassifications (b) (2.6) — (13.4) (16.0) Amounts reclassified from AOCL (2.8) 0.3 49.5 47.0 Net current period other comprehensive (loss) income (5.4) 0.3 36.1 31.0 Ending balance $ (2.3) $ (5.1) $ (72.1) $ (79.5) (a) With the exception of the CTA, for which no tax effect is recorded, the changes in the components of AOCL presented in the tables above are reflected net of applicable income taxes. (b) The Company recorded foreign exchange loss of $2.0 million and $3.4 million in the three and nine months ended June 30, 2023, respectively, and foreign exchange gain of $2.4 million and $1.7 million in the three and nine months ended June 30, 2022, respectively, in AOCL related to intercompany notes which were deemed to be of a long-term investment nature. The amounts reclassified from AOCL to expense (income) for the three and nine months ended June 30, 2023 and 2022, are shown below (in millions): Amount Reclassified from AOCL Three Months Ended Nine Months Ended Line Item Impacted in the 2023 2022 2023 2022 Loss (gain) on cash flow hedges: Natural gas instruments $ 2.4 $ (1.5) $ 2.9 $ (3.8) Product cost Income tax expense (0.6) 0.4 (0.8) 1.0 Reclassifications, net of income taxes 1.8 (1.1) 2.1 (2.8) Amortization of defined benefit pension: Amortization of loss — 0.1 0.1 0.3 Product cost Income tax benefit — — — — Reclassifications, net of income taxes — 0.1 0.1 0.3 Amortization of other post-employment benefits: Amortization of loss — — — — Product cost Income tax benefit — — — — Reclassifications, net of income taxes — — — — Reclassifications, CTA due to sale of foreign entity — 49.5 — 49.5 Total reclassifications, net of income taxes $ 1.8 $ 48.5 $ 2.2 $ 47.0

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Jun. 30, 2023
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. The Company manages a portion of its commodity pricing risks and foreign currency exchange rate risks by using derivative instruments. From time to time, the Company may enter into foreign exchange contracts to mitigate foreign exchange risk. 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 its Consolidated Balance Sheets. The assets and liabilities recorded as of June 30, 2023 and September 30, 2022 were not material. 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 Consolidated Statements of Operations. Any ineffectiveness related to these instruments accounted for as 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 changes in natural gas prices impact the Company’s operating margin. The Company seeks 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 June 30, 2023, the Company had entered into natural gas derivative instruments to hedge a portion of its natural gas purchase requirements through September 2024. As of June 30, 2023 and September 30, 2022, the Company had agreements in place to hedge forecasted natural gas purchases of 2.9 million a nd 3.8 million MMBtus, respectively. On March 1, 2023, the Company de-designated its natural gas cash flow hedges related to its Ogden, Utah production facility as the Company did not believe these hedges were probable of being highly effective in the second fiscal quarter of 2023. Beginning March 1, 2023, the change in the derivative was and will be recorded in other expense, net in the Consolidated Statements of Operations. Since the transactions are still probable of occurring, previously recognized amounts in AOCL of $0.5 million will remain in AOCL until the underlying forecasted transaction occurs. The Company recognized $2.4 million of expense in other expense, net on the Consolidated Statements of Operations during the nine months ended June 30, 2023. Following the de-designation, these natural gas economic hedging instruments will be recorded at fair value through earnings unless re-designated or until settlement. Substantially all other natural gas derivative instruments held by the Company as of June 30, 2023 and September 30, 2022 qualified and were designated as cash flow hedges. As of June 30, 2023, the Company expects to reclassify from AOCL to earnings during the next twelve months $2.8 million of net losses on derivative instruments related to its natural gas hedges. Refer to Note 15 for the estimated fair value of the Company’s natural gas derivative instruments as of June 30, 2023 and September 30, 2022. The following tables present the fair value of the Company’s derivatives (in millions): Asset Derivatives Liability Derivatives Consolidated Balance Sheet Location June 30, 2023 Consolidated Balance Sheet Location June 30, 2023 Derivatives designated as hedging instruments: Commodity contracts Other current assets $ 1.0 Accrued expenses and other current liabilities $ 3.8 Commodity contracts Other assets — Other noncurrent liabilities 0.5 Total derivatives designated as hedging instruments 1.0 4.3 Derivatives not designated as hedging instruments: Commodity contracts Other current assets — Accrued expenses and other current liabilities 0.1 Total derivatives not designated as hedging instruments — 0.1 Total derivatives (a) $ 1.0 $ 4.4 (a) The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $1.0 million of its commodity contracts that are in receivable positions against its contracts in payable positions. Asset Derivatives Liability Derivatives Consolidated Balance Sheet Location September 30, 2022 Consolidated Balance Sheet Location September 30, 2022 Derivatives designated as hedging instruments: Commodity contracts Other current assets $ 2.7 Accrued expenses and other current liabilities $ 3.3 Commodity contracts Other assets 0.2 Other noncurrent liabilities 0.7 Total derivatives designated as hedging instruments (a) $ 2.9 $ 4.0 (a) The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $2.9 million of its commodity contracts that are in receivable positions against its contracts in payable positions.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements: The Company’s financial instruments are measured and reported at their estimated fair values. 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), except as stated in Note 2 . The Company holds marketable securities associated with its defined contribution and pre-tax savings plans, which are valued based on readily available quoted market prices. The Company utilizes derivative instruments to manage its risk of changes in natural gas prices and foreign exchange rates (see Note 14 ). The fair values of the natural gas and foreign currency derivative instruments 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): June 30, Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified savings plan (a) $ 2.7 $ 2.7 $ — $ — Total Assets $ 2.7 $ 2.7 $ — $ — Liability Class: Derivatives designated as hedging instruments - natural gas instruments, net $ (3.3) $ — $ (3.3) $ — Derivatives not designated as hedging instruments - natural gas instruments, net (0.1) — (0.1) — Liabilities related to non-qualified savings plan (2.7) (2.7) — — Total Liabilities $ (6.1) $ (2.7) $ (3.4) $ — (a) Includes mutual fund investments of approximately 25% in common stock of large-cap U.S. companies, 5% in common stock of small to mid-cap U.S. companies, 10% in international companies, 10% in bond funds, 5% in short-term investments and 45% in blended funds. September 30, Asset Class: Mutual fund investments in a non-qualified savings plan (a) $ 1.8 $ 1.8 $ — $ — Total Assets $ 1.8 $ 1.8 $ — $ — Liability Class: Derivatives – natural gas instruments, net $ (1.1) $ — $ (1.1) $ — Liabilities related to non-qualified savings plan (1.8) (1.8) — — Total Liabilities $ (2.9) $ (1.8) $ (1.1) $ — (a) Includes mutual fund investments of approximately 30% in the common stock of large-cap U.S. companies, 5% in the common stock of small to mid-cap U.S. companies, 10% in the common stock of international companies, 15% in bond funds, 5% in short-term investments and 35% in blended funds. Cash and cash equivalents, receivables (net of allowance 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 non-qualified retirement plan of $2.7 million at June 30, 2023 and $1.8 million at September 30, 2022, are stated at fair value based on quoted market prices. As of September 30, 2022, the estimated fair value of the Company’s fixed-rate 4.875% Senior Notes due July 2024, based on available trading information (Level 2), total ed $235.9 million compared with the aggregate principal amount at maturity of $250.0 million. Proceeds from the 2023 Credit Agreement were used to redeem the 4.875% Senior Notes in May 2023. As of June 30, 2023 and September 30, 2022, the estimated fair value of the Company’s fixed-rate 6.75% Senior Notes due December 2027, based on available trading information (Level 2), totaled $480.7 million and $468.9 million, respectively, compared with the aggregate principal amount at maturity of $500.0 million. The fair value at June 30, 2023 and September 30, 2022 of amounts outstanding under the Company’s term loans and revolving credit facility, based upon available bid information received from the Co mpany’s lender (Level 2), totaled approxima tely $198.0 million and $158.5 million, respectively, compared with the aggregate principal amount at maturity of $200.0 million and $168.4 million, respectively. The Company is currently performing the analysis needed to finalize the fair values of intangible assets, intangible asset useful lives and the final purchase price including the value of contingent consideration. The fair value of the two contingent considerations involve significant inputs not observable in the market and a Monte Carlo simulation, respectively, and are therefore considered Level 3 measurements. Refer to Note 2 for a discussion of fair value as it relates to the Company’s acquisition of Fortress.

Earnings per Share

Earnings per Share	9 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share: The Company calculates earnings per share using the two-class method. 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): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Numerator: Net earnings (loss) from continuing operations $ 39.9 $ (10.7) $ 18.0 $ (31.8) Less: net earnings allocated to participating securities (a) (0.4) (0.1) (0.2) (0.2) Net earnings (loss) from continuing operations available to common stockholders 39.5 (10.8) 17.8 (32.0) Net earnings from discontinued operations available to common stockholders — 2.8 — 14.2 Net earnings (loss) available to common stockholders $ 39.5 $ (8.0) $ 17.8 $ (17.8) Denominator (in thousands): Weighted-average common shares outstanding, shares for basic earnings per share 41,142 34,154 40,663 34,105 Weighted-average awards outstanding (b) — — — 5 Shares for diluted earnings per share 41,142 34,154 40,663 34,110 Basic net earnings (loss) from continuing operations per common share $ 0.96 $ (0.32) $ 0.44 $ (0.94) Basic net earnings from discontinued operations per common share — 0.08 — 0.42 Basic net earnings (loss) per common share $ 0.96 $ (0.23) $ 0.44 $ (0.52) Diluted net earnings (loss) from continuing operations per common share $ 0.96 $ (0.32) $ 0.44 $ (0.94) Diluted net earnings from discontinued operations per common share — 0.08 — 0.42 Diluted net earnings (loss) per common share $ 0.96 $ (0.23) $ 0.44 $ (0.52) (a) Weighted participating securities include RSUs and PSUs that receive non-forfeitable dividends and consist of 453,000 and 469,000 weighted participating securities for the three and nine months ended June 30, 2023, respectively and 372,000 and 423,000 weighted participating securities for the three and nine months ended June 30, 2022, respectively.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Jun. 30, 2023
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions: As discussed in Note 13 , on October 18, 2022, KII, through its KM&T subsidiary, purchased common stock representing an ownership interest of approximately 17% of the outstanding common stock of the Company. As part of the Stock Purchase Agreement, KM&T appointed two members to the Company’s Board of Directors, effective November 13, 2022. In addition, the companies continue to explore value creation opportunities. During the three and nine months ended June 30, 2023, the Company recorded SOP sales of approximately $0.9 million and $2.7 million, respectively, to certain subsidiaries of KII, compared to $1.1 million and $2.5 million during the three and nine months ended June 30, 2022, respectively. As of June 30, 2023 and September 30, 2022, the Company had approximately $0.5 million and $0.4 million, respectively, of Receivables from related parties on its Consolidated Balance Sheets. Additionally, a subsidiary of KII has recently provided engineering services for the Company’s lithium development project for which it capitalized approximately $4.0 million into Property, Plant and Equipment, net, as of June 30, 2023. There were no amounts payable outstanding as of June 30, 2023. On December 20, 2022, March 20, 2023 and June 20, 2023, the Company paid a cash dividend to its stockholders of record at the close of business on December 9, 2022, March 10, 2023 and June 9, 2023, respectively, in the amount of $0.15 per share. KM&T received approximately $1.0 million and $3.0 million in respect to its common shares for the three and nine months ended June 30, 2023, respectively.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pay vs Performance Disclosure
Net earnings (loss)	$ 39.9	$ (7.9)	$ 18	$ (17.6)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Accounting Policies and Basis_2

Accounting Policies and Basis of Presentation (Policies)	9 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of Consolidation	CMI is a holding company with no significant operations other than those of its wholly-owned subsidiaries. The 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.
Basis of Presentation	The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete consolidated financial statements. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements of the Company for the annual period ended September 30, 2022, as filed with the Securities and Exchange Commission (the “SEC”) in its Annual Report on Form 10-K on December 14, 2022. In the opinion of management, all adjustments, consisting of normal recurring adjustments considered necessary for a fair presentation, have been included.
Significant and Recent Accounting Pronouncements	Significant Accounting Policies The Company’s significant accounting policies are detailed in “Note 2 – Summary of Significant Accounting Policies” within Part II, Item 8 of its Annual Report on Form 10-K for the annual period ended September 30, 2022. The Company reports its financial results from discontinued operations and continuing operations separately to recognize the financial impact of disposal transactions apart from ongoing operations. Discontinued operations reporting occurs when a component or a group of components of an entity has been disposed or classified as held for sale and represents a strategic shift that has a major effect on the entity’s operations and financial results. In the Company’s Consolidated Statements of Cash Flows, the cash flows from discontinued operations are not separately classified. Unless otherwise indicated, amounts provided in these Notes pertain to continuing operations. See Note 2 for information on the Company’s business acquisition, Note 3 for information on discontinued operations and Note 12 for information on the Company’s reportable segments. Recent Accounting Pronouncements In October 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2021-08, “Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers.” ASU 2021-08 requires the company acquiring contract assets and contract liabilities obtained in a business combination to recognize and measure them in accordance with Accounting Standards Codification (“ASC”) 606, “Revenue from Contracts with Customers”. Following the acquisition date, the company acquiring the business should record related revenue as if it had originated the contracts. Before the update, contract assets and contract liabilities from acquired contracts were recognized by the acquiring company at fair value on the acquisition date. The amendments are effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted, including in interim periods, for any financial statements that have not yet been issued. The Company early adopted these requirements, effective on January 1, 2023, with no material impact to its consolidated financial statements.
Strategic Evaluation and Plan to Sell Businesses	Strategic Evaluation and Plan to Sell Businesses Following an evaluation of the strategic fit of certain of the Company’s businesses and subsequent restructuring of its former South American Plant Nutrition segment to enable separate sales processes for its chemicals and specialty plant nutrition businesses and equity investment in Fermavi Eletroquímica Ltda. (“Fermavi”), in fiscal 2021 the Company’s Board of Directors approved the plan to sell each of these businesses and the North America micronutrient business (the “Specialty Businesses”) with a goal of reducing the Company’s leverage and enabling increased focus on optimizing the Company’s core businesses.
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. The Company manages a portion of its commodity pricing risks and foreign currency exchange rate risks by using derivative instruments. From time to time, the Company may enter into foreign exchange contracts to mitigate foreign exchange risk. 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 its Consolidated Balance Sheets. The assets and liabilities recorded as of June 30, 2023 and September 30, 2022 were not material. 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 Consolidated Statements of Operations. Any ineffectiveness related to these instruments accounted for as 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.
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 softening, and agricultural and industrial applications. The Company’s Plant Nutrition segment produces and markets SOP in various grades worldwide to distributors and retailers of crop inputs, as well as growers and for industrial uses. The Company operates a records management business utilizing excavated areas of its Winsford salt mine with one other location in London, England and is the owner of Fortress North America, a next-generation fire retardant company. The Company has also entered into a full-service contract with the U.S. Forest Service (“USFS”). This contract is between Fortress and the USFS for the supply and service of long-term fire retardant to USFS designated air tanker bases. 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. The Company also derives revenue from full-service air base fire retardant contracts with customers. Full-service air bases include sales from the supply of fire retardant product and related equipment and service for inspection and loading the fire retardant onto aircraft at designated air tanker bases. The revenue derived from the contract with the USFS is comprised of three performance obligations, namely product sales, providing operations and maintenance personnel services and leasing of specified equipment. For full-service fire-retardant contracts, the Company identifies the fire-retardant product, equipment leases and services as separate units of account. The performance obligation for product sales is satisfied at a point in time when product is shipped and control is transferred to the customer, typically when the product is consumed by the customer. The services and leases represent “stand-ready obligations” and the revenue is recognized straight-line over the service period, which could be intermittent. 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. 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. Payment terms vary by contract and sales to customers are deemed collectible at the time of sale based on customer history, prior credit checks, and controls around customer credit limits. Sales and other taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction, which are collected by the Company from a customer, are excluded from revenue. 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. Therefore, there is no estimated obligation for returns. Standard terms of delivery are generally included in the Company's contracts of sale, order confirmation documents and invoices. Shipping and Handling The Company uses the policy election to account for the shipping and handling activities as activities to fulfill the Company’s promise to transfer goods to the customer, rather than as a performance obligation. Accordingly, the costs of the shipping and handling activities are accrued for at the time of shipment. Deferred Revenue
Earnings per Share	The Company calculates earnings per share using the two-class method. The two-class method requires allocating the Company’s net earnings to both common shares and participating securities.

Business Acquisition (Tables)

Business Acquisition (Tables)	9 Months Ended
	Jun. 30, 2023
Business Combination and Asset Acquisition [Abstract]
Schedule of Business Acquisitions	A summary of the acquisition-date fair value of the consideration transferred is presented in the table below (in millions): May 5, 2023 Cash paid at closing (a) $ 25.4 Fair value of contingent consideration (b) 47.4 Fair value of 45% equity investment 59.6 Total $ 132.4 (a) Gross amount of cash held at Fortress at the time of the acquisition. (b) Contingent consideration includes the fair value of payments to be made upon the achievement of certain performance measures ($22.9 million) and the 10-year cash earn-out ($24.5 million), both described in the Background
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	Based upon the estimated purchase price and the preliminary valuation, the purchase price allocation, which is subject to change based on the Company’s final analysis, is presented in the table below (in millions): Purchase Price Allocation Cash and cash equivalents $ 6.5 Inventories 3.7 Other current assets 0.5 Property, plant and equipment 2.5 Identified intangible assets 75.3 Other noncurrent assets 0.8 Accounts payable (0.3) Accrued expenses and other current liabilities (1.4) Other noncurrent liabilities (1.3) Total identified intangible assets $ 86.3 Goodwill 46.1 Total fair value of business combination $ 132.4
Schedule of Estimated Fair Values And Weighted Average Amortization Period of Identifiable Intangible Assets	The estimated fair values and weighted average amortization period of the identifiable intangible assets are presented in the table below: Estimated Fair Value (in millions) Weighted-Average Amortization Period (in years) Customer relationships $ 56.8 25 years Developed technology 2.4 10 years In-process research and development 15.9 Indefinite Trade name 0.2 5 years Total identified intangible assets $ 75.3

Discontinued Operations (Tables

Discontinued Operations (Tables)	9 Months Ended
	Jun. 30, 2023
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Disposal Groups, Including Discontinued Operations	The following table represents summarized Consolidated Statements of Operations information of discontinued operations (in millions): Three Months Ended Nine Months Ended 2022 2022 Sales $ 6.9 $ 53.6 Shipping and handling cost 0.3 2.8 Product cost 3.1 28.4 Gross profit 3.5 22.4 Selling, general and administrative expenses 0.5 3.5 Operating earnings 3.0 18.9 Interest expense — 0.1 Gain on foreign exchange (0.2) (17.5) Net (gain) loss on adjustment to fair value less estimated costs to sell (1.6) 23.1 Other income, net (0.1) (0.6) Earnings from discontinued operations before income taxes 4.9 13.8 Income tax expense (benefit) 2.1 (0.4) Net earnings from discontinued operations $ 2.8 $ 14.2 The significant components included in the Company’s Consolidated Statements of Cash Flows for discontinued operations are as follows (in millions): Nine Months Ended 2022 Loss on impairment of long-lived assets $ 23.1 Capital expenditures (1.6) Proceeds from sale of businesses 61.2

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Jun. 30, 2023
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories consist of the following (in millions): June 30, September 30, Finished goods $ 272.4 $ 251.6 Raw materials and supplies 67.7 52.8 Total inventories $ 340.1 $ 304.4

Property, Plant and Equipment_2

Property, Plant and Equipment, Net (Tables)	9 Months Ended
	Jun. 30, 2023
Property, Plant and Equipment [Abstract]
Summary of Property, Plant and Equipment, Net	Property, plant and equipment, net, consists of the following (in millions): June 30, September 30, Land, buildings and structures, and leasehold improvements $ 549.1 $ 534.8 Machinery and equipment 1,103.2 1,026.3 Office furniture and equipment 21.8 56.8 Mineral interests 170.6 167.1 Construction in progress 81.0 64.3 1,925.7 1,849.3 Less: accumulated depreciation and depletion (1,108.6) (1,072.7) Property, plant and equipment, net $ 817.1 $ 776.6

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets, Net (Tables)	9 Months Ended
	Jun. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets	Amounts related to the Company’s amortization of intangible assets are as follows (in millions): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Aggregate amortization expense $ 0.8 $ 0.4 $ 1.6 $ 1.2
Summary of Goodwill	Amounts related to the Company’s goodwill are as follows (in millions): June 30, September 30, Plant Nutrition $ 51.3 $ 50.9 Corporate & Other (a) 52.0 5.5 Total $ 103.3 $ 56.4 (a) Includes approximately $46.1 million of goodwill related to the Company’s acquisition of Fortress, as discussed further in Note 2 .

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Summary of Long-Term Debt	Long-term debt consists of the following (in millions): June 30, September 30, 4.875% Senior Notes due July 2024 $ — $ 250.0 Term Loan due January 2025 — 16.9 Revolving Credit Facility due January 2025 — 151.5 6.75% Senior Notes due December 2027 500.0 500.0 Term Loan due May 2028 200.0 — Revolving Credit Facility due May 2028 — — AR Securitization Facility expires June 2025 30.2 37.5 730.2 955.9 Less unamortized debt issuance costs (9.2) (8.3) Total debt 721.0 947.6 Less current portion 5.0 — Long-term debt $ 716.0 $ 947.6

Operating Segments (Tables)

Operating Segments (Tables)	9 Months Ended
	Jun. 30, 2023
Segment Reporting [Abstract]
Summary of Segment Information	Segment information is as follows (in millions): Three Months Ended June 30, 2023 Salt Plant Corporate & Other (a) Total Sales to external customers $ 155.5 $ 47.5 $ 4.6 $ 207.6 Intersegment sales — 2.8 (2.8) — Shipping and handling cost 48.2 5.6 — 53.8 Operating earnings (loss) (b)(c) 21.7 2.5 (24.8) (0.6) Depreciation, depletion and amortization 14.2 8.2 1.9 24.3 Total assets (as of end of period) 995.7 468.2 268.7 1,732.6 Three Months Ended June 30, 2022 Salt Plant Corporate & Other (a) Total Sales to external customers $ 156.2 $ 55.6 $ 2.9 $ 214.7 Intersegment sales — 1.9 (1.9) — Shipping and handling cost 52.2 6.5 — 58.7 Operating earnings (loss) (b) 12.4 10.6 (26.5) (3.5) Depreciation, depletion and amortization 15.3 8.8 2.9 27.0 Total assets (as of end of period) 980.6 441.2 155.2 1,577.0 Nine Months Ended June 30, 2023 Salt Plant Corporate & Other (a) Total Sales to external customers $ 824.1 $ 136.8 $ 10.2 $ 971.1 Intersegment sales — 7.1 (7.1) — Shipping and handling cost 274.9 16.4 — 291.3 Operating earnings (loss) (b)(c) 141.9 12.8 (79.5) 75.2 Depreciation, depletion and amortization 42.9 24.6 5.2 72.7 Nine Months Ended June 30, 2022 Salt Plant Corporate & Other (a) Total Sales to external customers $ 821.4 $ 164.5 $ 8.8 $ 994.7 Intersegment sales — 5.0 (5.0) — Shipping and handling cost 294.0 20.5 — 314.5 Operating earnings (loss) (b) 101.1 24.5 (88.7) 36.9 Depreciation, depletion and amortization 47.7 26.4 9.1 83.2
Summary of Disaggregated Revenue by Product Type	Disaggregated revenue by product type is as follows (in millions): Three Months Ended June 30, 2023 Salt Plant Corporate & Other (a) Total Highway Deicing Salt $ 79.0 $ — $ — $ 79.0 Consumer & Industrial Salt 76.5 — — 76.5 SOP — 50.3 — 50.3 Fire Retardant — — 1.9 1.9 Eliminations & Other — (2.8) 2.7 (0.1) Sales to external customers $ 155.5 $ 47.5 $ 4.6 $ 207.6 Three Months Ended June 30, 2022 Salt Plant Corporate & Other (a) Total Highway Deicing Salt $ 78.5 $ — $ — $ 78.5 Consumer & Industrial Salt 77.7 — — 77.7 SOP — 57.5 — 57.5 Eliminations & Other — (1.9) 2.9 1.0 Sales to external customers $ 156.2 $ 55.6 $ 2.9 $ 214.7 Nine Months Ended June 30, 2023 Salt Plant Corporate & Other (a) Total Highway Deicing Salt $ 543.0 $ — $ — $ 543.0 Consumer & Industrial Salt 281.1 — — 281.1 SOP — 143.9 — 143.9 Fire Retardant — — 1.9 1.9 Eliminations & Other — (7.1) 8.3 1.2 Sales to external customers $ 824.1 $ 136.8 $ 10.2 $ 971.1 Nine Months Ended June 30, 2022 Salt Plant Corporate & Other (a) Total Highway Deicing Salt $ 542.3 $ — $ — $ 542.3 Consumer & Industrial Salt 279.1 — — 279.1 SOP — 169.5 — 169.5 Eliminations & Other — (5.0) 8.8 3.8 Sales to external customers $ 821.4 $ 164.5 $ 8.8 $ 994.7 (a) Corporate and Other includes corporate entities, records management operations, the Fortress fire retardant business, equity method investments, lithium development costs 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, lithium-related expenses, as well as costs for the human resources, information technology, legal and finance functions. (b) Corporate operating results include net reimbursements related to the settled SEC investigation of $0.1 million for the nine months ended June 30, 2023 and executive transition costs of $3.8 million for the nine months ended June 30, 2022. Corporate operating results for the three and nine months ended June 30, 2022 include a contingent loss accrual and costs related to the SEC investigation of $2.8 million and $19.5 million, respectively. Refer to Note 11 for more information regarding the SEC investigation.
Summary of Revenue by Geographic Area	The Company’s revenue by geographic area is as follows (in millions): Three Months Ended Nine Months Ended Revenue 2023 2022 2023 2022 United States (a) $ 164.4 $ 167.8 $ 695.7 $ 716.9 Canada 35.9 36.7 224.5 230.6 United Kingdom 6.6 5.5 43.9 40.9 Other 0.7 4.7 7.0 6.3 Total revenue $ 207.6 $ 214.7 $ 971.1 $ 994.7 (a) United States sales exclude product sold to foreign customers at U.S. ports.

Stockholders' Equity and Equi_2

Stockholders' Equity and Equity Instruments (Tables)	9 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Summary of Stock-Based Compensation Activity	The following table summarizes stock-based compensation activity during the nine months ended June 30, 2023: Stock Options RSUs PSUs (a) Number Weighted-average Number Weighted-average Number Weighted-average Outstanding at September 30, 2022 774,580 $ 60.68 208,735 $ 63.02 331,359 $ 71.51 Granted — — 318,380 37.19 183,974 68.33 Exercised (b) — — — — — — Released from restriction (b) — — (128,573) 61.15 — — Cancelled/expired (102,566) 67.75 (23,536) 45.05 (114,238) 66.61 Outstanding at June 30, 2023 672,014 $ 59.60 375,006 $ 42.88 401,095 $ 71.45 (a) Until the performance period is completed, PSUs are included in the table at the target level at their grant date and at that level represent one share of common stock per PSU. (b) Common stock issued for exercised options and for vested and earned RSUs and PSUs was issued from treasury stock.
Summary of Components and Changes in Accumulated Other Comprehensive Income (Loss)	The components of and changes in AOCL are as follows (in millions): Three Months Ended June 30, 2023 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Other Post-Employment Benefits Foreign Currency Total Beginning balance $ (5.5) $ (2.6) $ 1.3 $ (97.8) $ (104.6) Other comprehensive income before reclassifications (b) 0.4 — — 11.8 12.2 Amounts reclassified from AOCL 1.8 — — — 1.8 Net current period other comprehensive income 2.2 — — 11.8 14.0 Ending balance $ (3.3) $ (2.6) $ 1.3 $ (86.0) $ (90.6) Three Months Ended June 30, 2022 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ 2.1 $ (5.2) $ (101.3) $ (104.4) Other comprehensive loss before reclassifications (b) (3.3) — (20.3) (23.6) Amounts reclassified from AOCL (1.1) 0.1 49.5 48.5 Net current period other comprehensive (loss) income (4.4) 0.1 29.2 24.9 Ending balance $ (2.3) $ (5.1) $ (72.1) $ (79.5) Nine Months Ended June 30, 2023 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Other Post-Employment Benefits Foreign Currency Total Beginning balance $ (1.6) $ (2.7) $ 1.3 $ (112.3) $ (115.3) Other comprehensive (loss) income before reclassifications (b) (3.8) — — 26.3 22.5 Amounts reclassified from AOCL 2.1 0.1 — — 2.2 Net current period other comprehensive (loss) income (1.7) 0.1 — 26.3 24.7 Ending balance $ (3.3) $ (2.6) $ 1.3 $ (86.0) $ (90.6) Nine Months Ended June 30, 2022 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ 3.1 $ (5.4) $ (108.2) $ (110.5) Other comprehensive loss before reclassifications (b) (2.6) — (13.4) (16.0) Amounts reclassified from AOCL (2.8) 0.3 49.5 47.0 Net current period other comprehensive (loss) income (5.4) 0.3 36.1 31.0 Ending balance $ (2.3) $ (5.1) $ (72.1) $ (79.5) (a) With the exception of the CTA, for which no tax effect is recorded, the changes in the components of AOCL presented in the tables above are reflected net of applicable income taxes. (b) The Company recorded foreign exchange loss of $2.0 million and $3.4 million in the three and nine months ended June 30, 2023, respectively, and foreign exchange gain of $2.4 million and $1.7 million in the three and nine months ended June 30, 2022, respectively, in AOCL related to intercompany notes which were deemed to be of a long-term investment nature.
Summary of Reclassifications out of Accumulated Other Comprehensive Income	The amounts reclassified from AOCL to expense (income) for the three and nine months ended June 30, 2023 and 2022, are shown below (in millions): Amount Reclassified from AOCL Three Months Ended Nine Months Ended Line Item Impacted in the 2023 2022 2023 2022 Loss (gain) on cash flow hedges: Natural gas instruments $ 2.4 $ (1.5) $ 2.9 $ (3.8) Product cost Income tax expense (0.6) 0.4 (0.8) 1.0 Reclassifications, net of income taxes 1.8 (1.1) 2.1 (2.8) Amortization of defined benefit pension: Amortization of loss — 0.1 0.1 0.3 Product cost Income tax benefit — — — — Reclassifications, net of income taxes — 0.1 0.1 0.3 Amortization of other post-employment benefits: Amortization of loss — — — — Product cost Income tax benefit — — — — Reclassifications, net of income taxes — — — — Reclassifications, CTA due to sale of foreign entity — 49.5 — 49.5 Total reclassifications, net of income taxes $ 1.8 $ 48.5 $ 2.2 $ 47.0

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Jun. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Fair Value of Hedges	The following tables present the fair value of the Company’s derivatives (in millions): Asset Derivatives Liability Derivatives Consolidated Balance Sheet Location June 30, 2023 Consolidated Balance Sheet Location June 30, 2023 Derivatives designated as hedging instruments: Commodity contracts Other current assets $ 1.0 Accrued expenses and other current liabilities $ 3.8 Commodity contracts Other assets — Other noncurrent liabilities 0.5 Total derivatives designated as hedging instruments 1.0 4.3 Derivatives not designated as hedging instruments: Commodity contracts Other current assets — Accrued expenses and other current liabilities 0.1 Total derivatives not designated as hedging instruments — 0.1 Total derivatives (a) $ 1.0 $ 4.4 (a) The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $1.0 million of its commodity contracts that are in receivable positions against its contracts in payable positions. Asset Derivatives Liability Derivatives Consolidated Balance Sheet Location September 30, 2022 Consolidated Balance Sheet Location September 30, 2022 Derivatives designated as hedging instruments: Commodity contracts Other current assets $ 2.7 Accrued expenses and other current liabilities $ 3.3 Commodity contracts Other assets 0.2 Other noncurrent liabilities 0.7 Total derivatives designated as hedging instruments (a) $ 2.9 $ 4.0 (a) The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $2.9 million of its commodity contracts that are in receivable positions against its contracts in payable positions.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The estimated fair values for each type of instrument are presented below (in millions): June 30, Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified savings plan (a) $ 2.7 $ 2.7 $ — $ — Total Assets $ 2.7 $ 2.7 $ — $ — Liability Class: Derivatives designated as hedging instruments - natural gas instruments, net $ (3.3) $ — $ (3.3) $ — Derivatives not designated as hedging instruments - natural gas instruments, net (0.1) — (0.1) — Liabilities related to non-qualified savings plan (2.7) (2.7) — — Total Liabilities $ (6.1) $ (2.7) $ (3.4) $ — (a) Includes mutual fund investments of approximately 25% in common stock of large-cap U.S. companies, 5% in common stock of small to mid-cap U.S. companies, 10% in international companies, 10% in bond funds, 5% in short-term investments and 45% in blended funds. September 30, Asset Class: Mutual fund investments in a non-qualified savings plan (a) $ 1.8 $ 1.8 $ — $ — Total Assets $ 1.8 $ 1.8 $ — $ — Liability Class: Derivatives – natural gas instruments, net $ (1.1) $ — $ (1.1) $ — Liabilities related to non-qualified savings plan (1.8) (1.8) — — Total Liabilities $ (2.9) $ (1.8) $ (1.1) $ — (a) Includes mutual fund investments of approximately 30% in the common stock of large-cap U.S. companies, 5% in the common stock of small to mid-cap U.S. companies, 10% in the common stock of international companies, 15% in bond funds, 5% in short-term investments and 35% in blended funds.

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Summary of Basic and Diluted Earnings Per Common 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): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Numerator: Net earnings (loss) from continuing operations $ 39.9 $ (10.7) $ 18.0 $ (31.8) Less: net earnings allocated to participating securities (a) (0.4) (0.1) (0.2) (0.2) Net earnings (loss) from continuing operations available to common stockholders 39.5 (10.8) 17.8 (32.0) Net earnings from discontinued operations available to common stockholders — 2.8 — 14.2 Net earnings (loss) available to common stockholders $ 39.5 $ (8.0) $ 17.8 $ (17.8) Denominator (in thousands): Weighted-average common shares outstanding, shares for basic earnings per share 41,142 34,154 40,663 34,105 Weighted-average awards outstanding (b) — — — 5 Shares for diluted earnings per share 41,142 34,154 40,663 34,110 Basic net earnings (loss) from continuing operations per common share $ 0.96 $ (0.32) $ 0.44 $ (0.94) Basic net earnings from discontinued operations per common share — 0.08 — 0.42 Basic net earnings (loss) per common share $ 0.96 $ (0.23) $ 0.44 $ (0.52) Diluted net earnings (loss) from continuing operations per common share $ 0.96 $ (0.32) $ 0.44 $ (0.94) Diluted net earnings from discontinued operations per common share — 0.08 — 0.42 Diluted net earnings (loss) per common share $ 0.96 $ (0.23) $ 0.44 $ (0.52) (a) Weighted participating securities include RSUs and PSUs that receive non-forfeitable dividends and consist of 453,000 and 469,000 weighted participating securities for the three and nine months ended June 30, 2023, respectively and 372,000 and 423,000 weighted participating securities for the three and nine months ended June 30, 2022, respectively.

Business Acquisition - Narrativ

Business Acquisition - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	May 05, 2023	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Sep. 30, 2022
Business Acquisition [Line Items]
Acquisition of business, net of cash acquired				$ 18.9	$ 0
Gain from remeasurement of equity method investment		$ 16.2	$ 0	16.2	$ 0
Goodwill		$ 103.3		$ 103.3			$ 56.4
Fortress
Business Acquisition [Line Items]
Ownership interest in investment	45%					45%
Fortress
Business Acquisition [Line Items]
Remaining interest acquired (as a percent)	55%
Acquisition of business, net of cash acquired	$ 18.9
Cash held by acquiree	6.5
Contingent consideration, liability	$ 28
Performance period	5 years
Contingent consideration period	10 years
Fair value of 45% equity investment	$ 59.6
Gain from remeasurement of equity method investment	16.2
Goodwill	$ 46.1

Business Acquisition - Acquisit

Business Acquisition - Acquisition Date Fair Value of Consideration Transferred (Details) - USD ($) $ in Millions	May 05, 2023	Mar. 31, 2023
Fortress
Business Acquisition [Line Items]
Ownership interest in investment	45%	45%
Fortress
Business Acquisition [Line Items]
Cash paid at closing	$ 25.4
Contingent consideration, liability	47.4
Fair value of 45% equity investment	59.6
Total	132.4
Fair value payment, upon performance measures	$ 22.9
Contingent consideration period	10 years
Fair value payment, cash earnout	$ 24.5

Business Acquisition - Estimate

Business Acquisition - Estimated Purchase Price And Preliminary Valuation (Details) - USD ($) $ in Millions	Jun. 30, 2023	May 05, 2023	Sep. 30, 2022
Business Acquisition [Line Items]
Goodwill	$ 103.3		$ 56.4
Fortress
Business Acquisition [Line Items]
Cash and cash equivalents		$ 6.5
Inventories		3.7
Other current assets		0.5
Property, plant and equipment		2.5
Identified intangible assets		75.3
Other noncurrent assets		0.8
Accounts payable		(0.3)
Accrued expenses and other current liabilities		(1.4)
Other noncurrent liabilities		(1.3)
Total identified intangible assets		86.3
Goodwill		46.1
Total fair value of business combination		$ 132.4

Business Acquisition - Estima_2

Business Acquisition - Estimated Fair Values And Weighted Average Amortization Period (Details) - Fortress $ in Millions	May 05, 2023 USD ($)
In-process research and development
Acquired Indefinite-Lived Intangible Assets [Line Items]
Estimated Fair Value, Indefinite-Lived	$ 15.9
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value, Finite-Lived	$ 56.8
Weighted-Average Amortization Period (in years)	25 years
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value, Finite-Lived	$ 2.4
Weighted-Average Amortization Period (in years)	10 years
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value, Finite-Lived	$ 0.2
Weighted-Average Amortization Period (in years)	5 years

Discontinued Operations - Narra

Discontinued Operations - Narrative (Details) R$ in Millions, $ in Millions			3 Months Ended	9 Months Ended		12 Months Ended
	Jun. 30, 2023 BRL (R$)	Apr. 20, 2022 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2021 BRL (R$)	Apr. 07, 2022 USD ($)	Sep. 30, 2021 BRL (R$)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business				$ 0	$ 61.2
Fermavi
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Potential proceeds from sale of investments						$ 2.9	R$ 45.0
Deferred purchase price | R$	R$ 22.5						R$ 30.0
Deferred proceeds receivable						4.8
Discontinued Operations, Held-for-sale or Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal			$ 1.6		(23.1)
Release of accumulated currency translation adjustment			0.2		17.5
Discontinued Operations, Held-for-sale or Disposed of by Sale | Plant Nutrition South America
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business						318.4
Additional earn out payment								$ 18.5	R$ 88.0
Discontinued Operations, Held-for-sale or Disposed of by Sale | North America Micronutrient Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross proceeds received						$ 56.7
Discontinued Operations, Held-for-sale or Disposed of by Sale | South America Chemicals Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross proceeds received		$ 51.5
Cash on hand		6.4
Selling costs		2.4
Loss recovery on sale			$ 1.6
Gain (loss) on disposal					$ (23.1)
Release of accumulated currency translation adjustment		$ 49.5

Discontinued Operations - Sched

Discontinued Operations - Schedule of Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Net earnings from discontinued operations	$ 0	$ 2.8	$ 0	$ 14.2
Discontinued Operations, Held-for-sale or Disposed of by Sale
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Sales		6.9		53.6
Gross profit		3.5		22.4
Selling, general and administrative expenses		0.5		3.5
Operating earnings		3		18.9
Interest expense		0		0.1
Gain on foreign exchange		(0.2)		(17.5)
Net (gain) loss on adjustment to fair value less estimated costs to sell		(1.6)		23.1
Other income, net		(0.1)		(0.6)
Earnings from discontinued operations before income taxes		4.9		13.8
Income tax expense (benefit)		2.1		(0.4)
Net earnings from discontinued operations		2.8		14.2
Disposal Group, Including Discontinued Operation, Additional Disclosures [Abstract]
Loss on impairment of long-lived assets				23.1
Capital expenditures				(1.6)
Proceeds from sale of businesses				61.2
Discontinued Operations, Held-for-sale or Disposed of by Sale | Shipping and handling cost
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Cost of goods and services sold		0.3		2.8
Discontinued Operations, Held-for-sale or Disposed of by Sale | Product cost
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Cost of goods and services sold		$ 3.1		$ 28.4

Revenues (Details)

Revenues (Details) $ in Millions	9 Months Ended
	Jun. 30, 2023 USD ($)
Revenue from Contract with Customer [Abstract]
Payment terms for delivery	30 days
Deferred revenue	$ 1.2

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Inventory Disclosure [Abstract]
Finished goods	$ 272.4	$ 251.6
Raw materials and supplies	67.7	52.8
Total inventories	$ 340.1	$ 304.4

Property, Plant and Equipment_3

Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Total property plant and equipment	$ 1,925.7	$ 1,849.3
Less: accumulated depreciation and depletion	(1,108.6)	(1,072.7)
Property, plant and equipment, net	817.1	776.6
Land, buildings and structures, and leasehold improvements
Property, Plant and Equipment [Line Items]
Total property plant and equipment	549.1	534.8
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property plant and equipment	1,103.2	1,026.3
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Total property plant and equipment	21.8	56.8
Mineral interests
Property, Plant and Equipment [Line Items]
Total property plant and equipment	170.6	167.1
Construction in progress
Property, Plant and Equipment [Line Items]
Total property plant and equipment	$ 81	$ 64.3

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets, Net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	May 05, 2023	Sep. 30, 2022
Goodwill [Line Items]
Aggregate amortization expense	$ 0.8	$ 0.4	$ 1.6	$ 1.2
Goodwill	103.3		103.3			$ 56.4
Fortress
Goodwill [Line Items]
Goodwill					$ 46.1
Plant Nutrition | Operating Segments
Goodwill [Line Items]
Goodwill	51.3		51.3			50.9
Corporate & Other
Goodwill [Line Items]
Goodwill	$ 52		$ 52			$ 5.5

Equity Method Investments (Deta

Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	May 05, 2023	Sep. 30, 2022
Schedule of Equity Method Investments [Line Items]
Net loss in equity investee	$ (0.8)		$ (1.3)	$ (3.1)	$ (3.4)
Equity method investments	0			0			$ 46.6
Fortress
Schedule of Equity Method Investments [Line Items]
Remaining interest acquired (as a percent)						55%
Fortress
Schedule of Equity Method Investments [Line Items]
Investment in investee		$ 50
Ownership interest in investment		45%				45%
Net loss in equity investee	0.3		1.1	1.8	2.4
Basis difference		$ 27
Equity method investments		$ 44.3					45.8
Other Immaterial Investments
Schedule of Equity Method Investments [Line Items]
Net loss in equity investee	0.5		$ 0.2	1.3	$ 1
Equity method investments	$ 0			$ 0			$ 0.8

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Line Items]
Nondeductible executive compensation	$ 1
U.S. Federal
Income Tax Disclosure [Line Items]
Deferred tax asset valuation allowance recorded	10.8
Foreign Tax Authority
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	73.4	$ 94.1
Foreign Tax Authority | Canadian Tax Authority
Income Tax Disclosure [Line Items]
Total reassessments including interest	180.2
Amount of security posted in the form of a performance bond	146.9
Amount of security posted in the form of cash	37.6	37.6
State and Local | NOL carryforwards expire beginning in 2035
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 3.3	$ 3.2

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Millions	Jun. 30, 2023	May 05, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Long-term debt, gross	$ 730.2		$ 955.9
Less unamortized debt issuance costs	(9.2)		(8.3)
Total debt	721		947.6
Less current portion	5		0
Long-term debt	$ 716		$ 947.6
Senior Notes | 4.875% Senior Notes due July 2024
Debt Instrument [Line Items]
Stated interest rate (as a percent)	4.875%	4.875%	4.875%
Long-term debt, gross	$ 0		$ 250
Senior Notes | 6.75% Senior Notes due December 2027
Debt Instrument [Line Items]
Stated interest rate (as a percent)	6.75%		6.75%
Long-term debt, gross	$ 500		$ 500
Line of Credit | Term Loan due May 2028
Debt Instrument [Line Items]
Long-term debt, gross	200		0
Line of Credit | Revolving Credit Facility due May 2028
Debt Instrument [Line Items]
Long-term debt, gross	0		0
Line of Credit | AR Securitization Facility expires June 2025
Debt Instrument [Line Items]
Long-term debt, gross	30.2		37.5
Line of Credit | Term Loan due January 2025 | 2023 Credit Agreement
Debt Instrument [Line Items]
Long-term debt, gross	0		16.9
Line of Credit | Revolving Credit Facility due January 2025 | 2023 Credit Agreement
Debt Instrument [Line Items]
Long-term debt, gross	$ 0		$ 151.5

Long-Term Debt - Narrative (Det

Long-Term Debt - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	May 05, 2023	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Loss on extinguishment of debt		$ (1.1)	$ 0	$ (1.1)
Weighted average interest rate of debt (as a percent)		7.50%		7.50%
Quarter ending June 30, 2023
Debt Instrument [Line Items]
Consolidated total net leverage ratio		500%
Quarter ending March 31, 2024
Debt Instrument [Line Items]
Consolidated total net leverage ratio		475%
Fiscal quarter ended June 30, 2024
Debt Instrument [Line Items]
Consolidated total net leverage ratio		450%
Line of Credit | 2023 Credit Agreement
Debt Instrument [Line Items]
Aggregate principal amount due at maturity	$ 575
Line of Credit | 2023 Credit Agreement | Minimum
Debt Instrument [Line Items]
Revolving commitment fee	300
Line of Credit | 2023 Credit Agreement | Maximum
Debt Instrument [Line Items]
Revolving commitment fee	375
Line of Credit | Revolving Credit Facility | 2023 Credit Agreement
Debt Instrument [Line Items]
Aggregate principal amount due at maturity	375
Debt deferred financing costs		$ 4.3		$ 4.3
Amount of fee paid		3.9		3.9
Financing expense		0.4		0.4
Line of Credit | Revolving Credit Facility | Revolving Credit Facility due January 2025
Debt Instrument [Line Items]
Maximum unrestricted cash		$ 75		$ 75
Line of Credit | Term Loan due May 2028 | 2023 Credit Agreement
Debt Instrument [Line Items]
Aggregate principal amount due at maturity	$ 200
Senior Notes | 2023 Credit Agreement
Debt Instrument [Line Items]
Spread on rate (as a percent)	0.25%
Conversion ratio	4
Repayments of lines of credit	$ 250
Senior Notes | 4.875% Senior Notes due July 2024
Debt Instrument [Line Items]
Stated interest rate (as a percent)	4.875%	4.875%		4.875%	4.875%
Senior Notes | Term Loan due January 2025
Debt Instrument [Line Items]
Repayments of term loan balance	$ 16.9
Revolving Credit Facility | Term Loan due May 2028
Debt Instrument [Line Items]
Aggregate principal amount due at maturity	$ 200

Commitments and Contingencies (

Commitments and Contingencies (Details) - SEC Investigation - USD ($) $ in Millions	Sep. 29, 2022	Sep. 23, 2022
Loss Contingencies [Line Items]
Loss contingency, damages sought, value		$ 12
Loss contingency, damages paid, value	$ 2
Contingent loss accrual		$ 10

Operating Segments (Details)

Operating Segments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($) segment	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($) segment
Segment Reporting [Abstract]
Number of reportable segments | segment	2	2	2	2
Segment Reporting Information [Abstract]
Sales	$ 207.6	$ 214.7	$ 971.1	$ 994.7
Operating earnings (loss)	(0.6)	(3.5)	75.2	36.9
Depreciation, depletion and amortization	24.3	27	72.7	83.2
Total assets (as of end of period)	1,732.6	1,577	1,732.6	1,577
Costs related to ongoing SEC investigation			(0.1)	19.5
Executive transition costs				3.8
Accrued loss reserve		2.8
Restructuring charges	2.2		5.5
United States
Segment Reporting Information [Abstract]
Sales	164.4	167.8	695.7	716.9
Canada
Segment Reporting Information [Abstract]
Sales	35.9	36.7	224.5	230.6
United Kingdom
Segment Reporting Information [Abstract]
Sales	6.6	5.5	43.9	40.9
Other
Segment Reporting Information [Abstract]
Sales	0.7	4.7	7	6.3
Shipping and handling cost
Segment Reporting Information [Abstract]
Shipping and handling cost	53.8	58.7	291.3	314.5
Highway Deicing Salt
Segment Reporting Information [Abstract]
Sales	79	78.5	543	542.3
Consumer & Industrial Salt
Segment Reporting Information [Abstract]
Sales	76.5	77.7	281.1	279.1
SOP
Segment Reporting Information [Abstract]
Sales	50.3	57.5	143.9	169.5
Fire Retardant
Segment Reporting Information [Abstract]
Sales	1.9		1.9
Eliminations & Other
Segment Reporting Information [Abstract]
Sales	(0.1)	1
Operating Segments | Salt
Segment Reporting Information [Abstract]
Sales	155.5	156.2	824.1	821.4
Operating earnings (loss)	21.7	12.4	141.9	101.1
Depreciation, depletion and amortization	14.2	15.3	42.9	47.7
Total assets (as of end of period)	995.7	980.6	995.7	980.6
Operating Segments | Salt | Shipping and handling cost
Segment Reporting Information [Abstract]
Shipping and handling cost	48.2	52.2	274.9	294
Operating Segments | Salt | Highway Deicing Salt
Segment Reporting Information [Abstract]
Sales	79	78.5	543	542.3
Operating Segments | Salt | Consumer & Industrial Salt
Segment Reporting Information [Abstract]
Sales	76.5	77.7	281.1	279.1
Operating Segments | Salt | SOP
Segment Reporting Information [Abstract]
Sales	0	0	0	0
Operating Segments | Salt | Fire Retardant
Segment Reporting Information [Abstract]
Sales	0		0
Operating Segments | Salt | Eliminations & Other
Segment Reporting Information [Abstract]
Sales	0	0	0	0
Operating Segments | Plant Nutrition
Segment Reporting Information [Abstract]
Sales	47.5	55.6	136.8	164.5
Operating earnings (loss)	2.5	10.6	12.8	24.5
Depreciation, depletion and amortization	8.2	8.8	24.6	26.4
Total assets (as of end of period)	468.2	441.2	468.2	441.2
Operating Segments | Plant Nutrition | Shipping and handling cost
Segment Reporting Information [Abstract]
Shipping and handling cost	5.6	6.5	16.4	20.5
Operating Segments | Plant Nutrition | Highway Deicing Salt
Segment Reporting Information [Abstract]
Sales	0	0	0	0
Operating Segments | Plant Nutrition | Consumer & Industrial Salt
Segment Reporting Information [Abstract]
Sales	0	0	0	0
Operating Segments | Plant Nutrition | SOP
Segment Reporting Information [Abstract]
Sales	50.3	57.5	143.9	169.5
Operating Segments | Plant Nutrition | Fire Retardant
Segment Reporting Information [Abstract]
Sales	0		0
Operating Segments | Plant Nutrition | Eliminations & Other
Segment Reporting Information [Abstract]
Sales	(2.8)	(1.9)	(7.1)	(5)
Corporate & Other
Segment Reporting Information [Abstract]
Sales	4.6	2.9	10.2	8.8
Operating earnings (loss)	(24.8)	(26.5)	(79.5)	(88.7)
Depreciation, depletion and amortization	1.9	2.9	5.2	9.1
Total assets (as of end of period)	268.7	155.2	268.7	155.2
Corporate & Other | Shipping and handling cost
Segment Reporting Information [Abstract]
Shipping and handling cost	0	0	0	0
Corporate & Other | Highway Deicing Salt
Segment Reporting Information [Abstract]
Sales	0	0	0	0
Corporate & Other | Consumer & Industrial Salt
Segment Reporting Information [Abstract]
Sales	0	0	0	0
Corporate & Other | SOP
Segment Reporting Information [Abstract]
Sales	0	0	0	0
Corporate & Other | Fire Retardant
Segment Reporting Information [Abstract]
Sales	1.9		1.9
Corporate & Other | Eliminations & Other
Segment Reporting Information [Abstract]
Sales	2.7	2.9	8.3	8.8
Intersegment Eliminations
Segment Reporting Information [Abstract]
Sales	(2.8)	(1.9)	(7.1)	(5)
Intersegment Eliminations | Eliminations & Other
Segment Reporting Information [Abstract]
Sales			1.2	3.8
Intersegment Eliminations | Salt
Segment Reporting Information [Abstract]
Sales	0	0	0	0
Intersegment Eliminations | Plant Nutrition
Segment Reporting Information [Abstract]
Sales	$ 2.8	$ 1.9	$ 7.1	$ 5

Stockholders' Equity and Equi_3

Stockholders' Equity and Equity Instruments - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions			1 Months Ended	9 Months Ended		12 Months Ended
	Oct. 18, 2022	Sep. 14, 2022	Feb. 28, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2022	May 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Treasury stock reissued (in shares)						117,390
Tax deficiency from equity compensation awards recorded as an increase to income tax expense				$ 0.8
Compensation expense recorded during period pursuant to stock-based compensation plans				17.7	$ 13.2
Compensation expense to be paid in cash				$ 0.5	$ 1.5
Koch Minerals & Trading, LLC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ownership by noncontrolling interest (as a percent)	17%
Private Placement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued		6,830,700
Sale of stock, price (in dollars per share)		$ 36.87
Net proceeds		$ 240.7
Advancement of development project	$ 200
Portion to reduce debt	$ 40.7
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
Options 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
Reissued shares of treasury stock (in shares)				118,971
TSR PSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period of PSUs				2 years
Percentage of shares earned				0%
TSR PSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period of PSUs				3 years
Percentage of shares earned				300%
EBITDA Growth PSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned				0%
EBITDA Growth PSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned				300%
Stock Payments
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reissued shares of treasury stock (in shares)				65,168
Equity Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares withheld related to vesting of RSUs and PSUs (in shares)				37,525
Fair value of stock withheld related to vesting of RSUs and PSUs				$ 1.7
2015 Incentive Award Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period				1 year
2020 Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares)							2,977,933
Shares authorized for issuance (in shares)			750,000
2020 Incentive Award Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period				3 years

Stockholders' Equity and Equi_4

Stockholders' Equity and Equity Instruments - Stock-Based Compensation Activity (Details)	9 Months Ended
	Jun. 30, 2023 $ / shares shares
Stock Options
Number
Outstanding at beginning of period (in shares)	774,580
Granted (in shares)	0
Exercised (in shares)	0
Released from restriction (in shares)	0
Cancelled/expired (in shares)	(102,566)
Outstanding at end of period (in shares)	672,014
Weighted-average exercise price
Weighted-average exercise price at beginning of period (in dollars per share) | $ / shares	$ 60.68
Weighted-average exercise price, granted (in dollars per share) | $ / shares	0
Weighted-average exercise price, exercised (in dollars per share) | $ / shares	0
Weighted-average exercise price, released from restriction (in dollars per share) | $ / shares	0
Weighted-average exercise price, cancelled/expired (in dollars per share) | $ / shares	67.75
Weighted-average exercise price at end of period (in dollars per share) | $ / shares	$ 59.60
RSUs
Number
Outstanding at beginning of period (in shares)	208,735
Granted (in shares)	318,380
Exercised (in shares)	0
Released from restriction (in shares)	(128,573)
Cancelled/expired (in shares)	(23,536)
Outstanding at end of period (in shares)	375,006
Weighted-average fair value
Weighted-average fair value at beginning of period (in dollars per share) | $ / shares	$ 63.02
Weighted-average fair value, granted (in dollars per share) | $ / shares	37.19
Weighted-average fair value, exercised (in dollars per share) | $ / shares	0
Weighted-average fair value, released from restriction (in dollars per share) | $ / shares	61.15
Weighted-average fair value, cancelled/expired (in dollars per share) | $ / shares	45.05
Weighted-average fair value at end of period (in dollars per share) | $ / shares	$ 42.88
PSUs
Number
Outstanding at beginning of period (in shares)	331,359
Granted (in shares)	183,974
Exercised (in shares)	0
Released from restriction (in shares)	0
Cancelled/expired (in shares)	(114,238)
Outstanding at end of period (in shares)	401,095
Weighted-average fair value
Weighted-average fair value at beginning of period (in dollars per share) | $ / shares	$ 71.51
Weighted-average fair value, granted (in dollars per share) | $ / shares	68.33
Weighted-average fair value, exercised (in dollars per share) | $ / shares	0
Weighted-average fair value, released from restriction (in dollars per share) | $ / shares	0
Weighted-average fair value, cancelled/expired (in dollars per share) | $ / shares	66.61
Weighted-average fair value at end of period (in dollars per share) | $ / shares	$ 71.45
PSU at grant date (in shares per unit)	1

Stockholders' Equity and Equi_5

Stockholders' Equity and Equity Instruments - Components and Changes In AOCL (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 485.4	$ 286.5	$ 256.4	$ 293.1
Other comprehensive (loss) income before reclassifications	12.2	(23.6)	22.5	(16)
Amounts reclassified from AOCL	1.8	48.5	2.2	47
Net current period other comprehensive (loss) income	14	24.9	24.7	31
Ending balance	536.7	300.9	536.7	300.9
Gains (loss) on foreign exchange of intercompany notes of long-term nature	(2)	2.4	(3.4)	1.7
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(104.6)	(104.4)	(115.3)	(110.5)
Ending balance	(90.6)	(79.5)	(90.6)	(79.5)
Gains and (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(5.5)	2.1	(1.6)	3.1
Other comprehensive (loss) income before reclassifications	0.4	(3.3)	(3.8)	(2.6)
Amounts reclassified from AOCL	1.8	(1.1)	2.1	(2.8)
Net current period other comprehensive (loss) income	2.2	(4.4)	(1.7)	(5.4)
Ending balance	(3.3)	(2.3)	(3.3)	(2.3)
Benefit Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(5.2)		(5.4)
Other comprehensive (loss) income before reclassifications		0		0
Amounts reclassified from AOCL		0.1		0.3
Net current period other comprehensive (loss) income		0.1		0.3
Ending balance		(5.1)		(5.1)
Benefit Plans | Defined Benefit Pension
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(2.6)		(2.7)
Other comprehensive (loss) income before reclassifications	0		0
Amounts reclassified from AOCL	0		0.1
Net current period other comprehensive (loss) income	0		0.1
Ending balance	(2.6)		(2.6)
Benefit Plans | Other Post-Employment Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	1.3		1.3
Other comprehensive (loss) income before reclassifications	0		0
Amounts reclassified from AOCL	0		0
Net current period other comprehensive (loss) income	0		0
Ending balance	1.3		1.3
Foreign Currency
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(97.8)	(101.3)	(112.3)	(108.2)
Other comprehensive (loss) income before reclassifications	11.8	(20.3)	26.3	(13.4)
Amounts reclassified from AOCL	0	49.5	0	49.5
Net current period other comprehensive (loss) income	11.8	29.2	26.3	36.1
Ending balance	$ (86)	$ (72.1)	$ (86)	$ (72.1)

Stockholders' Equity and Equi_6

Stockholders' Equity and Equity Instruments - Reclassifications From AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax benefit (expense)	$ (42.7)	$ (1.1)	$ 24.3	$ 28.1
Net earnings (loss)	39.9	(7.9)	18	(17.6)
Product cost
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product cost	(119.2)	(122.1)	(490)	(521.8)
Amount Reclassified from AOCL
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net earnings (loss)	1.8	48.5	2.2	47
Amount Reclassified from AOCL | Loss (gain) on cash flow hedges:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax benefit (expense)	(0.6)	0.4	(0.8)	1
Net earnings (loss)	1.8	(1.1)	2.1	(2.8)
Amount Reclassified from AOCL | Loss (gain) on cash flow hedges: | Natural gas instruments | Product cost
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product cost	2.4	(1.5)	2.9	(3.8)
Amount Reclassified from AOCL | Amortization of defined benefit pension:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax benefit (expense)	0	0	0	0
Net earnings (loss)	0	0.1	0.1	0.3
Amount Reclassified from AOCL | Amortization of defined benefit pension: | Product cost
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product cost	0	0.1	0.1	0.3
Amount Reclassified from AOCL | Amortization of other post-employment benefits:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax benefit (expense)	0	0	0	0
Net earnings (loss)	0	0	0	0
Amount Reclassified from AOCL | Amortization of other post-employment benefits: | Product cost
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product cost	0	0	0	0
Amount Reclassified from AOCL | Reclassifications, CTA due to sale of foreign entity
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net earnings (loss)	$ 0	$ 49.5	$ 0	$ 49.5

Derivative Financial Instrume_3

Derivative Financial Instruments - Narrative (Details) MMBTU in Millions, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) MMBTU	Jun. 30, 2022 USD ($)	Sep. 30, 2022 USD ($) MMBTU	Mar. 01, 2023 USD ($)
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 4.4		$ 4.4
Expense recognized	(2.7)	$ 0.1	(3.7)	$ 0
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Liability Derivatives	4.3		4.3		$ 4
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 0.1		$ 0.1
Natural gas instruments
Derivatives, Fair Value [Line Items]
Notional amount (in MMBtus) | MMBTU			2.9		3.8
Expense recognized			$ 2.4
Net gains to be reclassified from accumulated other comprehensive loss to earnings during the next 12 months			$ 2.8
Natural gas instruments | Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Percent of forecasted usage to be hedged	90%		90%
Maximum period which the company hedges in advance of forecasted purchase			36 months
Natural gas instruments | Derivatives Designated as Hedging Instruments | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 3.8		$ 3.8		$ 3.3
Natural gas instruments | Not Designated as Hedging Instrument | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 0.1		$ 0.1			$ 0.5

Derivative Financial Instrume_4

Derivative Financial Instruments - Summary of Fair Value of Hedged Items (Details) - USD ($) $ in Millions	Jun. 30, 2023	Mar. 01, 2023	Sep. 30, 2022
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 1
Liability Derivatives	4.4
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives	1		$ 2.9
Liability Derivatives	4.3		4
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Asset Derivatives	0
Liability Derivatives	0.1
Natural gas instruments
Derivatives, Fair Value [Line Items]
Netting of contracts in a receivable position against contracts in payable position	1		2.9
Other current assets | Natural gas instruments | Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives	1		2.7
Other current assets | Natural gas instruments | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Asset Derivatives	0
Other assets | Natural gas instruments | Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives	0		0.2
Accrued expenses and other current liabilities | Natural gas instruments | Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Liability Derivatives	3.8		3.3
Accrued expenses and other current liabilities | Natural gas instruments | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Liability Derivatives	0.1	$ 0.5
Other noncurrent liabilities | Natural gas instruments | Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 0.5		$ 0.7

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Estimated Fair Values (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Common Stock, Large Cap US Companies | Mutual Fund Investments, Concentration Risk | Investment Benchmark
Liability Class:
Investment concentration risk (as a percent)	25%	30%
Common Stock of Small to Mid Cap US Companies | Mutual Fund Investments, Concentration Risk | Investment Benchmark
Liability Class:
Investment concentration risk (as a percent)	5%	5%
Common Stock, International Companies | Mutual Fund Investments, Concentration Risk | Investment Benchmark
Liability Class:
Investment concentration risk (as a percent)	10%	10%
Bond Funds | Mutual Fund Investments, Concentration Risk | Investment Benchmark
Liability Class:
Investment concentration risk (as a percent)	10%	15%
Short-Term Investments | Mutual Fund Investments, Concentration Risk | Investment Benchmark
Liability Class:
Investment concentration risk (as a percent)	5%	5%
Blended Funds | Mutual Fund Investments, Concentration Risk | Investment Benchmark
Liability Class:
Investment concentration risk (as a percent)	45%	35%
Fair Value, Measurements, Recurring
Asset Class:
Mutual fund investments in a non-qualified savings plan	$ 2.7	$ 1.8
Total Assets	2.7	1.8
Liability Class:
Derivatives – natural gas instruments, net		(1.1)
Liabilities related to non-qualified savings plan	(2.7)	(1.8)
Total Liabilities	(6.1)	(2.9)
Fair Value, Measurements, Recurring | Derivatives Designated as Hedging Instruments
Liability Class:
Derivatives – natural gas instruments, net	(3.3)
Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument
Liability Class:
Derivatives – natural gas instruments, net	(0.1)
Fair Value, Measurements, Recurring | Level One
Asset Class:
Mutual fund investments in a non-qualified savings plan	2.7	1.8
Total Assets	2.7	1.8
Liability Class:
Derivatives – natural gas instruments, net		0
Liabilities related to non-qualified savings plan	(2.7)	(1.8)
Total Liabilities	(2.7)	(1.8)
Fair Value, Measurements, Recurring | Level One | Derivatives Designated as Hedging Instruments
Liability Class:
Derivatives – natural gas instruments, net	0
Fair Value, Measurements, Recurring | Level One | Not Designated as Hedging Instrument
Liability Class:
Derivatives – natural gas instruments, net	0
Fair Value, Measurements, Recurring | Level Two
Asset Class:
Mutual fund investments in a non-qualified savings plan	0	0
Total Assets	0	0
Liability Class:
Derivatives – natural gas instruments, net		(1.1)
Liabilities related to non-qualified savings plan	0	0
Total Liabilities	(3.4)	(1.1)
Fair Value, Measurements, Recurring | Level Two | Derivatives Designated as Hedging Instruments
Liability Class:
Derivatives – natural gas instruments, net	(3.3)
Fair Value, Measurements, Recurring | Level Two | Not Designated as Hedging Instrument
Liability Class:
Derivatives – natural gas instruments, net	(0.1)
Fair Value, Measurements, Recurring | Level Three
Asset Class:
Mutual fund investments in a non-qualified savings plan	0	0
Total Assets	0	0
Liability Class:
Derivatives – natural gas instruments, net		0
Liabilities related to non-qualified savings plan	0	0
Total Liabilities	0	$ 0
Fair Value, Measurements, Recurring | Level Three | Derivatives Designated as Hedging Instruments
Liability Class:
Derivatives – natural gas instruments, net	0
Fair Value, Measurements, Recurring | Level Three | Not Designated as Hedging Instrument
Liability Class:
Derivatives – natural gas instruments, net	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	Jun. 30, 2023	May 05, 2023	Sep. 30, 2022
Senior Notes | 4.875% Senior Notes due July 2024
Debt Instrument [Line Items]
Stated interest rate (as a percent)	4.875%	4.875%	4.875%
Fair value of senior notes			$ 235,900,000
Aggregate principal amount due at maturity			$ 250,000,000
Senior Notes | 6.75% Senior Notes due December 2027
Debt Instrument [Line Items]
Stated interest rate (as a percent)	6.75%		6.75%
Fair value of senior notes	$ 480,700,000		$ 468,900,000
Senior Notes due 2027
Debt Instrument [Line Items]
Debt fair value amount	500,000,000		500,000,000
Term Loan
Debt Instrument [Line Items]
Aggregate principal amount due at maturity	200,000,000		168,400,000
Fair value of credit agreement debt	198,000,000		158,500,000
Fair Value, Measurements, Recurring
Debt Instrument [Line Items]
Mutual fund investments in a non-qualified savings plan	$ 2,700,000		$ 1,800,000

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Numerator:
Net earnings (loss) from continuing operations	$ 39.9	$ (10.7)	$ 18	$ (31.8)
Less: net earnings allocated to participating securities	(0.4)	(0.1)	(0.2)	(0.2)
Net earnings (loss) from continuing operations available to common stockholders	39.5	(10.8)	17.8	(32)
Net earnings from discontinued operations available to common stockholders	0	2.8	0	14.2
Net earnings (loss) available to common stockholders	$ 39.5	$ (8)	$ 17.8	$ (17.8)
Denominator (in thousands):
Weighted-average common shares outstanding, shares for basic earnings per share (in shares)	41,142	34,154	40,663	34,105
Weighted-average awards outstanding (in shares)	0	0	0	5
Shares for diluted earnings per share (in shares)	41,142	34,154	40,663	34,110
Basic net earnings (loss) from continuing operations per common share (in dollars per share)	$ 0.96	$ (0.32)	$ 0.44	$ (0.94)
Basic net earnings from discontinued operations per common share (in dollars per share)	0	0.08	0	0.42
Basic net earnings (loss) per common share (in dollars per share)	0.96	(0.23)	0.44	(0.52)
Diluted net earnings (loss) from continuing operations per common share (in dollars per share)	0.96	(0.32)	0.44	(0.94)
Diluted net earnings from discontinued operations per common share (in dollars per share)	0	0.08	0	0.42
Diluted net earnings (loss) per common share (in dollars per share)	$ 0.96	$ (0.23)	$ 0.44	$ (0.52)
Participating securities (in shares)	453,000	372,000	469,000	423,000
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive weighted options outstanding (in shares)	1,151,000	1,051,000	1,267,000	1,107,000

Related Party Disclosures (Deta

Related Party Disclosures (Details) $ / shares in Units, $ in Millions				3 Months Ended		9 Months Ended
	Jun. 20, 2023 $ / shares	Mar. 20, 2023 $ / shares	Dec. 20, 2022 $ / shares	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Nov. 13, 2022 board_member	Oct. 18, 2022	Sep. 30, 2022 USD ($)
Related Party Transaction [Line Items]
Number of board members | board_member								2
Revenue				$ 207.6	$ 214.7	$ 971.1	$ 994.7
Receivables				95.8		95.8				$ 167.2
Accounts payable				96.9		96.9				114.7
Cash dividend declared (in dollars per share) | $ / shares	$ 0.15	$ 0.15	$ 0.15
Payments of dividends						18.7	15.7
Koch Minerals & Trading, LLC
Related Party Transaction [Line Items]
Revenue				0.9	$ 1.1	2.7	$ 2.5
Receivables				0.5		0.5				$ 0.4
Capitalized cost				4		4
Accounts payable				0		0
Payments of dividends				$ 1		$ 3
Koch Minerals & Trading, LLC
Related Party Transaction [Line Items]
Ownership by noncontrolling interest (as a percent)									17%